Nimodipine (Nimotop) 💊
💡 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 The gel capsule can be pierced and contents withdrawn with a syringe.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).
