title: Therapeutic drug monitoring in the treatment of tuberculosis: a retrospective analysis.
abstract: METHODS
  Tuberculosis (TB) in-patient treatment unit in Vancouver, Canada.
  
  
  OBJECTIVE
  To examine the results of therapeutic drug monitoring (TDM) in anti-tuberculosis treatment.
  
  
  METHODS
  We performed a retrospective analysis of TDM data from 2000 to 2010. All in-patients treated  for TB with TDM performed during their treatment course were included.
  
  
  RESULTS
  TDM was performed on 52 patients in 76 treatment episodes from 2000 to 2010. Overall, 103/213 (48.4%) drug levels measured were low, and 5/213 (2.3%) were high. At least one drug level was low in 47/52 (90.3%)  patients. Initial serum levels were low in respectively 76.6% and 68.4% of isoniazid (INH) and rifampicin (RMP) levels. In contrast, only 2.9% of initial pyrazinamide levels were low. Five patients with a susceptible strain on initial presentation later developed drug-resistant disease, with  all five patients demonstrating at least one low drug level and two demonstrating multiple low levels. Dose adjustments were made in response to 26 INH and RMP levels, with variable serum responses.
  
  
  CONCLUSIONS
  In this population with high rates of treatment failure and acquired resistance,  we demonstrate that most patients had low drug levels. Prospective studies are required to examine the relationship between drug levels and clinical outcomes.
authors: Division of Respiratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
authors: L
authors: L
authors: Van Tongeren
authors: S
authors: S
authors: Nolan
authors: V J
authors: VJ
authors: Cook
authors: J M
authors: JM
authors: FitzGerald
authors: J C
authors: JC
authors: Johnston
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use; D001955:British Columbia / Q000453:epidemiology; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D014376:Tuberculosis / Q000097:blood / Q000188:drug therapy* / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents