A pilot study to determine the occurrence of concomitant diseases and drug intake in patients on antituberculosis therapy

INTRODUCTION: Altered pharmacokinetics of antituberculosis (anti-TB) drugs due to interaction with non-TB medications or concomitant diseases may lead to suboptimal plasma levels of the affected drugs and hence contribute to the emergence of drug resistance in mycobacteria. Yet, few studies have investigated the prevalence of concomitant drug intake or concurrent diseases in patients on anti-TB therapy (ATT). The objective of this study is to study the prevalence of concomitant diseases and intake of non-TB drugs in patients on ATT. METHODS: Adult patients who were undergoing treatment for TB at a directly observed treatment short-course (DOTS) center were interviewed to find out any concomitant drug intake and ailments they were suffering from. Data were also collected from the patients’ treatment cards. RESULTS: A total of 105 patients were interviewed for the study over a period of 1 month. Among these, 66 (62.9%) patients reported having taken a non-ATT drug in the last 3 months, 61 (58.1%) of which were drugs that may affect the ATT. A comparable number of patients (61 [58.1%]) reported suffering from one or the other concurrent illnesses or symptoms while on DOTS, including one patient with AIDS and eight with diabetes mellitus. Fluoroquinolones had been prescribed to four patients while on DOTS. CONCLUSION: A large proportion of the patients with TB were found to be on non-TB concomitant medications including drugs with potential for interactions that are capable of affecting ATT outcomes. It is, therefore, important that the patients and prescribing physicians be aware of any possible drug interactions.