Inhaled levodopa is a novel formulation of levodopa used for the rapid relief of “off” episodes in adult patients with Parkinson’s disease who are already taking carbidopa/levodopa. It allows levodopa to be absorbed through the lungs for a faster onset of action compared to oral tablets.

Indications

Inhaled levodopa (Inbrija) is indicated for:

The intermittent treatment of episodes of “off” periods in adults with Parkinson’s disease.
Patients who are already being treated with a combination of carbidopa and levodopa.

Mechanism of Action

After inhalation, levodopa particles are absorbed through the alveoli into the bloodstream, bypassing the gastrointestinal tract. Once in the brain, levodopa is converted into dopamine, which helps restore normal motor control. This route provides a faster onset (typically within 10 minutes) than oral tablets.

Dosing and Administration

Formulation: Capsules containing 42 mg levodopa powder for oral inhalation, used with the Inbrija inhaler device.
Typical dose: Two capsules (total 84 mg levodopa) inhaled per “off” episode.
Maximum: Up to 5 doses per day (420 mg total daily dose).
Note: Inhaled levodopa must be used together with oral carbidopa/levodopa therapy.

Pharmacokinetics (Comparison)

Parameter	Inhaled Levodopa	Oral Levodopa
Onset of effect	~10 minutes	30–60 minutes
Peak plasma level (Tmax)	≈ 10 minutes	≈ 45–60 minutes
Duration	60–90 minutes	2–3 hours

Side Effects

Most side effects are mild and temporary. Common ones include:

Cough
Nausea
Upper respiratory tract irritation
Sputum discoloration
Dizziness

Less common side effects can include shortness of breath in patients with chronic lung disease. Routine monitoring is not usually required, but patients with asthma or COPD should use with caution.

Contraindications

Hypersensitivity to levodopa or any excipient in the formulation.
Concurrent use of non-selective MAO inhibitors (e.g. phenelzine, tranylcypromine).

Precautions

May cause somnolence or sudden onset of sleep — caution with driving or operating machinery.
Monitor for dyskinesia and impulse control disorders as with oral levodopa.
Use cautiously in patients with chronic pulmonary disease.

Availability in the UK

Inbrija is approved in the UK for specialist prescription. It may not be available at all NHS hospitals, but can be accessed through neurologists or private clinics. It is licensed under the MHRA for the intermittent treatment of “off” episodes in Parkinson’s disease.

Key Clinical Study

The SPAN-PD Trial demonstrated that inhaled levodopa significantly improved motor function (UPDRS Part III score) within 30 minutes compared to placebo, with benefits evident as early as 10 minutes after dosing.

Summary Points

Provides fast, on-demand symptom relief during “off” episodes.
Convenient, non-invasive delivery through inhalation.
Used alongside regular carbidopa/levodopa therapy.
Generally well tolerated with manageable side effects.

References

LeWitt PA et al. Mov Disord. 2019;34(4):491–500.
Acorda Therapeutics. Inbrija Prescribing Information. 2023.
Poewe W, Seppi K, et al. Lancet Neurology. 2022;21(10):930–942.

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Levodopa Inhaled Inbrija

Inhaled Levodopa (Inbrija®)

Overview