Antitubercular Drugs

Introduction

• Tuberculosis (TB) is a chronic granulomatous infection by Mycobacterium tuberculosis; India is the highest-burden country and TB kills more Indian adults than any other infection. ~⅓ of the world is latently infected, of whom 10–15% develop active disease.
• Why TB is hard to treat — three natural barriers — a waxy mycolic-acid cell wall (>60% lipid) blocking drug entry, abundant efflux pumps, and an intracellular + caseous-lesion location drugs must reach. Slow growth and dormant bacilli add further resistance to killing.
• Cardinal principle — combination of ≥2 (massive infection ≥3) drugs is mandatory — to kill the bacillus AND prevent emergence of resistance over the months of therapy; single-drug treatment is only ever for prophylaxis (small bacillary load).
• TB therapy gave medicine its first randomized controlled trial (streptomycin vs bed rest).