04 Drug Elimination

Zero Order

• for each unit of time (horizontal line), eliminate 5 units

• rate is constant x drug concentration to 0th power

• know the drugs

First order

• unit change is varying, percent change same

• time it takes to fall from 4 to 2 is same as time takes from 2 to 1

Elimination

• more blood flow = more elimination

• at high concentration of drug, drug operating at Vmax rate = zero order operation

Urine pH

• A- and B+ excreted

• acidic urine: favors HA form and reabsorption

• alkaline urine: favors BOH and reabsorption

Metabolism

Phase 1

• active, not ready for excretion

• prodrug to drug

Phase 2

• very polar inactive to kidney for excretion