Coadministration of Allopurinol To Increase Antimycobacterial Efficacy of Pyrazinamide as Evaluated in a Whole-Blood Bactericidal Activity Model

Antimicrob Agents Chemother. 2017 Sep 22;61(10):e00482-17. doi: 10.1128/AAC.00482-17. Print 2017 Oct.


Coadministering pyrazinamide (PZA) with the xanthine oxidase inhibitor allopurinol increases systemic levels of the active metabolite, pyrazinoic acid (POA), but the effects on bactericidal activity against tuberculosis are unknown. We randomized healthy volunteers to take a single dose of PZA (either 10 or 25 mg/kg of body weight) at the first visit and the same dose 7 days later, coadministered with allopurinol (100 mg daily; 2 days before to 1 day after the PZA dose). Blood was drawn at intervals until 48 h after each PZA dose, and drug levels were measured using liquid chromatography-tandem mass spectrometry. Whole-blood bactericidal activity (WBA) was measured by inoculating blood samples with Mycobacterium tuberculosis and estimating the change in bacterial CFU after 72 h of incubation. Allopurinol increased the POA area under the concentration-time curve from 0 to 8 h (AUC0-8) (18.32 h · μg/ml versus 24.63 h · μg/ml for PZA alone versus PZA plus allopurinol) (P < 0.001) and its peak plasma concentration (Cmax) (2.81 μg/ml versus 4.00 μg/ml) (P < 0.001). There was no effect of allopurinol on mean cumulative WBA (0.01 ± 0.02 ΔlogCFU versus 0.00 ± 0.02 ΔlogCFU for PZA alone versus PZA plus allopurinol) (P = 0.49). Higher systemic POA levels were associated with greater WBA levels (P < 0.001), but the relationship was evident only at low POA concentrations. The lack of an effect of allopurinol on WBA despite a significant increase in blood POA levels suggests that host-generated POA may be less effective than POA generated inside bacteria. Coadministration of allopurinol does not appear to be a useful strategy for increasing the efficacy of PZA in clinical practice. (This study has been registered at under registration no. NCT02700347.).

Keywords: Mycobacterium tuberculosis; WBA; allopurinol; pyrazinamide; whole-blood bactericidal activity.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Allopurinol / blood*
  • Allopurinol / pharmacology
  • Antitubercular Agents / blood*
  • Antitubercular Agents / pharmacology
  • Blood Bactericidal Activity / drug effects*
  • Drug Therapy, Combination
  • Enzyme Inhibitors / blood*
  • Enzyme Inhibitors / pharmacology
  • Healthy Volunteers
  • Humans
  • Microbial Sensitivity Tests
  • Middle Aged
  • Mycobacterium tuberculosis / drug effects*
  • Pyrazinamide / blood*
  • Pyrazinamide / pharmacology
  • Xanthine Oxidase / antagonists & inhibitors
  • Young Adult


  • Antitubercular Agents
  • Enzyme Inhibitors
  • Pyrazinamide
  • Allopurinol
  • Xanthine Oxidase

Associated data