Nifedipine Irinotecan

CALCIUM CHANNEL BLOCKERS IRINOTECAN Risk oft serum concentrations of irinotecan with nifedipine. No cases of toxicity reported Inhibition of hepatic microsomal enzymes but exact mechanism uncertain at present Watch for symptoms/signs of toxicity (especially diarrhoea, an early manifestation of acute cholinergic syndrome)... 

In studies in human liver microsomes, nifedipine, clonazepam, methylprednisolone, omeprazole, and vinorelbine had significant effects on the metabolism of irinotecan. However, only the effect of vinorelbine occurred at a concentration considered clinically relevant. Similarly, of various potential carboxylesterase inhibitors, only physostigmine was considered sufficiently potent to possibly inhibit irinotecan activation. Further study is needed to assess the clinical relevance of these findings. 

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