What is the difference between Osmolex ER and Gocovri?

The main differences between Gocovri and Osmolex ER center around their approved uses, dosage forms, and submitted studies for FDA approval.

Approval of Gocovri was based on placebo-controlled clinical studies in patients with Parkinson's disease with levodopa-induced dyskinesias, while the effectiveness of Osmolex ER was based upon bioavailability studies that compared Osmolex ER to immediate-release amantadine. Gocovri and Osmolex ER are not interchangeable with other amantadine immediate- or extended-release products.

What is Gocovri?

In August 2017, the FDA approved Adamas Pharmaceuticals Gocovri (amantadine) extended-release capsules for treatment of dyskinesia (uncontrolled involuntary movements) in patients with Parkinson's disease receiving levodopa-based therapy, with or without dopaminergic medications. Gocovri is given by mouth once daily at bedtime, and is available in extended-release capsules in 68.5 mg and 137 mg strength.

What is Osmolex ER?

In February 2018, the FDA approved Osmotica Pharmaceutical's extended-release Osmolex ER tablets, a combination of extended-release and immediate-release amantadine for the treatment of Parkinson's disease and drug-induced extrapyramidal reactions in adults. The tablet consists of an immediate-release outer layer and an extended-release inner core. Osmolex ER is taken once-daily in the morning, and is available containing 129 mg, 193 mg, or 258 mg of amantadine.

How do the Gocovri and Osmolex ER clinical trials differ?

Gocovri is the first Parkinson's disease medicine demonstrated in controlled clinical trials to reduce both dyskinesia and “OFF-time” in patients receiving levodopa. Dyskinesias are a result of treatment with levodopa that leads to involuntary movements during waking hours which impacts the activities of daily living. In two studies, a statistically significant reduction in the Unified Dyskinesia Rating Scale was seen in patients compared to placebo: 37% vs. 12%, respectively, in study 1, and 46% vs. 16% in study 2, both at 12 weeks. The placebo-adjusted reduction in OFF time in both studies was roughly one hour daily. The most common side effects with Gocovri (>10% and greater than placebo) were hallucinations, dizziness, dry mouth, peripheral edema, constipation, falls and orthostatic hypotension.

The effectiveness of Osmolex ER is based upon bioavailability studies that compared Osmolex ER to immediate-release amantadine, not in controlled clinical studies in Parkinson's disease patients. The FDA approved Osmolex ER under the FDA's 505(b)(2) pathway using amantadine data from previous clinical trials. The most common side effects reported in ≥5% of patients at the recommended dosage of immediate-release amantadine were nausea, dizziness, lightheadedness, and insomnia.

There are no studies directly comparing Gocovri and Osmolex ER in Parkinson's disease patients with drug-induced dyskinesias.