Calcium channel blockers drug interactions with

A patient taking chlorpromazine who was given nifedipine [dosage not stated] for 2 days before snidery, developed marked hypotension during surgery, which was eventually controlled with noradrenaline (norepinephrine). Other phenothiazines and calcium-channel blockers may interact similarly, see Antihypertensives + Other drugs that affect blood pressure , p.880. 

Batra S (1990) Interaction of antiestrogens with binding sites for muscarinic cholinergic drugs and calcium channel blockers in cell membranes. Cancer Chemother Pharmacol 26 310-312... 

Ma, B., Prueksaritanont, T. and Lin, J.H. (2000) Drug interactions with calcium channel blockers possible involvement of metabolite-intermediate complexation with CYP3A. Drug Metabolism and Disposition, 28 (2), 125-130. 

Drugs that can significantly interact adversely with calcium-channel blockers include ... 

Drugs that may interact with nitrates include alcohol, alteplase, aspirin, beta-blockers, calcium channel blockers, dihydroergotamine, heparin, nondepolarizing muscle relaxants, phenothiazines, phosphodiesterase inhibitors (eg, sildenafil, tadalafil, vardenafil), and vasodilators. 

The following drug classes may have a potential drug interaction with nevirapine Antiarrhythmics, anticonvulsants, antifungals, calcium channel blockers, cancer chemotherapy (cyclophosphamide), ergot alkaloids, immunosuppressants, motility agents, opiate agonists. 

Mibefradil, a calcium channel blocker, is not toxic when used alone for cardiovascular treatment but on the market it was found to interact with at least 25 other drugs, resulting in increased plasma concentrations and consequently, toxicity. This example was one that increased regulatory focus on drug-drug interactions but only common interactions can be researched premarketing and the commonality of multiple polytherapy, for example in the elderly, cannot be fully legislated. 

In a meta-analysis of megatrials of simvastatin, the overall incidence of myopathy was 0.025% the same proportion of those with myositis had used calcium channel blockers as the proportion overall, suggesting that there is no important interaction between these two groups of drugs (32). 

F-D-C Reports, Inc. Roche Posicor withdrawn due to complexities of drug interactions, Roche says FDA cites 25 drugs dangerous in combination with the calcium channel blocker, June 9, 1998. 

MORACIZINE CALCIUM CHANNEL BLOCKERS Co-administration is associated with t bioavailability of moracizine and 1 availability of diltiazem Postulated that diltiazem inhibits metabolism of moracizine, while moracizine t metabolism of diltiazem the precise mechanism of interaction is uncertain at present Monitor PR, BP and ECG adjust doses of each drug accordingly... 

Single oral or sublingual dose of a calcium channel blocker (e.g., nifedipine) for urgent treatment of hypertension due to drug interaction or dietary tyramine Many side effects cannot be improved with an augmenting agent... 

The calcium channel blocker mibefradil (Posicor ) was removed from the market in 1998. The headline for the Pink Sheets article describing this action was "Posicor Withdrawal Reflects Complexity of Interaction Profile" (59). Products identified as potentially dangerous in combination with mibefradil included cardiac drugs, such as amiodarone, flecainide, and propafenone oncologic products, such as tamoxifen, cyclophosphamide, etoposide, ifosfamide, and vinblastine and the immunosuppressant medications cyclosporine and tacrolimus. The sponsor s decision to withdraw mibefradil was based on the complexity of the drug interaction information that would have to be communicated to ensure safe usage. 

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