💡 Key Point: Nimodipine is given after aneurysmal subarachnoid haemorrhage (SAH) to reduce the risk of delayed cerebral vasospasm and secondary ischaemia. It should be started as soon as possible (within 4 days) and continued for 21 days under specialist guidance.

🧠 About

Used in aneurysmal SAH and occasionally in Reversible Cerebral Vasoconstriction Syndrome (RCVS) under expert supervision.
Derived from the dihydropyridine class of calcium channel blockers, but uniquely selective for cerebral vessels rather than cardiac tissue.
Always check the BNF link here for updated dosing and interactions.

⚙️ Mode of Action

Nimodipine blocks L-type calcium channels in vascular smooth muscle, preventing calcium influx and vasoconstriction.
It has minimal cardiac effects - unlike verapamil or diltiazem, it does not significantly depress AV node conduction.
Highly lipophilic, enabling good penetration across the blood–brain barrier and selective action on cerebral arteries.
By reducing vasospasm, it lowers the incidence of delayed cerebral ischaemia following SAH.

🎯 Indications & Dosing

Indication	Route	Typical Dose / Duration	Notes
Aneurysmal SAH	Oral / NG	60 mg (2 × 30 mg) every 4 hours for 21 days	Start within 4 days of SAH. If hypotension develops, reduce to 30 mg 4-hourly.
Unable to take orally	IV infusion	0.5–2 mg/hour (max 2 mg/h)	Begin at 0.5 mg/h (or lower if <70 kg), increase after 2 h if BP stable.
RCVS (off-label)	Oral / IV	As per SAH protocol (under neurologist guidance)	Used to reduce vasoconstriction and headache frequency.

💊 Administration Notes

Give via NG tube or PEG if patient is nil-by-mouth. The gel capsule can be pierced and contents withdrawn with a syringe.
Monitor BP closely during the first 48 hours - hypotension limits therapy.
If hypotensive, reduce dose rather than stopping completely to maintain cerebral protection.

⚖️ Interactions & Precautions

Metabolised by CYP3A4 - avoid concurrent strong inhibitors (e.g. clarithromycin, erythromycin, ketoconazole).
🍊 Avoid grapefruit juice - increases plasma concentration and risk of hypotension.
Reduce dose in hepatic impairment.
Monitor BP, HR, and neurological status throughout treatment.

🚫 Contraindications

Known hypersensitivity to nimodipine or dihydropyridines.
Severe hypotension (systolic <100 mmHg).
Concurrent IV administration with other calcium channel blockers (risk of profound hypotension).

⚠️ Side Effects

🩸 Hypotension (most common, dose-related).
💓 Bradycardia or reflex tachycardia.
🧬 Thrombocytopenia (rare).
😵 Headache, flushing, nausea, or dizziness due to vasodilatation.
🧠 In severe hypotension → risk of reduced cerebral perfusion.

🩺 Clinical Pearls

💡 Vasospasm risk peaks at days 4–10 after SAH - ensure nimodipine is given continuously during this window.
🧠 Reduction in delayed ischaemic neurological deficit (DIND) is the main evidence-based benefit - not mortality reduction.
🫀 In hypotensive or septic patients, balance cerebral perfusion pressure before giving full-dose nimodipine.
💉 Avoid IV boluses - infusion should be controlled and titrated.
🧾 Document baseline BP and neurological status before initiation.

📚 References

BNF: Nimodipine
Pickard JD et al. Effect of Nimodipine on Cerebral Infarction and Outcome After SAH (British Aneurysm Nimodipine Trial). BMJ 1989;298:636–642.
RCP Stroke Guidelines (2023): Acute SAH Management.
AHA/ASA Guidelines for Aneurysmal SAH (2023 Update).

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Nimodipine (Nimotop)