II. Indications
- Active Tuberculosis
- Mycobacterium Avium Complex in HIV (off-label use)
III. Mechanism
- Bacteriostatic
- Inhibits arabinogalactan synthesis (key component of the Mycobacterial cell wall)
- Widely distributes including CNS, and concentrates in tubercles
IV. Precautions
- Drug resistance emerges rapidly
- Must be used with other antituberculous drugs
V. Dosing
- Dose based on estimated Lean Body Mass
- Ethambutol is always combined with other agents
- Adult: 15-25 mg/kg (max 1600 mg/day) orally daily
- Weight 40 to 55 kg: 800 mg/day
- Weight 56 to 75 kg: 1200 mg/day
- Weight 79 to 90 kg: 1600 mg/day
- Child: 15-25 mg/kg (max 1000 mg/day) orally daily
-
Renal Dosing
- Reduce dose in Renal Insufficiency
VI. Adverse Effects
-
Vision changes (obtain dilated Eye Exam prior to starting Ethambutol)
- Decreased Visual Acuity
- Retrobulbar Optic Neuritis (2.25% of patients)
- Associated with a loss of central Vision
- Typically reversible
- Peripheral Neuropathy
- Rash
VII. Safety
- Pregnancy Category C
- Considered safe in Lactation
VIII. Monitoring
- Baseline
- Serum Creatinine
- Renal Dosing may be needed due to primarily Renal Clearance
- Visual acquity
- Color Perception
- Serum Creatinine
- Monthly retesting
- Visual acquity
- Color Perception
- Other monitoring
- Consider monitoring blood levels in weight >90 kg
IX. Drug Interactions
- Avoid Antacids with aluminum hydroxide for at least 4 hours after dose
X. Resources
- Ethambutol Tablet (DailyMed)
XI. References
- (2019) Presc Lett, Resource #350309, Tuberculosis Treatment in Adults: FAQ
- (2012) Med Lett Drugs Ther 10(116): 29-36
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| ethambutol (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| ETHAMBUTOL HCL 400 MG TABLET | Generic | $0.66 each |