Half-life

In pharmacology, the half-life of a drug is the duration of time required for the concentration of the substance in the bloodstream to be reduced by exactly one-half. This measurement is crucial for determining dosing frequency and understanding how long a drug will remain active in the body after the final dose is administered.

For medications like tirzepatide, which has a half-life of approximately five days, the drug remains at therapeutic levels for a significant period. This long half-life is what enables 'cycling' strategies; because the drug clears slowly, the patient can experience continued appetite suppression and metabolic benefits even during weeks when no active injection is taken, as the plasma concentration tapers off gradually rather than dropping abruptly.