Levodopa/Carbidopa/Entacapone Viatris (Entacapone, Levodopa, Carbidopa Monohydrate)

Levodopa/Carbidopa/Entacapone is used within the antiparkinson therapeutic class to manage motor symptoms and fluctuations in Parkinson's disease.

• Parkinson's disease (motor fluctuations): reduces OFF periods and improves overall motor control.
• Parkinson's disease (early stage): enhances response to levodopa and delays progression of motor symptoms.
• Parkinson's disease (advanced stage): provides more consistent dopaminergic stimulation, helping to maintain daily activities.

• Levodopa crosses the blood‑brain barrier and is decarboxylated to dopamine. Carbidopa inhibits peripheral aromatic L‑amino acid decarboxylase, limiting peripheral conversion of levodopa and increasing its central availability. Entacapone blocks catechol‑O‑methyltransferase (COMT), decreasing peripheral levodopa metabolism, prolonging its plasma half‑life, and thereby stabilising dopaminergic stimulation in the brain.

Levodopa/Carbidopa/Entacapone may cause a range of adverse reactions. Patients should be monitored for both common and serious events.

Common Side Effects

• Nausea
• Vomiting
• Orthostatic hypotension
• Dizziness
• Insomnia
• Dyskinesia

Serious or Rare Side Effects

• Severe hypotension or syncope
• Hallucinations or psychosis
• Neuroleptic malignant‑like syndrome
• Agranulocytosis or severe leukopenia
• Hepatic dysfunction
• Severe allergic reactions (e.g., Stevens‑Johnson syndrome)

Use of this combination requires careful clinical oversight to minimise risks.

• Dose titration: adjust gradually under physician supervision.
• Cardiovascular monitoring: watch for orthostatic hypotension and arrhythmias.
• Psychiatric assessment: monitor for hallucinations, confusion, or mood changes.
• Renal/hepatic impairment: consider dose reduction or increased monitoring.
• Drug interactions: review all concomitant medications for potential conflicts.
• Store at ambient temperature: keep in the original container, protect from moisture and light.

Levodopa/Carbidopa/Entacapone interacts with several drug classes; some combinations should be avoided while others require close monitoring.

Major Interactions (Avoid)

• Non‑selective MAO inhibitors: risk of hypertensive crisis.
• MAO‑B inhibitors (e.g., selegiline, rasagiline): may cause severe hypertension.
• Antihypertensive agents (especially alpha‑blockers): can exacerbate hypotension.
• Dopamine antagonists (typical antipsychotics): reduce therapeutic effect.
• Certain anti‑emetics (e.g., metoclopramide): may diminish levodopa efficacy.

Moderate Interactions (Monitor Closely)

• Other COMT inhibitors: additive effect on levodopa levels.
• CNS depressants (e.g., benzodiazepines): may increase sedation.
• Diuretics: may potentiate orthostatic hypotension.
• Iron or calcium supplements: can impair levodopa absorption.
• SSRIs or SNRIs: monitor for serotonin syndrome when combined with MAO‑B inhibitors.