Trecator Indications, Dosage, Storage, Stability - Ethionamide

Trecator Indications, Dosage, Storage, Stability - Ethionamide

INDICATIONS

Trecator-SC (ethionamide) is primarily indicated for the treatment of active tuberculosis in patients with M. tuberculosis resistant to isoniazid or rifampin, or when there is intolerance on the part of the patient to other drugs. Its use alone in the treatment of tuberculosis results in the rapid development of resistance. It is essential, therefore, to give a suitable companion drug or drugs, the choice being based on the results of susceptibility tests. If the susceptibility tests indicate that the patient's organism is resistant to one of the first-line antituberculosis drugs (i.e., isoniazid or rifampin) yet susceptible to ethionamide, ethionamide should be accompanied by at least one drug to which the M. tuberculosis isolate is known to be susceptible. ⁶ If the tuberculosis is resistant to both isoniazid and rifampin, yet susceptible to ethionamide, ethionamide should be accompanied by at least two other drugs to which the M. tuberculosis isolate is known to be susceptible. ⁶

Patient nonadherence to prescribed treatment can result in treatment failure and in the development of drug-resistant tuberculosis, which can be life-threatening and lead to other serious health risks. It is, therefore, essential that patients adhere to the drug regimen for the full duration of treatment. Directly observed therapy is recommended for all patients receiving treatment for tuberculosis. Patients in whom drug-resistant M. tuberculosis organisms are isolated should be managed in consultation with an expert in the treatment of drug-resistant tuberculosis.

In the treatment of tuberculosis, a major cause of the emergence of drug-resistant organisms, and thus treatment failure, is patient nonadherence to prescribed treatment. Treatment failure and drug-resistant organisms can be life-threatening and may result in other serious health risks. It is, therefore, important that patients adhere to the drug regimen for the full duration of treatment. Directly observed therapy is recommended when patients are receiving treatment for tuberculosis. Consultation with an expert in the treatment of drug-resistant tuberculosis is advised for patients in whom drug-resistant tuberculosis is suspected or likely. Ethionamide should be administered with at least one, sometimes two, other drugs to which the organism is known to be susceptible (see

INDICATIONS

Trecator-SC (ethionamide) is administered orally. The usual adult dose is 15 to 20 mg/kg/day, administered once daily or, if patient exhibits poor gastrointestinal tolerance, in divided doses with a maximum daily dosage of 1 gram. Thus far, there is insufficient evidence to indicate the lowest effective dosage levels. Therefore, in order to minimize the risk of resistance developing to the drug or to the companion drug, the principle of giving the highest tolerated dose (based on gastrointestinal intolerance) has been followed. In the adult this would seem to be between 0.5 and 1.0 gm daily, with an average of 0.75 gm daily.

The optimum dosage for pediatric patients has not been established. However, pediatric dosages of 10 to 20 mg/kg p.o. daily in 2 or 3 divided doses given after meals or 15 mg/kg/24 hrs as a single daily dose have been recommended. ^4,5 As with adults, ethionamide may be administered to pediatric patients once daily. It should be noted that in patients with concomitant tuberculosis and HIV infection, malabsorption syndrome may be present. Drug malabsorption should be suspected in patients who adhere to therapy, but who fail to respond appropriately. In such cases, consideration should be given to therapeutic drug monitoring (see CLINICAL PHARMACOLOGY).

The best times of administration are those which the individual patient finds most suitable in order to avoid or minimize gastrointestinal intolerance, which is usually at mealtimes. Every effort should be made to encourage patients to persevere with treatment when gastrointestinal side effects appear, since they may diminish in severity as treatment proceeds.

Initiation of therapy at a dose of 250 mg daily, with gradual titration to optimal doses as tolerated by the patient, also may be beneficial. A regimen of 250 mg daily for 1 or 2 days, followed by 250 mg twice daily for 1 or 2 days with a subsequent increase to 1 gm in 3 or 4 divided doses has been reported. ²

Concomitant administration of pyridoxine is recommended.

Duration of treatment should be based on individual clinical response. In general, continue therapy until bacteriological conversion has become permanent and maximal clinical improvement has occurred.

Trecator®-SC (ethionamide tablets, USP) are supplied in bottles of 100 tablets as follows:

250 mg, NDC 0008-4130, reddish orange, sugar-coated tablet marked WYETH and 4130.

Store at room temperature, approximately 25°C (77°F). Dispense in a tight container.

REFERENCES

1. Jenner, P.J.: Plasma Levels of Ethionamide and Prothionamide in a Volunteer Following Intravenous and Oral Dosages, Lepr Rev 58:31-37, 1987.
2. Peloquin, C.A.: Pharmacology of the Antimycobacterial Drugs, Med Clin North Am 77(6):1253-1262, 1993.
3. Lansdown, F.S., Beran, M., Litwak, T.: Psychotoxic Reaction During Ethionamide Therapy, Am Rev Resp Dis 95(6):1053-1055, 1967.
4. Feigin, R.D., and Cherry, J.D.: Textbook of Pediatric Infectious Diseases, 2nd Edition. Philadelphia, W.B. Saunders Co., 1987, pp. 1371-1372.
5. Nelson, W.E., Behrman, R.E., Vaughan, V.C. (eds): Nelson Textbook of Pediatrics, 13th edition. Philadelphia, W.B. Saunders Co., 1987, p.636
6. Treatment of Tuberculosis and Tuberculosis Infection in Adults and Children, Am J Respiratory and Critical Care Medicine, 149:1359-1374. 1994.

Manufactured by:
Wyeth Laboratories
A Wyeth-Ayerst Company
Philadelphia, PA 19101