Screening of bulk drug samples and anti-tuberculosis products for the presence of therapeutically less active diasteriomeric (R,S) form of ethambutol dihydrochloride.
BACKGROUND
The present study was carried out to screen various ethambutol dihydrochloride (EB2HCI) bulk drug samples and anti-tuberculosis (anti-TB) products for the presence of less active (R,S)-EB2HCl.


METHODS
Samples of pure EB2HCl were received gratis from various companies and the formulations were procured from local market, and also from a Directly Observed Treatment Short-course (DOTS) centre. Some products available in the institute from Global Drug Facility were also included in the study. In total, 5 API samples and 35 formulations containing EB2HCI were investigated. These were subjected to evaluation for the presence of (R,S)-EB2HCl using a previously published differential scanning calorimetric method. The thermograms were recorded between 25 degrees C and 250 degrees C at a rate of 10 degrees C/min.


RESULTS
1 API sample and 12 formulations were found to contain (R,S)-EB2HCI up to an extent of 30-100%. One of the DOTS centres supply was also found to contain approximately 97% of the less active isomer.


CONCLUSIONS
The presence of therapeutically inactive form of the EB2HCl from 30-100% in approximately 30% of the products in the local market is an alarming finding, which means low quality anti-TB products are in circulation. The same may be contributory to the developing resistance of the drugs against the mycobacterium.
Prasad
Bhagwat
B
Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education and Research, SAS Nagar, Punjab.
Kumar
Vijay
V
Bhutani
Hemant
H
Singh
Saranjit
S
D000995:Antitubercular Agents / Q000032:analysis* / Q000592:standards; D002626:Chemistry, Pharmaceutical; D004977:Ethambutol / Q000032:analysis* / Q000737:chemistry* / Q000592:standards; D006801:Humans; D007194:India; D007536:Isomerism; D011785:Quality Assurance, Health Care; D013817:Thermography
D000995:Antitubercular Agents; D004977:Ethambutol