FIXED-DOSE COMBINATIONS OF ANTITUBERCULOUS MEDICATIONS TO PREVENT DRUG-RESISTANCE

The treatment of tuberculosis requires at least two drugs to retard th e development of drug resistance. Unfortunately, patients may take onl y one drug (monotherapy) when more than one is prescribed. Fixed-dose combinations with two or more antituberculous drugs in one capsule or tablet are available to prevent this. In the United States, these drug s are Rifamate (Marion Merrell Dow), which contains isoniazid plus rif ampin, and Rifater (Marion Merrell Dow), which contains isoniazid plus rifampin and pyrazinamide. Because these preparations make monotherap y impossible, they are clearly preferable to individual drugs. In the United States in 1993, however, only 15% to 18% of rifampin was sold i n the form of fixed-dose combinations. To correct this deficiency, fix ed-dose combinations should be widely promoted and accepted as a prima ry way to prevent drug-resistant tuberculosis. There are two caveats r egarding these preparations. First, many fixed-dose combinations, espe cially those in developing countries, achieve inadequate blood levels of one or more of the component drugs, especially rifampin. Our recomm endations apply only to preparations with proven bioavailability. Seco nd, because the name Rifamate is similar to the name rifampin, mistake s in prescribing and dispensing can result in the patient receiving ri fampin alone when Rifamate is intended. A name change from Rifamate to a highly distinctive name such as Rif-Isoniazid is needed to prevent such occurrences.