Anti-Tuberculosis Drugs: Pharmacology, Mechanisms, Resistance and Therapeutic Advances

Tuberculosis (TB) continues to rank among the most formidable infectious diseases confronting global public health, claiming more than 1.3 million lives annually and affecting nearly ten million individuals worldwide each year. Caused by Mycobacterium tuberculosis — a slow-growing, aerobic, acid-fast bacillus — the disease predominantly targets the pulmonary system, although it is capable of disseminating to virtually any organ. The management of tuberculosis relies on a combination chemotherapy strategy employing both first-line and second-line agents, with treatment courses typically extending from six months to over twenty-four months depending on drug sensitivity profiles. This review article provides a thorough and critical appraisal of the pharmacological landscape of anti-tuberculosis drugs. It discusses the chemical nature, mechanisms of action, therapeutic applications, pharmacokinetic profiles, and adverse effect spectra of key agents, including isoniazid, rifampicin, pyrazinamide, ethambutol, streptomycin, fluoroquinolones, and newer compounds such as bedaquiline, delamanid, and pretomanid. Special emphasis is placed on the escalating global crisis of drug-resistant tuberculosis — including multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) — along with the molecular mechanisms that confer resistance. The review further addresses treatment regimens recommended by the World Health Organization (WHO), the management of adverse drug reactions, and considerations for special populations including TB-HIV co-infection, pregnancy, and pediatric cases. Finally, emerging therapeutic targets, novel drug candidates, and the future trajectory of anti-tuberculosis drug development are examined.