Answer to Practice Problem #1 Hepatic Clearance Tutorial:

 

We need to consider each route separately. Since the peak concentration will not change in the presence of cimetidine after iv administration, the maximal intensity of effect will not change. In addition, the time to onset will not change when the drug is given by iv bolus. However, the duration of effect will be prolonged since the slowed elimination will maintain concentrations above the minimally effective concentration for a longer period of time. After oral administration, the peak concentration is increased, therefore, the maximal intensity is increased in the presence of cimetidine. Moreover, then prolonged elimination increases the duration of action. The onset might be somewhat faster … since you are slowing elimination and the drug will accumulate more quickly, which has the effect of causing the drug to reach the minimally effective concentration more quickly – though it would probably be hard to detect this difference.

 

 

 

Last revised 07/13/05

 

ã 2005 -  Craig K. Svensson, Pharm.D., Ph.D.

 

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