SMITHKLINE BEECHAM’s HALFAN WILL BE DISTRIBUTED MAINLY TO U.S. MILITARY
SMITHKLINE BEECHAM's HALFAN WILL BE DISTRIBUTED MAINLY TO U.S. MILITARY following FDA approval of the malaria treatment on July 24. Codeveloped by the Walter Reed Army Institute of Research, the drug was approved for treatment of acute adult cases of mild-to- moderate malaria caused by Plasmodium falciparum or Plasmodium vivax. Halfan (halofantrine) has been granted orphan drug status, with a current U.S. treatment population of fewer than 1,000 cases, SmithKline Beecham said. The product is already approved in more than 50 countries. At a July 11 meeting of FDA's Anti-Infective Drugs Advisory Committee, Division of Anti-Infective Drugs Director Murray Lumpkin, MD, said the agency considered Halfan a "priority NDA" due to the emergence overseas of resistent strains of malaria, plentiful efficacy evidence in other countries, and increasing travel of Americans to areas infected with resistant malaria ("The Pink Sheet" July 13, p. 13). The application was submitted Jan. 3 and approved in less than seven months. However, the agency rated the approval "1S," indicating a new molecular entity with a standard review. Before it can market Halfan, SB must produce and validate two batches of the drug and submit to FDA accelerated three months stability data on Halfan produced at its Bristol, Tenn. facility. SmithKline Beecham said that it intends to comply with all the conditions contained in the approval letter but did not specify when Halfan will be launched. The approved product labeling for Halfan calls for "non-immune patients" to receive two courses of Halfan seven days apart. Each course consists of 500 mg of Halfan every six hours for three doses. "Omitting the second course of therapy may be considered" for semi-immune patients, the labeling states. Semi-immune patients are defined as those who have resided in endemic areas and who have a previous history of malarial infection with the same species of parasite. The Anti-Infective Drugs Advisory Committee was concerned that requiring a second course of Halfan therapy in non-immune patients could lead to poor patient compliance. Apparently to address that concern, FDA's approval letter states that SmithKline Beecham is required to submit data from clinical trials comparing Halfan use "in non-immune patients when administered as one course of therapy versus that observed when administered as two courses of therapy." The company should also "consider other potentially effective dosing regimens in non-immune patients that may be less problematic from a patient compliance standpoint," FDA directed. The approval letter stipulates that any advertisement or promotional labeling for Halfan must include the entire indications and usage section. The indications include a statement that "patients with acute P. vivax malaria treated with Halfan are at risk of relapse because halofantrine does not eliminate the exo-erythrocytic (hepatic phase) parasites." Patients with P. vivax malaria "should subsequently be treated with an 8-aminoquinoline to eradicate the exo-erythrocytic parasites," the note says. Another note in the indications section states that "the efficacy of halofantrine in the prophylaxis of malaria has not been established." The Army is conducting a study of Halfan in the prophylaxis of malaria. The approval letter also states that SmithKline Beecham has committed to develop, in collaboration with Walter Reed, a suspension formulation of Halfan for a pediatric indication. The Anti-Infective Advisory Committee's discussion emphasized the importance of a pediatric indication. The company is also required to conduct a 100-patient efficacy study to demonstrate that cure rates obtained with Halfan tablets produced at the Tennessee facility are the same as those found for tablets produced in Welwyn, U.K. The U.K.-produced tablets were used in the Halfan NDA.
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