The Food and Drug Administration approved an enteral suspension of carbidopa-levodopa on Jan. 12 under an orphan drug designation for the treatment of motor fluctuations in patients with advanced Parkinson’s disease.
The drug combination, to be marketed as Duopa in the United States, is infused into the jejunum through a surgically placed percutaneous endoscopic gastrostomy tube with a jejunal extension. A portable infusion pump, called the CADD-Legacy 1400, is worn by the patient for up to 16 hours per day, sending 4.63 mg carbidopa and 20 mg levodopa per mL into the jejunum. The maximum recommended daily dose is one cassette, equivalent to 2,000 mg levodopa given over 16 hours, according to the label, which also advises that, prior to initiating Duopa, patients should be converted “from all forms of levodopa to oral immediate-release carbidopa-levodopa tablets (1:4 ratio).”
The rationale for the direct administration of Duopa to the small intestine is the need for a more efficacious way for patients with advanced disease to reduce periods of “off” time in which they experience poor mobility, slowness, and stiffness. Direct administration also bypasses the reduced frequency and predictability of spontaneous gastric emptying seen in patients with advanced disease that can affect “the timing of when orally administered medicines leave the stomach and are absorbed in the small intestine,” according to the manufacturer, AbbVie.
The approval is based on a 12-week, phase III trial of Duopa in 71 patients with advanced Parkinson’s that resulted in 1.9 fewer hours of “off” time and 1.9 more hours of “on” time without dyskinesia per day, compared with patients who were taking immediate-release, oral doses of carbidopa-levodopa.
The carbidopa-levodopa enteral suspension is currently marketed by AbbVie under the name Duodopa in 40 other countries.