Basic Neuroscience · Neuropharmacology
Anti-Parkinsonian Medications
Anti-parkinsonian medications by class — formulation, dosing, indications, and side effects. Verify doses before prescribing.
Motor symptoms
| Drug | Formulation | Initial dosage | Maximum dose | Indications / precautions | Side effects |
|---|---|---|---|---|---|
| Dopamine | |||||
| Levodopa/Carbidopa | Sinemet tab (10/100, 25/100, 25/250); Parcopa ODT; Sinemet CR (25/100, 50/200); Rytary ER caps (23.75/95 – 61.25/245) | 25/100 ½ tab TID | 8 tabs 25/250 per day (200 mg carbidopa) | Take 30 min before food Sudden interruption → hyperpyrexia & delirium Caution in arrhythmia | Common dopaminergic effects: falling asleep during ADLs, impulse-control disorders, hallucination/confusion, dyskinesia, nausea, dizziness, constipation, orthostatic hypotension, anxiety |
| Levodopa (inhaled) (Inbrija) | Inbrija inhalation powder 42 mg caps | 84 mg (2 caps) per "off" episode | 84 mg up to 5×/day | Intermittent rescue for "off" episodes Caution in asthma/COPD | Cough, URI, discolored sputum, nausea + dopaminergic effects |
| MAO-B inhibitors | |||||
| Selegiline | Eldepryl / Carbex tab (5 mg); Zelapar ODT (1.25 mg) | 5 mg BID (tab); 1.25 mg daily (ODT) | 5 mg BID; 1.25 mg daily | Adjunct to levodopa (long "off" periods) | Dopaminergic effects (as Sinemet) |
| Rasagiline | Azilect tab (0.5, 1 mg) | 0.5 mg daily | 1 mg daily | Adjunct to levodopa or monotherapy | Dopaminergic effects (as Sinemet) |
| Safinamide | Xadago tab (50, 100 mg) | 50 mg daily | 100 mg daily | Adjunct to levodopa/carbidopa for "off" periods only | Dopaminergic effects (as Sinemet); may cause/worsen dyskinesia |
| COMT inhibitors | |||||
| Entacapone | Comtan tab (200 mg) | 200 mg with each dose of levodopa | 8 tabs per day | Adjunct to levodopa (long "off" periods) | Dopaminergic effects (as Sinemet) + diarrhea – abdominal pain – orange-colored urine |
| Opicapone (Ongentys) | Ongentys caps (25, 50 mg) | 50 mg once daily at bedtime | 50 mg/day | Once-daily adjunct for "off" episodes; no food 1 h before to 1 h after the dose | Dyskinesia, constipation; less orange urine/diarrhea than entacapone |
| Tolcapone (Tasmar) | Tasmar tab (100, 200 mg) | 100 mg TID | 600 mg/day | Boxed warning: fatal hepatotoxicity — monitor LFTs; reserve for refractory "off" | Diarrhea, dyskinesia, hallucination, orange urine |
| Adenosine A2A antagonist | |||||
| Istradefylline (Nourianz) | Nourianz tab (20, 40 mg) | 20 mg daily | 40 mg daily | Adjunct to levodopa/carbidopa for "off" episodes; max 20 mg/day with strong CYP3A4 inhibitors; use 40 mg in heavy smokers (≥20/day); avoid strong CYP3A4 inducers | Dyskinesia, dizziness, hallucination, insomnia, nausea |
| Dopamine agonists | |||||
| Apomorphine | Apokyn solution 30 mg/3 mL (10 mg/mL) with multi-use injector | 0.2 mL (2 mg) SC test dose, then PRN for "off" episodes (doses ≥2 h apart) | 0.6 mL (6 mg)/dose; ≤5 doses/day | Pretreat antiemetic trimethobenzamide 300 mg TID starting 3 days prior; contraindicated with 5-HT3 antagonists (ondansetron) — severe hypotension | Dopaminergic effects (as Sinemet) + hallucinations (14%) – impulse-control disorders – dyskinesia (24%) – angina/MI (4%) – QTc prolongation – priapism |
| Bromocriptine | Parlodel tab (2.5, 5 mg) | 1.25 mg BID with meals | — | Titrate q14–28 days; avoid in valvular heart disease | Dopaminergic effects (as Sinemet) |
| Pramipexole | Mirapex tab (0.125, 0.25, 0.5, 0.75, 1, 1.5 mg); Mirapex ER (0.375, 0.75, 1.5, 2.25, 3, 3.75, 4.5 mg) | 0.125 mg TID (IR); 0.375 mg daily (ER) | 4.5 mg/day | — | Dopaminergic effects (as Sinemet) |
| Ropinirole | Requip tab (0.25, 0.5, 1, 2, 3, 4, 5 mg); Requip XL (2, 4, 6, 8, 12 mg) | 0.25 mg TID (IR); 2 mg daily (XL) | 24 mg/day | Binds to melanin (longer duration in patients with darker skin) | Dopaminergic effects (as Sinemet) + nausea – dizziness – leg edema |
| Rotigotine | Neupro patches (1, 2, 3, 4, 6, 8 mg/24h) | 2 mg patch daily | Early PD 6 mg/24h; advanced 8 mg/24h | Avoid in sulfite-allergic patients | Dopaminergic effects (as Sinemet) + application-site reactions |
| Anticholinergics | |||||
| Benztropine | Cogentin tab (0.5, 1, 2 mg) | 0.5–1 mg QHS | 6 mg/day | Tremor-predominant PD; avoid in elderly / cognitive impairment | Confusion, hallucination, dry mouth, blurred vision, urinary retention |
| Trihexyphenidyl (Artane) | Tab 2, 5 mg; soln 2 mg/5 mL | 1 mg/day | 6–10 mg/day | Tremor-predominant PD; avoid in elderly / cognitive impairment | Anticholinergic effects (as benztropine) |
| Other | |||||
| Amantadine | Symmetrel tab (100 mg) | 100 mg BID | 400 mg/day (supervised) | Caution in seizures, renal failure, CHF; reduce in renal impairment; do not stop abruptly | Suicidal ideation, lowers seizure threshold, confusion, hallucination, nausea, dizziness, insomnia, dry mouth, peripheral edema, livedo reticularis |
| Amantadine ER | Gocovri caps (68.5, 137 mg) | 137 mg QHS ×1 wk then 274 mg QHS | 274 mg/day | Dyskinesia + "off" episodes; contraindicated in ESRD (CrCl <15); ↓dose in renal impairment | Same as amantadine |
| Carbidopa/Levodopa/Entacapone | Stalevo tab (12.5/50/200, 18.75/75/200, 25/100/200, 31.25/125/200, 37.5/150/200, 50/200/200) | As Sinemet | 8 tabs/day (Stalevo 200: 6/day) | Combines levodopa + carbidopa + COMT inhibitor in one tablet | As Sinemet + entacapone effects |
Key interactions & cautions
- All dopaminergics: impulse-control disorders (gambling, hypersexuality, spending), sudden sleep onset during ADLs (driving), confusion, hallucination. Abrupt discontinuation → NMS.
- MAO-B inhibitors: serotonin syndrome with opioids (meperidine, methadone, tramadol), SNRIs, TCAs, cyclobenzaprine, stimulants, or St John's wort; hypertensive crisis with other MAOIs/linezolid; psychosis with dextromethorphan.
- Entacapone: can't combine with non-selective MAOIs; caution with epinephrine/norepinephrine/dopamine; microscopic colitis → diarrhea in ~10% (onset ~4 wks).
- Rotigotine: no meal interaction, no hepatic/renal adjustment; rotate sites (not same spot within 14 days); press 30 s on application.
- RLS terms: tolerance (needs ↑ dose), rebound (worsening at end of dose), augmentation (overall worsening — only with dopaminergics; manage with a ≥3-month dopaminergic holiday).
Non-motor manifestations
| Symptom | Drug of choice | Maximum dose | Side effects | Notes |
|---|---|---|---|---|
| Neurogenic orthostatic hypotension | Droxidopa (Northera 100/200/300 mg) | 600 mg TID | Boxed: supine hypertension; nausea, dizziness | Synthetic NE precursor; start 100 mg TID, titrate q24–48 h; last dose ≥3 h before bed; may exacerbate ischemic heart disease |
| Psychosis (hallucinations/delusions) | Pimavanserin (Nuplazid 34 mg cap / 10 mg tab) | 34 mg daily (↓10 mg with strong CYP3A4 inhibitor) | Peripheral edema, confusion, QT prolongation | Only FDA-approved drug for PD psychosis (5-HT2A inverse agonist) |
| Clozapine (Clozaril) | — | Agranulocytosis (REMS/ANC monitoring), seizures, myocarditis | Most evidence-based; does not worsen motor function | |
| Quetiapine (Seroquel 25/50/100) | — | Sedation, QT prolongation, orthostasis | Off-label; commonly used first for convenience | |
| Dementia | Rivastigmine (Exelon cap 1.5–6 mg; patch 4.6/9.5/13.3) | 6 mg BID | Nausea, anorexia, weight loss | Only FDA-approved cholinesterase inhibitor for PD dementia |
| Donepezil (Aricept 5/10/23 mg) | 10 mg daily | Bradycardia, heart block, N/V/D, worsens GERD/PUD, asthma/COPD | Off-label in PDD (Alzheimer's-indicated); start 5 mg QHS ×4 wk | |
| REM behavior disorder | Clonazepam (0.5–2 mg QHS); melatonin (3–6 mg QHS) | — | — | — |
| RLS / PLM | Dopamine agonists (pramipexole, ropinirole, rotigotine); opioids, gabapentin, clonazepam | — | — | — |
| Drooling | Glycopyrrolate (Robinul 1–2 mg); ipratropium spray; clonidine; modafinil; botox | 2 mg TID | Anticholinergic effects | Glycopyrrolate is anti-muscarinic, doesn't cross BBB |
Neuro.Wiki by Ahmed Koriesh, MD — Educational only, not a substitute for clinical judgement