benserazide hydrochloride + levodopa: clinical use

Prescribing considerations

• Treat administrations as time critical and avoid abrupt withdrawal because acute akinesia and a potentially life-threatening neuroleptic malignant-like syndrome may occur.
• Assess cardiovascular, psychiatric, endocrine, renal, hepatic, pulmonary, ophthalmic, peptic-ulcer and melanoma history.
• Review somnolence, sudden sleep onset, dyskinesia, motor fluctuations, impulse-control behaviours and dopamine dysregulation.
• Inform the anaesthetic team before surgery and minimise treatment interruption.

Contraindications and cautions

• Hypersensitivity to levodopa, benserazide or relevant excipients; prolonged-release capsules are also contraindicated with peanut or soya allergy.
• Concurrent non-selective MAO inhibition, or combined selective MAO-A and MAO-B inhibition.
• Decompensated endocrine, renal, hepatic or cardiac disease; severe arrhythmia or cardiac failure; psychotic illness; closed-angle glaucoma.
• Age below 25 years, pregnancy or inadequate contraception where pregnancy is possible, and current or previous malignant melanoma.

Monitoring

• Motor response, wearing-off, dyskinesia and adherence.
• Blood pressure; cardiac function where cardiovascular disease is present.
• Mood, psychosis, sudden sleep, impulse-control disorders and excessive medicine use.
• Periodic hepatic, renal, cardiovascular and haematological assessment; blood glucose in diabetes and intraocular pressure in open-angle glaucoma.
• Skin surveillance for melanoma.

Clinical pharmacology

Levodopa is a dopamine precursor transported across the blood–brain barrier. Benserazide inhibits peripheral aromatic L-amino-acid decarboxylase and does not appreciably cross the barrier, increasing central levodopa availability and reducing peripheral dopamine formation.

Formulation and product differences

• Standard hard capsules are immediate release.
• Dispersible tablets are licensed for swallowing difficulty and may offer faster onset in delayed-on, wearing-off or akinetic periods.
• Prolonged-release capsules release levodopa more slowly, produce later peaks and have lower bioavailability than standard preparations; conversion requires specialist supervision.
• Prolonged-release capsules must remain whole and contain soya oil. Meals may delay onset, and antacids reduce absorption.

Capsule

Route: Oral

Strengths: 50 mg + 12.5 mg, 100 mg + 25 mg, 200 mg + 50 mg

Dispersible tablet

Route: Oral

Strengths: 50 mg + 12.5 mg, 100 mg + 25 mg