The main differences between Gocovri and Osmolex ER center around their approved uses, dosage forms, strength and study designs for FDA approval. Approval of Gocovri was based on placebo-controlled clinical studies in patients with Parkinson's disease with levodopa-induced dyskinesias, whereas 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.