Recurrent tuberculosis due to subtherapeutic levels of antitubercular treatment

Abstract

Most patients with tuberculosis respond well to treatment. Even in patients with good compliance to DOTS and sensitive to first-line drugs, treatment failure or relapse still occurs, the phenomenon of cryptic adherence needs careful evaluation. We present a case of frequent recurrence due to possible subtherapeutic levels of isoniazid (INH) and rifampicin. A 32-year-old male with no other comorbidities came with complaints of cough with expectoration with constitutional symptoms. He was treated for the primary complex at the age of 12 years and declared as cured. In 2006, he was diagnosed as right axillary TB lymphadenitis which was confirmed by histopathological examination and treated with Anti tubercular treatment (ATT) for 9 months. After 2 years (2008), he had developed left axillary lymphadenitis for which he was treated again with Anti tubercular treatment empirically. In 2016, he was diagnosed as smear-negative pulmonary tuberculosis (PTB) whose chest X-ray suggestive of PTB. Hence, he was treated with Anti tubercular treatment for 6 months, declared as cured. Now (2018), he was diagnosed as sputum-positive PTB with INH and rifampicin sensitive. Hence, we did a pharmacokinetics study, which revealed subtherapeutic levels of rifampicin and isoniazid. The patient responded well after increasing the dosage of drugs. Slow responders and patients with complications warrant the need of therapeutic drug monitoring (TDM). Drug concentrations which may be help resolve the problem of slow response to Anti Tuberculosis Therapy. TDM however is not routinely indicated in each case.

Keywords

• pharmacokinetics study
• recurrent tuberculosis
• therapeutic drug monitoring