Ethionamide dosage

Most tubercle bacilli are inhibited in vitro by ethionamide, 2.5 mcg/mL or less. Some other species of mycobacteria also are inhibited by ethionamide, 10 mcg/mL. Serum concentrations in plasma and tissues of approximately 20 mcg/mL are achieved by a dosage of 1 g/d. Cerebrospinal fluid concentrations are equal to those in serum. 

Ethionamide is administered at an initial dose of 250 mg once daily, which is increased in 250-mg increments to the recommended dosage of 1 g/d (or 15 mg/kg/d), if possible. The 1 g/d dosage, though theoretically desirable, is poorly tolerated because of the intense gastric irritation and neurologic symptoms that commonly occur, and one often must settle for a total daily dose of 500-750 mg. Ethionamide is also hepatotoxic. Neurologic symptoms may be alleviated by pyridoxine. 

Ethionamide is a synthetic derivative of thio-isonicotinamide. The initial oral dosage for adults is 250 mg/day, slowly increasing up to 15-20 mg/kg/day (maximum 1 g/day). 

Various types of malabsorption, including steatorrhea, were reported with previous dosage forms of p-aminosalicylic acid. Hypersensitivity may occur and, rarely, severe hepatitis. p-Aminosalicylic acid is known to produce goiter, with or without myxedema, that seems to occur more frequently with concomitant ethionamide therapy. 

---