PHAR 300 Lecture Notes - Lecture 5: Breathalyzer, Half-Life, Nephron

• School: McGill University
• Department: Pharmacology and Therapeutics
• Course: PHAR 300
• Professor: Edith Zorychta

Document Summary

Drugs can be: protein-bound drugs can"t enter the kidney but there"s an equilibrium, sometimes the kidney can excrete the drug without metabolism, filtered out (bowman"s capsule, secreted. Ex: through sweat and saliva, bile: exhaled. Kidney processes that get rid of the drug. Calculated as concentration before concentration after. Measure amount coming out of urine, for example. Impacted by ph in kidney: hepatic clearance. Total body clearance: sum of ways your body gets rig of the drug. Look at drug administration and where it is moving in the body. Distribution phase is usually fast (alpha slope) Extrapolate back from the elimination phase (to t=0) gives us the hypothetical drug concentration predicted if the distribution was achieved instantly. The half-life of the drug is the time it takes to drop its concentration by half. 4 half-lives are necessary to eliminate the drug. Tells you when to administer the drug and the danger period during an overdose.