Efficacy

Efficacy of Inbrija (Levodopa) in Parkinson's Disease

Inbrija (levodopa inhalation powder) is specifically indicated for the intermittent treatment of off episodes in patients with Parkinson's disease (PD) treated with carbidopa/levodopa. Off episodes are characterized by the re-emergence of Parkinson's symptoms such as tremor, stiffness, and difficulty moving. Inbrija works by delivering levodopa to the brain more quickly, as it is inhaled directly into the lungs and absorbed into the bloodstream. Clinical trials have demonstrated that Inbrija significantly improves motor function during off episodes compared to placebo, with patients experiencing improved scores on the Unified Parkinson's Disease Rating Scale (UPDRS) part III, which measures motor ability.

The efficacy of Inbrija was established in a 12-week, randomized, placebo-controlled study in patients experiencing at least two off periods per day. The results showed that Inbrija improved motor function at 30 minutes post-dose compared to placebo and the effect was maintained at 60 minutes. However, it is important to note that Inbrija is not a substitute for regular carbidopa/levodopa medications, as it is designed to act as a complement for episodes when the regular medication's effect is waning.

Efficacy of Nourianz/Nouriast (Istradefylline) in Parkinson's Disease

Nourianz (istradefylline) in the United States and Nouriast in Japan, is an adenosine A2A receptor antagonist approved as an add-on treatment to carbidopa/levodopa in adult patients with Parkinson's disease experiencing "off" episodes. It works by a different mechanism than levodopa, modulating the adenosinergic signaling in the brain, which is thought to improve motor symptoms without directly increasing dopamine levels. Clinical trials have shown that istradefylline can reduce the amount of time patients spend in the off state and increase on time without troublesome dyskinesia.

The approval of istradefylline was based on multiple randomized, placebo-controlled trials, which demonstrated that patients taking istradefylline experienced a statistically significant decrease in off time. The most common dose used in these trials was 40 mg once daily. While the results are promising, it is essential to consider that the response to istradefylline can be variable, and some patients may experience more benefit than others. Additionally, istradefylline is not a cure for Parkinson's disease, but it offers an additional option for managing off episodes in conjunction with other PD medications.