PHAR 300 Lecture Notes - Lecture 7: Tegmentum, Tissue Culture, Problem Gambling
8 Dec 2017
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Document Summary
Review dosing schedules: half-life: the time needed for half the drug to be eliminated in the body. Start with 1 unit of drug administered. After 1 hour, the concentration decreases by half to 0. 5 unit. After 4 half-lives, the concentration is at 0. 0625 unit which is too small to be biologically active and produce a therapeutic effect: the half-life is also important to determine how long the effects of an overdose will last. It is also important in determining how often the drug needs to be administered in order to keep the concentration within the therapeutic index. Ex: fig 1 shows examples of four different dosing schedules: (a) 1000mg daily: concentrations that are toxic and too low to be effective. (b) 500mg 2 times daily, smaller dose: concentration is still slightly too high. (c) 333mg 3 times daily, smaller: still too close to toxic concentrations.
