PHAR 315 Lecture 16: 16. Design and Optimization of Dosage Regimens
13 Apr 2016
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Document Summary
Given as coninuous iv infusion, drugs accumulate to css css is determined by the dose rate and cl. If cl is known, the maintenance dose rate to achieve the desired concentraion can be determined: target concentraion (css) = maintenance dose rate/cl. At the point that double the dose has accumulated, css is reached: i. e. each new dose drops down to a single dose in one half-life rate in = rate out. [drug] luctuates over the dosing interval between cmax and cmin: the extent of luctuaion depends on the raio of t1/2 to dosing interval, the lower the raio, the greater the luctuaion (and vice versa) Dosing intervals ~equivalent to t1/2 are appropriate when the drug has a t1/2 between 8 24 hours. For drugs with a long t1/2: dosing daily may sill be appropriate (and convenient) the luctuaion over t1/2 is small, but remember, it sill takes 4 to 5 half-lives to reach css.
