Levodopa / Benserazide

What it is and how it works

Levodopa crosses the blood–brain barrier and is converted to dopamine, replenishing striatal dopamine in Parkinson’s disease. Benserazide inhibits peripheral dopa decarboxylase, reducing peripheral conversion of levodopa, which lowers the required dose and peripheral adverse effects such as nausea.

Indications

Parkinson’s disease; restless legs syndrome (in some countries, specific formulations).

Dosage and administration (summary)

Oral (expressed as levodopa): initially 50 mg one to four times daily (or 100 mg three times daily in some regimens), increased gradually according to response; usual maintenance 400–800 mg daily in divided doses. Modified-release and dispersible forms are used for specific indications.

Contraindications

Concomitant non-selective MAO inhibitors; angle-closure glaucoma; severe decompensated endocrine, renal, hepatic or cardiac disease; severe psychiatric disorders with psychosis; patients under 25 years; history of melanoma or suspicious undiagnosed skin lesions; pregnancy.

Warnings and precautions

Nausea, dyskinesias, motor fluctuations, orthostatic hypotension, hallucinations, excessive daytime somnolence and sudden sleep onset may occur. Impulse-control disorders (pathological gambling, hypersexuality) should be monitored. Do not stop abruptly because of the risk of a neuroleptic malignant-like syndrome; dietary protein may reduce absorption.

Pregnancy

Contraindicated in pregnancy and in women of childbearing potential without adequate contraception.

Storage and supply

Store below 25 °C in a tightly closed container, protected from moisture.

Source: reference summary prepared from the EU SmPC/EPAR, BNF and WHO Model Formulary. The approved product information in Iran governs.