Adverse Drug Events from First-Line Anti-tuberculosis Drugs in a Tertiary Medical Center

Background: Tuberculosis (TB) has remained one of the top causes of morbidity and mortality in the Philippines since 2018. However, adverse drug reactions (ADR) from first-line anti-tuberculosis medications such as rifampicin, isoniazid, pyrazinamide, and ethambutol cause significant impact on treatment adherence. This study aimed to determine the incidence of ADRs among patients treated with first-line anti-tuberculosis medications at a Philippine Department of Health tertiary medical centre. Methods: In this retrospective cohort study, rifampicin-susceptible patients undergoing first-line anti-TB treatment enrolled in the Tuberculosis-Directly Observed Treatment Strategy at the East Avenue Medical Centre, Quezon City, Philippines, were included.Pertinent data obtained from chart review included sociodemographic factors, clinical characteristics, duration of treatment prior to the appearance of adverse drug reactions, type of ADRs, TB medication causing the ADR, and treatment outcomes. Results: A total of 524 patients treated with first-line anti-TB treatment were identified, with 46 (8.78%) noted to have ADRs to the treatment regimen. Most reaction types included mild or localised skin reactions (34.8%), severe skin rash secondary to hypersensitivity (32.6%), and jaundice due to hepatitis (21.7%). Reaction to more than one medication was seen in 89.1% of patients with ADRs, with rifampicin having the highest frequency of ADR (4.3%) among the anti-TB medications. Conclusion: The incidence of ADRs among patients treated with first-line anti-TB medications at East Avenue Medical Centre in the Tuberculosis-Directly Observed Treatment Strategy is frequent and comparable to other relevant study populations. A larger sample size and exploration of other methodological studies are recommended to further expand on this study.