This document provides an overview of pharmacokinetics, which describes what the body does to a drug. It discusses the processes of absorption, distribution, metabolism, and excretion. It describes factors that affect these processes such as routes of administration, molecular properties, and physiological variables. It also covers concepts such as bioavailability, volume of distribution, half-life, and drug clearance.

1. Pharmacokinetics 2011 Maria Luisa D. Delacruz. MD DLS-HSI College of Medicine Department of Pharmacology

10. Passive Diffusion

25. Determinants of Bioavalability 1. Plasma data

29. Routes of Administration, Bioavailability, and General Characteristics Route Bioavailability (%) Characteristics Intravenous (IV) 100 (by definition) most rapid onset Intramuscular (IM) 75 to ≤ 100 large volumes often feasible; may be painful Subcutaneous (SC) 75 to ≤ 100 smaller volumes than IM; may be painful; slower onset than IV or IM Oral (PO) 5 to < 100 most convenient; first-pass effect may be significant Rectal (PR) 30 to < 100 less first-pass effect than oral Transdermal 80 to ≤ 100 usually very slow absorption; used for lack of first-pass effect; prolonged duration of action

37. Blood brain barrier Placental barrier

54. Half- life (T½) T ½ = 0.7 x Vd Cl Where: Vd = volume of distribution Cl = clearance

56. Steady State

61. Elimination of Drugs Order of Elimination 1. First Order 2. Zero Order

62. Zero order Elimination Time after Drug Administration Drug in Body (mg) Amount of Drug Eliminated Fraction of Drug Eliminated 0 1000 ---- ---- 1 850 150 0.15 2 700 150 0.18 3 550 150 0.21 4 400 150 0.27 5 250 150 0.38 6 100 150 0.60

63. First order Elimination Time after Drug Administration Drug in Body (mg) Amount of Drug Eliminated Fraction of Drug Eliminated 0 1000 ---- ---- 1 850 150 0.15 2 723 127 0.15 3 614 109 0.15 4 522 92 0.15 5 444 78 0.15 6 377 67 0.15

64. “ The gift of true friendship is that it takes us by the hand and reminds us we are not alone in the journey! “