pharm review 1
Terms
undefined, object
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- Name the routes of drug administration
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enteral (oral, sublingual, rectal)
parenteral (intravascular- IV or IA)
subcutaneoas(sc)
other (inhalation, intranasal,intrathecal /intraventricular,topical,transdermal) - effect of pH on drug absorption
-
henderson-hasselbach equation:
ph=pKa+log(non-protonated species/(protonated species) - bioavailibilty
-
is fraction of administered drug that reaches the systemic circulation (70%)
(= AUC oral/AUC injected x100) - factors that influence bioaivailibilty
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- first-pass hepatic metabolism (eg propanolol,
lidocain)
- solubility of drug (eg hydrophilic & very hydrophobic poorly absorbed)
chemical instability (eg penicillin G, Insulin)
- nature of drug formation (particle salt, salt form - Bioequivalence
- if drugs show comparable bioavaililibity and similar times to achieve peak blood concentration
- therapeutic equivalence
- have comparable efficacy and safety
- drug distribution depends on
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blood flow
capillary permeability (capillary structure & drug structure)
binding of drugs to proteins - blood brain barrier
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-lipid soluble durgs readily penetrate into the CNS
-ionized or polar drugs fail - Volume of Distribution (Vd)
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Vd = D/C (in absence of elimination)
D = total amount of drug in the body
C = Plasma concentration of the drug - Binding capacity of albumin
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low capacity =(1 drug molecule per albumin
molecule)
high capacity =(a number of drug molecules per albumin molecule) - Class I drugs
- = if the dose of drug is less than the binding capacity of albumin
- Class II drugs
- = if the dose of drug is greater than the binding capacity of albumin
- drug displacement
- = if class I and class II drugs are given simultaneously
- drug metabolism
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kinetics
- first-order
v= Vmax[C]/Km+[C]
-Zero-order (aspirin, ethanol, phenytoin)
v = Vmax[C]/[C]=Vmax
v+ - reactions of drug metabolism
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Phase I
- phase I utilizing the p450 system
-phase I not involving P450
Phase II
- consist of conjugatioin reactions