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Ethambutol

    Brands

    DEA Class; Rx

    Common Brand Names; Myambutol

    • Antitubercular Agents

    Used for mycobacterial infections including tuberculosis and atypical mycobacterial infections. First-line antituberculosis agent in combination with isoniazid, pyrazinamide, rifampin, and/or streptomycin. Appears to be more effective and less toxic than other antitubercular agents.

    Indicated for the treatment of drug-susceptible tuberculosis infection as part of combination therapy.
    For the treatment of drug-resistant tuberculosis infection as part of combination therapy.
    For the treatment of Mycobacterium avium complex infection (MAC) in persons with HIV.

    Also indicated for

    • Disseminated MAC (Off-label)
    • Pulmonary M. Avium Complex (MAC) without HIV (Off-label)

    Other Indications & Uses

    Tuberculosis: intended to be used concomitantly with other anti-TB drugs; usually isoniazid initially; subsequently, use second-line anti-TB drugs

    Off-label: MAC infections

    Hypersensitivity

    Known optic neuritis (unless clinical judgment determines that it may be used)

    Patients unable to appreciate and report visual side effects or changes in vision (eg, young children, unconscious patients)

    • Acute gout or hyperuricemia
    • Abdominal pain
    • Anaphylaxis
    • Anorexia
    • Confusion, disorientation
    • Fever
    • Headache
    • LFT abnormalities
    • Malaise
    • Nausea
    • Optic neuritis; symptoms may include decreased acuity, color blindness or visual defects (usually revrsible with discontinuation, though irreversible blindness has been reported)
    • Peripheral neuritis
    • Pruritis
    • Rash
    • Vomiting

    May produce decreases in visual acuity which appear to be due to optic neuritis; effect may be related to dose and duration of treatment; effect is generally reversible when administration of drug is discontinued promptly; however, irreversible blindness has been reported

    Liver toxicities including fatalities reported; baseline and periodic assessment of hepatic function should be performed

    Not recommended for use in pediatric patients <13 years; safe conditions for use not established

    Patients with decreased renal function need dosage reduced as determined by serum levels of the drug; main path of excretion of this drug is by the kidneys

    Drug may have adverse effects on vision; physical examination should include ophthalmoscopy, finger perimetry and testing of color discrimination

    In patients with visual defects such as cataracts, recurrent inflammatory conditions of the eye, optic neuritis, and diabetic retinopathy, the evaluation of changes in visual acuity is more difficult, and care should be taken to be sure the variations in vision are not due to underlying disease conditions

    In such patients, consideration should be given to relationship between benefits expected and possible visual deterioration since evaluation of visual changes is difficult

    As with any potent drug, baseline and periodic assessment of organ system functions, including renal, hepatic, and hematopoietic, should be performed

    Pregnancy Category: B

    Lactation: enters breast milk; use with caution (AAP Committee states “compatible with nursing”)

    Dosing is based on lean body weight.

    Adults

    25 mg/kg/dose (Max: 2.5 g/dose) PO once daily is the FDA-approved maximum dosage. Other regimens and maximum dosages have been used off-label.
    Weighing more than 90 kg: 25 mg/kg/dose (Max: 2.5 g/dose) PO once daily.
    Weighing 76 to 90 kg: 1.6 g PO once daily or 5 days/week, 2.4 g PO 3 days/week, or 4 g PO twice weekly.
    Weighing 56 to 75 kg: 1.2 g PO once daily or 5 days/week, 2 g PO 3 days/week, or 2.8 g PO twice weekly.
    Weighing 40 to 55 kg: 800 mg PO once daily or 5 days/week, 1.2 g PO 3 days/week, or 2 g PO twice weekly.

    Geriatric

    25 mg/kg/dose (Max: 2.5 g/dose) PO once daily is the FDA-approved maximum dosage. Other regimens and maximum dosages have been used off-label.
    Weighing more than 90 kg: 25 mg/kg/dose (Max: 2.5 g/dose) PO once daily.
    Weighing 76 to 90 kg: 1.6 g PO once daily or 5 days/week, 2.4 g PO 3 days/week, or 4 g PO twice weekly.
    Weighing 56 to 75 kg: 1.2 g PO once daily or 5 days/week, 2 g PO 3 days/week, or 2.8 g PO twice weekly.
    Weighing 40 to 55 kg: 800 mg PO once daily or 5 days/week, 1.2 g PO 3 days/week, or 2 g PO twice weekly.

    Adolescents

    25 mg/kg/dose (Max: 2.5 g/dose) PO once daily is the FDA-approved maximum dose. 25 mg/kg/dose (Max: 1.6 g/dose) PO once daily or 5 days/week or 50 mg/kg/dose PO 3 days/week (Max: 2.4 g/dose) or twice weekly (Max: 4 g/dose) has been used off-label.

    Children

    Safety and efficacy have not been established. 25 mg/kg/dose (Max: 1.6 g) PO once daily or 5 days/week or 50 mg/kg/dose PO 3 days/week (Max: 2.4 g/dose) or twice weekly (Max: 4 g/dose) has been used off-label.

    Infants

    Safety and efficacy have not been established. 25 mg/kg/dose PO once daily or 5 days/week or 50 mg/kg/dose PO 3 days/week or twice weekly has been used off-label.

    Neonates

    Safety and efficacy have not been established. 25 mg/kg/dose PO once daily has been used off-label.

    Tuberculosis

    Prescribing information

    • Initial TB treatment: 15 mg/kg PO qDay
    • Prior TB treatment: 25 mg/kg PO qDay; after 60 days, decrease to 15 mg/kg PO qDay

    Daily administration

    • Guidelines from American Thoracic Society (ATS), Centers for Disease Control and Prevention (CDC), and the Infectious Diseases Society of America (IDSA)
    • 40-55 kg: 800 mg PO
    • 56-75 kg: 1.2 g PO
    • >75 kg: 1.6 g PO

    Twice weekly administration

    • Guidelines from American Thoracic Society (ATS), Centers for Disease Control and Prevention (CDC), and the Infectious Diseases Society of America (IDSA)
    • 40-55 kg: 2 g PO
    • 56-75 kg: 2.8 g PO
    • >75 kg: 4 g PO

    3x per week administration

    • Guidelines from American Thoracic Society (ATS), Centers for Disease Control and Prevention (CDC), and the Infectious Diseases Society of America (IDSA)
    • 40-55 kg: 1.2 g PO
    • 56-75 kg: 2 g PO
    • >75 kg: 2.4 g PO

    Ethambutol hydrochloride

    tablet

    • 100mg
    • 400mg