| Nimotop tablets should not be administered concomitantly with Nimotop solution. Drugs that affect nimodipine Concurrent twice daily administration of 30mg nimodipine and daily administration of 20mg of the antidepressant fluoxetine to elderly patients resulted in an increase in nimodipine plasma levels, a reduction in fluoxetine levels and a trend towards increased norfluoxetine levels. The daily dose used in patients with subarachnoid haemorrhage is four times the daily dose used in this trial, and as a steady state norfluoxetine level was not achieved, the clinical significance of this interaction in the treatment of aneurysmal subarachnoid haemorrhage (aSAH) is uncertain. Concurrent three times daily administration of 30mg nimodipine and three times daily administration of 10mg of the antidepressant nortriptyline to elderly patients resulted in a slight decrease in nimodipine plasma levels with no effect on nortriptyline plasma levels. The daily dose used in patients with subarachnoid haemorrhage is four times the daily dose used in this trial, thus the clinical significance of this interaction in the treatment of aneurysmal subarachnoid haemorrhage (aSAH) is uncertain. Nimodipine is metabolised via the cytochrome P450 3A4 system, located both in the intestinal mucosa and in the liver. Although no formal interaction studies have been performed to investigate the potential interaction between nimodipine and inhibitors of cytochrome P450 3A4, the potential for drug interaction and increased nimodipine plasma concentrations cannot be excluded. (See section 4.4 Special warnings and precautions for use). Upon co-administration with the following inhibitors of the cytochrome P450 3A4 system the blood pressure should be monitored and, if necessary, an adaption in the nimodipine dose should be considered (see section 4.2 Posology and method of administration):- macrolide antibiotics (e.g. erythromycin)- anti-HIV protease inhibitors (e.g. ritonavir)- azole anti-mycotics (e.g. ketoconazole)- nefazodone.Effects of nimodipine on other drugs Blood pressure lowering drugs Nimodipine may increase the blood pressure lowering effect of concomitant antihypertensives, such as diuretics, beta-blockers, ACE inhibitors, A1-antagonists, other calcium antagonists, alpha-adrenergic blocking agents, PDE5 inhibitors and alpha-methyldopa. If a combination of this type proves unavoidable, particularly careful monitoring of the patient is necessary. Simultaneous intravenous administration of beta-blockers may lead to mutual potentiation of negative inotropic action going as far as decompensated heart failure Renal function can deteriorate if potentially nephrotoxic drugs (e.g. aminoglycosides, cephalosporins, furosemide) are given simultaneously and also in patients whose renal function is already impaired. Renal function must be monitored carefully in such cases and if deterioration is found discontinuation of the treatment should be considered. Animal studies have shown that when nimodipine and zidovudine are administered concomitantly, the AUC for zidovudine was increased, and the volume of distribution and clearance rate decreased. The clinical relevance of this interaction is unknown, but since the side-effect profile of zidovudine is known to be dose related, this interaction should be considered in patients receiving nimodipine and zidovudine concomitantly. Other forms of interaction Since Nimotop solution contains 23.7 vol % ethanol (alcohol), patients should be monitored for any possible interactions with alcohol-incompatible drugs (see Section 4.4 Special warnings and precautions for use). The simultaneous administration of cimetidine or sodium valproate may lead to an increase in the plasma nimodipine concentration. The intake of grapefruit juice is not recommended in combination with nimodipine as it can result in increased plasma nimodipine concentrations due to the inhibition of the oxidative metabolism of dihydropyridines.Interactions shown not to exist A study examining the effects of 90mg nimodipine (in divided doses) on elderly patients receiving haloperidol did not show evidence of potential interactions. It is unclear whether this study is relevant to use in subarachnoid haemorrhage because of the higher dose of nimodipine used. Concomitant administration of oral nimodipine and diazepam, digoxin, glibenclamide, indometacin, ranitidine and warfarin did not reveal any potential for mutual interaction. | |