Strategy To Limit Sampling of Antituberculosis Drugs Instead of Determining Concentrations at Two Hours Postingestion in Relation to Treatment Response

We fully agree with Burhan et al. that “Numerous studies havereported low concentrations of antituberculosis drugs in tuberculosis (TB) patients, but few studies have examined whether low drug concentrations affect TB treatment response” (1). The current anti-TB drug regimen of 2HRZE-4HRE (2 months treatment with isoniazid, rifampin, pyrazinamide, and ethambutol, followed by 4 months treatment with isoniazid, ri-fampin, and ethambutol) for drug-susceptible TB was based on numerous trials with similar favorable results, as this study shows (2). Fortunately, the majority of patients who receive and finish the treatment for drug-susceptible TB will respond completely to treatment (2). In cases of suspicion of inadequate exposure to anti-TB drugs and thereby a possibly suboptimal treatment re-sponse, indications for therapeutic drug monitoring (TDM) are those circumstances where the risk of treatment failure or toxicity is increased (3). Burhan et al. showed that first-line anti-TB dru