結核病 Treatment of tuberculosis infection

Antitubercular Agent
Ethambutol diffuses into actively growing mycobacterium cells. It is active against organsims of Mycobacterium tuberculosis, M. bovis, M. marinum and some strains of M. kansasii, M. avium, M. fortuiturn and M. intracellulare. Ethambutol is generally administered orally in combination with other antimycobacterial agents. No cross-resistance with other available antimycobacterial agents has been demonstrated.

1. Absorption: ~80%
2. Distribution: Widely throughout body; Protein binding: 20-30%
3. Metabolism: Hepatic (20%) to inactive metabolite
4. Half-life elimination: 2.5-3.6 hours; (ESRD) 7-15 hours
5. Time to peak, serum: 2-4 hours
6. Excretion: Urine (~50% as unchanged drug, 8% to 15% as metabolites); feces (~20% as unchanged drug)

1. Hypersensitivity to ethambutol
2. Patients with known optic neuritis (unless clinical judgment determines that it may be used)
3. Patients unable to appreciate and report visual side effects or changes in vision (eg, young children)

C

Enters breast milk/use caution

Optic neuritis; symptoms may include decreased acuity, scotoma, color blindness, or visual defects (usually reversible with discontinuation, irreversible blindness has been described)

Once-daily therapy:
1. 40-55 kg: 800 mg (14.5 to 20 mg/kg)
2. 56-75 kg: 1,200 mg (16 to 21.4 mg/kg)
3. 76-90 kg: 1,600 mg (17.8 to 21.1 mg/kg)
Three-times-weekly:
1. 40-55 kg: 1,200 mg (21.8 to 30 mg/kg)
2. 56-75 kg: 2,000 mg (26.7 to 35.7 mg/kg)
3. 76-90 kg: 2,400 mg (26.7 to 31.6 mg/kg)
Twice-weekly:
1. 40-55 kg: 2,000 mg (36.4 to 50 mg/kg)
2. 56-75 kg: 2,800 mg (37.3 to 50 mg/kg)
3. 76-90 kg: 2,400 mg (44.4 to 52.6 mg/kg)

1. ClCr 10-50 mL/min: 15 mg/kg every 24-36 hours or 7.5-10 mg/kg/day
2. ClCr <10 mL/min: 15 mg/kg every 48 hours or 5 mg/kg/day
3. Hemodialysis: Slightly dialyzable (5% to 20%); administer dose postdialysis