We define a new parameter, “operational multiple dosing half-life” ( t 1/2, op), as equal to the dosing interval at steady-state where the maximum concentration at steady-state is twice the maximum concentration found for the first dose. An apparent multiple dosing half-life ( t 1/2, app) was determined from peak and trough steady-state ratios and found to be significantly less than reported terminal t 1/2s for eight orally dosed drugs with t 1/2,z values longer than one day. However, accumulation at steady state may be markedly over predicted utilizing t 1/2, z. Alternatively, terminal half-life ( t 1/2,z) is utilized as the single defining t 1/2 for most drugs. Half-life ( t 1/2) is the oldest but least well understood pharmacokinetic parameter, because most definitions are related to hypothetical 1-compartment body models that don’t describe most drugs in humans.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |