Ethambusin^® (Tablets) Instructions for Use

ATC Code

J04AK02 (Ethambutol)

Active Substance

Ethambutol (Rec.INN registered by WHO)

Clinical-Pharmacological Group

Antituberculosis drug

Pharmacotherapeutic Group

Antitubercular agent

Pharmacological Action

Second-line antituberculosis agent. It has a bacteriostatic effect only on Mycobacterium tuberculosis, including strains resistant to streptomycin, kanamycin, isoniazid, PAS, and ethionamide.

The mechanism of action is not precisely established. Apparently, Ethambutol, penetrating into mycobacteria, disrupts RNA synthesis. It is active only against intensively dividing bacteria. Resistance of Mycobacterium tuberculosis to ethambutol develops relatively slowly.

Pharmacokinetics

After oral administration, absorption from the gastrointestinal tract is 80%, the remainder of the dose is excreted in the feces unchanged. Food intake has little effect on absorption.

After a single dose of 25 mg/kg, the C_max of ethambutol in blood plasma is reached 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, and erythrocytes. It penetrates into the cerebrospinal fluid when the meninges are inflamed.

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

The T_1/2 is 3-4 hours. It is excreted mainly in the urine unchanged, 8-15% as inactive metabolites.

Indications

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

MAC infection.

ICD codes

Dosage Regimen

Administer Ethambusin^® orally once daily, with or without food.

For initial treatment, use a dose of 15-25 mg/kg of body weight.

For retreatment, use a dose of 25 mg/kg once daily for two months, followed by a reduction to 15 mg/kg once daily.

Alternatively, for supervised intermittent therapy, administer 50 mg/kg as a single dose twice per week.

A second intermittent regimen is 25-30 mg/kg administered three times per week.

Do not exceed the maximum daily dose of 2.5 grams for any regimen.

Calculate the dose based on ideal body weight, not actual weight, for all patients.

Adjust the dosage regimen in patients with renal impairment; the drug is contraindicated in significant renal dysfunction.

Use only as part of a combination antituberculosis therapy to prevent the development of resistance.

Monitor visual acuity and color discrimination before starting therapy and at least monthly during treatment.

Adverse Reactions

From the central and peripheral nervous system: dizziness, depression, peripheral neuritis, retrobulbar neuritis, color vision disturbances (mainly green and red), reduction in central and peripheral visual fields, occurrence of scotomas.

From the digestive system: nausea, vomiting, loss of appetite.

From the musculoskeletal system: arthritis.

Allergic reactions: skin rash.

Contraindications

Optic neuritis, cataract, diabetic retinopathy, inflammatory eye diseases, pregnancy, renal impairment, children under 13 years of age, hypersensitivity to ethambutol.

Use in Pregnancy and Lactation

Use during pregnancy is contraindicated.

Ethambutol crosses the placental barrier and is excreted in breast milk.

Experimental studies have established the teratogenic effect of ethambutol.

Use in Renal Impairment

Contraindicated in renal impairment.

Pediatric Use

Contraindicated in children under 13 years of age.

Special Precautions

At the beginning of treatment, an increase in cough and sputum production is possible.

Ethambutol should be used only in combination with other antituberculosis drugs. In combination with isoniazid and rifampicin, it is highly effective in the treatment of tuberculosis.

During long-term therapy, it is necessary to regularly monitor visual function, peripheral blood picture, and the functional state of the liver and kidneys.

Drug Interactions

With simultaneous use with aluminum hydroxide, the absorption of ethambutol from the gastrointestinal tract decreases.

There is evidence of a possible increase in optical neuropathy caused by ethambutol when used in combination with isoniazid.

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

Storage Conditions

Store at 2°C (36°F) to 25°C (77°F). Keep in original packaging, protected from light. Keep out of reach of children.

Dispensing Status

Rx Only

Important Safety Information

This information is for educational purposes only and does not replace professional medical advice. Always consult your doctor before use. Dosage and side effects may vary. Use only as prescribed.