Rifater (Rifampin / Isoniazid / Pyrazinamide) - Indications and Dosage

INDICATIONS AND USAGE

RIFATER is indicated in the initial phase of the short-course treatment of pulmonary tuberculosis. During this phase, which should last 2 months, RIFATER should be administered on a daily, continuous basis (see DOSAGE AND ADMINISTRATION section).

Following the initial phase and treatment with RIFATER, treatment should be continued with rifampin and isoniazid (eg, RIFAMATE) for at least 4 months. Treatment should be continued for a longer period of time if the patient is still sputum or culture positive, if resistant organisms are present, or if the patient is HIV positive.

In the treatment of tuberculosis, the small number of resistant cells present within large populations of susceptible cells can rapidly become the predominant type. Since resistance can emerge rapidly, susceptibility tests should be performed in the event of persistent positive cultures during the course of treatment. Bacteriologic smears or cultures should be obtained before the start of therapy to confirm the susceptibility of the organism to rifampin, isoniazid, and pyrazinamide and they should be repeated throughout therapy to monitor response to the treatment. If test results show resistance to any of the components of RIFATER and the patient is not responding to therapy, the drug regimen should be modified.

DOSAGE AND ADMINISTRATION

Adults

Patients should be given the following single daily dose of RIFATER either 1 hour before or 2 hours after a meal with a full glass of water.

Patients weighing ≤44 kg – 4 tablets

Patients weighing between 45–54 kg – 5 tablets

Patients weighing ≥55 kg – 6 tablets

Pediatric Patients

The ratio of the drugs in RIFATER may not be appropriate in pediatric patients under the age of 15 (eg, higher mg/kg doses of isoniazid are usually given in pediatric patients than adults).

RIFATER is recommended in the initial phase of short-course therapy which is usually continued for 2 months. The Advisory Council for the Elimination of Tuberculosis, the American Thoracic Society, and the Centers for Disease Control and Prevention recommend that either streptomycin or ethambutol be added as a fourth drug in a regimen containing isoniazid (INH), rifampin and pyrazinamide for initial treatment of tuberculosis unless the likelihood of INH or rifampin resistance is very low. The need for a fourth drug should be reassessed when the results of susceptibility testing are known. If community rates of INH resistance are currently less than 4%, an initial treatment regimen with less than four drugs may be considered.

Following the initial phase, treatment should be continued with rifampin and isoniazid (eg, RIFAMATE^®) for at least 4 months. Treatment should be continued for longer if the patient is still sputum or culture positive, if resistant organisms are present, or if the patient is HIV positive.

Concomitant administration of pyridoxine (B₆) is recommended in the malnourished, in those predisposed to neuropathy (eg, alcoholics and diabetics), and in adolescents.

See CLINICAL PHARMACOLOGY: General for dosing information in patients with renal failure.

HOW SUPPLIED

RIFATER tablets are light beige, smooth, round, and shiny sugar-coated tablets imprinted with "RIFATER" in black ink and contain 120 mg rifampin, 50 mg isoniazid, and 300 mg pyrazinamide, and are supplied as:

Bottles of 60 tablets (NDC 0088-0576-41).

Storage Conditions

Store at controlled room temperature 59–86°F (15–30°C). Protect from excessive humidity.

Reference

1. National Committee for Clinical Laboratory Standards. 1990. Antimycobacterial Susceptibility Testing (Proposed Standard). Document M24-P.