Felodipine Erythromycin

Bailey DG, Bend JR, Arnold JM, Tran LT, Spence ID. Erythromycin-felodipine interaction magnitude, mechanism, and comparison with grapefruit juice. Clin Pharmacol Ther 1996 60(l) 25-33. 

Clinically important, potentially hazardous interactions with acetylcysteine, adenosine, aprepitant, aripiprazole, buprenorphine, caffeine, charcoal, clarithromycin, clobazam, dorazepate, clozapine, darunavir, dasatinib, delavirdine, dexamethasone, diltiazem, doxacurium, erythromycin, felodipine, fesoterodine, fosamprenavir, imatinib, influenza vaccines, lacosamide, lapatinib, levetiracetam, lopinavir, methylprednisolone, midazolam, nelfinavir, nilotinib, piracetam, prednisolone, propoxyphene, ritonavir, rivaroxaban, rufinamide, solifenacin, St John s wort, telithromycin, temsirolimus, terbinafine, tolvaptan, troleandomycin, verapamil, voriconazole... 

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

Erythromycin Drugs that may be affected by erythromycin include alfentanil, anticoagulants, benzodiazepines, buspirone, carbamazepine, cisapride, cyclosporine, digoxin, disopyramide, ergot alkaloids, felodipine, fluoroquinolones, HMG-CoA reductase inhibitors, lincosamides, methylprednisolone, penicillins, and theophyllines. Drugs that may affect erythromycin include antacids, pimozide, rifamycins, and theophyllines. 

A4 Midazolam, Testosterone (strongly recommended to use at least two structurally unrelated substrates) Nifedipine, Felodipine, Cyclosporine, Terfenadine, Erythromycin, Simvastatin Ketoconazole (recent evidence that it is also a potent inhibitor of 2C8), Troleandomycin Cyclosporine... 

CALCIUM CHANNEL BLOCKERS MACROLIDES t plasma concentrations of felodipine when co-administered with erythromycin cases of adverse effects of verapamil (bradycardia and 1 BP) with both erythromycin and clarithromycin Erythromycin inhibits CYP3A4-mediated metabolism of felodipine and verapamil. Clarithromycin and erythromycin inhibit intestinal P-gp, which may t the bioavailability of verapamil Monitor PR and BP closely watch for bradycardia and 1 BP. Consider reducing the dose of calcium channel blocker during macrolide therapy... 

Clinically important, potentially hazardous interactions with amlodipine, anisindione, anticoagulants, aprepitant, atorvastatin, barbiturates, benzodiazepines, butabarbital, carbamazepine, chlordiazepoxide, clarithromycin, clonazepam, dorazepate, corticosteroids, cyclosporine, dexamethasone, diazepam, dicumarol, erythromycin, ethotoin, felodipine, flurazepam, fluvastatin, fosphenytoin, isradipine, itraconazole, ketoconazole, lorazepam, lovastatin, mephenytoin, mephobarbital, midazolam, nicardipine, nifedipine, nimodipine, nisoldipine, oxazepam, pentobarbital, phenobarbital, pimozide, pravastatin, primidone, quazepam, rifampin, secobarbital, simvastatin, St John s wort, temazepam, warfarin... 

Midazolam, testosterone, nifedipine, felodipine, cyclosporine, terfenadine, erythromycin, simvastatin... 

Isolated case reports suggest that erythromycin increases felodipine adverse effects (felodipine is metabolized by CYP3A4). 

Erythromycin markedly increases the bioavailability of felodipine. isolated reports describe increased felodipine, nifedipine or verapamil effects and toxicity in patients also given erythromycin. There are also a few reports of verapamil toxicity with clarithromycin, and one with telithromycin. 

Twelve healthy subjects were given felodipine 10 mg before and after taking erythromycin 250 mg four times daily for a day. The felodipine AUC was increased almost threefold by the erythromycin, the maximum plasma levels were more than doubled and the half-life prolonged iiom 6.9 to 11.1 hours. ... 

A hypertensive woman taking felodipine 10 rag daily developed taehy-cardia, flushing and massive ankle oedema within 2 to 3 days of starting to take erythromycin 250 mg twice daily. Her blood pressure had fallen from 120/90 to 110/70 mmHg. She fully recovered within a few days of stopping the erythromycin. ... 

Information seems to be limited but the interaction would appear to be established and clinically important, although its incidence is probably low. Anticipate the need to reduce the felodipine or verapamil dosage if erythromycin or clarithromycin, or possibly also telithromycin, is added. Nifedipine may also interact. Other reports suggests that the cardiac toxicity of erythromycin may be increased by verapamil, and diltiazem, and the authors of one of these reports consider that erythromycin should not be used with CYP3A4 inhibitors (that is diltiazem and verapamil). There seem to be no reports of interactions between any of the other calcium-channel blockers and macrolides. However, because of the theoretical possibility of an interaction, many of the manufacturers of calcium-channel blockers warn of the possibility of increased plasma levels and the need to either avoid use with macrolides such as erythromycin, or troleandomycin, or to monitor and reduce doses where necessary. 

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