A Federal program which will limit reimbursement for prescription drugs under the Medicare and Medicaid programs, and Public Health Service projects to the lowest cost at which the drug is generally available. Specifically, the program limits reimbursement for drugs under programs administered by HEW to the lowest of the maximum allowable cost (MAC) of the drug, if any, plus a reasonable dispensing fee, the acquisition cost of the drug plus a dispensing fee, or the providers’ usual and customary charge to the general public for the drug. The MAC is the lowest unit price at which a drug available from several sources or manufacturers can be purchased on a national basis.