A U.S. District Court judge has set Friday as the deadline for the federal government to stop Medicare and Medicaid reimbursements for prescription drugs for which the Food and Drug Administration has found no substantial evidence of effectiveness.

In congressional budget action in August, payments for those drugs were ordered stopped as of Oct. 1. When the Department of Health and Human Services implemented that directive, it allowed a 90-day grace period for administrative changes and to notify suppliers about the new rules.

Judge Thomas A. Flannery ruled Friday that the agency could not ignore an explicit congressional mandate to discontinue immediately reimbursements for ineffective drugs.

Acting in a case brought by the National Council of Senior Citizens, Flannery also rejected the government's argument that it needed the extra time to complete a list of affected drugs. Flannery cited the council's concern that individuals would be exposed to "significant health risks" if permitted to obtain prescriptions for the ineffective drugs during the grace period.

Frederic Townsend, an attorney for the council, said the government estimates that, in a three-month period, $10 million is paid in Medicaid and Medicare reimbursements in connection with more than 200 drugs classified by the FDA as ineffective.