Pharmacokinetics

Question 1

Factors Affecting Vd

Answer 1

Uremia, burn patients → ↓ albumin binding → ↑ Vd

Pregnancy, ascites, edema → ↓ plasma concentration(increased nonvascular fluid-less drug in blood) → ↑Vd

Dehydration → ↑ plasma concentration → ↓ Vd

CHF, ESRD → ↓ clearance of drugs excreted by kidneys → ↓ Vd or ↑ Vd

Question 2

Factors Affecting Drug Half life: Vd

Answer 2

Decreased total body water (aging, dehydration) and muscle mass (aging) → ↓Vd → ↓ t1/2

􀁺 Obesity → ↑ tissue binding → ↑ Vd → ↑ t1/2

􀁺 Increased nonvascular fluid (pregnancy, ascites, edema) → ↑ Vd→ ↑ t1/2

􀁺 Decreased albumin (hepatic disease, uremia, burns) → ↓ proteinbinding → ↑ Vd → ↑ t1/2

Question 3

Factors Affecting Drug Half life: CL

Answer 3

CYP induction → ↑ metabolism → ↑ CL → ↓t1/2

􀁺 CYP inhibition → ↓ metabolism → ↓ CL → ↑ t1/2

􀁺 Cardiac failure → ↓ CL → ↑ t1/2

􀁺 Hepatic failure → ↓ CL → ↑ t1/2

􀁺 Renal failure → ↓ CL → ↑ t1/2