Inbrija (Levodopa)

Inbrija, a levodopa inhalation powder, acts on the dopaminergic pathway to treat Parkinson’s disease.

• Parkinson's disease (off episodes): Provides rapid relief of motor symptoms during off periods when oral medication is insufficient.
• Parkinson's disease (adjunct therapy): Used alongside oral levodopa to improve overall motor control.
• Parkinson's disease (motor fluctuations): Helps reduce the frequency and severity of motor fluctuations throughout the day.

• Levodopa is absorbed through the pulmonary alveolar membrane after inhalation, entering the bloodstream and crossing the blood‑brain barrier where it is decarboxylated to dopamine. The resulting increase in central dopamine concentrations compensates for the loss of dopaminergic neurons in Parkinson’s disease, thereby improving motor function and reducing off‑episode symptoms.

Inbrija may cause a range of adverse reactions, some of which are more frequently observed than others.

Common Side Effects

• Cough: Mild irritation of the throat leading to coughing after inhalation.
• Throat irritation: Discomfort or soreness in the throat.
• Nausea: Feeling of queasiness or urge to vomit.
• Headache: Mild to moderate head pain.
• Dizziness: Sensation of light‑headedness or unsteadiness.
• Dyskinesia: Involuntary movements, especially with higher cumulative levodopa exposure.

Serious or Rare Side Effects

• Hallucinations: Visual or auditory disturbances that may require medical attention.
• Orthostatic hypotension: Significant drop in blood pressure upon standing, leading to faintness.
• Pulmonary edema: Accumulation of fluid in the lungs, a rare but serious condition.
• Severe allergic reaction: Rash, swelling, or difficulty breathing indicating anaphylaxis.

Before prescribing Inbrija, clinicians should consider several safety measures.

• Cardiovascular assessment: Monitor for orthostatic hypotension and arrhythmias.
• Concomitant MAO‑B inhibitors: Avoid use together due to risk of hypertensive crisis.
• Respiratory status: Use with caution in patients with chronic lung disease.
• Dyskinesia monitoring: Adjust therapy if excessive involuntary movements develop.
• Pregnancy and lactation: Safety not established; prescribe only if potential benefit justifies the risk.
• Store at ambient temperature: Keep in original container, protect from moisture and light.

Levodopa inhalation can interact with several medications, requiring attention to avoid reduced efficacy or increased toxicity.

Major Interactions (Avoid)

• Non‑selective MAO inhibitors: May precipitate hypertensive crisis.
• High‑dose peripheral DOPA decarboxylase inhibitors: Can alter levodopa absorption and effect.
• Dopamine antagonists (e.g., typical antipsychotics): May diminish therapeutic benefit.

Moderate Interactions (Monitor Closely):\n- COMT inhibitors: May increase levodopa plasma levels, requiring dose adjustment.

• SSRIs/SNRIs: Monitor for signs of serotonin syndrome when combined.
• Antihypertensive agents: May enhance blood pressure‑lowering effects.