Interaction between Nisoldipine and Carbamazepine
Major Metabolism

ID DDInter1298 and DDInter293
Interaction Coadministration with carbamazepine may significantly decrease the plasma concentrations and pharmacologic effects of calcium channel blockers (CCBs), especially the dihydropyridines (e.g., amlodipine, felodipine, nicardipine, nifedipine, nimodipine, nisoldipine). The proposed mechanism is carbamazepine induction of CYP450-mediated metabolism.
Management Concomitant use of calcium channel blockers with potent CYP450 3A4 inducers such as carbamazepine should generally be avoided. If coadministration is necessary, pharmacologic response should be monitored more closely following the initiation, discontinuation or change of dosage of carbamazepine, and the CCB dosage adjusted accordingly.
References
Alternative for Nisoldipine C08C
Alternative for Carbamazepine N03A
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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.