Rifampin, a semisynthetic broad - spectrum bactericidal antibiotic, inhibits bacterial RNA synthesis by binding strongly to the beta subunit of DNA - dependent RNA polymerase, preventing attachment of the enzyme to DNA and thus blocking initiation of RNA transcription.

- Tuberculosis (treatment) - It is indicated in combination with other antituberculosis medications in the treatment of all forms of tuberculosis, including tuberculous meningitis.
- Leprosy (treatment) - It is used in combination with other agents in the treatment of leprosy (Hansen's disease).
- Meningococcal infections (prophylaxis) - It is indicated in the treatment of close contacts of patients with proved or suspected infection caused by Neisseria meningitidis.

Risk - benefit should be considered when the following medical problems exist:
Hepatic function impairment - Hypersensitivity to rifampin - Alcoholism, active or in remission.

Rifampin crosses the placenta. It is recommended that pregnant women with tuberculosis be treated for a minimum of 9 months with multidrug therapy, including rifampin. FDA pregnancy category C.
Rifampin is distributed into breast milk. Problems in humans have not been documented.

Rifampin is known to induce the hepatic microsomal enzymes that metabolize various drugs listed in the table below. The therapeutic effects of these drugs may be decreased.

Combinations containing any of the following medications, may also interact with this medication: Diazepam, Isoniazid, Probenecid, Phenytoin, Trimethoprim.

Those indicating need for medical attention: Incidence less frequent: "Flu - like" syndrome - hypersensitivity.
Incidence rare: Blood dyscrasias - hepatitis (yellow eyes or skin) - hepatitis prodromal symptoms - interstitial nephritis.
Those not indicating need for medical attention:
Incidence more frequent: Reddish orange to reddish brown discoloration of urine, feces, saliva, sputum, sweat and tears. Tears discolored by rifampin may also discolor soft contact lenses.

Usual adult and adolescent dose: Tuberculosis - In combination with other antituberculosis medication: Oral, 600 mg once a day for the entire treatment period; or 10 mg per kg of body weight, up to 600 mg, two or three times a week, depending on the treatment regimen.
Meningococcal infection (prophylaxis) - Oral, 600 mg two times a day for two days.
Usual adult prescribing limits: Up to 600 mg daily.
Children 1 month of age and over: Tuberculosis - In combination with other antituberculosis medications: Oral, 10 to 20 mg per kg of body weight, up to 600 mg, once a day; or 10 to 20 mg per kg of body weight, up to 600 mg, two or three times a week, depending on the treatment regimen.
Meningococcal infection (prophylaxis): Oral, 10 mg per kg of body weight every twelve hours for two days.