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Objective: To determine the content of certain antituberculosis (TB) drugs supplied at TB treatment centres of the Revised National TB Control Programme (RNTCP) in the state of Tamil Nadu, India., Methods: Eight districts across the state were selected, and the following drugs were collected from five settings (District TB centre, TB unit, designated microscopy centres, DOT providers) in each district: rifampicin (150 and 450 mg), isoniazid (300 mg), pyrazinamide (500 and 750 mg), ethambutol (400 and 600 mg), ethionamide (250 mg), levofloxacin (500 mg) and cycloserine (250 mg). A maximum of 10 tablets/capsules were collected from each setting. The drugs were coded prior to analysis. All drugs were assayed by validated spectrophotometric methods. The acceptable limits for drug content were taken as 90-110% of the stated content., Results: More than 90% of tablets of rifampicin 450 mg, isoniazid 300 mg, pyrazinamide 500 and 750 mg, ethambutol 400 and 600 mg and ethionamide 250 mg were within acceptable limits. Eighty per cent of rifampicin 150 mg, 21% of cycloserine 250 mg and 87% of levofloxacin 500 mg were within acceptable limits. The mean cycloserine content was below the acceptable limit in all districts, the mean drug content being 200 mg (range: 108-245 mg)., Conclusion: This systematic study showed that the stated drug content of cycloserine was not reached in all districts. Deterioration of cycloserine could be minimised by storing the drug in refrigerators. The geographical location of the districts had no influence on the drug content., (© 2013 John Wiley & Sons Ltd.)

Gross deterioration of cycloserine during transit and storage in the tropics is reported from the Tuberculosis Chemotherapy Centre, Madras. Laboratory experiments suggest that high humidity, rather than high temperature, is the main cause of the deterioration. Further investigations undertaken at the Centre indicate that deterioration can be prevented by storing the drug in tightly closed glass bottles in an air-conditioned room (18 degrees C); if such facilities are not available, and the drug has to be stored at ambient temperature and humidity, the use of air-tight polyethylene bottles will serve to delay the deterioration. The findings also suggest that, when cycloserine is dispensed to patients, individual doses should be heat-sealed in polyethylene strips and that not more than a week's supply should be given at any one time. The authors discuss various measures that could be employed by manufacturers and by shipping and clearing agents to minimize the possibility of deterioration.