Pharmokinetics and Processes Flashcards
What is Xenobiotics?
Foreign Compounds with no nutrional value
What happens when a drug goes into your body?
ADME - Absorption (into body) Distribution (to tissues) Metabolism (chemical breakdown) Excrete (out of body)
What does Absorption, Distribution and Metabolism depend on?
Route of Administration and Physico-Chemical properties of a drug
List some Physico-chemical properties of drugs?
Drug structure, Molecular weight, Polarity, Ionisation
What drug Chemical Properties can affect Drug Absorption?
Structure, Molecular weight, Liphopilicty, Ionisation
What Physiological Variables can affect Drug Absorption?
PH, Surface area of membrane, Mesenteric blood flow, Gastric Emptying, Food and Efflux Transporters
What is Bioavailbility (F) ?
Percentage of administered dose reaching systematic circulation as an unchanged drug (not as metabolites)
What is Bioavailibilty governed by?
Absorption and First Pass Metabolism
What are the 3 methods of Drug Elimination?
- Renal Excretion ( Urine, Faeces, Saliva)
- Liver Metabolism
- Chemical Transformation (excretion)
2 compounds are not metabolised and are cleared by what in the kidney?
Glomerular Filtration
What are the 3 pathways of drug metabolism?
Phase I - Functionalisation Reactions
Phase II - Conjugation Reactions
Phase III - Formation of Xenobiotics (Macromolecule adducts)
What are the 3 Major Chemical Reactions?
- Oxidation
- Reduction
- Hydrolysis
What happens between Phase I and Phase II of drug Metabolites?
Addition of Polar Group
Catalysed by Transferases
Cofactor Donor
List some Properties of Drug-Metabolising Enzymes?
Low Substrate/Reaction Specifity
Low Catalytic Rates (may present in high concentrations)
Substrates usually Lipophilic
Enzymes Inducible
What 2 Sub-Compartments in the Liver does Drug Metabolism occur?
- Endoplasmic Reticulum (cell disruption breaks into small microsomes)
- Cytosol