NPDUIS - PMPRB CEPMB · commensurate with the generic price discount. Methodology is report employs...

Patented Conseil d’examenMedicine Prices du prix des médicamentsReview Board brevetés

The Impact of Generic Entry on the Utilization of the IngredientSeptember 2011

NPDUISNational Prescription Drug Utilization Information System

Published by the Patented Medicine Prices Review Board

e Impact of Generic Entry on the Utilization of the Ingredientis available in electronic format at www.pmprb-cepmb.gc.ca

Une traduction de ce document est également disponible en française sous le titre :« Incidence de l’arrivée sur le marché des médicaments génériques sur l’utilisation de l’ingrédient ».

e Patented Medicine Prices Review BoardStandard Life CentreBox L40333 Laurier Avenue WestSuite 1400Ottawa, ON K1P 1C1Tel.: 1-877-861-2350

613-952-7360Fax: 613-952-7626TTY 613-957-4373Email: [email protected]: www.pmprb-cepmb.gc.ca

ISBN: 978-1-100-19411-0Cat. No.: H82-10/2011E-PDF

The statements and opinions expressed in this NPDUIS report do not represent the official position of the PMPRB. NPDUIS is a research initiative that operates independently of the regulatory activities of the Board.

About the PMPRB

e Patented Medicine Prices Review Board (PMPRB) is an independent quasi-judicial body established byParliament in 1987.

e PMPRB has a dual role: to ensure that prices at which patentees sell their patented medicines in Canadaare not excessive; and to report on pharmaceutical trends of all medicines and R&D spending by patentees.

e PMPRB reports annually to Parliament, through the Minister of Health, on its activities, onpharmaceutical trends relating to all medicines, and on R&D spending by patentees.

The NPDUIS Initiative

e National Prescription Drug Utilization Information System (NPDUIS) provides critical analyses of drugprice, utilization, and cost trends in Canada to support drug plan policy decision-making for participatingfederal, provincial, and territorial governments.

e NPDUIS initiative is a partnership between the PMPRB and the Canadian Institute for HealthInformation. It was established in 2001 by the federal/provincial/territorial Ministers of Health.

Acknowledgements

is report was prepared by the Patented Medicine Prices Review Board (PMPRB) under the provisions of theNational Prescription Drug Utilization Information System (NPDUIS).

e PMPRB recognizes the contributions of the members of the NPDUIS Steering Committee for theirexpert oversight and guidance in the preparation of this report.

iThe Impact of Generic Entry on the Utilization of the Ingredient – September 2011

Introduction Over the past decade a number of blockbuster drugshave lost their patent protection, allowing for theintroduction of lower cost generic versions on thepharmaceutical market. Because of public drug planpolicies governing the interchangeability betweenbrand and generic versions of a drug product, a near-complete generic substitution often occurs within thefirst few months of a generic drug product’s availability.While the effect of generic price discounts is wellunderstood, the purpose of this study is to identifythe impact that generic entry has on the utilization of the ingredient itself.

is study identifies the impact of generic entry onseven top-selling drugs that have lost their patentprotection in recent years. e analysis incorporatesdata from eight public drug plans to determinewhether the ingredient continues to be utilized to thesame extent, thus allowing for cost savings levelscommensurate with the generic price discount.

Methodologyis report employs a case-study approach to analyzethe impact of generic competition on the utilizationof the ingredient. It assesses the immediate and long-term impact of generic entry on a target list of seventop-selling drugs with various therapeutic profiles.e immediate impact analysis incorporates monthlytrends in utilization over the 12-month period priorto and post generic entry. e long-term impactanalysis assesses fiscal-year trends in utilization overthe three years prior to and post generic entry.

e utilization reported in this study encompassesboth the brand name and generic utilization at theingredient level. An analysis of the trends inutilization, in terms of the volume of claims and theirmarket share, identifies any break in the patternfollowing generic entry. A projection of theutilization trends in the absence of genericcompetition compares extrapolated data to the actualutilization rates.

General FindingsGenerally, the utilization of the ingredient was notimpacted by generic entry. Post generic entry, theutilization of the ingredient followed the trendestablished by the brand name product prior togeneric entry. In most cases, any short- or long-termchanges in utilization could not be directly and solelyattributable to generic entry:

• In the case of gabapentin, pravastatin, risperidoneand citalopram, the number of claims and marketshare following generic entry continued the trendestablished by the brand name under marketexclusivity.

• In the case of omeprazole, changes in utilizationoccurred in almost all of the jurisdictionsfollowing generic entry; however, this was likelythe result of drug plan policy changes.

• In the case of simvastatin, the decline in utilizationcorresponded to both the introduction of a genericversion and the launch of a new competitor drugin the same class. us, it is difficult to attributethe change to one specific event.

Paroxetine was the only exception. e utilization ofthe antidepressant dropped significantly across alljurisdictions approximately one year after genericentry. Around this time, Health Canada issuedwarnings related to the possible negative side effectsof using any of the drugs in the same class. However,none of the other ingredients were affected to thesame extent as paroxetine, including citalopram,which also lost its patent protection and faced genericcompetition during the same time period.

ii The Impact of Generic Entry on the Utilization of the Ingredient – September 2011

Executive Summary

Implications for Public Drug Planse main implication of the findings is that the onlysavings that can be expected from generic entry arethose related to the generic price discount.Nevertheless, it should be recognized that over timethese savings may be eroded by utilization growth;growth that would occur in the presence or absenceof generic competition.

LimitationsWhile this study was conducted on a small sample oftop-selling drug products utilized in public drugplans, it covers various therapeutic profiles, marketconditions (price differential, number and type ofcompetitors) and formulary statuses. erefore, thefindings should be applicable to other drug productsfacing generic competition.

Nevertheless, the findings may not apply to all drugproducts, as utilization can be affected by a numberof factors, including reimbursement policies, pricing,demographics, physician prescribing practices, andthe incidence of a particular condition. In addition,public drug plan data represents only one componentof the overall pharmaceutical market. Results maydiffer for drugs reimbursed by private insurers ordrugs paid for out-of-pocket by patients.

is analysis is limited to the impact of generic entryon the utilization of the ingredient in public drugplans and does not assess the cost implications of thegeneric entry impact on drug plan expenditures.

iiiThe Impact of Generic Entry on the Utilization of the Ingredient – September 2011

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

1 Omeprazole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

2 Risperidone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

3 Pravastatin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

4 Simvastatin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

5 Paroxetine and Citalopram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

6 Gabapentin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

General Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

iv The Impact of Generic Entry on the Utilization of the Ingredient – September 2011

Table of Contents

Over the past decade a number of top-sellingprescription drug products used to treat high-prevalenceconditions have lost their patent protection. esubsequent introduction of lower-priced generic drugproducts1 has translated into savings for public drugplans, private insurers and patients.

As a result of public drug plan policies governing theinterchangeability between brand name and genericversions of a drug, a near-complete generic substitutionoften occurs shortly after the introduction of thegeneric. While the cost savings resulting from such asubstitution are well understood, the purpose of thisstudy is to identify the impact of generic entry on theutilization of the ingredient. Two hypotheses areproposed: on the one hand, the availability of a drugproduct at a lower price may lead to increasedutilization; on the other hand, diminished advertisingmay decrease the utilization of a particular drug, asbrand-name manufacturers generally cease toadvertise once they lose market exclusivity and beginthe promotion of a substitute product.

Given the number of blockbuster drugs that haveeither lost patent protection in recent years or areexpected to come to the end of their patent life in thenear future, the impact of generic competition on theutilization of the ingredient (brand and generic) is ofinterest to policy makers and drug plan managers.

is study identifies the impact of generic entry onthe utilization of the ingredient in the case of seventop-selling drugs that have lost patent protection inrecent years. e analysis was conducted usingavailable data for eight public drug plans. e focusof the study is on utilization at the ingredient level,encompassing both the brand name and genericversions of each drug product. e ingredient’sutilization is analyzed in the context of its relevantmarket, which includes medications prescribed forthe same indication.

e next section of this report details the methodologyemployed. e following analysis section is organizedin six subsections corresponding to each of the drugsreviewed. Subsection 5 analyzes two drugs conjointly:paroxetine and citalopram. ese drugs share theanti-depressants market, and generic versions of both were released within months of each other. Each subsection includes a market profile and ashort- and a long-term analysis. e general findingsare provided in the final section of the report.

is study is restricted to the utilization of theingredient and does not make any assessment on the cost implications of generic entry on drug plan expenditures.

1The Impact of Generic Entry on the Utilization of the Ingredient – September 2011

Introduction

1 Generic drug in this study refers to any drug for which the trade name contains the name of the active ingredient, irrespective of whether the drug is a licensed generic or has any patent protection.

Target Drugsis study focuses on public drug plan data using a case-study approach. A target list of seven drugswith various therapeutic profiles was established inconsultation with the NPDUIS Steering Committee(see Methodology Table—Target Drug List). edrugs were selected from top-selling single-sourcedrugs with first time generics entering the marketbetween 2000 and 2006.

Short- versus Long-Term ImpactAssessmentAn analysis of both the short- and long-term impactof generic entry was conducted, providing a completeimpact assessment.

e short-term impact of generic entry was assessedby analyzing monthly trends in utilization. Forconsistency, the reporting was based on the 12-monthperiod prior to and post generic entry. e analysiswas conducted on six public drug plans based on theavailability of claims-level data in the CanadianInstitute for Health Information (CIHI) NPDUISdatabase: Alberta, Saskatchewan, Manitoba, NewBrunswick, Nova Scotia and Prince Edward Island.Claims-level data refers to data in which each recordis related to a single claim made to an insurer forreimbursement by an individual.

e long-term impact was assessed by analyzingfiscal-year trends in utilization. For consistency, thereporting was based on the three year period prior to and post generic entry. In addition to the dataavailable from the six jurisdictions included in theshort-term analysis, DIN-level2 data provided byOntario and British Columbia were used to estimatelong-term impacts.

Data SourcesPrice and utilization data for this study came fromtwo sources: the NPDUIS claims-level databasehoused within CIHI; and the NPDUIS aggregateDIN-level database housed within the PMPRB. Both databases contain administrative data fromvarious provincial drug plans. e data is based onprescriptions dispensed and accepted as claims bypublic drug programs, either for reimbursement ortoward a plan deductible. It is not known whetherdrugs were utilized as dispensed. e administrativedrug plan data does not capture information onprescriptions dispensed but not claimed under thedrug plan, or claimed but not approved.

Size-standardized Claimse analysis was conducted at the ingredient level, andthe utilization reported in this study encompassesboth brand name and generic utilization. Utilizationrefers to the number of claims reimbursed by thepublic drug program, standardized by quantity toaccount for changes in claim size that might haveoccurred over time or for differences in the claim size between the brand name and generic versions.e utilization patterns were analyzed in terms ofboth the volume and the market share of the size-standardized claims.

2 The Impact of Generic Entry on the Utilization of the Ingredient – September 2011

Methodology

Target drug list

Drug MarketOmeprazole (Losec) Proton pump inhibitorsRisperidone (Risperidal) Antipsychotics for the treatment

of schizophreniaSimvastatin (Zocor) HMG CoA reductase inhibitorsPravastatin (Pravacol) HMG CoA reductase inhibitorsCitalopram (Celexa) Selective serotonin reuptake inhibitorsParoxetine (Paxil) Selective serotonin reuptake inhibitorsGabapentin (Neurontin) Treatments for neuropathic pain

2 A Drug Identification Number (DIN) is a computer-generated eight digit number assigned by Health Canada to a drug product prior to being marketed in Canada. It uniquelyidentifies all drug products sold in a dosage form in Canada.

Normalized Timing of Generic Entry For the purpose of this study, generic entry time wasdetermined at the drug plan level and refers to thetime when notable utilization of the generic versionoccurred in each public drug plan. e time refers toa month in the case of the short-term impactassessment and a fiscal year in the case of the long-term impact assessment. Given that the timing ofgeneric entry differed across jurisdictions, it wasnormalized to zero (month zero or fiscal year zero).e time periods prior to generic entry were assignednegative sequential values (-1, -2, etc.), and the timeperiods post generic entry were assigned positivesequential values (1, 2, etc.).

e trends in utilization prior to and post genericentry were analyzed to identify any break in the trendfollowing generic entry. Projections of utilizationpatterns in the absence of generic competition weremade and compared to the actual utilization patterns.Projections were made using Microsoft Excel’s baseforecasting function, which uses a linear regressionmodel to calculate future values. While the short-term assessments were reported based on 12-monthperiods prior to and post generic entry, the long-termprojections were based on 24- to 36-month trends,data permitting.

Given the significant differences in drug utilizationacross jurisdictions, to facilitate the presentation ofthe data for the long-term analysis, utilization rateswere indexed. Since the first year for whichjurisdictional data was available is indexed to one,year-over-year changes reported in the chartseffectively represent percent change over the baseyear. Zero represents the year of generic entry.


12 months prior to generic entry

Actual vs. Projected Utilization

-12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12

12 months post generic entry

Generic Entry20

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Normalizing time of generic entry

1 OmeprazoleOmeprazole is a proton pump inhibitor (PPI)prescribed to reduce the secretion of gastric acids(i.e., for gastroesophageal reflux disease, pepticulcer)3. In the case of omeprazole, the first genericdrug product to enter the market had a differentformulation (capsule) than the brand-name Losec(tablet) and contained a different salt. esedifferences had an impact on the interchangeabilitystatus across jurisdictions, and thus, on the uptake ofthe generic version. Omeprazole utilization wasassessed in the context of its relevant market, whichincludes esomperazole, lansoprazole, pantoprazoleand rabeprazole. Since data was not available for alljurisdictions, the analysis in this section is limited toBritish Columbia, Alberta, Saskatchewan, Manitoba,Ontario, New Brunswick and Nova Scotia.

1.1 Market Profile

Public drug plans began receiving claims for genericomperazole in 2004 (Table 1.1). While omperazolewas the dominant drug in the market at that time, itsshare had been declining prior to generic entry, losingground in all jurisdictions to either pantoprazole orrabeprazole. Notwithstanding the differences betweenthe brand-name and generic omeprazole, a number

of jurisdictions chose to list the generic asinterchangeable with the brand name, includingOntario, Manitoba and Alberta. However, even inthis case, the uptake in the first year variedsignificantly, from 96.0% in Alberta to 22.4% inOntario (see Table 1.1). In Saskatchewan, wheregeneric omeprazole was not interchangeable with thebrand name, the generic uptake was 61.8%.4

e market composition for PPIs is indicated inTable 1.2 along with the formulary status acrossjurisdictions around the time of generic entry. Exceptfor Alberta, PPIs were available on a restricted basis.

Omeprazole was the first drug in its market to facegeneric competition. Its branded cost per unit of$2.29 (in the 12-month period prior to genericentry) was just slightly higher than the other brandsin its class, except for rabeprazole, which was pricedsignificantly below its competitors (Table 1.3). Withan average cost per unit of $1.32 (standardized forchanges in utilization strength), generic omperazoleoffered a 42% discount over the brand-name price.


Analysis

3 Canadian Pharmacists Association, Compendium of Pharmaceuticals and Specialties (CPS), 2009.

4 It should be noted that while Saskatchewan’s formulary did not list generic omeprazole as being interchangeable with the brand-name version, the drug plan’s MAC policyfavoured the use of the generic, Apo-Omeprazole, and rabeprazole. Apo-Omeprazole was essentially treated as if it was a unique product.

Table 1.1. Omeprazole market profile—Jurisdictional variations

Jurisdiction BC AB SK MB ON NB NS

Timing of generic entry* 2004** June 2006 Oct. 2004 June 2004 July 2004 Feb. 2004 May 2004Market share & trend 26.1% 42.1% 35.0% 63.7% 43.0% 58.5% 43.7% in claims 12 months Large Slight Constant Slight Moderate Slight Large prior to generic entry decrease decrease increase increase increase decreaseGeneric share of ingredient 12 months 71.6% 96.0% 61.8% 88.0% 22.4% 10.9% 25.4%post generic entry* Determined at the jurisdictional level and refers to the time of notable generic utilization.** The generic entry month is unknown. Data is limited to the yearly aggregate level.

1.2 Results

e impact of generic entry was assessed in terms ofboth the volume of size-standardized claims andmarket share.

Short-Term Analysis: Figure 1.1 reports the volumeof claims by jurisdiction over the 12-month periodprior to and post generic entry. Actual and projectedamounts are compared for the 12-month periodfollowing generic entry. e results indicate that,

with the exception of Nova Scotia, the entry of thegeneric version had no immediate notable impact onthe utilization of the ingredient. Prior to genericentry, the utilization rates of omeprazole in alljurisdictions except Nova Scotia were either flat orgrowing slightly. is trend continued once thegeneric version arrived on the market. In NovaScotia, the downward trend was the result of the slowerosion of omeprazole’s market share caused theintroduction of rabeprazole a year earlier.


Table 1.2. Formulary status for drugs in the relevantmarket 12 months prior to and postgeneric entry

BC AB SK MB ON NB NS

Omeprazole EsomeprazoleLansoprazolePantoprazole Rabeprazole

Restricted Unrestricted

Table 1.3. Average cost per unit for drugs in themarket, selected jurisdictions†

Generic availability Average costat time of per unit

Relevant omeprazole Prior to & post omeprazolemarket generic entry generic entry (24 months)

Brand* Generic**Omeprazole — $2.29 $1.32(-42%)

Strength standardized

Esomeprazole No $2.17Lansoprazole No $2.12Pantoprazole No $2.07Rabeprazole No $0.74

* 12 months prior to generic entry ** 12 months post generic entry† Alberta, Saskatchewan, Manitoba, New Brunswick, Nova Scotia and

Prince Edward Island

25,000

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Actual Projected

12 months prior to generic entry 12 months post generic entry

AB

SK

MB

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NS

Generic Entry

AB

SK

MB

NB

NS

Figure 1.1. Omeprazole – Number of claims by jurisdiction


Figure 1.2 shows the extent to whichthe actual market share for omeprazolevaried from the projected amount. Inall jurisdictions except Nova Scotia, thevariations are minimal and inconsistent(within +/- 2%). is supports theconclusion drawn from the volume ofclaims analysis: generally generic entrydid not have an immediate impact onthe utilization of omeprazole.

In Nova Scotia, where the genericomeprazole was not listed asinterchangeable with the brand nameversion, the introduction of the genericincreased the utilization of theingredient. Figure 1.3 reports on thenumber of claims for omeprazole overthe 12-month period prior to and post generic entry.e results show that the brand-name version continuedto follow the trend established 2 years before genericentry and that all of the increase in overall utilizationoccurred because of the addition of the generic.During this period, the generic was effectivelyretaking the market share back from rabeprazole.Nova Scotia eventually granted generic omeprazolefull interchangeability status in May 2006, 2 years

after adding it to their formulary. is resulted in the sharp generic uptake in month 24, as seen inFigure 1.3.

Following generic entry, the utilization of omeprazoleexpanded in Nova Scotia by an estimated 7% in thefirst fiscal year. is increase coincided with a changein the drug plan design that effectively expandedbenefit eligibility to a larger population.

10%

8%

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21 43 65 87 109 12 Months

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Generic Entry

Figure 1.2. Omeprazole – Actual market shares variation fromprojected (claims)

0 6-6 12-12 18-18 24-24

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500


Brand actual

Brand projected

Generic

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Generic Entry

Figure 1.3. Omeprazole – Number of claims in Nova Scotia: Brand vs. generic

Long-Term Analysis: Figure 1.4reports the volume of claims over the3-year period prior to and post genericentry, indexed for the first year thatjurisdictional data was available. Zerorepresents the year of generic entry.

On the surface, the long-term trendsrepresented in Figure 1.4 appear tosuggest that there may have been someimpact on utilization in all of thejurisdictions except Alberta. Whileutilization appears to be decliningacross most of the jurisdictions, bothSaskatchewan and Nova Scotia seem toexperience a marked growth followinggeneric entry. However, a more detailedreview of the data, as well as the drug plan policies ofthe various jurisdictions, shows that in fact thechanges in omeprazole’sutilization in at least BritishColumbia, Saskatchewan and Nova Scotia were theresult of drug plan changes rather than simply theentry of the generic.

In British Columbia, drug plan design changes tookeffect in 2002, and in 2003 Fair Pharmacare wasimplemented along with a policy change favouringthe use of rabeprazole. All these changes contributedto the sharp drop in omeprazole’suse. Similarly, thedrug plan in Saskatchewan, while not promotingomeprazole’sbrand/generic interchangeability,implemented a reimbursement policy that encouragedpatients to switch to either the generic version ofApo-omeprazole or rabeprazole. Finally in the case ofNova Scotia, the expansion of benefits among itssenior population coincided with the generic entry.

e long-term decline in omeprazole’s utilization seenin the remaining jurisdictions, Manitoba, Ontario andNew Brunswick, is difficult to interpret. While there isno clear explanation for the decline in New Brunswick,given that the change occurs two years following genericentry lessens the chance that this would be the cause.In the cases of Manitoba and Ontario, the decline inthe utilization growth appears to coincide with genericentry. However, a closer analysis of the data suggests that,while the end of patent protection may have had animpact, the declining growth in utilization began wellbefore and may be indicative of a maturing market.

1.3 Conclusion

While the data suggests that changes in the utilizationof omeprazole occurred in almost all the jurisdictionsfollowing generic entry, a more detailed review of themarket for PPIs shows that these changes were theresult of other factors. In most cases, changes to thedrug plan design and reimbursement policy appear to have been the primary cause. While loss ofomeprazole’s patent protection may have had someimpact on the utilization of the ingredient inManitoba, Ontario and New Brunswick, the evidencesuggests that these were maturing markets, making itdifficult to attribute the decline in utilization solely to generic entry.

Of all the markets analyzed, the most interesting wasthat of Nova Scotia. As shown, the generic versionarrived on the market as if it were a new competitor,drawing market share away from other PPIs, inparticular rabeprazole. Because it was not listed asinterchangeable, the introduction of the generic hadalmost no impact on the utilization trend of theoriginal branded product until 2006 when its status changed.


1.6

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Generic Entry

Figure 1.4. Omeprazole – Ingredient utilization index

2 RisperidoneRisperidone is an anti-psychotic drug prescribed inthe treatment of schizophrenia, the management ofinappropriate behavior related to severe dementia andthe management of manic episodes associated withbipolar disorder5. Risperidone utilization was assessedin the context of its relevant market, which includesthe anti-psychotic medications clozapine, loxapine,olanzapine and quetiapine.

2.1 Market Profile

Public drug plans began receiving claims for genericrisperidone in the summer and fall of 2006 (Table2.1), with a near-complete generic substitutionoccurring shortly after. While risperidone was thedominant drug in the market at that time, its marketshare was stagnant or slightly decreasing.

e market composition for anti-psychotic drugsused in the treatment of schizophrenia is indicated inTable 2.2 along with the formulary status acrossjurisdictions around the time of generic entry.Risperidone was available as an unrestricted benefitduring this period in all jurisdictions except PrinceEdward Island, which extended benefit status justfollowing the arrival of the generic on the market.

At the time of the generic risperidone’s arrival, onlythe two least utilized drugs in the market had genericversions (clozapine and loxapine). e patents for theremaining drugs, olanzapine and quetiapine, expiredin 2007 and 2008, respectively. With an average costper unit of $0.71 (standardized for changes in utilizationstrength), generic risperidone offered a 41% discountover the name-brand price (Table 2.3).


Table 2.1. Risperidone market profile – Jurisdictional variations

Jurisdiction BC AB SK MB ON NB NS PEI

Timing of generic entry* 2006** Aug. 2006 Aug. 2006 Sept. 2006 Sept. 2006 July 2006 Oct. 2006 Oct. 2006Market share & trend 30.2% 33.4% 48.2% 40.6% 38.5% 41.4% 44.8% 43.0%in claims 12 months Moderate Constant Slight Constant Moderate Constant Slight Slightprior to generic entry decrease decrease decrease decrease decrease* Determined at the jurisdictional level and refers to the time of notable generic utilization.** The generic entry month is unknown. Data is limited to the yearly aggregate level.


BC AB SK MB ON NB NS PEI

Risperidone ClozapineLoxapineOlanzapine Quetiapine




Relevant risperidone Prior to & post risperidonemarket generic entry generic entry (24 months)

Brand* Generic**Risperidone — $1.20 $0.71(-41%)


Clozapine Yes $2.87Loxapine Yes $0.24Olanzapine No $4.76Quetiapine No $1.09




Nov2006

2.2 Results

e impact of generic entry wasassessed in terms of both the volume ofsize-standardized claims and marketshare.

Short-term Analysis: Figure 2.1reports the volume of claims byjurisdiction over the 12-month periodprior to and post generic entry. Actualand projected amounts are comparedfor the 12-month period followinggeneric entry. e results indicate thatthe entry of the generic version had nonotable impact on the utilization ofthe ingredient.

e Figure 2.2 shows the extent towhich the actual market share forrisperidone varied from the projected amount. Formost jurisdictions the variations are minimal andinconsistent (within +/- 2%), although in the case ofNova Scotia and Prince Edward Island, there ismarked yet contrasting variation, suggesting apositive impact (market share increase) and negativeimpact (market share decrease), respectively.


11,000

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AB

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PEIAB

PEI

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Generic Entry

Figure 2.1. Risperidone – Number of claims by jurisdiction

6%

4%

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0%

-2%

-4%

-6%

21 43 65 87 109 12 Months11

Generic Entry

AB

SK

MB

NB

NS

PEI

Figure 2.2. Risperidone – Actual market shares variation fromprojected (claims)

Nevertheless, the trend in the volume of claims forrisperidone in these jurisdictions was virtuallyunchanged. e variations in the market share areexplained by the changes in the utilization patterns ofother drugs in the same therapeutic class, in particularquetiapine. In Nova Scotia, for instance, both thenumber of claims for quetiapine and its market sharegrew at a fast pace prior to arrival of generic risperidone,after which it slowed somewhat. Conversely, in PrinceEdward Island, the number of claims (and marketshare) for both quetiapine and olanzapine continuedto increase, while the number of claims for risperidoneremained relatively unchanged.

Long-term Analysis: e long-termanalysis in the case of risperidone islimited by data availability. Figure 2.3reports the volume of claims over athree year period prior to generic entryand a one year period post genericentry, indexed for the first year thatjurisdictional data was available. Zerorepresents the year of generic entry.

e results for the year following the generic entryseem to confirm the observations made in the short-term analysis, namely, that the utilization ofrisperidone has not been impacted by generic entry.

2.3 Conclusion

e analysis of utilization patterns across thejurisdictions indicates that the utilization of risperidonehas not been impacted by generic entry. e isolatedvariations cannot be attributed explicitly to risperidonegeneric entry.


2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.00 1-1-2-3 Fiscal

years

BC

AB

SK

MB

ON

NB

NS

PEI

Generic Entry

Figure 2.3. Risperidone – Ingredient utilization index

3 PravastatinPravastatin is a HMG CoA reductase inhibitor (statin)used to control hypercholesterolemia (elevatedcholesterol levels) and in the prevention of cardiovasculardisease6. Pravastatin utilization was assessed in thecontext of its relevant market, which includes theother statins: atorvastatin, cerivastatin, fluvastatin,lovastatin and simvastatin. Since data was not availablefor all jurisdictions, the analysis in this section islimited to British Columbia, Alberta, Saskatchewan,Manitoba, Ontario and New Brunswick.

3.1 Market Profile

Public drug plans began receiving claims for genericpravastatin in late 2000 and early 2001 (Table 3.1),with a near-complete generic substitution occurringshortly after. When the generic arrived on themarket, pravastatin was already losing its marketshare to atorvastatin, the market leader, and to alesser extent, to simvastatin.

e market composition for statins is listed in Table 3.2 along with the formulary status acrossjurisdictions around the time the generic entry. In allof the jurisdictions analyzed, except New Brunswickand Saskatchewan, statins were available on anunrestricted basis. e status in Saskatchewanchanged to unrestricted in January 2001.


Table 3.1. Pravastatin market profile – Jurisdictional variations

Jurisdiction BC AB SK MB ON NB

Timing of generic entry* 2000** Nov. 2000 Aug. 2000 Apr. 2001 2001** Aug. 2000Market share & trend in 19.9% 25.0% 16.5% 16.2% 23.8% 13.9%claims 12 months Moderate Slight Slight Slight Moderate Slightprior to generic entry decrease decrease decrease decrease decrease decrease* Determined at the jurisdictional level and refers to the time of notable generic utilization.** The generic entry month is unknown. Data is limited to the yearly aggregate level.


BC AB SK MB ON NB

Pravastatin AtorvastatinCerivastatinFluvastatinLovastatin Simvastatin




Relevant pravastatin Prior to & post pravastatinmarket generic entry generic entry (24 months)

Brand* Generic**Pravastatin — $1.87 $1.31(-30%)


Atorvastatin No $1.89Cerivastatin No $1.37Fluvastatin No $0.92Lovastatin Yes $1.59Simvastatin No $1.85



Jan2001

Jan2001

Jan2001

Jan2001

Jan2001

Jan2001


Pravastatin was the second statin to face genericcompetition after lovastatin. Its branded cost per unitof $1.87 (in the 12-month period prior to genericentry) was the second highest on the market (Table 3.3). With an average cost per unit of $1.31(standardized for changes in utilization strength),generic pravastatin offered a 30% discount over thebranded price.

3.2 Results


Short-Term Analysis: Figure 3.1 reports the volumeof claims by jurisdiction over the 12-month periodprior to and post generic entry. Actual and projectedamounts are compared for the 12-month periodfollowing generic entry. In the case of New Brunswick,Saskatchewan, Manitoba and Alberta, data wasavailable for parts of the 12-month period prior togeneric entry. e results suggest that the entry of the generic version of pravastatin had little impact on the utilization of the ingredient.

e Figure 3.2 shows the extent to which the actualmarket share for pravastatin varies from the projected amount. In the four jurisdictions analyzed,the variations are minimal and inconsistent (within+/- 2%), supporting the above conclusion.


7,000

6,000

5,000

4,000

3,000

2,000

1,000

0

0 2-2 4-4 6-6 8-8 10-10 12-12

Actual Projected


AB

SK

MB

NB

AB

SKMB

NB

Generic Entry

Figure 3.1. Pravastatin – Number of claims by jurisdiction

Long-Term Analysis: Figure 3.3reports the volume of claims over a 3-year period prior to and post genericentry, indexed for the first year thatjurisdictional data was available. Zerorepresents the year of generic entry.

Data availability for this analysis islimited to Ontario and BritishColumbia.7 In Ontario, the annualtrend seems to suggest that theutilization of pravastatin has not beenimpacted by generic entry. In BritishColumbia, however, there does appearto be a slight increase in utilizationfollowing generic entry. e decline at the end of the period coincides with the arrival of rosuvastatin on the market.

3.3 Conclusion

e analysis of utilization patternsacross the jurisdictions indicates that,with the possible exception of BritishColumbia, the utilization of pravastatinhas not been impacted by generic entry.


6%

4%

2%

0%

-2%

-4%

-6%

21 43 65 87 109 12 Months11

Generic Entry

AB

SK

MB

NB

Figure 3.2. Pravastatin – actual market shares variation fromprojected (claims)

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0


BC

ON

Generic Entry

Figure 3.3. Pravastatin – Ingredient utilization index

7 To be able to perform a long-term analysis, a minimum of 3 years of data are required to develop a trend in utilization. Data for most of the jurisdictions in this study startswith March, 1999, barely 12 months before generic entry. Only data for Ontario and British Columbia is available back to 1997, offering the 3 years worth of data requiredby the methodology.

4 SimvastatinSimvastatin is a HMG CoA reductase inhibitor(statin) used to control hypercholesterolemia(elevated cholesterol levels) and in the prevention ofcardiovascular disease8. Simvastatin utilization isassessed in the context of its relevant market, whichincludes the other statins: atorvastatin, fluvastatin,lovastatin, pravastatin and rosuvastatin. Since datawas not available for all jurisdictions, the analysis inthis section is limited to British Columbia, Alberta,Saskatchewan, Manitoba, Ontario, New Brunswickand Nova Scotia.

4.1 Market Profile

Public drug plans began receiving claims for genericsimvastatin late in 2002 and early 2003 (Table 4.1),with a near-complete generic substitution occurringshortly after. At the time, simvastatin was the secondmost utilized drug in the class (after atorvastatin),with constant or slight increasing trends in marketshare ranging from 23.5% to 34.2% depending onthe jurisdiction.

e market composition for statins is listed in Table 4.2 along with their formulary status acrossjurisdictions around the time the generic entry.Except for New Brunswick and Nova Scotia, statinswere available on an unrestricted basis.




Relevant pravastatin Prior to & post simvastatin market generic entry generic entry (24 months)

Brand* Generic**Simvastatin — $2.17 $1.24(-43%)


Atorvastatin No $1.92Fluvastatin No $0.94Lovastatin Yes $1.73Pravastatin Yes $1.16Rosuvastatin No** $1.49**





Simvastatin AtorvastatinFluvastatinLovastatin Pravastatin Rosuvastatin


Table 4.1. Simvastatin market profile – Jurisdictional variations


Timing of generic entry* 2002** Feb. 2003 Feb. 2003 May 2003 Apr. 2003 Dec. 2002 Mar. 2003Market share & trend 23.5% 23.6% 24.6% 27.3% 27.4% 32% 34.2% in claims 12 months Constant Slight Slight Constant Slight Slight Slight prior to generic entry increase increase increase increase increase* Determined at the jurisdictional level and refers to the time of notable generic utilization.** The generic entry month is unknown. Data is limited to the yearly aggregate level.


Simvastatin was the third statin to face genericcompetition, after lovastatin and pravastatin. Itsbranded cost per unit of $2.17 (in the 12-monthperiod prior to generic entry) was the highest on themarket (Table 4.3). With an average cost per unit of$1.24 (standardized for changes in utilizationstrength), generic simvastatin offered a 43% discountover the branded price.

4.2 Results

e impact of generic entry was assessed in terms ofboth the volume of size-standardized claims and theirmarket share.9 e assessment of the generic impacton the utilization of the ingredient is affected by yetanother event in the market: the launch ofrosuvastatin (Crestor) a few months later.

Short-Term Analysis: Figure 4.1 reports the volumeof claims by jurisdiction over the 12-month periodprior to and post generic entry. Actual and projectedamounts are compared for the 12-month periodfollowing generic entry. On the one hand, thecomparative analysis of the actual versus projectedvolume of claims seems to suggest that the entry ofthe generic had a negative impact on the utilizationof simvastatin in Alberta and Saskatchewan. However,given the arrival of rosuvastatin so soon afterward, theextent to which each event contributed to the overallchange in the ingredient’s utilization is unknown.


9 Size standardization was not preformed for Manitoba because of inconsistent unit reporting. Nevertheless, the reporting of the non-standardized claims for this province andfor this market is not expected to affect the interpretation of the results.

14,000

12,000

10,000

8,000

6,000

4,000

2,000

0

0 2-2 4-4 6-6 8-8 10-10 12-12

Actual Projected

12 months prior to generic entry

AB

SK

MB

NB

NS

AB

SK

MB

NB

NS

Rosuvastatin Entry

Generic Entry

12 months post generic entry

Figure 4.1. Simvastatin – Number of claims by jurisdiction

Figure 4.2 shows the extent to whichthe actual market share for simvastatinvaried from the projected amountfollowing generic entry. Whilesimvastatin appears to lose marketshare following generic entry, thedecline in the first few months prior tothe arrival of rosuvastatin on themarket was minimal (less than 2%).e launch of rosuvastatin and itsrapid market uptake drastically erodedsimvastatin’s utilization and marketshare. e utilization of other drugs inthe market experienced a similarlynegative impact.

Long-Term Analysis: Figure 4.3 reportsthe volume of claims over a 3-yearperiod prior to and post generic entry, indexed for the first year thatjurisdictional data was available. Zerorepresents the year of generic entry.

e results suggest that the growth inutilization of simvastatin does slowduring the fiscal year following genericentry. Nevertheless, as indicated in theshort-term analysis, the trends cannotbe solely attributed to generic entry, as the impact of rosuvastatin’s launch is unknown.

4.3 Conclusion

Due to the dual market impact of the entry ofgeneric simvastatin and the launch of a new drug(rosuvastatin), it is unclear which event had thegreatest effect on the utilization of simvastatin.Nevertheless, the immediate generic entry impactseems to suggest a small negative impact consistentlyacross jurisdictions, exacerbated by the launch ofrosuvastatin shortly thereafter.


3.0

2.5

2.0

1.5

1.0

0.5

0.0


BC

AB

SK

MB

ON

NB

NS

Generic Entry

Figure 4.3. Simvastatin – Ingredient utilization index

10%

5%

0%

-5%

-10%

AB

SK

MB

NB

NS

21 43 65 87 109 12 Months11

Rosuvastatin Entry

Generic Entry

Figure 4.2. Simvastatin – actual market shares variation fromprojected (claims)

5 Paroxetine and CitalopramParoxetine and citalopram are selective serotoninreuptake inhibitors (SSRIs) prescribed for thetreatment of major depressive disorder, obsessive–compulsive disorder, panic disorder, social phobiaand post-traumatic stress10. ese two drug productsare analyzed conjointly in this chapter due to the factthat they have a similar generic entry date and theimpact that this may have on their utilization.Paroxetine and citalopram utilization are assessed inthe context of their relevant market, which includesthe other SSRIs: fluoxetine, fluvoxamine and sertraline.Since data was not available for all jurisdictions, theanalysis in this section is limited to British Columbia,Alberta, Saskatchewan, Manitoba, Ontario, NewBrunswick and Nova Scotia.

5.1 Market Profile

Public drug plans began receiving claims for genericparoxetine in late 2003 and early 2004, with genericcitalopram entering at the same time or immediatelyafter (Table 5.1). A near-complete generic substitutionoccurred shortly after generic entry in the case of bothdrugs. e two drug products accounted for a significantshare of the overall claims made in this market. Overthe period reviewed, paroxetine was slowly losing itsplace as market leader to citalopram.


Table 5.1. Paroxetine and citalopram market profile – Jurisdictional variations


Paroxetine / Citalopram: 2003 / Dec. 2003 / Nov. 2003 / Apr. 2004 / Apr. 2004 / Nov. 2003 / Dec. 2003 / Timing of generic entry* 2003** Feb. 2004 Mar. 2004 Apr. 2004 Apr. 2004 Feb. 2004 Mar. 2004Paroxetine: Market share & trend 35.9% 28.1% 38.7% 33.4% 29.3% 40.4% 36.8%

in claims 12 months Slight Slight Slight Constant Slight Slight Slight

prior to generic entry decrease decrease decrease decrease decrease decrease

Citalopram: Market share & trend 28.0% 38.5% 24.4% 35.9% 35.5% 29.2% 33.8%

in claims 12 months Moderate Moderate Moderate Slight Moderate Moderate Moderate

prior to generic entry increase increase increase increase increase increase increase

* Determined at the jurisdictional level and refers to the time of notable generic utilization.** The generic entry month is unknown. Data is limited to the yearly aggregate level.



Paroxetine CitalopramFluoxetineFluvoxamine Sertraline


Mar2004

Mar2004

Mar2004

Mar2004

Mar2004


e market composition for SSRIs is indicated inTable 5.2 along with their formulary status acrossjurisdictions around the time the generic entry. SSRIswere available on an unrestricted basis, except inNova Scotia, where the status changed from restrictedto unrestricted in March of 2004 (coinciding withthe entry of generic citalopram).

Paroxetine and citalopram were the last two drugproducts in the market to lose patent protection.eir average brand price per quantity was $1.75 and$1.42, respectively, in the 12-month period prior togeneric entry (Table 5.3). e two drug products hada comparable generic price discount (38% and 36%,respectively), bringing the generic price more in linewith that of their competitors.

5.2 Results


Short-Term Analysis: e actual and projectedvolume of claims after generic entry are reported byjurisdiction in Figures 5.1 and 5.2. e resultssuggest that the entry of the generic version had little

impact on the utilization of either ingredient, at leastin the short term. While there does seem to be aslight drop in the utilization of paroxetine part waythrough the first year, rates appear to reboundtowards the end.




Relevant paroxetine Prior to & post paroxetine market generic entry generic entry (24 months)

Brand* Generic**Paroxetine — $1.75 $1.08(-38%)


Brand* Generic**Citalopram — $1.42 $0.91(-36%)


Fluoxetine Yes $1.02Fluvoxamine Yes $0.73Sertraline Yes $0.98



14,000

12,000

10,000

8,000

6,000

4,000

2,000

0

0 2-2 4-4 6-6 8-8 10-10 12-12

Actual Projected


AB

SK

MB

NB

NS

AB

SK

MB

NB

NS

Generic Entry

Figure 5.1. Paroxetine – Number of claims by jurisdiction

Figures 5.3 and 5.4 show the extent to which the actual market share foreach of the two drugs varied from theprojected amount following genericentry. In both cases, the variations areminimal and inconsistent (within +/-2%). is supports the conclusiondrawn from the volume of claimsanalysis, namely, that there was noimpact on utilization after genericentry for either paroxetine orcitalopram.

While there does appear to be a smallimpact on the market share ofparoxetine in New Brunswick, a moredetailed review of the utilization of allof the drugs in the market reveals thatparoxetine was the only one with a change from itsearly trend, albeit small. As none of the competitorsappears to have benefited from this decline, the lossin utilization and market share are likely the result of market maturation rather than the entry of generic paroxetine.


16,000

14,000

12,000

10,000

8,000

6,000

4,000

2,000

0

0 2-2 4-4 6-6 8-8 10-10 12-12

Actual Projected


AB

SK

MB

NB

NSAB

SK

MB

NB

NS

Generic Entry

Figure 5.2. Citalopram – Number of claims by jurisdiction

6%

4%

2%

0%

-2%

-4%

-6%

21 43 65 87 109 12 Months11

Generic Entry

AB

SK

MB

NB

NS

Figure 5.3. Paroxetine – actual market shares variation fromprojected (claims)

Long-Term Analysis: Figures 5.5 and5.6 report the volume of claims over athree year period prior to and postgeneric entry, indexed for the first yearthat jurisdictional data was available.Zero is the year of generic entry.

e results of the long-term analysissuggest two different outcomes. On the one hand, in the case ofparoxetine, the slight decline inutilization that appeared near themiddle of the first year followinggeneric entry becomes more pronouncedin all jurisdictions except BritishColumbia where the decline inutilization began the year before.

On the other hand, the results forcitalopram suggest that the utilization followed thetrend established prior to generic entry. is confirmsthe observation made in the short-term analysis,namely, that the utilization of citalopram has notbeen impacted by generic entry.

It should be noted that the change in utilization ofparoxetine does seem to coincide with warnings onthe long-term use of SSRIs. While initial reports out of the United States about the side-effects of their use focused on paroxetine, warnings were issuedby Health Canada for all the drugs in the class,including citalopram. Unfortunately, there is notenough information available to assess the impact of this event.

5.3 Conclusion

e analysis of utilization patterns across thejurisdictions suggests that, at least in the short-term,the utilization of paroxetine and citalopram wasunaffected by the generic entry. e long-term analysispaints a different picture for the utilization of paroxetine,which, with the exception of British Columbia, saw a significant drop following generic entry.


6%

4%

2%

0%

-2%

-4%

-6%

21 43 65 87 109 12 Months11

Generic Entry

AB

SK

MB

NB

NS

Figure 5.4. Citalopram – actual market shares variation fromprojected (claims)


1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2


BC

AB

SK

MB

ON

NB

NS

Generic Entry

Figure 5.5. Paroxetine – Ingredient utilization index

7.0

6.0

5.0

4.0

3.0

2.0

1.0

0.0


BC

AB

SK

MB

ON

NB

NS

Generic Entry

Figure 5.6. Citalopram – Ingredient utilization index

6 GabapentinGabapentin is an anticonvulsant indicated for themanagement of patients with epilepsy11. It is alsoextensively used on an off-label basis for the treatmentof neuropathic pain. e utilization of gabapentinwas analyzed in the context of the market foranticonvulsants and tricyclic antidepressants used totreat neuropathic pain, which includes amitriptyline,carbamazepine, desipramine, imipramine andnortriptyline. Since data was not available for alljurisdictions, the analysis in this section is limited toBritish Columbia, Alberta, Saskatchewan, Manitoba,Ontario and New Brunswick.

6.1 Market Profile

Public drug plans began receiving claims for genericgabapentin in 2001 (Table 6.1), with a near-completegeneric substitution occurring within the same year.While gabapentin was not the dominant drug in themarket, it was the fastest growing, with double-digitincreases in the volume of claims in manyjurisdictions including British Columbia, Alberta,Saskatchewan and Manitoba.


Table 6.1. Gabapentin market profile – Jurisdictional variations

Jurisdiction BC AB SK MB ON NB

Timing of generic entry* 2001** Aug. 2001 Apr. 2001 Aug. 2001 2001* Mar. 2001Market share & trend in 23.3% 19.8% 8.5% 12.9% 4.6% 8.5%claims 12 months prior Large Moderate Slight Moderate Large Slightto generic entry increase increase increase increase increase increase * Determined at the jurisdictional level and refers to the time of notable generic utilization.** The generic entry month is unknown. Data is limited to the yearly aggregate level.



Relevant gabapentin Prior to & post gabapentinmarket generic entry generic entry (24 months)

Brand* Generic**Gabapentin — $0.90 $0.60(-33%)


Amitriptyline Yes $0.04Carbamazepine Yes $0.17Desipramine Yes $0.32Imipramine Yes $0.05Nortriptyline Yes $0.20




BC AB SK MB ON NB

Gabapentin AmitriptylineCarbamazepineDesipramineImipramine Nortriptyline



e market composition is considered in Table 6.2along with the formulary status across jurisdictionsaround the time of generic entry. In four of thejurisdictions analyzed, all drugs in the market wereavailable without restriction. Gabapentin was availablein Ontario and New Brunswick on a restricted basis.New Brunswick had further restrictions onamitripyline and imipramine. Saskatchewan removedthe formulary restrictions on all these drugs threemonths before the generic gabapentin entry.

Gabapentin was the last drug in its market to facegeneric competition. Its branded cost per unit of$0.90 (in the 12-month period prior to genericentry) was the highest on the market (Table 6.3).With an average cost per unit of $0.60 (standardizedfor changes in utilization strength), generic gabapentinoffered a 33% discount over the branded price.

6.2 Results

e impact of generic entry was assessed in terms of both the volume of size-standardized claims andmarket share.

Short-Term Analysis: Figure 6.1 reports the volumeof claims by jurisdiction over the 12-month periodprior to and post generic entry. Actual and projectedamounts are compared for the 12-month periodfollowing generic entry. e results indicate that theentry of the generic version of gabapentin had nonotable impact on the utilization of the ingredient,with the exception of a slight decline in utilization in Alberta.


3,000

2,500

2,000

1,500

1,000

500

0

0 2-2 4-4 6-6 8-8 10-10 12-12

Actual Projected


AB

SK

MB

NBAB

SK

MB

NB

Generic Entry

Figure 6.1. Gabapentin – Number of claims by jurisdiction

e Figure 6.2 shows the extent towhich the actual market share forgabapentin varied from the projectedamount. Generally, the variation issmall and inconsistent (within +/- 2%),supporting the conclusion drawn fromthe volume of claims analysis, namelythat the gabapentin utilization was notimpacted by generic entry.

While the apparent modest decline (-2%) in gabapentin’s market share inAlberta along with the slowing growthin utilization suggests that there mayhave been some impact from genericentry, a more detailed review of trendsin the other drugs in the market showthat gabapentin was the only ingredientgrowing in both utilization and marketshare, though at a slower rate followinggeneric entry. is suggests that thedeviations from the earlier trends werethe result of a maturing market ratherthan a change in utilization related tothe arrival of the generic.

Long-Term Analysis: Figure 6.3 reportsthe volume of claims over a three yearperiod prior to and post generic entry,indexed for the first year thatjurisdictional data was available. Zerorepresents the year of generic entry.

is analysis is limited to Ontario andBritish Columbia for reasons of dataavailability. In Ontario, the data seemsto confirm observations made in theshort-term analysis, namely that theutilization of gabapentin has not beenimpacted by generic entry. On theother hand, utilization in British Columbia appearsto slow in its uptake in the two years following thearrival of a generic on the market. If the cause wasindeed generic entry, then the impact was relativelysmall, approximately 4%, and short lived, as growthreturned to its previous levels in subsequent years.

6.3 Conclusion

e analysis of utilization patterns across thejurisdictions indicates that the utilization of gabapentinhas not been impacted by generic entry. e isolatedvariations cannot be attributed solely to gabapentingeneric entry.


6%

4%

2%

0%

-2%

-4%

-6%

21 43 65 87 109 12 Months11

Generic Entry

AB

SK

MB

NB

Figure 6.2. Gabapentin – Actual market shares variation fromprojected (claims)

9.0

8.0

7.0

6.0

5.0

4.0

3.0

2.0

1.0

0.0


BC

ON

Generic Entry

Figure 6.3. Gabapentin – Ingredient utilization index

e purpose of this study was to identify the impactthat generic entry had on the utilization of theingredient in the case of top-selling drug productsthat have lost patent protection in recent years, asobserved in public drug plan data. Seven drugproducts were selected for analysis: omeprazole,risperidone, pravastatin, simvastatin, paroxetine,citalopram and gabapentin. ese drugs cover varioustherapeutic classes, market conditions (pricedifferential, number and type of competitors) andformulary statuses.

Generally, this research shows that there is very littlechange in the trend in utilization once the firstgeneric version is launched. Typically the number ofclaims and market share following generic entrycontinue the trend established by the brand nameunder market exclusivity. In most cases the changes in utilization that are identified cannot be directlyand/or solely attributable to generic entry.

is is the case for simvastatin. While there appearsto be a notable negative impact on utilization acrossjurisdictions both in the short- and long-term, it isdifficult to separate out how much of the change wasa result of the introduction of the generic and howmuch was a result of the arrival of rosuvastatin a fewmonths later.

In the case of omeprazole, the changes observed inlong-term utilization for some jurisdictions can beexplained by drug plan policy changes. In otherjurisdictions the slowing growth in utilization around the time of generic entry may indicate amaturing market.

e most significant change in utilization followinggeneric entry was in the case of paroxetine. e long-term analysis revealed a sizable drop in utilizationacross every jurisdiction beginning 1 year after theend of the patent life. At the same time, another drugin the same market, citalopram, experienced almostno change in utilization despite facing a similarchallenge from a generic. It should be noted that, whileHealth Canada issued warnings for all the drugs inthe class at the time, there is no data available toassess the impact on utilization.

ImplicationsTwo hypotheses were proposed at the start of thisanalysis. e first hypothesis proposed that theavailability of a drug product at a lower price maylead to increased utilization. is hypothesis does notseem to be supported by the results. ere may betwo explanations for this. Firstly, a patient may bereluctant to switch from one drug to another becauseof a better clinical response, or based on other reasonsrelated to their therapeutic choices. Secondly, theanalysis was done on public drug plans wherebeneficiaries are generally responsible for a portion ofthe cost. In such cases, there may be limited priceelasticity, in the sense that a price reduction on a drug product may not necessarily translate to anincreased demand.

e second hypothesis proposed that the utilizationmay diminish due to a decrease in drug advertising,which is generally conducted by brand manufacturersand ceases with the loss of market exclusivity. is hypothesis does not seem to be supported by theresults either. is may be explained by the fact thatmost of the drug products that were analyzed havemature markets with a limited number of new patients.us advertising would not have played a significantrole in the market trends.


General Findings

In conclusion, the utilization of the drug productsanalyzed was not impacted by generic entry. isimplies that any cost savings after generic entry willbe solely related to the generic price discount.Nevertheless, it should be recognized that over timethese savings may be eroded by a growth in utilization;a growth that is unrelated to generic competition.

LimitationsWhile this study was conducted on a limited numberof top-selling drug products utilized in public drugplans, it covers various therapeutic classes, marketconditions (price differential, number and type ofcompetitors) and formulary statuses. erefore, weshould be able to apply these findings to other drugs.

However, utilization can be affected by a number offactors including reimbursement policies, pricing,demographics, physician prescribing practices, andthe incidence of a particular condition. In addition,public drug plan data represents only one componentof the overall pharmaceutical market. Results maydiffer for markets reimbursed by private insurers ordrugs paid for out-of-pocket by patients.

is study is purely a drug utilization analysis thatassesses the impact of the generic entry on the utilizationof the ingredient in public drug plans. e study doesnot make any assessment on the cost implications ofgeneric entry impact on drug plan expenditures.


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