How is clearance defined in pharmacokinetics?

Clearance is defined as the rate at which a drug is removed from the body. This concept is crucial in pharmacokinetics because it helps determine how long a drug will remain effective in the systemic circulation and can influence dosing regimens. It is expressed as a volume of plasma from which the drug is completely removed per unit of time, typically measured in units such as liters per hour.

Understanding clearance aids in predicting the drug's behavior over time, which is essential for ensuring therapeutic effectiveness while minimizing toxicity. It accounts for various routes of elimination, including metabolism and excretion via the kidneys or liver. By knowing the clearance of a drug, healthcare providers can adjust dosages appropriately to maintain desirable drug levels in the blood.