RETROVIR PEDIATRIC USE APPROVED BY FDA ON MAY 3

RETROVIR PEDIATRIC USE APPROVED BY FDA ON MAY 3, roughly six months after the agency cleared a Treatment IND for use of the antiretroviral in children. To date, approximately 525 children have received the drug free of charge from Burroughs Wellcome under the Treatment IND. The firm plans to continue to provide the children with Retrovir (zidovudine) free of charge for two additional months while families arrange for reimbursement. The approved pediatric indication is somewhat broader than the Treatment IND criteria. Approved labeling states that the drug is "indicated for HIV-infected children over three months of age who have HIV-related symptoms or who are asymptomatic with abnormal laboratory values indicating significant HIV-related immunosuppression." The Treatment IND protocol called for use in children with HIV-associated symptoms or CD4 counts below 400. Current estimates put the number of fully developed pediatric AIDS cases at 2,000; 1,200 of those patients have died. The number of HIV-infected children could reach up to 10,000, according to estimates cited by Burroughs-Wellcome. The recommended dose for children is 180 mg/m of body surface area every six hours (total daily dose of 720 mg/m), not to exceed 200 mg every six hours. FDA's press release on the approval noted that the "currently recommended dose for children may be lowered as a result of a clinical trial now underway" at the National Institute of Allergy and Infectious Diseases' AIDS Clinical Trial Groups. The recommended adult dose of zidovudine was lowered in January after clinical trials showed the lower dose to be as effective and safer than standard higher dosage regimens being used. Based on the average doses administered to children in the Treatment IND, which used the Retrovir syrup formulation approved in September 1989, Burroughs Wellcome estimates that the cost (price to wholesalers) for Retrovir syrup will be approximately$4.80 a day/patient or about $1,750 a year. The product is sold in 240 ml bottles (50 mg/5 ml), at a price to wholesalers of $28.85. Burroughs Wellcome's capsule product carries a similar per mg cost. The approved indication and dosing regimen follow recommendations made by FDA's Antiviral Drug Products Advisory Committee at its March 30 meeting ("The Pink Sheet" April 2, T&G-1). The committee based its approval recommendation on study data in adults as well as children. The committee felt that the data in children alone was insufficient to support approval. The committee's review of pediatric data focused on a Phase I and Phase II study in 124 patients. Reporting on results in the two trials, Burroughs Wellcome said "there was a low probability of developing an opportunistic infection through 12 months of follow-up." The overall survival rate over a mean duration of nine months follow-up was 89%, which "exceeds most published data on the natural history of HIV infection in children," the firm reported. Clinical improvements "included weight gain in previously growth retarded children, a reduction in the size of enlarged livers and spleens, improvements in I.Q. scores and other measures of brain function, [and]...improvements in immune system function, as measured by a reduction in elevated immunoglobulin levels and stabilization of CD4 cell counts," Burroughs Wellcome said.