NIMODIPINE- nimodipine capsule, liquid filled
DO NOT ADMINISTER NIMODIPINE INTRAVENOUSLY OR BY OTHER PARENTERAL ROUTES. DEATHS AND SERIOUS, LIFE THREATENING ADVERSE EVENTS HAVE OCCURRED WHEN THE CONTENTS OF NIMODIPINE CAPSULES HAVE BEEN INJECTED PARENTERALLY (See WARNINGS and DOSAGE AND ADMINISTRATION).
Nimodipine belongs to the class of pharmacological agents known as calcium channel blockers. Nimodipine is isopropyl 2 -methoxyethyl 1,4 –dihydro -2,6 –dimethyl -4-(m-nitrophenyl) -3,5-pyridinedicarboxylate. It has a molecular weight of 418.5 and a molecular formula of C 21 H 26 N 2 O 7 . The structural formula is:
Nimodipine is a yellow crystalline substance, practically insoluble in water.
Nimodipine capsules are formulated as soft gelatin capsules for oral administration. Each liquid filled capsule contains 30 mg of nimodipine. In addition the capsules contain the following inactive ingredients: gelatin, glycerin, hypromellose, iron oxide black, kosher glycerin, mannitol, peppermint oil, polyethylene glycol, propylene glycol, sorbitol, sorbitol anhydrides and titanium dioxide.
Nimodipine is a calcium channel blocker. 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; concentrations of nimodipine as high as 12.5 ng/mL have been detected in the cerebrospinal fluid of nimodipine-treated subarachnoid hemorrhage (SAH) patients.
The precise mechanism of action of nimodipine in humans is unknown. Although the clinical studies described below demonstrate a favorable effect of nimodipine on the severity of neurological deficits caused by cerebral vasospasm following SAH, there is no arteriographic evidence that the drug either prevents or relieves the spasm of these arteries. However, whether or not the arteriographic methodology utilized was adequate to detect a clinically meaningful effect, if any, on vasospasm is unknown.
In man, nimodipine is rapidly absorbed after oral administration, and peak concentrations are generally attained within one hour. The terminal elimination half-life is approximately 8 to 9 hours but earlier elimination rates are much more rapid, equivalent to a half-life of 1 to 2 hours; a consequence is the need for frequent (every 4 hours) dosing. There were no signs of accumulation when nimodipine was given three times a day for seven days. Nimodipine is over 95% bound to plasma proteins. The binding was concentration independent over the range of 10 ng/mL to 10 μg/ml. Nimodipine is eliminated almost exclusively in the form of metabolites and less than 1% is recovered in the urine as unchanged drug. Numerous metabolites, all of which are either inactive or considerably less active than the parent compound, have been identified. The metabolism of nimodipine is mediated by CYP3A4. Because of a high first-pass metabolism, the bioavailability of nimodipine averages 13% after oral administration. The bioavailability is significantly increased in patients with hepatic cirrhosis, with C max approximately double that in normals which necessitates lowering the dose in this group of patients (see DOSAGE AND ADMINISTRATION). In a study of 24 healthy male volunteers, administration of nimodipine capsules following a standard breakfast resulted in a 68% lower peak plasma concentration and 38% lower bioavailability relative to dosing under fasted conditions.
In a single parallel-group study involving 24 elderly subjects (aged 59 to 79) and 24 younger subjects (aged 22 to 40), the observed AUC and C max of nimodipine was approximately 2-fold higher in the elderly population compared to the younger study subjects following oral administration (given as a single dose of 30 mg and dosed to steady-state with 30 mg t.i.d. for 6 days). The clinical response to these age-related pharmacokinetic differences, however, was not considered significant. (See PRECAUTIONS, Geriatric Use.)
Nimodipine has been shown, in 4 randomized, double-blind, placebo-controlled trials, to reduce the severity of neurological deficits resulting from vasospasm in patients who have had a recent subarachnoid hemorrhage (SAH). The trials used doses ranging from 20 to 30 mg to 90 mg every 4 hours, with drug given for 21 days in 3 studies, and for at least 18 days in the other. Three of the four trials followed patients for 3 to 6 months. Three of the trials studied relatively well patients, with all or most patients in Hunt and Hess Grades I — III (essentially free of focal deficits after the initial bleed) the fourth studied much sicker patients, Hunt and Hess Grades III — V. Two studies, one U.S., one French, were similar in design, with relatively unimpaired SAH patients randomized to nimodipine or placebo. In each, a judgment was made as to whether any late-developing deficit was due to spasm or other causes, and the deficits were graded. Both studies showed significantly fewer severe deficits due to spasm in the nimodipine group; the second (French) study showed fewer spasm-related deficits of all severities. No effect was seen on deficits not related to spasm.
|Study||Dose||Grade *||Number Analyzed||Any Deficit Due to Spasm||Numbers with Severe Deficit|
|U.S.||20 to 30 mg||I-III|| |
|French||60 mg||I-III|| |
A third, large, study was performed in the United Kingdom in SAH patients with all grades of severity (but 89% were in Grades I-III). Nimodipine was dosed 60 mg every 4 hours. Outcomes were not defined as spasm related or not but there was a significant reduction in the overall rate of infarction and severely disabling neurological outcome at 3 months:
|Good recovery||199 *||169|
|Severe disability||12 †||31|
A Canadian study entered much sicker patients, (Hunt and Hess Grades III-V), who had a high rate of death and disability, and used a dose of 90 mg every 4 hours, but was otherwise similar to the first two studies. Analysis of delayed ischemic deficits, many of which result from spasm, showed a significant reduction in spasm-related deficits. Among analyzed patients (72 nimodipine, 82 placebo), there were the following outcomes.
Delayed Ischemic Deficits
|DID Spasm Alone||8 (11) *||25 (31)||5 (7)*||22 (27)|
|DID Spasm Contributing||18 (25)||21 (26)||16 (22)||17 (21)|
|DID Without Spasm||7 (10)||8 (10)||6 (8)||7 (9)|
|No DID||39 (54)||28 (34)||45 (63)||36 (44)|
When data were combined for the Canadian and the United Kingdom studies, the treatment difference on success rate (i.e., good recovery) on the Glasgow Outcome Scale was 25.3% (nimodipine) versus 10.9% (placebo) for Hunt and Hess Grades IV or V. The table below demonstrates that nimodipine tends to improve good recovery of SAH patients with poor neurological status post-ictus, while decreasing the numbers with severe disability and vegetative survival.
|Glasgow Outcome *||Nimodipine (n=87)||Placebo (n=101)|
A dose-ranging study comparing 30, 60 and 90 mg doses found a generally low rate of spasm-related neurological deficits but no dose response relationship.
INDICATIONS AND USAGE
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 intracranial berry aneurysms regardless of their post-ictus neurological condition (i.e., Hunt and Hess Grades I-V).
The concomitant use of nimodipine with strong inhibitors of CYP3A4 such as some macrolide antibiotics (e.g., clarithromycin, telithromycin), some anti-HIV protease inhibitors (e.g., delaviridine, indinavir, nelfinavir, ritonavir, saquinavir), some azole antimycotics (e.g., ketoconazole, itraconazole, voriconazole) and some antidepressants (e.g., nefazadone) is contraindicated because of a risk of significant hypotension (See PRECAUTIONS, Drug Interactions).
DEATH DUE TO INADVERTENT INTRAVENOUS ADMINISTRATION: DO NOT ADMINISTER NIMODIPINE INTRAVENOUSLY OR BY OTHER PARENTERAL ROUTES. DEATHS AND SERIOUS, LIFE THREATENING ADVERSE EVENTS, INCLUDING CARDIAC ARREST, CARDIOVASCULAR COLLAPSE, HYPOTENSION, AND BRADYCARDIA, HAVE OCCURRED WHEN THE CONTENTS OF NIMODIPINE CAPSULES HAVE BEEN INJECTED PARENTERALLY (SEE DOSAGE AND ADMINISTRATION).
Reduced Efficacy with CYP3A4 Inducers: Concomitant use of strong CYP3A4 inducers (e.g. rifampin, phenobarbital, phenytoin, carbamazepine, St John’s wort) and nimodipine should generally be avoided, as nimodipine plasma concentration and efficacy may be very significantly reduced (see PRECAUTIONS, Drug Interactions).
Moderate and weak inducers of CYP3A4 may also reduce the efficacy of nimodipine to a lesser extent. Patients on these should be closely monitored for lack of effectiveness, and a nimodipine dosage increase may be required. Moderate and weak CYP3A4 inhibitors include, for example: amprenavir, aprepitant, armodafinil, bosentan, efavirenz, etravirine, echinacea, modafinil, nafcillin, pioglitazone, prednisone and rufinamide.
Blood Pressure: Nimodipine has the hemodynamic effects expected of a calcium channel blocker, although they are generally not marked. However, intravenous administration of the contents of nimodipine capsules has resulted in serious adverse consequences including death, cardiac arrest, cardiovascular collapse, hypotension, and bradycardia. In patients with subarachnoid haemorrhage given nimodipine in clinical studies, about 5% were reported to have had lowering of the blood pressure and about 1% left the study because of this (not all could be attributed to nimodipine). Nevertheless, blood pressure should be carefully monitored during treatment with nimodipine based on its known pharmacology and the known effects of calcium channel blockers. (see WARNINGS and DOSAGE AND ADMINISTRATION).
Hepatic Disease: The metabolism of nimodipine is decreased in patients with impaired hepatic function. Such patients should have their blood pressure and pulse rate monitored closely and should be given a lower dose (see DOSAGE AND ADMINISTRATION).
Intestinal pseudo-obstruction and ileus have been reported rarely in patients treated with nimodipne. A causal relationship has not been established. The condition has responded to conservative management.
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.
In addition, the blood pressure lowering effects of antihypertensives could be enhanced when taken concomitantly with nimodipine.
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