Fluoxetine Calcium-channel blockers

Drugs that may affect cyclosporine include allopurinol, amiodarone, androgens (eg, danazol, methyltestosterone), anticonvulsants (eg, carbamazepine, phenobarbital, phenytoin), azole antifungals (eg, fluconazole, ketoconazole), beta-blockers, bosentan, bromocriptine, calcium channel blockers, colchicine, oral contraceptives, corticosteroids, fluoroquinolones (eg, ciprofloxacin), foscarnet, HMG-CoA reductase inhibitors, imipenem-cilastatin, macrolide antibiotics, methotrexate, metoclopramide, nafcillin, nefazodone, orlistat, potassium-sparing diuretics, probucol, rifamycins (rifampin, rifabutin), serotonin reuptake inhibitors (SSRIs eg, fluoxetine, sertraline),... 

Omeprazole, like cimetidine, can impair benzodiazepine metabolism and lead to adverse effects (SEDA-18, 43). Other drugs, including antibiotics (erythromycin, chloramphenicol, isoniazid), antifungal drugs (ketoconazole, itraconazole, and analogues), some SSRIs (fluoxetine, paroxetine), other antidepressants (nefazodone), protease inhibitors (saquinavir), opioids (fentanyl), calcium channel blockers (diltiazem, verapamil), and disulfiram also compete for hepatic oxidative pathways that metabolize most benzodiazepines, as well as zolpidem, zopiclone, and buspirone (SEDA-22,39) (SEDA-22,41). 

CALCIUM CHANNEL BLOCKERS SSRIs Reports oft serum levels of nimodipine and episodes of adverse effects of nifedipine and verapamil (oedema, flushing and i BP) attributed to t levels when co-administered with fluoxetine Fluoxetine inhibits CYP3A4-mediated metabolism of calcium channel blockers. It also inhibits intestinal P-gp, which may t the bioavailability of verapamil Monitor BP at least weekly until stable. Warn patients to report symptoms of hypotension (lightheadedness, dizziness on standing, etc.). Consider reducing the dose of calcium channel blocker or using an alternative antidepressant... 

The combination of fluoxetine with the calcium-channel blockers nifedipine and verapamil has been reported to be associated with signs of toxicity such as edema, nausea and flushing. 

The calcium-channel blockers are metabolised by the cytochrome P450 isoenzyme CYP3A4, which can be inhibited by fluoxetine. This results in a marked reduction in the metabolism and clearance of the calcium-channel blockers. The reactions reported appear to be the exaggeration of the adverse effects of these calcium-channel blockers, possibly due to an increase in their levels. 

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