Methadone maintenance and tuberculosis treatment

摘要

Rifampicin is a potent inducer of hepatic microsomal enzymes. It increases drug clearance and reduces the half life of a wide range of drugs, including barbiturates, oral contraceptives, propranolol, sulphonylureas, and methadone. Without a concomitant increase in methadone dose, patients also taking rifampicin are likely to experience opiate withdrawal symptoms and may stop their antituberculosis drugs or supplement their methadone prescription with illicitly obtained opiates. Failure to comply with antituberculosis treatment compromises recovery and increases the risk of secondary resistance. The symptoms of methadone withdrawal usually occur only when intake is reduced and are not expected by a user starting rifampicin. Notifications of tuberculosis in the United Kingdom rose from a plateau of some 5100 in 1987 to over 5700 in 1994. Drug misusers account for only a small number of cases, but they share nationally identified risk factors; thus high rates of tuberculosis can be expected among drug misusers and especially those who are HIV positive.