Pharmacokinetics made easy 11 Designing dose regimens ... | 合法藥品大搜索

1showsthatwherethedosingintervalisequaltothehalf-lifeofthedrug,aloadingdoseoftwicethemaintenancedoseimmediatelyachievessteadystate.

Information from previous articles in this series can be used to design dose regimens.

1. Intravenous infusion and intermittent intravenous bolus dosing Continuous intravenous infusions and intermittent intravenous boluses are common ways of administering drugs such as gentamicin, lignocaine and theophylline. Fig. 1 illustrates the plasma concentration time course of theophylline given intravenously. Given as a continuous infusion, the drug accumulates to a steady state concentration (Css) determined only by the dose rate and clearance (CL) (see Article 1 Clearance Aust Prescr 1988;11:12-3). The maintenance dose rate to achieve a desired concentration can be calculated if the clearance is known.

equation 1 Desired concentration (Css) = maintenance dose rate / CL The time to reach steady state is determined by the half-life (3-5 half-lives, see Article 3 Half-life Aust Prescr 198...