Isoniazid

General characteristics. Structure:

Active ingredient: 300 mg of an isoniazid in 1 tablet.

Excipients: potato starch, stearic acid.

Pharmacological properties:

Pharmacodynamics. Antituberculous remedy of the I row. Has bactericidal effect. The isoniazid is active in the relation out of - and intracellular Mycobacterium tuberculosis, first of all concerning actively sharing. The exact mechanism of its action is unknown. It is supposed that it is connected with suppression of synthesis of the mikoliyevy acids which are a part of a cell wall of mycobacteria.

Pharmacokinetics. After intake it is quickly absorbed from digestive tract. At reception with food absorption and bioavailability decrease. It is widely distributed in all fabrics and liquids of an organism. Linkng with proteins of plasma very low (0 - 10%). It is metabolized in a liver. A small amount - with a stake is removed with urine.

Indications to use:

Treatment of all forms of active tuberculosis, including tubercular meningitis (as a part of a combination therapy).

Prevention of tuberculosis at the persons which are in close contact with TB patients; at persons with positive skin reaction (more than 5 mm) to tuberculine and the radiological data indicating not progressing tuberculosis; at children 4 years with positive reaction to tuberculine (more than 10 mm) and the increased risk of dissimination are younger.

Route of administration and doses:

The dose is established individually, depending on character and a form of a disease.

Inside to adults and children 14 years – on 300 mg of 1 times/days (to 300 mg) or on 15 mg/kg/days 2 – 3 times a week (to 900 mg as it is defined by the scheme of therapy), to children up to 14 years – 10 – 20 mg/kg of 1 times/days (to 300 mg), or on 20 – 40 mg/kg 2 – 3 times a week are more senior (to 900 mg as it is defined by the scheme of therapy).

Duration of treatment is established individually. The maximum daily dose – 300 mg.

Features of use:

Pregnancy and lactation. At pregnancy medicine is appointed in a dose by not higher than 10 mg/kg. Medicine gets into breast milk in small doses therefore for the period of treatment for breastfeeding to refuse there is no need.

It is not recommended to apply an isoniazid in a dose more than 10 mg/kg at severe forms of cardiopulmonary insufficiency and/or arterial hypertension, coronary heart disease, widespread atherosclerosis, diseases of a nervous system, bronchial asthma, psoriasis, eczema in an aggravation phase, a myxedema.

In order to avoid bystry development of stability of Mycobacterium tuberculosis the isoniazid is applied in a combination with other antituberculous remedies.

For reduction of side effects along with an isoniazid appoint a pyridoxine (inside or intramusculary) or glutaminic acid (inside), or thiamin (intramusculary).

It is necessary to consider that the isoniazid is metabolized in a liver by acetylation to inactive metabolites. Extent of acetylation is determined by genetic factors. Due to unequal extent of metabolism before use of an isoniazid it is reasonable to determine the speed of its inactivation by the content of active agent in blood and urine. At patients at whom the bystry inactivation is observed the isoniazid is applied in higher doses.

Side effects:

From the central nervous system and peripheral nervous system: headache, dizziness; seldom - psychosis, euphoria, sleep disorders, peripheral neuritis.

From the alimentary system: nausea, vomiting, medicinal hepatitis.

From cardiovascular system: pains in heart.

Allergic reactions: skin rash, itch.

From endocrine system: very seldom - a gynecomastia at men, menorrhagias at women.

Interaction with other medicines:

At simultaneous use with rifampicin the risk of development of a hepatotoxic action increases (especially at patients with abnormal liver functions).

At simultaneous use with paracetamol the risk of development of a hepatotoxic action since the isoniazid induces P450 cytochrome that leads to increase in maintenance of toxic metabolites of paracetamol increases.

At simultaneous use of an isoniazid with carbamazepine or Phenytoinum metabolism of the last is suppressed that leads to increase in their concentration in a blood plasma and to strengthening of toxic action.

Contraindications:

Epilepsy, convulsive attacks and poliomyelitis in the anamnesis, an abnormal liver function and/or kidneys, atherosclerosis.

With care apply at alcoholism, a liver failure, a renal failure, convulsive attacks, pregnancy (not to appoint higher than 10 mg/kg in a dose), dekompensirovanny diseases of cardiovascular system (chronic heart failure, stenocardia, arterial hypertension), a hypothyroidism.

Overdose:

Symptoms: dizziness, a dysarthtia, slackness, a disorientation, a hyperreflexia, a peripheral polyneuropathy, an abnormal liver function, a metabolic acidosis, a hyperglycemia, a glucosuria, a ketonuria, spasms (in 1 - 3 h after medicine use), a coma.

Treatment: a peripheral polyneuropathy - B6, B1, B12 vitamins, adenosine triphosphoric acid, glutaminic acid, niacinamide, massage, physiotherapeutic procedures; spasms - intramusculary B6 vitamin - 200-250 mg, intravenously 40% dextrose solution - 20 ml, intramusculary 25% sulfate magnesium solution - 10 ml, diazepam; an abnormal liver function - methionine, lipamidum, adenosine triphosphoric acid, B12 vitamin.

Storage conditions:

In the place protected from light and moisture, at a temperature not over 25 ºС. To store in the place, unavailable to children. A period of validity - 5 years. Not to apply after the termination of a period of validity.

Issue conditions:

According to the recipe

Packaging:

10 tablets in a blister strip packaging; 1 or 2 blister strip packagings in a pack (No. 10 × 1, No. 10 × 2).