Drugs Used In Tuberculosis - Rifampicin

• First line anti tubercular agent
• Semi synthetic antibiotic
  
• Orally effective
  
• Active against all sub populations of Mycobacteria including persisters. (Hence called a Sterilising Agent)
  
• Has tuberculocidal action

• Inhibits bacterial DNA dependent RNA polymerase and thereby suppresses the chain initiation in RNA synthesis.

• Mycobacteria
• Staphylococcus aureus
• Hemophillus influenzae,E.coli,Pseudomonas,Klebsiella
• N.Meningitides
  

• Orally administered and completely absorbed from the gastrointestinal tract
• Food interferes with its absorption
  
• Widely distributed across all the body cavities,tissues and fluids.
• Attains high concentrations in the CSF.
• Stains all body fluids harmless orange-red color.
  
• Metabolised in the liver to its active deacetylated form which is excreted in the bile and undergoes enterohepatic cycling.
  
• The other metabolites are excreted in urine.

• Tuberculosis : Along with Isoniazid and other anti-tubercular agents.
• Leprosy: Along with Dapsone and clofazimine
• Prophylaxis of Meningococcal and H.influenzae meningitis
• Penicillins are ineffective for prophylaxis as they penetrate poorly into the naso-pharynx where these organisms are commensals
• 600mg P.O. 12th hourly for 4 doses
• Minocycline can also be used for prophylaxis but rarely due to toxicity.
• Staphylococcal endocarditis and osteomyelitis : along with ß-lactam antibiotics
• Brucellosis: In combination with Doxycycline is the preferred therapy.
  

• Hepatitis
• More common among the elderly and chronic alcoholics.
  
• Gastrointestinal disturbance
• Flu-like syndrome
• Respiratory syndrome
• Cutaneous syndrome
• Abdominal syndrome
  

• Repeated administration of rifampin causes enzyme induction and reduces the plasma concentration of co-administered drugs such as oral contraceptive pills. oral anti-coagulants, oral anti-diabetic agents, Anti-HIV protease inhibitors,NNRTI's,Digoxin,Quinidine, propranolol etc.
• Causes auto induction of its own metabolism.

Category: Pharmacology Notes