TREATMENT A standard four-drug regimen, consisting of isoniazid, rifampicin, pyrazinamide, and ethambutol , is recommended for ATT in intra-abdominal/gastrointestinal tuberculosis. These four drugs are used thrice weekly for the initial two months, followed by isoniazid and rifampin for an additional four months. ATT is usually reported to be highly effective with good cure rates. Healing of intestinal ulcers can be seen as early as the end of the ATT initiation phase (2 months).