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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?
RZH HA - Faculty of Medicine - USU
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Drug absorption
Through the biologic membrane(>>>phospholipids & protein)
RZH HA - Faculty of Medicine - USU
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
RZH HA - Faculty of Medicine - USU
Active transport Facilitated diffusion Pinocytosis
Through the biologic membrane
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Passive diffusion
RZH HA - Faculty of Medicine - USU
Higher conc. lower conc.(the process requiring no direct
expenditure of energy bybiologic system)
Through the biologic membrane
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Facilitated diffusion
RZH HA - Faculty of Medicine - USU
Higher conc. lower conc.(the process is limited by the
availability of carrier)
Through the biologic membrane
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Active transport
RZH HA - Faculty of Medicine - USU
Lower conc. higher conc.(the process requiring
cellular energy)
Through the biologic membrane
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Pinocytosis
RZH HA - Faculty of Medicine - USU
The process of engulfing particles ordissolved materials by local
invagination of cell membrane(vesiculation)
(the process requiring of cellular energy)
Through the biologic membrane
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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
RZH HA - Faculty of Medicine - USU
Physical propeties
Chemical properties
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Physical properties
RZH HA - Faculty of Medicine - USU
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
RZH HA - Faculty of Medicine - USU
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Chemical properties
RZH HA - Faculty of Medicine - USU
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