Tuberculosis chemoprophylaxis is a therapeutic measure for the prevention of infection by Mycobacterium tuberculosis or to avoid development of the disease in individuals already infected with it. Isoniazid is the most commonly used therapy; however, the use of rifampicin and pyrazinamide has recently been introduced. The objectives of this study were to review the results of the principal studies evaluating the indications for chemoprophylaxis with isoniazid alone and in association with other drugs, its efficacy in the prevention of tuberculosis with respect to the different risk groups and the alternative regimens available. A systematic revision of the medical literature was carried out with particular emphasis on clinical trials and meta-analyses. Official records were also consulted. Those studies involving randomized clinical trials on the use of isoniazid, rifampicin or pyrazinamide in HIV-positive or negative patients were selected. Isoniazid continues to be effective for the prevention of tuberculosis in populations of both HIV-negative and HIV-positive individuals. The standard dose of 5-15 mg/kg/day has shown similar protection over treatment periods ranging from six to twelve months. The risk of developing hepatitis was less than 1%; however monitoring during treatment is recommended in patients over 35 years of age and in users of alcohol. Studies involving treatment regimens with other forms of medication were inconclusive and new studies would have to be performed to evaluate the efficacy of these regimens in populations at high risk of developing tuberculosis.

Keywords: Tuberculosis. Chemoprophylaxis. Isoniazid.