Ethambutol

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By Medifit Education

ETHAMBUTOL

Ethambutol 1

1.       TYPE OF DRUG -ETHAMBUTOL
Ethambutol eliminates certain bacteria that cause tuberculosis (TB).

 

2.       INDICATIONS (USE) -ETHAMBUTOL
For use, as an adjunct, in the treatment of tuberculosis.

 

3.       MECHANISM OF ACTION (MOA) -ETHAMBUTOL
Ethambutol inhibits arabinosyl transferases which is involved in cell wall biosynthesis. By inhibiting this enzyme, the bacterial cell wall complex production is inhibited. This leads to an increase in cell wall permeability.

 

4.       ROUTES OF ADMINISTRATION -ETHAMBUTOL
Tablet

 

5.       ONSET OF EFFECT OR ACTION -ETHAMBUTOL
It may take several days for the symptoms to improve.

 

6.      DOSAGE (DOSING INFORMATION) -ETHAMBUTOL
Oral

Primary treatment of pulmonary and extrapulmonary tuberculosis

Adult: As hydrochloride: Initial 8 wk: 15 mg/kg/day or 30 mg/kg thrice wkly given with isoniazid, rifampicin and pyrazinamide. For patients with history of antimycobacterial therapy: Initial doses: 25 mg/kg/day for 60 days, thereafter reduce to 15 mg/kg/day.

Child: For treatment of drug-resistant tuberculosis: 15-25 mg/kg daily or 50 mg/kg twice wkly. For congenitally acquired tuberculosis: Neonates: 15 mg/kg once daily and ≥1 mth: 15 mg/kg once daily or 30 mg/kg 3 times wkly for 2 mth initial treatment phase.

 

Elderly

Renal impairment: Dose reduction may be required.

 

7.       HALF LIFE (DURATION OF ACTION) -ETHAMBUTOL
In patients with normal renal function, 3 to 4 hours. In patients with impaired renal function, up to 8 hours.

 

8.       ADVERSE EFFECTS OR SIDE EFFECTS -ETHAMBUTOL
Retrobulbar neuritis with a reduction in visual acuity, constriction of visual field, central or peripheral scotoma and green-red colour blindness. Retinal haemorrhage (rare); reduced renal clearance of urates (acute gout); GI disturbances eg, nausea, vomiting, abdominal pain, anorexia; rash, headache, dizziness, confusion, hallucinations, malaise, jaundice; thrombocytopenia; pulmonary infiltrates.

 

9.       CONTRAINDICATIONS -ETHAMBUTOL
Hypersensitivity; optic neuritis. Lactation

 

10.   DRUG INTERACTIONS -ETHAMBUTOL
Absorption delayed or reduced by aluminum hydroxide. Synergistic effect with other antitubercular agents.

 

11.    EXCRETION -ETHAMBUTOL
During the 24-hour period following oral administration of ethambutol hydrochloride approximately 50 percent of the initial dose is excreted unchanged in the urine, while an additional 8 to 15 percent appears in the form of metabolites. From 20 to 22 percent of the initial dose is excreted in the feces as unchanged drug.

 

Ethambutol 3

By Medifit Education

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