Clinical Pharmacokinetics 🏥

Question 1

Clearance

Answer 1

Clearance is defined as the volume of blood cleared of drug per unit time and predicts the rate of elimination in relation to drug concentration.

Question 2

Half-life

Answer 2

Half-life is the time taken for the plasma concentration of a drug to reduce by half and is related to volume of distribution and clearance in determining dosing regimens.

Question 3

Volume of Distribution

Answer 3

Volume of distribution is a measure of the apparent space in the body available to contain the drug, allowing for the conversion of concentrations to amounts.

Question 4

Drug Infusion

Answer 4

During constant IV infusion, every half-life the drug concentration changes by 50% of the difference between the steady-state concentration and the current concentration.

Question 5

Factors Affecting Half-life

Answer 5

Obesity, pathologic fluid accumulation, CYP induction, CYP inhibition, aging, cardiac failure, liver failure, and renal failure can impact the half-life of drugs.

Question 6

Zero Order Elimination

Answer 6

Observed in drugs like aspirin at high doses, ethanol, and phenytoin, where a constant amount of drug is eliminated per unit of time regardless of drug concentration.

Question 7

Clinical Pharmacokinetics

Answer 7

Clinical pharmacokinetics aims to design dosage regimens to optimize therapeutic response of a drug and minimize the chance of adverse reactions.

Question 8

First-order kinetics

Answer 8

First-order kinetics of drug elimination describes drugs where the rate of drug elimination is directly proportional to the drug concentration, often observed due to unsaturated physiological elimination mechanisms.

Question 9

First Order Kinetics

Answer 9

A constant fraction of the drug is eliminated per unit of time, and plotting the log of concentration against time yields a straight line.

Question 10

Half-life

Answer 10

The time required to reduce the amount of drug in the body by 50% during elimination, and determines the rate at which blood concentration rises and falls.

Question 11

Half-life Graphical Determination

Answer 11

Half-life can also be determined graphically by plotting the percentage of steady-state plasma concentration against time.

Question 12

Saturation Kinetics

Answer 12

Some drugs exhibit saturation kinetics of elimination where the elimination rate is maximal and independent of drug concentration, resembling zero-order kinetics.