levodopa: clinical use

Prescribing considerations

• Confirm that the patient can recognise an OFF episode and can prepare and use the inhaler, independently or with a carer.
• Inhaled levodopa is adjunctive to established levodopa/dopa-decarboxylase inhibitor treatment, not a replacement for background therapy.
• Avoid inhaled levodopa in asthma, COPD or other chronic underlying lung disease because of bronchospasm risk.
• Use caution in severe renal or hepatic disease, severe cardiovascular disease, previous myocardial infarction with residual arrhythmia, psychosis, peptic ulcer disease and controlled chronic glaucoma.
• Avoid abrupt withdrawal or major reduction of dopaminergic treatment because hyperpyrexia, rigidity and confusion resembling neuroleptic malignant syndrome may occur.

Contraindications and cautions

• Hypersensitivity to levodopa or product excipients
• Narrow-angle glaucoma
• Phaeochromocytoma
• Concomitant non-selective MAO-inhibitor treatment
• Previous neuroleptic malignant syndrome or non-traumatic rhabdomyolysis

Monitoring

• Inhaler technique and ability to recognise OFF episodes
• Cough, bronchospasm and worsening respiratory symptoms
• Dyskinesia and overall motor response
• Somnolence, sudden sleep, hallucinations, psychosis, suicidality and impulse-control disorders
• Standing blood pressure and falls risk
• Cardiac function when significant cardiovascular disease or residual arrhythmia is present
• Intraocular pressure in chronic glaucoma
• Periodic skin examination for melanoma
• Liver, renal and haematological tests where clinically indicated; account for interference with some urine and catecholamine tests

Clinical pharmacology

Levodopa is a dopamine precursor. Inhalation produces pulmonary absorption, while background peripheral dopa-decarboxylase inhibition limits conversion outside the brain. Levodopa is principally metabolised through aromatic amino-acid decarboxylase and COMT pathways.

Formulation and product differences

• The selected product contains inhalation powder in hard capsules used only with its dedicated inhaler.
• Unlike oral co-careldopa or co-beneldopa, this formulation contains levodopa alone and relies on established background dopa-decarboxylase inhibition.
• The inhaled formulation is intended for episodic OFF symptoms rather than maintenance treatment.
• Food-related absorption issues described with some oral levodopa products do not determine administration of the inhaled formulation.

Capsule

Route: Oral

Strengths: 33 mg