PPT Slide
Notes:
The pharmacokinetics of a drug describe quantitatively how the body deals with a drug after it is administered 2. When a drug is administered it undergoes absorption, distribution and elimination in the body. After a drug is taken orally, it is quickly absorbed and enters the systemic circulation, and drug concentrations begin to rise. At the same time, the body’s organs (e.g., liver and/or kidneys) work at a constant rate to break down the drug. When the rate at which a drug is being absorbed is equal to the rate at which it is being removed from the plasma the maximum plasma concentration of drug is reached (= Cmax). The time it takes to reach this plasma concentration is called Tmax. After Cmax is reached, the rate of distribution and/or elimination starts to exceed the rate of absorption and so plasma drug levels begin to decline. The time it takes for plasma levels of drug to decrease by half (50%) is called the half-life or t1/2. When a drug is taken repeatedly over time a series of peaks and troughs occur, where the peak is Cmax, and the trough is called Cmin (Cmin reflects the lowest level of drug in the plasma usually just before the next dose is given). The area under the curve (or AUC) represents the total amount of drug in the plasma during a certain time period. With repeated dosing the AUC is usually expressed as the amount of drug in the plasma over a 24 hour period.6
ref: Back D. Essential Pharmacokinetic Principles for Understanding ART. Liverpool HIV Pharmacology Website. http://www.liv.ac.uk/~hivgroup/learning/learning.html