The goal of this observational study is to investigate whether model-informed precision dosing (MIPD), as a clinical support for early individualised dosing in addition to the national TB care program, can optimise the drug exposure of TB drugs during TB treatment. Main research questions: In adult patients with drug-susceptible pulmonary tuberculosis, can current dose recommendations and information received from MIPD help clinicians in a timely manner to optimise the drug exposure of TB drugs in the early treatment phase, i.e., the time from PK sampling to dose adjustment (keep or adjust dose)? Specific aims I. To perform a process evaluation of early MIPD for rifampicin, isoniazid, pyrazinamide and ethambutol during active TB treatment. II. To study the target attainment of first-line TB drugs with MIPD. III. To evaluate model precision of predicted versus detected drug concentrations. Drug concentrations will be measured in study participants during TB treatment, and drug exposure and the optimal dose will be predicted by MIPD using pharmacokinetic population models.