Interaction between Zalcitabine and Orlistat
Moderate Absorption

ID DDInter1956 and DDInter1348
Interaction Orlistat may theoretically reduce the gastrointestinal absorption and therapeutic efficacy of antiretroviral agents. The mechanism may involve retention of lipophilic medicines in the gastrointestinal tract or reduced gastrointestinal tract transit time.
Management The potential reduction in antiretroviral efficacy should be considered before initiating treatment with orlistat. Patients who take antiretroviral medications should be advised to consult their physician before using the non-prescription brand of orlistat.
References
Alternative for Zalcitabine J05A
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Alternative for Orlistat A08A

Potential Metabolism Interactions

Substrate-Substrate Interaction:If more than one drug is metabolized by the same CYP, it is possible that its metabolism is inhibited because of the competition between the drugs. That means, it can be useful to lower the dosage of the drugs in the drug-cocktail because they remain longer in the organism than in monotherapy.
Inhibitor-Inhibitor Interaction:Combining two or more inhibitors of one CYP, should be compensated by lowering the dosage of these drugs because the metabolism is reduced and the drugs remain longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.
Inhibitor-Substrate Interaction:Combining drugs that have inhibitory effect and are substrates of one particular CYP, should be compensated by lowering the dosage. They rest longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.