Neurology
MAO-B inhibitors
Rasagiline, selegiline, safinamide (Parkinson's) — Tablets that modestly boost and smooth the effect of the brain's own and replacement dopamine in Parkinson's disease.
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
Quick answer
What is MAO-B inhibitors?
MAO-B inhibitors are tablets for Parkinson's disease that slow the breakdown of dopamine in the brain, giving a modest, steady boost to its effect. They are used alone early on, or added to levodopa later to smooth out "wearing off" between doses.
- How it works: Dopamine — the brain chemical that runs low in Parkinson's — is broken down by an enzyme called monoamine oxidase B (MAO-B).
- In practice: In practice MAO-B inhibitors (such as rasagiline, selegiline and safinamide) are used in Parkinson's disease to give a modest, smooth boost to dopamine activity in the brain.
What it is
MAO-B inhibitors are tablets for Parkinson's disease that slow the breakdown of dopamine in the brain, giving a modest, steady boost to its effect. They are used alone early on, or added to levodopa later to smooth out "wearing off" between doses.
How it works
Dopamine — the brain chemical that runs low in Parkinson's — is broken down by an enzyme called monoamine oxidase B (MAO-B). These medicines block that enzyme, so dopamine (both the brain's own and that made from levodopa) lingers longer and works more steadily. This eases symptoms modestly and helps prevent the "off" periods between levodopa doses — but the same lift to brain chemicals explains the interaction risks.
In practice
In practice MAO-B inhibitors (such as rasagiline, selegiline and safinamide) are used in Parkinson's disease to give a modest, smooth boost to dopamine activity in the brain. They can be used early, on their own, to delay the need for levodopa when symptoms are mild, and later as an add-on to levodopa to reduce "wearing off" — the return of symptoms before the next dose is due. Their appeal is convenience (usually once daily) and a generally well-tolerated profile, though the symptomatic benefit is modest compared with levodopa. The practical themes are about interactions and timing. At the low doses used for Parkinson's they are selective for the MAO-B enzyme and do not usually require the strict tyramine ("cheese") diet needed for older non-selective MAO inhibitors, but caution remains. The most important safety concern is the risk of serotonin syndrome when combined with certain antidepressants and other serotonergic drugs, and with the painkiller pethidine and some others — so the full medicine list is checked before starting. They can add to levodopa side effects such as involuntary movements (dyskinesia), nausea, dizziness on standing and, occasionally, hallucinations or impulse-control problems, so the levodopa dose is sometimes reduced. Safinamide has an additional non-dopamine action and specific cautions. They are part of a wider Parkinson's plan rather than a stand-alone fix.
Examples
Practical use
How to take it & use it well
- Take it as prescribed, usually once a day, as a tablet that gives a modest, smooth boost to dopamine activity to help your Parkinson's symptoms.
- Take it at around the same time each day, and follow your team's advice on timing, as some are best taken in the morning to avoid disturbing your sleep.
- Keep taking it steadily even when you feel well, and do not stop suddenly on your own, as it is part of a wider Parkinson's plan rather than a quick fix.
- Tell every clinician and pharmacist that you take this before you start any new antidepressant or strong painkiller, as some combinations can be dangerous.
- Report new confusion, agitation, sweating, shivering or a racing heart urgently, as together these can signal a serious reaction called serotonin syndrome.
- Watch for any new gambling, shopping, eating or other impulsive urges and tell your team, as these can happen with Parkinson's medicines and can be eased by adjusting treatment.
Common uses
- Early Parkinson's disease (alone, to delay levodopa)
- Add-on to levodopa for "wearing off"
- Smoothing motor fluctuations
Monitoring
- Motor symptoms and "off" time; benefit vs side effects
- Blood pressure (postural drops), mood and any hallucinations or impulsive behaviour
- Interacting medicines (antidepressants, opioids) at every review
Weighing it up
Advantages & disadvantages
Advantages
- It gives a smooth, modest boost to your own and replacement dopamine, helping symptoms feel steadier through the day.
- Used early on its own, it can delay the need to start levodopa when symptoms are still mild.
- Added later to levodopa, it can reduce 'wearing off', the return of symptoms before your next dose is due.
- It is usually a simple once-daily tablet, which is convenient and easy to fit into a routine.
- It is generally well tolerated, so many people manage it with few troublesome effects.
Disadvantages
- Its benefit is modest compared with levodopa, so it is a helpful add-on rather than a powerful treatment on its own.
- It can worsen levodopa side effects such as involuntary movements, nausea and dizziness on standing, so the levodopa dose may need reducing.
- It can occasionally bring on hallucinations or impulse-control problems, which need to be reported to your team.
- The most serious concern is serotonin syndrome if it is combined with certain antidepressants or painkillers, so your full medicine list must be checked.
- Safinamide has an extra action beyond dopamine and its own specific cautions, so the choice within this group is individual.
Key safety principles
What to watch for
- Risk of serotonin syndrome with certain antidepressants (SSRIs/SNRIs, others), the opioid pethidine and other serotonergic drugs — the full medicine list is checked before starting.
- Can worsen levodopa side effects (involuntary movements, nausea, dizziness on standing, hallucinations, impulse-control problems) — the levodopa dose may be reduced.
- At Parkinson's doses they are MAO-B selective and usually do not need the strict tyramine diet of older MAO inhibitors, but caution still applies (especially at higher doses).
Key interactions
What to avoid or check alongside
- Combined with certain antidepressants, such as SSRIs and SNRIs and some others, it can cause serotonin syndrome, so any new antidepressant is checked carefully first.
- The painkiller pethidine and some other strong painkillers can also trigger serotonin syndrome with it and are generally avoided.
- It often increases the effects and side effects of levodopa, so your levodopa dose is sometimes lowered when it is started.
- At the doses used for Parkinson's it is usually selective and does not need the strict tyramine ('cheese') diet of older MAO inhibitors, but caution still applies at higher doses.
- Tell your team about every medicine, including those bought without a prescription and any cold or cough remedies, as some can interact.
Patient & carer advice
- Tell every clinician and pharmacist you take this before starting any new antidepressant or strong painkiller
- Report new confusion, agitation, sweating or shivering urgently — these can signal a serious interaction
- Watch for new gambling, shopping or other impulsive urges and tell your team, as these can occur with Parkinson's drugs
Answers
MAO-B inhibitors: frequently asked questions
What do MAO-B inhibitors do in Parkinson's?
They give a modest, smooth boost to dopamine activity in the brain, which is the chemical that runs low in Parkinson's. They can be used early on their own to delay starting levodopa, or added later to make each levodopa dose last and reduce 'wearing off'. The benefit is gentle rather than dramatic, and they form part of a wider treatment plan.
Why is my medicine list checked so carefully before I start?
The main safety concern is a serious reaction called serotonin syndrome, which can happen if these are combined with certain antidepressants or strong painkillers such as pethidine. Checking your full medicine list before starting helps avoid this. Always tell any clinician or pharmacist that you take this medicine before they prescribe anything new.
Do I need to avoid cheese and other foods?
At the low doses used for Parkinson's, these are selective for the MAO-B enzyme and do not usually need the strict tyramine, or 'cheese', diet that older non-selective MAO inhibitors required. Some caution still applies, especially at higher doses, so follow your team's specific advice rather than assuming no food matters at all.
Could this medicine make my movements worse?
Because it boosts dopamine, it can add to levodopa's side effects, including involuntary movements, nausea and dizziness on standing, and occasionally hallucinations. For this reason your team may reduce your levodopa dose when it is started. Tell them about any new or worsening movements so the balance can be adjusted.
Why should I report new urges to gamble or shop?
Parkinson's medicines that boost dopamine can sometimes trigger impulse-control problems, such as new urges to gamble, shop, eat or behave in other out-of-character ways. These can creep up gradually and may be missed. Telling your team early matters, as adjusting the treatment usually settles them, and it is nothing to feel embarrassed about.
Authoritative sources
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