2. Antituberculosis

• Tuberculosis


  Pulmonary tuberculosis (TB) is a contagious bacterial infection caused by Mycobacterium tuberculosis (M. tuberculosis). The lungs are primarily involved, but the infection can spread to other organs.
• Various Other Tuberculosis Infections

  • Tubercular meningitis – nervous system
  • Skin Tuberculosis
  • Arthritic Tuberculous - joint
  • Pleural effusion - lung
• Isoniazid (INH)


  • Inhibits synthesis of mycolic acids, which are essential components of mycobacterial cell walls
  • Isoniazid is a prodrug that is activated by KatG, the mycobacterial catalase-peroxidase
  • The activated form of isoniazid inhibits protein synthetase, which in turn blocks mycolic acid synthesis
• Rifampin (US) / Rifampicin (UK)


  • Impairs RNA synthesis by inhibiting DNA- dependent RNA polymerase
  • May be bacteristatic or bactericidal, depending upon organism susceptibility and drug level at the site of infection
• Rifampin is an alternative to isoniazid prophylaxis / prevention for patients who are unable to take isoniazid or who have had close contact with a case of active tuberculosis caused by an isoniazid-resistant, rifampin-susceptible strain.
• Pyrazinamide


  Mechanism of action is unknown. May be bacteristatic or bactericidal, depending upon organism susceptibility and drug level at the site of infection
• Ethambutol


  • Inhibits cell wall synthesis by inhibiting mycobacterial arabinosyl transferases
  • Arabinosyl transferases are involved in the polymerization reaction of arabinoglycan, an essential component of the mycobacterial cell wall
• Streptomycin


  Bactericidal, binds directly to 30s ribosomal subunit, inhibiting bacterial protein synthesis