Pharm

Ethambutol

search

Ethambutol

  • See Also
  1. Active Tuberculosis
  • Indications
  1. Active Tuberculosis
  2. Mycobacterium Avium Complex in HIV (off-label use)
  • Mechanism
  1. Bacteriostatic
  2. Inhibits arabinogalactan synthesis (key component of the Mycobacterial cell wall)
  3. Widely distributes including CNS, and concentrates in tubercles
  • Precautions
  1. Drug resistance emerges rapidly
    1. Must be used with other antituberculous drugs
  • Dosing
  1. Dose based on estimated Lean Body Mass
  2. Ethambutol is always combined with other agents
  3. Adult: 15-25 mg/kg (max 1600 mg/day) orally daily
    1. Weight 40 to 55 kg: 800 mg/day
    2. Weight 56 to 75 kg: 1200 mg/day
    3. Weight 79 to 90 kg: 1600 mg/day
  4. Child: 15-25 mg/kg (max 1000 mg/day) orally daily
  5. Renal Dosing
    1. Reduce dose in Renal Insufficiency
  • Adverse Effects
  1. Vision changes (obtain dilated Eye Exam prior to starting Ethambutol)
    1. Decreased Visual Acuity
    2. Retrobulbar Optic Neuritis (2.25% of patients)
      1. Associated with a loss of central Vision
      2. Typically reversible
  2. Peripheral Neuropathy
  3. Rash
  • Safety
  1. Pregnancy Category C
  2. Considered safe in Lactation
  • Monitoring
  1. Baseline
    1. Serum Creatinine
      1. Renal Dosing may be needed due to primarily Renal Clearance
    2. Visual acquity
    3. Color Perception
  2. Monthly retesting
    1. Visual acquity
    2. Color Perception
  3. Other monitoring
    1. Consider monitoring blood levels in weight >90 kg
  • Drug Interactions
  1. Avoid Antacids with aluminum hydroxide for at least 4 hours after dose
  • Resources
  1. Ethambutol Tablet (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b362b3cd-2c26-4af5-baa4-084217729fa5
  • References
  1. (2019) Presc Lett, Resource #350309, Tuberculosis Treatment in Adults: FAQ
  2. (2012) Med Lett Drugs Ther 10(116): 29-36