What is the recommended dosing regimen of nimodipine for aneurysmal subarachnoid hemorrhage?

Nimodipine Dosing in Subarachnoid Hemorrhage

The recommended dose of nimodipine for aneurysmal subarachnoid hemorrhage is 60 mg orally every 4 hours for 21 consecutive days, starting within 96 hours of hemorrhage onset. 1, 2

Standard Dosing Protocol

• Dose: 60 mg (two 30 mg capsules) every 4 hours 2
• Duration: 21 consecutive days 1, 2
• Timing: Initiate within 96 hours of SAH onset 3, 2
• Route: Oral administration, preferably 1 hour before or 2 hours after meals 2

Alternative Administration for Patients Unable to Swallow

If the patient cannot swallow (e.g., unconscious, intubated, perioperative): 2

• Pierce both ends of the capsule with an 18-gauge needle 2
• Extract contents with a parenteral syringe, then transfer to an oral/enteral syringe labeled "Not for IV Use" 2
• Administer via nasogastric tube or PEG tube 2
• Flush with 30 mL normal saline 2

Critical warning: Never administer nimodipine intravenously—this can cause life-threatening hypotension requiring vasopressor support. 2

Managing Hypotension While Maintaining Full Dose

The most important principle: Continue nimodipine at full dose even if vasopressors are required. 4

• Hypotension occurs in up to 78% of patients on standard dosing 5
• Concurrent vasopressor use is NOT a contraindication to nimodipine 4
• Attempt standard medical interventions to maintain blood pressure before reducing nimodipine dose 4, 3
• Once the aneurysm is secured, blood pressure can be safely augmented with vasopressors without rebleeding risk 4
• Maintain euvolemia (not hypervolemia) while titrating vasopressors 4, 3

When Dose Reduction May Be Necessary

Only reduce the dose after exhausting blood pressure support measures, as dose reduction is associated with worse outcomes. 6

• If hypotension persists despite vasopressor support, reduce to 30 mg every 4 hours 2
• Patients with severe liver dysfunction (cirrhosis) should start at 30 mg every 4 hours due to increased bioavailability 2
• Application of full nimodipine dosage decreases risk of unfavorable outcome (OR 0.895, p = 0.029) 6

Critical Importance of Consistent Dosing

Disruption of nimodipine therapy directly correlates with increased delayed cerebral ischemia (ρ=0.431, P<0.001). 4

• Only 33-44% of patients in real-world practice complete the full 21-day course at standard dosing 7, 6
• Nimodipine is the only FDA-approved medication proven to prevent delayed cerebral ischemia and improve neurological outcomes in aSAH 1, 3
• The benefit extends beyond vasospasm prevention to include neuroprotective effects 3

Common Pitfalls to Avoid

• Do not discontinue nimodipine simply because vasopressors are needed—this is manageable, not a contraindication 4
• Do not discharge patients before 21 days without prescribing nimodipine to continue at home—47% of patients in one study were discharged early without continuation orders 7
• Avoid grapefruit juice during treatment as it interferes with metabolism 2
• Do not use strong CYP3A4 inhibitors (contraindicated) or strong inducers (generally avoid) concomitantly 2
• Monitor closely if using moderate CYP3A4 inhibitors or inducers—may require dose adjustment 2

Evidence Quality Note

The Class I, Level A recommendation from the American Heart Association/American Stroke Association represents the highest quality evidence, supported by multiple randomized controlled trials demonstrating improved neurological outcomes. 1 The FDA labeling reinforces this exact dosing regimen. 2