Drugs Used In Tuberculosis - Streptomycin and Ethambutol

• First line anti tubercular agent
• First Drug discovered to have anti-tubercular acivity
• Given inramuscularly
• Effective only against extracellular bacilli in alkaline pH

Ethambutol

• Only first line anti-tubercular agent with tuberculostatic effect

• Inhibits arabinosyl transferase enzyme involved in mycobacterial cell wall synthesis
  

• Orally administered and well absorbed from the gastrointestinal tract
• Widely distributed
• Attains high concentrations and is stored in the Eryhrocytes.
• Metabolised in the liver and excreted in urine.

Rationale as First Agent

• Resistance to ethambutol develops slowly and it also prevents development of resistance against Isoniazid and Rifampicin
• It is effecive against mycobacteria resistant to Isoniazid and Rifampicin and many Atypical Mycobacteria
• No Cross resistance with other anti-tubercular agents
• Has tuberculocidal action at high concentrations.

• Optic Neuriis
• Decreased visual acuity
• Color vision defects Especially Red-green Discrimination
• Central Scotoma
• Advise periodic ophthalmic examinations
• Avoid in children less than 6 yrs of age
• they cannot report eye disurbances accurately
• It is difficult assess visual acuity in them
  
  

Category: Pharmacology Notes