Ethambutol hydrochloride
Ethambutol hydrochloride (Myambutol)
Ethambutol hydrochloride
(eh- THAM-byou-tohl) Etibi Myambutol (Rx)

Classification: Primary antitubercular agent

Action/Kinetics: Inhibits the synthesis of metabolites resulting in impairment of cell metabolism, arrest of multiplication, and ultimately cell death. Is active against Mycobacterium tuberculosis but not against fungi, other bacteria, or viruses. Readily absorbed after PO administration. Widely distributed in body tissues except CSF. Peak plasma concentration: 2-5 mcg/mL after 2-4 hr. t 1/2: 3-4 hr. About 65% of metabolized and unchanged drug excreted in urine and 20%-25% unchanged drug excreted in feces. Drug accumulates in clients with renal insufficiency.

Uses: Pulmonary tuberculosis in combination with other tuberculostatic drugs. Use only in conjunction with at least one other antituberculostatic.

Contraindications: Hypersensitivity to ethambutol, preexisting optic neuritis, and in children under 13 years of age.

Special Concerns: Use with caution and in reduced dosage in clients with gout and impaired renal function and in pregnant women.

Side Effects: Ophthalmologic: Optic neuritis, decreased visual acuity, loss of color (green) discrimination, temporary loss of vision or blurred vision. GI: N&V;, anorexia, abdominal pain. CNS: Fever, headache, dizziness, confusion, disorientation, malaise, hallucinations. Allergic: Pruritus, dermatitis, anaphylaxis. Miscellaneous: Peripheral neuropathy (numbness, tingling), precipitation of gout, thrombocytopenia, joint pain, toxic epidermal necrolysis. Renal damage. Also anaphylactic shock peripheral neuritis (rare), hyperuricemia, and decreased liver function. Adverse symptoms usually appear during the early months of therapy and disappear thereafter. Periodic renal and hepatic function tests as well as uric acid determinations are recommended.

Drug Interactions: Aluminum may delay and decrease the absorption of ethambutol.

How Supplied: Tablet: 100 mg, 400 mg

Dosage
?Tablets
Adults, initial treatment: 15 mg/kg/day until maximal improvement noted; for retreatment: 25 mg/kg/day as a single dose with at least one other tuberculostatic drug; after 60 days: 15 mg/kg/day.