Mathematical considerations in the estimation of peak drug concentrations under uniform and nonuniform dosing conditions.

General one-compartment model equations for computing peak drug concentrations following uniform and nonuniform dosing are discussed. Evidence is presented to confirm that time of peak concentration times (tmax) following oral or intramuscular dosing may be highly variable when doses, dosing intervals, or drug elimination rates are changing. A new tmax equation (t delta max) is presented which can provide correct times for peak concentrations under both fixed and variable dosing, and can be used when other tmax equations apply. Clinical examples involving its application are shown.