Inbrija (levodopa inhalation powder) is an inhalable rescue medication for the treatment of "off" episodes in patients with Parkinson's disease. Developed by Acorda Therapeutics, Inc. of the United States, this drug enables the rapid absorption of levodopa through the lungs, relieving motor symptoms within 10-15 minutes. It must be used with a dedicated inhaler. Currently, Inbrija has not been launched in China nor included in the national medical insurance catalog.
What is Levodopa Inhalation Powder?
As an innovative dosage form, levodopa inhalation powder changes the administration method of traditional Parkinson's disease medications, providing a rapid solution for sudden loss of motor function.
Mechanism of Action
Levodopa is directly absorbed through the pulmonary capillaries, bypassing the first-pass effect, and reaches peak plasma concentration within 10 minutes. After inhalation, it is converted into dopamine to supplement the neurotransmitters deficient in the nigrostriatal pathway.
Core Indications
It is specifically indicated for Parkinson's disease patients who are already receiving combined carbidopa/levodopa therapy, targeting the following situations:
Morning akinesia (morning stiffness)
End-of-dose deterioration (end-of-dose phenomenon)
Unpredictable "off" episodes
Dosage Form Characteristics
It comes in 42mg capsules, which must be used with a dedicated inhaler, and features an aluminum foil packaging design for moisture resistance.
Each capsule contains micronized levodopa (with a particle size of 3-5μm), achieving a pulmonary deposition rate of over 30%.
This medication cannot replace regular oral therapy; it is only used for intermittent symptom relief.
Administration Method and Dosage
Levodopa inhalation powder is an oral inhalation medication and must be used exclusively with the dedicated inhaler. The contents of the capsules are intended for inhalation to take effect and must not be swallowed.
The recommended dosage is: when a patient feels the onset of "off" symptoms, they should use this product immediately, inhaling two 42mg capsules at a time (totaling 84mg).
Therapeutic Effects of Levodopa Inhalation Powder
Clinical data show that this medication can significantly improve sudden motor symptoms in Parkinson's disease patients and enhance their quality of life.
Advantage in Onset Time
The median onset time after inhalation administration is 12 minutes, which is 3-4 times faster than oral formulations. Patients can switch from the "off" state to the "on" state within 30 minutes.
Improvement in Motor Function
Phase III clinical trials demonstrated that:
The average score on the Unified Parkinson's Disease Rating Scale Part III (UPDRS-III) decreased by 15.2 points.
The daily "on" time was extended by 2.1 hours.
The ability to perform activities of daily living was improved.
Usage Limitations
Using the medication more than 5 times a day may induce dyskinesia.
Long-term overuse may exacerbate the end-of-dose phenomenon; thus, the maximum single dose of 84mg must be strictly followed.
Its efficacy depends on combined use with carbidopa; using it alone cannot maintain stable plasma drug concentrations.
Storage Methods for Levodopa Inhalation Powder
Proper storage is crucial for maintaining the drug's activity and ensuring safe use.
Temperature and Humidity Control
Store in a dry environment at 20-25°C (68-77°F) with a relative humidity below 60%.
The unopened aluminum foil packaging provides moisture protection; once opened, the contents must be used within 7 days.
Preparation Before Use
Capsules should only be removed from the aluminum blister pack immediately before use; exposure to air for more than 5 minutes will reduce the drug's efficacy.
The inhaler should be cleaned once a month with a dry cotton swab.
Carry the medication with you during travel; do not check it in as luggage. Avoid storing it in humid areas such as bathrooms or kitchens.
