Ethambutol (Myambutol)

Category:

• Miscellaneous

Description:

• Antituberculosis agent

Indications:

• Adjunct in treatment of pulmonary tuberculosis

• Mycobacterium avium complex (MAC) in AIDS (2^nd line) (non-FDA approved)

Contraindications:

• Optic neuritis

• Child <13 years

Precautions:

• Pregnancy category B; compatible with breast feeding

• Renal disease diabetic retinopathy

• Cataracts, ocular defects, hepatic and hematopoietic disorders, gout

Adverse Reactions (Side Effects):

• CNS: confusion, disorientation, dizziness, fever, hallucinations, headache, malaise

• EENT: bloody sputum, blurred vision, changes in color perception, decreased visual acuity, optic neuritis, photophobia

• GI: abdominal distress, anorexia, nausea, vomiting

• HEME: thrombocytopenia

• METAB: acute gout, elevated uric acid, liver function impairment

• MS: joint pain

• SKIN: dermatitis, pruritis

Dosage:

Administered orally

• Adult and Child >13 years: Tuberculosis: Initial treatment: PO 15 mg/kg/day as a single daily dose; Retreatment: PO 25 mg/kg/day as a single dose for 2 months with at least 1 other drug, then decrease to 15 mg/kg/day as single daily dose.

• Mycobacterium avium complex in AIDS: PO 15 mg/kg with 3 or 4 other antimycobacterial agents

Special considerations:

• Initial therapy in tuberculosis should include 4 drugs; isoniazid, rifampin, pyrazinamide, and ethambutol, until drug susceptibility results available

• Administer with meals to decrease GI symptoms