The FDA has approved inhaled levodopa (Inbrija), indicated for the intermittent treatment of OFF episodes in patients with Parkinson’s disease who are treated with carbidopa/levodopa. Inbrija is therefore a “rescue drug,” not meant to replace oral levodopa, but to be given when it is failing. Acorda Therapeutics, who owns the patent to this drug, projects Inbrija will be on pharmacy shelves in the first quarter of 2019. As yet, the cost of Inbrija is not being disclosed. For a summary of the study data leading to approval, see the Spring MPDN article “Pipeline drugs, part I: levodopa.”
Per the prescribing information of Inbrija, dosing will allow a patient to inhale the contents of two 42 mg capsules as needed for OFF symptoms, up to 5 times daily. Inbrija capsules are not meant to be swallowed. The maximum dose per OFF period is 84 mg, and the maximum recommended daily dosage of is 420 mg.
In summary of potential side effects seen in studies: in the phase II safety trial, among the 43 people who used the drug, the most frequently reported adverse events were dizziness, cough, and nausea, (each seen in 3 patients). In the phase III clinical/efficacy trial 339 participants were randomized to 84 mg, 60 mg, or placebo, and were allowed to self-administer treatment up to five times daily for 12 weeks. In the 84 mg dose group nausea was reported in 5.3% (2.7% with placebo), cough in 15% (1.8% with placebo), upper respiratory tract infection in 6% (2.7% with placebo). When cough was reported, it was “typically mild and reported once per participant during the course of treatment.” Three people discontinued the study due to cough.
The manufacturer recommends doctors monitor patients on MAO-B inhibitors for orthostatic hypotension, and dopamine D2 antagonists, isoniazid, and iron salts, which may reduce the effectiveness of Inbrija.
Inbrija is contraindicated in patients currently taking a nonselective monoamine oxidase (MAO) inhibitor (e.g., phenelzine and tranylcypromine) or who have recently (within 2 weeks) taken a nonselective MAO inhibitor. Hypertension can occur if these drugs are used concurrently.
Some serious warnings are listed with the drug prescribing information, and these represent potential problems with using the drug:
sleep attack: falling asleep during activities of daily living, a rare side effect which can be seen in patients taking dopaminergic drugs
withdrawal-emergent hyperpyrexia and confusion: a very rare condition which may occcur with sudden discontinuation or rapid dose reduction of dopaminergic medications
hallucinations/ exacerbation of psychosis: patients with a
major psychotic disorder should not be treated with this drug
impulse control disorders: see the article in MPDN last winter on ICD in PD
dyskinesia: may be triggered or exacerbated
asthma, COPD, or other chronic underlying lung disease: not recommended in patients with these conditions
