Selegiline
🧠 Selegiline is a selective MAO-B inhibitor used in Parkinson’s disease to boost central dopamine.
✅ Can help early PD symptoms and reduce “wearing-off” as adjunct to levodopa.
⚠️ Interactions matter (serotonergic drugs, opioids like pethidine) - always check the BNF.
ℹ️ About
- 📚 Always check the BNF for the latest prescribing advice, contraindications, and interaction details.
- 🧓 Used in Parkinson’s disease (PD) as monotherapy in early disease or as an adjunct to levodopa in fluctuating PD.
- 🎯 Core benefit: improves motor symptoms and may reduce end-of-dose deterioration (“wearing-off”).
Mode of Action
- 🧪 Inhibits monoamine oxidase-B (MAO-B) in the CNS → reduces dopamine breakdown.
- ⬆️ Increases synaptic dopamine availability → improves bradykinesia/rigidity and reduces off time in some patients.
- ⚙️ At standard doses it is relatively selective for dopamine metabolism; at higher doses selectivity decreases → wider monoamine effects and more interaction risk.
Indication / Dose
- 🧠 Parkinson’s disease: commonly 5 mg once daily for 2–4 weeks, then increase (if tolerated) to 10 mg daily (often in divided doses depending on formulation).
- 🌞 Dose in the morning (and midday if divided) to reduce insomnia and stimulant-type adverse effects.
- 🔁 If adding to levodopa, monitor for dopaminergic adverse effects (dyskinesia, hallucinations) and adjust levodopa if needed.
Interactions (high-yield)
- 💊 Levodopa: can enhance levodopa effects and side effects (dyskinesia, nausea, hallucinations). Consider reducing levodopa if troublesome.
- 🚫 Serotonergic drugs: risk of serotonin syndrome with SSRIs/SNRIs/TCAs and other serotonergic agents - check BNF for specific combinations and washout periods.
- 🚫 Opioids: particularly pethidine (meperidine) is contraindicated with MAO inhibitors (serious reactions). Check other opioids in BNF too.
- 🥫 Tyramine (“cheese effect”): generally minimal at standard MAO-B doses, but risk increases if higher doses reduce selectivity. Use BNF guidance if dose escalated.
Cautions
- 🧠 Neuropsychiatric: can worsen hallucinations, confusion, agitation (especially in older/frail patients or those with cognitive impairment).
- 🫀 Cardiovascular: caution in significant cardiovascular disease; monitor postural BP if symptomatic.
- 🧓 Falls risk: insomnia, postural hypotension, and confusion can increase falls risk-review if recurrent falls/delirium.
Contraindications
- ⛔ Refer to BNF for the full list.
- 🚫 Generally includes use with certain antidepressants/other MAO inhibitors and specific interacting medicines where severe reactions may occur.
Side Effects
- 🫀 Postural hypotension, palpitations/arrhythmias (uncommon but important if symptomatic).
- 🧠 Confusion, hallucinations, low mood, agitation.
- 😴 Insomnia (especially if taken later in the day).
- 🤢 GI upset: nausea, abdominal discomfort, constipation/diarrhoea.
- 🦴 Musculoskeletal aches (back/joint pain).
💡 Clinical Pearls
- ⏱️ Wearing-off: useful adjunct when patients “dip” before the next levodopa dose, but monitor for hallucinations and dyskinesia.
- 🌞 Morning dosing is a simple practical trick to reduce insomnia.
- 🧓 In older patients with confusion/hallucinations, consider whether selegiline is contributing before escalating dopaminergic therapy.
- 🧾 Always document counselling on interaction risk and ensure medicines reconciliation (especially antidepressants and opioids).
References
