Isoniazid, rifampin, ethambutol, and pyrazinamide pharmacokinetics and treatment outcomes among a predominantly HIV-infected cohort of adults with tuberculosis from Botswana.
BACKGROUND
We explored the association between antituberculosis drug pharmacokinetics and treatment outcomes among patients with pulmonary tuberculosis in Botswana.


METHODS
Consenting outpatients with tuberculosis had blood samples collected 1, 2, and 6 h after simultaneous isoniazid, rifampin, ethambutol, and pyrazinamide ingestion. Maximum serum concentrations (C(max)) and areas under the serum concentration time curve were determined. Clinical status was monitored throughout treatment.


RESULTS
Of the 225 participants, 36 (16%) experienced poor treatment outcome (treatment failure or death); 155 (69%) were infected with human immunodeficiency virus (HIV). Compared with published standards, low isoniazid C(max) occurred in 84 patients (37%), low rifampin C(max) in 188 (84%), low ethambutol C(max) in 87 (39%), and low pyrazinamide C(max) in 11 (5%). Median rifampin and pyrazinamide levels differed significantly by HIV status and CD4 cell count category. Only pyrazinamide pharmacokinetics were significantly associated with treatment outcome; low pyrazinamide C(max) was associated with a higher risk of documented poor treatment outcome, compared with normal C(max) (50% vs. 16%; P < .01). HIV-infected patients with a CD4 cell count <200 cells/microL had a higher risk of poor treatment outcome (27%) than did HIV-uninfected patients (11%) or HIV-infected patients with a CD4 cell count 200 cells/microL (12%; P = .01). After adjustment for HIV infection and CD4 cell count, patients with low pyrazinamide C(max) were 3 times more likely than patients with normal pyrazinamide C(max) to have poor outcomes (adjusted risk ratio, 3.38; 95% confidence interval, 1.84-6.22).


CONCLUSIONS
Lower than expected antituberculosis drug C(max) occurred frequently, and low pyrazinamide C(max) was associated with poor treatment outcome. Exploring the global prevalence and significance of these findings may suggest modifications in treatment regimens that could improve tuberculosis cure rates.
Chideya
Sekai
S
Centers for Disease Control and Prevention, Atlanta, Georgia, USA. schideya@health.nyc.gov
Winston
Carla A
CA
Peloquin
Charles A
CA
Bradford
William Z
WZ
Hopewell
Philip C
PC
Wells
Charles D
CD
Reingold
Arthur L
AL
Kenyon
Thomas A
TA
Moeti
Themba L
TL
Tappero
Jordan W
JW
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D001902:Botswana; D018791:CD4 Lymphocyte Count; D004977:Ethambutol / Q000493:pharmacokinetics / Q000627:therapeutic use; D005260:Female; D015658:HIV Infections / Q000150:complications; D006801:Humans; D007538:Isoniazid / Q000493:pharmacokinetics / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011718:Pyrazinamide / Q000493:pharmacokinetics / Q000627:therapeutic use; D012293:Rifampin / Q000493:pharmacokinetics / Q000627:therapeutic use; D044967:Serum / Q000737:chemistry; D016896:Treatment Outcome; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy*; D055815:Young Adult
D000995:Antitubercular Agents; D011718:Pyrazinamide; D004977:Ethambutol; D007538:Isoniazid; D012293:Rifampin