Quantitative Pharmacokinetics

Question 1

Kinetic Order

Answer 1

Dependence of rate of a process on the exponent of the drug concentration

Question 2

First order kinetics

Answer 2

[drug]^1 = [drug] So, rate is directly dependent on [drug] and a constant percent is lost per unit time. Michaelis-Menten kinetics
Examples: drug metabolism under normal circumstances and renal excretion behave this way

Question 3

Zero order kinetics

Answer 3

[drug]^0 = 1 So, rate is independent of [drug] and a constant amount is lost per unit time. Examples: overdose and drug administration

Question 4

Rate of drug input

Answer 4

f(D/T) where f=fractional absorption D=dose and T=time

Question 5

Half-life

Answer 5

Time required for 50% clearance, only applies to first order processes. t1/2=(0.7 * Vd)/CL where CL is clearance.

Question 6

Clearance

Answer 6

Predicts rate of elimination in relation to drug concentration CL=(Vd)(Ke) only for 1st order

Question 7

Time course of drug effects

Answer 7

Immediate (may not be linearly proportional to concentration) Delayed (effected by distribution, tight binding, slow turnover of physiologic substance) Cumulative effects

Question 8

Steady State

Answer 8

Plateau phase: Input rate = output rate

f(D/T)=(Css)(Vd)(Ke)

Question 9

Loading Dose

Answer 9

Achieve steady state in one dose

LD=(Css)(Vd)

Question 10

Maintenance Dose

Answer 10

MD=(CL)(Css)

Question 11

Ke

Answer 11

=0.7/(t1/2)