PRN Medications

Bindu Swaroop, MDFundamentals of MedicineJuly 2014

Indications & Use

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Objectives

• Identify which prn medications are appropriate for inclusion in admission orders

• Identify contraindications and adverse effects associated with common prn medications

• Known when to evaluate the patient prior to ordering or the nurse giving a prn medication

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Common Uses

• Sleep

• Pain

• Cardiovascular: Hypertension

• Sedatives: ETOH withdrawal, agitation

• Pulmonary: Nebulizers, Mucolytics

• GI: Bowels, Heartburn

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Case Vignette

HPI: 59 year old male admitted for chest pain and acute ETOH intoxication. He also complains of hematemesis during his most recent drinking binge.

PMHx: AVNRT, Hepatitis C, insomnia, depression, COPD

Meds: combivent inhaler bid, ibuprofen 600mg po tid prn

EKG on admission reveals AVNRT @111 bpm

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Case Vignette

He is admitted to the medicine service with the following prn orders:

-Ativan 2mg IV q4hr prn withdrawal

-Albuterol neb q6h prn, Atrovent neb q6hr prn

-Acetaminophen 650mg q4hr prn pain

-Ibuprofen 600mg po tid prn pain

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Case Vignette

That night the patient subsequently requests pain medication for his chest pain. It is determined by the night float that there is no evidence of ACS. Since ibuprofen is ordered prn the night float instructs the nurse to give this to the patient. The patient still complains of pain later that night, and the night float writes an order for Morphine sulfate 2mg IVP q4hr prn pain.

Are these appropriate meds to give to the patient?

What other alternatives could have been given?

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Analgesics Oral Pain Severity SC/IM/IV Pain Severity Adverse Effects

Non-Opiods

Acetaminophen325-650mg

Mild Ketorolac30-60mg

Moderate Caution in hepatic or renal impairment

Ibuprofen600-800mg

Mild PUD, GI bleed, renal toxicity

Opiods Tramadol 50-100mg

Mild to Moderate

Tylenol w/ codeine30mg-60mg/300mg

Mild to Moderate

Morphine Moderate to Severe

Constipation, Ileus, n/v, respiratory depression, urinary retention

Vicodin(5mg/300mg)

Norco(10mg/325mg)

Moderate Dilaudid Severe Caution Hepatic or Renal Impairment

Percocet(5mg/325mg)

Moderate Fentanyl (IV or patch)

Severe

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Case Vignette

The next day his BP has risen to 170/105. He is given hydralazine

10mg IVP by the team with a drop in his BP to 125/78.

3. What is likely contributing to the rise in BP?

4. What side effects could occur from lowering the BP too much?

5. How else could this patient have been treated?

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Hypertension

Goal:-To identify and treat the underlying cause-Prevent end-organ damage

Common Causes:ReboundInadequate dosingDrug InteractionsETOH withdrawalHypoxemia, respiratory distressPain, AnxietyAutonomic response: urinary retention, constipation, SCI

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Hypertension

Approach to evaluating the patient:

-Determine patient’s baseline

-Confirm accuracy, both arms, cuff size

-Screen for the underlying cause

-Determine if hypertensive emergency or urgency is present

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Hypertension Treatment

Hypertensive Urgency

-SBP >180 or DBP >120

-gradual reduction of BP to 160/110 over 24-48 hours

-use ORAL meds

Hypertensive Emergency

-evidence of end-organ damage-Immediate reduction of SBP by 15-20%-Use PARENTERAL agents and transfer to ICU

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Hypertension Clinical Pearls

• Hypertensive treatment rarely requires immediate treatment in the middle of the night

• Avoid prn use of rapid acting agents (can precipitate ischemic events)

• For patients with sustained HTN, primary team should initiate treatment with long acting regimen

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Case Vignette

Later that night the patient requests something for sleep and receives Benadryl 25mg po, written as qhs prn per night float. On day three of admission he develops urinary retention with a PVR of 300cc. A foley catheter is placed. You review his chart and notice a prior urology note indicating the patients prostate size on DRE is 50g.

What could be contributing to the urinary retention?

What other alternatives could have been used for his insomnia?

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Hypnotics

Benadryl 25mg-50mg

Beers high severity Anti-cholinergic effects (confusion, dry mouth, urinary retention, wheezing; caution in pts with glaucoma and BPH

Temazepam (Restoril)15-30mg(geriatric 7.5mg)

Beers high severity Same AE as any benzo; contraindicated in glaucomacaution in those with falls risk, hepatic or renal impairment

Trazodone (unlabeled use)25-50mg

Okay in elderly Hypotension, increased bleeding risk if on NSAID’s or warfarin, priapism, serotonin syndrome, caution post-MI or with h/o seizures

Zolpidem (Ambien)5-10mg

Okay in elderly HA, dizziness, caution in those with respiratory compromise, myasthenia gravis

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Case Vignette

He remains hospitalized due to social issues including homelessness. On day 4 of admission you are called by the nurse due to the patient falling in his room. You evaluate his gait and notice he is unsteady in addition to being more somnolent than usual.

What could be contributing to the fall and gait impairment?

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Sedatives

Ativan: common use in ETOH withdrawal

-AE include sedation, respiratory depression

-Caution in those with acute angle glaucoma, sleep apnea, respiratory issues, hepatic/renal impairment, h/o drug abuse or falls risk

Anti-Psychotics: Typical (Haldol) & Atypical (Seroquel, Risperidone)

-anti-cholinergic side effects, QT prolongation

-careful in dementia related psychosis (increased risk of death compared to placebo)

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Case Vignette

A review indicates the patient has continued to receive Ativan despite no further evidence of withdrawal due to complaints of anxiety and insomnia.

A review of his chart reveals he was previously on mirtazapine but this medication had not been continued on admission.

During rounds, it is noted that the tachycardia noted on admission is persistent.

What else could be contributing to the tachycardia?

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Pulmonary

•Nebulizers:– Albuterol (max dose 3mL q4hours): can cause tachycardia, arrhythmia,

caution in patients with ischemia

– Atrovent: anti-cholinergic side effects; caution in those with glaucoma, BPH

•Mucolytics:– Mucomyst: can cause bronchospasm; use 10-20 minutes after

bronchodilator administration

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Case Vignette

The patient subsequently complains of diarrhea the next day. Stool studies are sent, and the intern orders lomotil prn for loose stools.

Is this an appropriate order?

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GastrointestinalHeartburn: Maalox (aluminum dioxide, magnesium hydroxide) or Maalox plus

AE: constipation, cramps, fecal discoloration; aluminum intoxication– Use with caution in renal impairment: hypophosphatemia or

hypermagnesemia– long list of drug interactions–Must be administered one hour apart from other oral meds

Constipation: phosphate (fleets) enema– Do not use in patients with renal impairment, ascites, heart failure,

GI obstruction or megacolon

Diarrhea: do not use in those with c.difficile colitis– Loperamide (Immodium): caution in hepatic impairment

– Lomotil (diphenoxylate/atropine): anti-cholinergic side effects)

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Case Vignette

The patient subsequently does well and is discharged. Upon discharging the patient, you order the following outpatient medication regimen:

• Ibuprofen 600mg po tid prn• Vicodin 2 tabs q6hr prn• Combivent inhaler q4hr prn• Benadryl 25mg po qhs prn• Librium taper

Are these appropriate orders?

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Summary

•For all PRN orders, know the correct dosage, common adverse effects and contraindications

•Check the next day to see if your patient actually received any of the PRN meds

•Convert frequently administered PRN meds into standing orders

•Don’t just put in PRN orders to save night float the “trouble” of getting called

•Evaluate underlying cause or condition requiring use of a PRN med and treat accordingly