Nimodipine

Nimodipine (marketed by Bayer as Nimotop®) is a dihydropyridine calcium channel blocker originally developed for the treatment of high blood pressure. It is not frequently used for this indication, but has shown good results in preventing a major complication of subarachnoid haemorrhage (a form of cerebral haemorrhage) termed vasospasm; this is now the main use of nimodipine.

Dosage

The regular dosage is 60 mg tablets four hourly. If the patient is unable to take tablets orally, it is given via intravenous infusion at a rate of 1-2 mg/hour (lower dosage if the body weight is <70 kg or blood pressure is too low).

Usage

Because it has some selectivity for cerebral vasculature, nimodipine's main use is in the prevention of cerebral vasospasm and resultant ischaemia, a complication of subarachnoid haemorrhage (a form of cerebral bleed). Its administration begins within 4 days of a subarachnoid haemorrhage and is continued for three weeks. If blood pressure drops by over 5%, dosage is adjusted. There is still controversy regarding the use of intravenous nimodipine on a routine basis (Allen et al 1983, Janjua & Mayer 2003).

A 2003 trial (Belfort et al) found nimodipine was inferior to magnesium sulfate in preventing seizures in women with severe preeclampsia.

There is some indication that nimodipine, either alone or in conjunction with carbamazepine, may be an effective therapy for sufferers of ultradian and rapid-cycling bipolar disorder. (Pazzaglia et al 1993, Pazzaglia et al 1998).

Mode of action

Nimodipine binds specifically to L-type voltage-gated calcium channels. There are numerous theories about its mechanism in preventing vasospasm, but none are conclusive.

Contraindications & side-effects

Nimodipine is associated with low blood pressure, flushing and sweating, oedema, nausea and other gastrointestinal problems. It is contraindicated in unstable angina or an episode of myocardial infarction more recent than one month.

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