title: Association between acquired rifamycin resistance and the pharmacokinetics of rifabutin and isoniazid among patients with HIV and tuberculosis.
abstract: BACKGROUND
  The occurrence of acquired rifamycin resistance despite use of directly observed therapy for tuberculosis is associated with advanced human immunodeficiency virus (HIV) disease and highly intermittent administration of antituberculosis drugs. Beyond these associations, the pathogenesis of acquired rifamycin resistance is unknown.
  
  
  METHODS
  We performed a pharmacokinetic substudy of patients in a trial of treatment with twice-weekly rifabutin and isoniazid.
  
  
  RESULTS
  A total of 102 (60%) of 169 patients in the treatment trial participated in the pharmacokinetic substudy, including 7 of 8 patients in whom tuberculosis treatment failure or relapse occurred in association with acquired rifamycin-resistant mycobacteria (hereafter, "ARR failure or relapse"). The median rifabutin area under the concentration-time curve (AUC(0-24)) was lower for patients with than for patients without ARR failure or relapse (3.3 vs. 5.2 microg*h/mL; P = .06, by the Mann-Whitney exact test). In a multivariate analysis adjusted for CD4+ T cell count, the mean rifabutin AUC(0-24) was significantly lower for patients with ARR failure or relapse than for other patients (3.0 microg*h/mL [95% confidence interval {CI}, 1.9-4.5] vs. 5.2 microg*h/mL [95% CI, 4.6-5.8]; P = .02, by analysis of covariance). The median isoniazid AUC(0-12) was not significantly associated with ARR failure or relapse (20.6 vs. 28.0 microg*h/mL; P = .24, by the Mann-Whitney exact test). However, in a multivariate logistic regression model that adjusted for the rifabutin AUC(0-24), a lower isoniazid AUC(0-12) was associated with ARR failure or relapse (OR, 10.5; 95% CI, 1.1-100; P = .04).
  
  
  CONCLUSIONS
  Lower plasma concentrations of rifabutin and, perhaps, isoniazid were associated with ARR failure or relapse in patients with tuberculosis and HIV infection treated with twice-weekly therapy.
authors.affiliation: University of Texas Health Science Center San Antonio, South Texas Veterans Health Care System, San Antonio, Texas, USA. weiner@uthscsa.edu
authors.forename: Marc
authors.initials: M
authors.lastname: Weiner
authors.forename: Debra
authors.initials: D
authors.lastname: Benator
authors.forename: William
authors.initials: W
authors.lastname: Burman
authors.forename: Charles A
authors.initials: CA
authors.lastname: Peloquin
authors.forename: Awal
authors.initials: A
authors.lastname: Khan
authors.forename: Andrew
authors.initials: A
authors.lastname: Vernon
authors.forename: Brenda
authors.initials: B
authors.lastname: Jones
authors.forename: Claudia
authors.initials: C
authors.lastname: Silva-Trigo
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhao
authors.forename: Thomas
authors.initials: T
authors.lastname: Hodge
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000493:pharmacokinetics / Q000627:therapeutic use; D019540:Area Under Curve; D018791:CD4 Lymphocyte Count; D023801:Directly Observed Therapy; D024881:Drug Resistance, Bacterial; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D007538:Isoniazid / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009169:Mycobacterium tuberculosis / Q000187:drug effects; D012008:Recurrence; D017828:Rifabutin / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D012294:Rifamycins / Q000494:pharmacology*; D012307:Risk Factors; D017211:Treatment Failure; D014376:Tuberculosis / Q000150:complications* / Q000188:drug therapy*
chemical_list: D000995:Antitubercular Agents; D012294:Rifamycins; D017828:Rifabutin; D007538:Isoniazid