title: Screening of bulk drug samples and anti-tuberculosis products for the presence of therapeutically less active diasteriomeric (R,S) form of ethambutol dihydrochloride.
abstract: 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.
authors.affiliation: Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education and Research, SAS Nagar, Punjab.
authors.forename: Bhagwat
authors.initials: B
authors.lastname: Prasad
authors.forename: Vijay
authors.initials: V
authors.lastname: Kumar
authors.forename: Hemant
authors.initials: H
authors.lastname: Bhutani
authors.forename: Saranjit
authors.initials: S
authors.lastname: Singh
mesh_terms: 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
chemical_list: D000995:Antitubercular Agents; D004977:Ethambutol