K56 PHARMACOKINETICS

7/28/2019 K56 PHARMACOKINETICS

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ROZAIMAH ZAIN-HAMID

HASANUL ARIFIN

Department of Pharmacology and Therapeutics

Faculty of Medicine, Universitas Sumatera Utara


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SYSTEMIC CIRCULATION

free drug

binding drug metabolite

Absorption Excretion

Biotransformation

Site of action/ receptorbinding drug free drug

Tissue depot

free drug binding drug

Pharmacokinetic

RZH HA - Faculty of Medicine - USU


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What is drug absorption?



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Drug absorption

Through the biologic membrane(>>>phospholipids & protein)


Drug bioavailability AUC

(Area Under the Curve)

Drug

Systemic circulation


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Drug bioavailability



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PharmacokineticBioavailability AUC

The fraction of the dose which reaches

the systemic circulationin unchanged form

depend on:

Drug absorption First pass metabolism

RZH HA- Faculty of Medicine - USU


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FACTORS AFFECTING BIOAVAILABILITY

Gutlumen

Portalcirc. Liver

Systemiccirc.

Drugs in

gut

Drug

absorbed

intact

Drug

absorbed intact

and escapingfirst-past metab.

Drug extracted

first-past

100 80

60

2060

RZH HA- Faculty of Medicine - USU


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Drug mechanismthrough the biologic membrane



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Drug absorption

Passive diffusion


Active transport Facilitated diffusion Pinocytosis

Through the biologic membrane


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Passive diffusion


Higher conc. lower conc.(the process requiring no direct

expenditure of energy bybiologic system)



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Facilitated diffusion


Higher conc. lower conc.(the process is limited by the

availability of carrier)



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Active transport


Lower conc. higher conc.(the process requiring

cellular energy)



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Pinocytosis


The process of engulfing particles ordissolved materials by local

invagination of cell membrane(vesiculation)

(the process requiring of cellular energy)



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JENIUS TERDIRI DARI

1 % ILHAM & 99 % KERINGAT/

KERJA KERAS



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Factors influencedrug absorption



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Factors influence

drug absorption


Physical propeties

Chemical properties


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Physical properties


Size of drugs particleRoute of drug administration

Surface area for absorptionBlood circulation on site of

absorption


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Drugs diffuse down concentration

Physical properties

The concentration are equalin all parts of the body



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Chemical properties


Lipid solubility of the drug

Degree of ionization

pKa of the drug


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Chemical properties of drugs

1. Unionized lipid soluble drugs pass

most readily through biologicmembrane

2. Ionized drugs or low lipid solubilitydrugsare relatively impermeable tobiologic membrane



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The lipid solubility and degree ofionization of the drug, regulateits absorption, distribution and

elimination

these same properties are major

determinant of drug selectivity,intensity and duration of action

RZH HA Faculty of Medicine USU

K56 PHARMACOKINETICS

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