HTHSCI 2H03 Lecture Notes - Lecture 3: Plasma Protein Binding, Drug Metabolism, Bioavailability

• School: McMaster University
• Department: Health Sciences
• Course: HTHSCI 2H03
• Professor: Kirsten Culver

Document Summary

Bioavailability fraction of administered dose that reaches plasma in chemically unchanged and biologically active form: amount of drug free and unbound. Factors influence this: first pass hepatic metabolism: chemical instability, drug formulation, plasma protein binding(albumin, alpha 1 acid glycoproteins) Orally administered drugs rarely demonstrate 100% bioavailability. Distribution and dosage regimen: process by which drug reversibly leaves the blood stream and enters body tissues impacted by blood flow, solubility of drug, organ size etc. Fat soluble- move into cells and tissue so distribution is greater. Therapeutic (plasma) concentration: for a drug to exert a therapeutic effect, concentration of drug must fall within therapeutic concentration range of that drug, therapeutic concentration range of drug ([d]th)is always weight by volume mg/l, ug/ml. Ex: therapeutic range 1-3 plasma concentration 2mg therapeutic response plasma concentration 5 cause adverse effects- toxicity bioavailability issue plasma concentration of 0. 5 mg/l below therapeutic range- produce little effect. Duration of action from onset to termination of action.