indication

For use as an adjunct to improve neurologic outcome following subarachnoid hemorrhage (SAH) from ruptured intracranial berry aneurysms by reducing the incidence and severity of ischemic deficits.

pharmacology

Nimodipine belongs to the class of pharmacological agents known as calcium channel blockers. Nimodipine is indicated for the improvement of neurological outcome by reducing the incidence and severity of ischemic deficits in patients with subarachnoid hemorrhage from ruptured congenital aneurysms who are in good neurological condition post-ictus (e.g., Hunt and Hess Grades I-III). The contractile processes of smooth muscle cells are dependent upon calcium ions, which enter these cells during depolarization as slow ionic transmembrane currents. Nimodipine inhibits calcium ion transfer into these cells and thus inhibits contractions of vascular smooth muscle. In animal experiments, nimodipine had a greater effect on cerebral arteries than on arteries elsewhere in the body perhaps because it is highly lipophilic, allowing it to cross the blood brain barrier.

mechanism of action

Although the precise mechanism of action is not known, nimodipine blocks intracellular influx of calcium through voltage-dependent and receptor-operated slow calcium channels across the membranes of myocardial, vascular smooth muscle, and neuronal cells. Nimodipine binds specifically to L-type voltage-gated calcium channels. The inhibition of calcium ion transfer results in the inhibition of vascular smooth muscle contraction. Evidence suggests that the dilation of small cerebral resistance vessels, with a resultant increase in collateral circulation, and/or a direct effect involving the prevention of calcium overload in neurons may be responsible for nimodipine's clinical effect in patients with subarachnoid hemorrhage.

toxicity

Symptoms of overdosage would be expected to be related to cardiovascular effects such as excessive peripheral vasodilation with marked systemic hypotension.

biotransformation

Hepatic metabolism via cytochrome P450 3A4.

absorption

Bioavailability is 100% following intravenous administration and 3-30% following oral administration due to extensive first-pass metabolism.

half life

1.7-9 hours

drug interactions

Cimetidine: Cimetidine increases the effect of the calcium channel blocker, nimodipine.

Quinupristin: This combination presents an increased risk of toxicity

Telithromycin: Telithromycin may reduce clearance of Nimodipine. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Nimodipine if Telithromycin is initiated, discontinued or dose changed.

Thiopental: The CYP3A4 inducer, Thiopental, may increase the metabolism and clearance of Nimodipine, a CYP3A4 substrate. Monitor for changes in the therapeutic/adverse effects of Nimodipine if Thiopental is initiated, discontinued or dose changed.

Tipranavir: Tipranavir may decrease the metabolism and clearance of the calcium channel blocker, Nimodipine. Monitor for changes in Nimodipine therapeutic and adverse effects if Tipranavir is initiated, discontinued or dose changed.

Treprostinil: Additive hypotensive effect. Monitor antihypertensive therapy during concomitant use.

Valproic Acid: Valproic acid increases the effect of nimodipine

Voriconazole: Voriconazole, a strong CYP3A4 inhibitor, may increase the serum concentration of nimodipine by decreasing its metabolism. Monitor for changes in the therapeutic and adverse effects of nimodipine if voriconazole is initiated, discontinued or dose changed.