It is possible that the cardiovascular action of other calcium channel blockers could be enhanced by the addition of Nimotop.
In Europe, Nimotop was observed to occasionally intensify the effect of antihypertensive compounds taken concomitantly by patients suffering from hypertension; this phenomenon was not observed in North American clinical trials.
Nimodipine is metabolized via the cytochrome P450 3A4 system located both in the intestinal mucosa and in the liver. Drugs that are known to either inhibit or to induce this enzyme system may therefore alter the first pass or the clearance of nimodipine.
Drugs, which are known inhibitors of the cytochrome P450 3A4 system and therefore may lead to increased plasma concentrations of nimodipine are, e.g.:
- macrolide antibiotics (e.g., erythromycin),
- anti-HIV protease inhibitors (e.g., ritonavir),
- azole antimycotics (e.g., ketoconazole),
- the antidepressants nefazodone and fluoxetine,
- valproic acid.
Upon co-administration with these drugs, the blood pressure should be monitored and, if necessary, a reduction of the nimodipine dose should be considered.
Drugs that affect nimodipine:
The extent as well the duration of interactions should be taken into account when administering nimodipine together with the following drugs:
From the experience with other calcium antagonists it has to be expected that rifampin accelerates the metabolism of nimodipine due to enzyme induction. Thus, efficacy of nimodipine could be significantly reduced when concomitantly administered with rifampin. The use of nimodipine in combination with rifampin is therefore contraindicated (see CONTRAINDICATIONS ).
There have been no reports of overdosage from the oral administration of Nimotop.
Symptoms of intoxication
Symptoms of acute overdosage to be anticipated are marked lowering of the blood pressure, tachycardia or bradycardia, and gastrointestinal complaints and nausea.
Treatment of intoxication
In the event of acute overdosage treatment with nimodipine must be discontinued immediately. Emergency measures should be governed by the symptoms. Gastric lavage with addition of charcoal should be considered as an emergency therapeutic measure. If there is a marked fall in blood pressure, dopamine or noradrenaline can be administered intravenously. Since no specific antidote is known, subsequent treatment for other side effects should be governed by the most prominent symptoms.
Since Nimotop is highly protein-bound, dialysis is not likely to be of benefit.
Nimotop capsules must not be used in patients with hypersensitivity to nimodipine or to any of the excipients.
The use of nimodipine in combination with rifampin is contraindicated as efficacy of nimodipine capsules could be significantly reduced when concomitantly administered with rifampin. (See PRECAUTIONS, Drug Interactions).
The concomitant use of oral nimodipine and the antiepileptic drugs phenobarbital, phenytoin or carbamazepine is contraindicated as efficacy of nimodipine capsules could be significantly reduced. (See PRECAUTIONS, Drug Interactions).