Simvastatin Diltiazem

The interaction of diltiazem with simvastatin has been investigated in 135 patients attending a hypertension clinic (39). Cholesterol reduction in the 19 patients taking diltiazem was 33% compared with 25% in the other 116 patients (median difference 8.6% 95% Cl = 1.1, 12). Multivariate analysis showed that concurrent diltiazem therapy, age, and the starting dose of simvastatin were independent predictors of percentage cholesterol response. The authors concluded that patients who take both diltiazem and simvastatin may need lower doses of simvastatin to achieve the recommended reduction in cholesterol. 

Results from two clinical studies of the interaction of diltiazem with simvastatin showed that diltiazem increased the Cmax of simvastatin (40) and enhanced its cholesterol-reducing effect (39). 

In 10 healthy volunteers taking oral simvastatin 20 mg/ day, diltiazem 120 mg bd for 2 weeks significantly increased the simvastatin Cmax 3.6-fold, the AUC 5-fold,... 

Rhabdomyolysis due to an interaction of simvastatin with diltiazem has been reported (41). 

A 75-year-old-man taking simvastatin 80 mg/day and diltiazem 240 mg/day developed extreme weakness and diffuse muscle pain. All drugs were withdrawn and he underwent hemodialysis. Within 3 weeks his muscle pain disappeared and he regained function in his legs. The activities of creatine kinase and transaminases gradually returned to normal, but he continued to need hemodialysis. 

Yeo KR, Yeo WW, Wallis EJ, Ramsay LE. Enhanced cholesterol reduction by simvastatin in diltiazem-treated patients. Br J Clin Pharmacol 1999 48(4) 610-5. 

Mousa O, Brater DC, Sunblad KJ, Hall SD. The interaction of diltiazem with simvastatin. Clin Pharmacol Ther 2000 67(3) 267-74. 

Peces R, Pobes A. Rhabdomyolysis associated with concurrent use of simvastatin and diltiazem. Nephron 2001 89(l) 117-8. 

CYP3A4 Inhibition Amiodarone, clarithromycin, erythromycin, cimetidine, cyclosporine, fluoxetine fluvoxamine, itraconazole, ketoconazole, nefazodone, verapamil, diltiazem HIV antivirals delaviridine, indanavire, nelfmavire, ritonavire, sequinavire Atorvastatin Lovastatin Simvastatin ... 

CALCIUM CHANNEL BLOCKERS STATINS t plasma levels of atorvastatin, lovastatin and simvastatin case reports of myopathy when atorvastatin and simvastatin are co-administered with diltiazem or verapamil Uncertain, but postulated to be due to inhibition of CYP3A4-mediated metabolism of statins in the intestinal wall. Also, diltiazem and verapamil inhibit intestinal P-gp, which may t the bioavailability of statins Watch for side-effects of statins. It has been suggested that the dose of simvastatin should not exceed 20 mg when given with verapamil, and 40 mg when given with diltiazem... 

However, diltiazem interacts with lovastatin although not with pravastatin (SEDA-24, 511), and an interaction has also been observed with simvastatin in a 75-year-old... 

D Rifampin significantly reduces the plasma concentrations of the calcium channel blockers verapamil, diltiazem, and nifedipine. Diltiazem is a substrate of Gi P3A4 and rifampin is an inducer of CYP3A4. Rifampin does not interact with metoprolol, aspirin, pravastatin, or nitroglycerin. However, if the patient had been on another HMG-CoA reductase inhibitor such as atorvastatin, lova-statin, or simvastatin instead of pravastatin, rifampin would have reduced the plasma concentrations of these agents since they are also metabolized via CYP3A4. 

Clinically important, potentially hazardous interactions with abarelix, acenocoumarol, amisulpride, amprenavir, anisindione, anticoagulants, arsenic, astemizole, carbimazole, celiprolol, ciprofloxacin, dabigatran, degarelix, dicumarol, digoxin, diltiazem, enoxacin, fentanyl, fosamprenavir, gatifloxacin, grapefruit juice, lomefloxacin, methotrexate, moxifloxacin, nilotinib, norfloxacin, ofloxacin, oxprenolol, quinidine, quinolones, rifabutin, rifampin, rifapentine, ritonavir, simvastatin, sparfloxacin, sulpiride, tacrolimus, tipranavir, verapamil, warfarin, zuclopenthixol... 

Clinically important, potentially hazardous interactions with amiloride, aminoglycosides, amphotericin B, ampicillin, anisindione, anticoagulants, armodafinil, atorvastatin, azathioprine, azithromycin, bacampicillin, basiliximab, bezafibrate, bosentan, bupropion, carbenicillin, caspofungin, cholestyramine, clarithromycin, cloxacillin, co-trimoxazole, corticosteroids, cyclophosphamide, daclizumab, danazol, dicloxacillin, dicumarol, digoxin, diltiazem, disulfiram, echinacea, erythromycin, ethotoin, etoposide, ezetimibe, flunisolide, fluoxymesterone, fluvastatin, foscarnet, fosphenytoin, gemfibrozil, hemophilus B vaccine, HMG-CoA reductase inhibitors, imatinib, imipenem/cilastatin, influenza vaccines, ketoconazole, lanreotide, lopinavir, lovastatin, mephenytoin, methicillin, methoxsalen, methylphenidate, methylprednisolone, methyltestosterone, mezlocillin, mizolastine, mycophenolate, nafcillin, nisoldipine, NSAIDs, orlistat, oxacillin, penicillins, phellodendron, phenytoin, pravastatin, prednisolone, prednisone, pristinamycin, ranolazine, red rice yeast, rifabutin, rifampin, rifapentine, ritonavir, rosuvastatin, simvastatin, sirolimus, spironolactone, St John s wort, sulfacetamide, sulfadiazine, sulfamethoxazole, sulfisoxazole, sulfonamides, tacrolimus, telithromycin, tenoxicam, testosterone, ticarcillin, tolvaptan, trabectedin, triamterene, troleandomycin, ursodeoxycholic acid, vaccines, vecuronium, warfarin, zofenopril... 

Clinically important, potentially hazardous interactions with alfentanil, aminophylline, amisulpride, amoxicillin, ampicillin, anticonvulsants, astemizole, atorvastatin, benzodiazepines, bromocriptine, buprenorphine, bupropion, carbamazepine, cilostazol, ciprofloxacin, cisapride, clindamycin, colchicine, cyclosporine, dasatinib, digoxin, dihydroergotamine, diltiazem, disopyramide, enoxacin, eplerenone, ergotamine, eszopiclone, everolimus, fluconazole, fluoxetine, fluvastatin, gatifloxacin, HMG-CoA reductase inhibitors, imatinib, itraconazole, ketoconazole, lomefloxacin, lorazepam, lovastatin, methadone, methylprednisolone, methysergide, midazolam, mizolastine, moxifloxacin, nitrazepam, norfloxacin, ofloxacin, paroxetine, pimozide, pravastatin, quinolones, ranolazine, repaglinide, rupatadine, sertraline, sildenafil, simvastatin, sparfloxacin, sulpiride, tacrolimus, terfenadine, triazolam, troleandomycin, vardenafil, verapamil, vinblastine, warfarin, zaleplon, zolpidem, zuclopenthixol... 

Clinically important, potentially hazardous interactions with cyclosporine, diltiazem, dofetilide, erythromycin, grapefruit, ketoconazole, quinidine, ritonavir, simvastatin, sotalol, thioridazine, verapamil, ziprasidone... 

CYP3A4 Alfentanil Alprazolam Astern izole Carbamazepine Cisapride Cyclosporine Diltiazem Erythromycin Felodipine Fluconazole Itraconazole Ketoconazole Lidocaine Lova statin Midazolam Nifedipine Quinidine Simvastatin Tacrolimus Terfenadine Verapamil... 

The concurrent use of ranolazine and moderate or potent inhibitors of CYP3A4, such as some azoles, diltiazem, grapefruit juice, macrolides, protease inhibitors, or verapamil will result in increased levels of ranolazine, and can predispose the patient to adverse effects including QT interval prolongation. Cimetidine and paroxetine do not interact to a clinically significant extent. Ranolazine may increase levels of ciclosporin, digoxin or simvastatin. 

Jerling M, Huan B-L, Leung K, Chu N, Abdallah H, Hussein Z. Studies to investigate die pharmacokinetic interactions between ranolazine and ketoconazole, diltiazem or simvastatin during combined administration in healthy subjects. J Clin Pharmacol. (2005) 45, 422-33. 

Marked rises in statin plasma levels have been seen when lovastatin or simvastatin were given with diltiazem, and when simvastatin was given with verapamil. Isolated cases of rhabdomyolysis have occurred as a result of these interactions. However, overall, it seems that problems with combinations of statins and calcium-channel blockers (particularly the dihydropyridine-type) are rare. 

Diitiazem. A single 20-mg dose of simvastatin was given to 10 healthy subjects after they had taken sustained-release diltiazem 120 mg twice daily for 2 weeks. Diltiazem caused about a fivefold increase in the simvastatin AUC, a fourfold increase in the maximum serum levels, and a 2.5-fold increase in the half-life."... 

The clinical relevance of the diltiazem interaction was demonstrated in a 53-year-old man, who developed rhabdomyolysis 3 months after diltiazem 30 mg four times daily was added to established treatment with simvastatin 40 mg daily. Both drugs were discontinued and he recovered over the following 10 days. Other similar cases have also been report-ed.3- 3... 

An in vitro study using human liver microsomes also found that diltiazem moderately inhibits simvastatin metabolism. 

Kanathur N, Mathai MG, Byrd RP, Fields CL, Roy TM Simvastatin-diltiazem dn interaction resulting in rhabdomyolysis and hepatitis. TetmMed( QO ) 94,339-41. 

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