Elimination Half-Life
The time required for the body to eliminate half of the drug present in the systemic circulation. Elimination half-life reflects the combined effects of metabolism and excretion. For peptide drugs, elimination occurs primarily through proteolytic degradation and renal filtration.
Technical Context
Elimination half-life reflects the terminal phase of drug decline in the body. For peptides with multi-compartmental pharmacokinetics (common for larger peptides and those with tissue binding), there may be an initial rapid distribution phase followed by a slower elimination phase. The elimination half-life is the clinically relevant parameter for determining dosing intervals. At steady state (reached after approximately 4-5 half-lives of regular dosing), the amount of drug eliminated between doses equals the amount administered. For semaglutide with a ~1 week elimination half-life, steady state is reached after approximately 4-5 weeks of weekly dosing.