DUPONT MERCK's SINEMET CR PARKINSON'S DRUG SHIPMENTS
DUPONT MERCK's SINEMET CR PARKINSON'S DRUG SHIPMENTS began in mid-June following a May 30 FDA approval of the continuous-release formulation of carbidopa 50 mg/levodopa 200 mg. Sinemet CR is indicated for "treatment of the symptoms of idiopathic Parkinson's disease (paralysis agitans), postencephalitic parkinsonism, and symptomatic parkinsonism which may follow injury to the nervous system by carbon monoxide intoxication and manganese intoxication," approved labeling states. The drug had been "approvable" since Nov. 27 ("The Pink Sheet," Jan. 21, p. 17). Merck filed the NDA in April 1988. As part of the launch efforts, DuPont Merck will mail a short videotape and product literature to 20,000 neurologists and physicians whose practices include Parkinson's patients and provide free starter samples to 50,000 retail drugstores. The company expects to have a sales force of 425 detailing Sinemet CR by the end of July. Sinemet CR will be promoted for "de novo" patients who have not been treated with levodopa or other Parkinson's therapies as well as for those currently on immediate release Sinemet. DuPont Merck is stressing patient benefit in its promotion of the new product, which is the first sustained-release Parkinson's drug to be approved in the U.S., while FDA labeling includes caveats about how much the product improves on regular Sinemet. At a June 26 press conference in New York City, researcher Roger Duvoisin, MD, Robert Wood Johnson Medical Center, said the polymeric drug delivery product "represents a significant therapeutic advance in the treatment of the symptoms of Parkinson's disease. The sustained-release formulation offers patients better management of symptoms and a smoother, steadier day." The "smoothing" effect of Sinemet CR is described in promotional literature as the product's greater effectiveness in "smoothing out the peaks and troughs in blood levels of levodopa" in patients compared to Sinemet. FDA assigned the product a "3C" rating (a new formulation offering no therapeutic gain over existing therapies). Labeling also contains an italicized statement that clinical trial participants with moderate to severe motor problems who received Sinemet CR "did not experience quantitatively significant reductions in 'off-time'" compared to regular Sinemet. "Off-time" refers to the periodic immobility that seizes patients in advanced stages of Parkinson's disease and which becomes progressively more difficult to suppress with drug therapy. Although Sinemet CR failed to quantitatively reduce motor fluctuations compared to regular Sinemet, the controlled-release product did produce better "global ratings" of improvement by patients and physicians, labeling states. In early-stage patients without motor fluctuations, "Sinemet CR, under controlled conditions, achieved the same therapeutic benefit with less frequent dosing when compared to Sinemet," DuPont Merck notes. Through use of the new formulation, the company says, "many patients may receive more continuous benefit yet take the medication less frequently than with Sinemet." However, not all patients will be able to obtain less frequent dosing with the new product since the drug must be individually titrated. Sinemet CR is also less bioavailable than regular Sinemet. Labeling states: "With Sinemet CR there is less variation in plasma levodopa levels than with Sinemet, the conventional formulation. However, Sinemet CR is less systematically bioavailable than Sinemet and may require increased daily doses to achieve the same level of symptomatic relief as provided by Sinemet." Patients receiving Sinemet CR may experience more dyskinesia than patients on regular Sinemet, the labeling's warning section notes, and the controlled-release formulation does not decrease any of the adverse effects caused by Sinemet or levodopa alone. Sinemet CR will be priced "in the same range" as Sinemet, according to the company, with the price to consumers expected to average $ 115 to $ 120 per 100 tablets. DuPont Merck will continue to market regular Sinemet. The joint-venture's products are marketed under the DuPont Pharmaceuticals label. DuPont acquired the marketing rights to both Sinemet and Sinemet CR in October 1989 from Merck, which developed Sinemet in the mid-1970s and experimented with five different versions of carbidopa/levodopa over a 10-year period to develop a sustained- release version of the product. Sinemet CR is the second newly- approved product to be marketed by the DuPont Merck joint venture since it began operations this January. The first was the radiopharmaceutical I.V. Persantine, launched in early February ("The Pink Sheet," Jan. 14, In Brief).
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