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

  • Aand 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