Etambutol - instructions for use, dose, side effects, contraindications

Second-line anti-tuberculosis drug. Has a bacteriostatic effect only on Mycobacterium tuberculosis, including strains resistant to streptomycin, kanamycin, isoniazid, PASC and ethionamide. The mechanism of action is not exactly fixed. Apparently, ethambutol, penetrating into mycobacteria, disrupts the synthesis of RNA. It is active only for intensively dividing bacteria. Sustainability Mycobacterium tuberculosis to ethambutol develops relatively slowly.

Pharmacokinetics:

After ingestion, the absorption from the digestive tract is 80%, the rest of the dose is excreted with feces unchanged.Food intake has little effect on absorption. At a single dose of 25 mg / kg, the maximum concentrationethambutol in blood plasma is achieved after 4 hours and is 5 μg / ml, after 24 hours the concentration is less than 1 μg / ml.

Ethambutol is distributed in most tissues, including the lungs, kidneys, red blood cells. Penetrates into the cerebrospinal fluid with inflamed meninges.

Etambutol is partially metabolized in the liver to inactive aldehyde and dicarboxylic derivatives, which are excreted in the urine.

The half-life period is 3-4 hours. It is excreted mostly with urine in unchanged form, 8-15% in the form of inactive metabolites.

Indications:

All forms of pulmonary and extrapulmonary tuberculosis (as part of combination therapy).

MAS infection.

ICD-10

I.A15-A19.A18 Tuberculosis of other organs

I.A15-A19.A17.0 Tuberculous meningitis (G01 *)

I.A15-A19.A15 Tuberculosis of respiratory organs, confirmed bacteriologically and histologically

I.A30-A49.A31.0 Pulmonary infection caused by Mycobacterium

Contraindications:

Hypersensitivity, gout, optic neuritis, cataracts, inflammatory eye diseases, diabetic retinopathy, impaired renal function.

Carefully:

Age to 13 years (no clinical data available).

Pregnancy and lactation:

Category of recommendations for FDA is not defined. During pregnancy, use only according to strict indications, comparing the prospective benefit and the potential risk to the fetus. Pregnant women with tuberculosis should be treated for at least 9 months by several means, including ethambutol. Ethambutol passes through the hematoplacental barrier, the concentration in the blood of the fetus is about 30% of the concentration in the mother's blood. Complications in humans are not documented.

In studies of embryo and fetotoxicity in animals receiving high doses of ethambutol, fetuses have a cleft of the upper lip and palate, exencephaly, developmental defects of the spine (often the cervical spine), cyclopia, limb defects.

Etambutol is found in breast milk in concentrations equal to the concentrations in the mother's serum, but no complications have been recorded in humans. For the duration of treatment, breastfeeding should be discontinued.

Dosing and Administration:

Inside after meals 1 time per day (in the morning). Adults who had not previously taken antituberculosis drugs - 15 mg / kg per day,treated patients - 25 mg / kg (up to 30 mg / kg / day) daily for 2 months, then at a maintenance dose of 50 mg / kg 2-3 times a week. The maximum daily dose is 2 g. Children from 13 years of age - 15-25 mg / kg per day. The maximum daily dose for children is 1 g. The duration of treatment is 9 months (up to 2 years). Dose correction in renal failure is required: with creatinine clearance> 100 ml / min - 20 mg / kg per day, 70-100 ml / min - 15 mg / kg per day, <70 ml / min - 10 mg / kg per day; at a hemodialysis - 5 mg / kg a day, on day of a dialysis - 7 mg / kg a day.

Side effects:

From the side nervous system and sense organs: depression, paresthesia, dizziness, headache, disorientation in space, hallucinations, peripheral neuritis and polyneuropathy, retrobulbar neuritis, optic nerve atrophy; deterioration of visual acuity, refraction and color perception (mainly green and red), narrowing of the central and peripheral fields of vision, the formation of cattle.

From the side respiratory system: increased cough, increased sputum.

From the side organs of the digestive tract: anorexia, metallic taste in the mouth, dyspeptic phenomena (nausea, vomiting, diarrhea), abdominal pain, impaired liver function.

Allergic reactions: skin rash, itching.

Other: leukopenia, hyperuricemia, exacerbation (attack) of gout, arthralgia.

Overdose:

Symptoms: nausea, vomiting, hallucinations, polyneuritis.

Treatment: symptomatic.

Interaction:

With the simultaneous use of aluminum hydroxide, a decrease in the absorption of ethambutol from the gastrointestinal tract occurs.

There is evidence of a possible increase in optical neuropathy due to ethambutol, when it is used in combination with isoniazid.

Under the influence of ethambutol, a change in the metabolism of zinc is possible.

Special instructions:

At the beginning of treatment, it is possible to increase cough, increase the amount of sputum.

Etambutol is used only in combination with other anti-TB drugs. In combination with isoniazid and rifampicin is highly effective in the treatment of tuberculosis.

When performing long-term therapy, it is necessary to regularly monitor the functions of vision, the picture of peripheral blood, as well as the functional state of the liver and kidneys.

Instructions

Ethambutol (Aethambutolum)