Metoclopramide
Contraindicated
Textbook-cited
Loss of antiparkinsonian effect; worsening of parkinsonism.
Concurrent use is contraindicated
Source: KDT 7e · p950
Drug reference
Levodopa
Dopamine Agonist · Antiparkinsonian
Dopamine AgonistAntiparkinsonian
CDSCO approvedSchedule H
EXCRETION
—
not curated
INTERACTIONS
12 major
incl. contraindicated
PREGNANCY
—
not curated
Top interactionssee all 12 →
- MetoclopramideContraindicatedTextbook-citedKDT 7e · p950
- Nonspecific Mao InhibitorsContraindicatedTextbookG&G 14e · p418
- ButyrophenonesSevereTextbookKDT 7e · p429
- MoclobemideSevereTextbookKDT 7e · p429
Mechanism
Levodopa is a dopaminergic therapy used to manage motor symptoms of Parkinson's disease. It works by compensating for the death of dopaminergic cells in the substantia nigra, leading to an improvement in motor performance.
Indications
Motor symptoms of Parkinson's diseaseTreatment of PDparkinsonismParkinson's diseaseHepatic coma (non-specific 'awakening' effect)
Dosing
- Adult
- Adult: Initially 150 mg daily in divided doses, then. increased in steps of 50 mg every 2–3 days, adjusted. according to response; usual dose 150–300 mg daily in. divided doses; maximum 400 mg per day. Orphenadrine hydrochloride 10 mg per 1 ml Orphenadrine
Pharmacokinetics
Peak effect
between 0.5 and 2 h after an oral dose
Half-life
1–2 hours
Bioavailability
41 ± 16%; 86 ± 19%
Protein binding
absorbed rapidly from the small bowel by the transport system for aromatic amino acids
Metabolism
Converted to DA by decarboxylation; metabolized by MAO and COMT
Excretion
<1%
Contraindications
- psychotic illness
Side effects
Common
Response fluctuationsDyskinesiasnauseavomitingpostural hypotensiontachycardiaangina exacerbation (in patients with pre-existing heart disease)alteration in taste sensationfacial ticsgrimacingtongue thrustingchoreoathetoid movements of limbsanxietynightmaresdepressionmaniahallucinationsmental confusionpsychosisend of dose deterioration (wearing off)'on-off' effect
Serious
- Impulse control disorders
- hallucinations
- confusion
- impulse control disorder (ICD)
- dyskinesias
- on/off phenomenon
- neuroleptic malignant syndrome
- increased risk of suicidality
- frank psychosis
- hypertensive crisis (with nonselective MAO inhibitors)
- involuntary movements (dyskinesias)
Drug interactions
Nonspecific Mao Inhibitors
Contraindicated
Textbook
Life-threatening hypertensive crisis and hyperpyrexia.
Nonspecific MAO inhibitors should be discontinued at least 14 days before levodopa is administered.
Source: G&G 14e · p418
Butyrophenones
Severe
Textbook
Reverse the therapeutic effect of levodopa.
Avoid co-administration.
Source: KDT 7e · p429
Moclobemide
Severe
Textbook
May cause hypertensive crisis.
Avoid co-administration.
Source: KDT 7e · p429
Phenothiazines
Severe
Textbook
Reverse the therapeutic effect of levodopa.
Avoid co-administration.
Source: KDT 7e · p429
Dextropropoxyphene
Severe
Database
Clinical effect not specified
Source: DDInter
Isocarboxazid
Severe
Database
May cause hypertensive crisis.
Avoid co-administration.
Source: DDInter
Linezolid
Severe
Database
Clinical effect not specified
Source: DDInter
Methylene Blue
Severe
Database
Clinical effect not specified
Source: DDInter
Ozanimod
Severe
Database
Clinical effect not specified
Source: DDInter
Phenelzine
Severe
Database
May cause hypertensive crisis.
Avoid co-administration.
Source: DDInter
Procarbazine
Severe
Database
May cause hypertensive crisis.
Avoid co-administration.
Source: DDInter
Related guidelines
Other Dopamine Agonist drugs
Ask House about Levodopa
Continue into a citation-backed clinical answer with the drug context already attached.
Sources: KD Tripathi 7e, Goodman & Gilman 14e, BNF·Verified: 2026-05-10 · House clinical team