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

Antiepilepticheskoe means, increases the sensitivity of gamma-aminobutyric acid receptors to gamma-aminobutyric acid, opens channels for chloride ions and increases their entry into the cell.Has a hypnotic, spasmolytic and miorelaksiruyuschee effect. In small doses has a sedative effect.

Has a direct inhibitory effect on the respiratory center (reduces sensitivity to carbon dioxide), lowers the tone of the smooth muscles of the gastrointestinal tract. In hypnotic doses slightly reduces the intensity of the basal metabolism, which is manifested by a slight hypothermia. Essentially does not affect the cardiovascular system.

Pharmacokinetics:

When ingestion is absorbed completely, slowly. The time of maximum concentration is 1-2 hours, the connection with plasma proteins is 50%, in newborns 30-40%. Metabolized in the liver, induces microsomal liver enzymes CYP3A4, CYP3A5 and CYP3A7 (the rate of enzymatic reactions increases 10-12 times).

Cumulates. Half-life - 3-4 day. It is excreted by the kidneys in the form of inactive metabolites, 25-50% - unchanged. It penetrates well through the placenta.

Indications:

- Epilepsy (all types of seizures except for absences), seizures of non-epileptic genesis;

- xaureus;

- spastic paralysis;

- sleep disturbances, anxiety, psychomotor agitation.

Contraindications:

Individual hypersensitivity to any component of the formulation, severe or moderate hepatic and / or renal insufficiency, drug dependency (including history), hyperkinesis, myasthenia gravis, severe anemia, porphyria, diabetes mellitus, hypofunction of the adrenal gland, hyperthyroidism, depressed, broncho-obstructive disease, active alcoholism, severe respiratory depression, porphyria (including history), suicidal thoughts and behavior deficits sucrase / isomaltase, fructose intolerance, glitch ozo-galactose malabsorption, children under 18 years of age.

Carefully:

In chronic renal or liver failure of mild severity, the drug should be used with caution.

Pregnancy and lactation:

Contraindicated in the first trimester of pregnancy (teratogenic effect is possible). The use of the drug in trimesters II and III pregnancy is possible only in cases where the expected benefit to the mother outweighs the potential risk to the fetus.

In newborns, whose mothers were taking phenobarbital in the III trimester of pregnancy, it is possible to develop physical dependence and the "withdrawal" syndrome.The use of the drug as an anticonvulsant during pregnancy leads to a violation of blood clotting (associated with vitamin K deficiency) in newborns, which can cause bleeding in the neonatal period (usually the first day after childbirth).

The use of the drug during labor can cause respiratory depression in a newborn, especially premature (in connection with the underdevelopment of liver function).

At the time of treatment, breastfeeding should stop (penetrates into breast milk and may cause central nervous system depression in infants).

Dosing and Administration:

How to use: inside. With a decrease in liver function should be administered in smaller doses.

- sleep disorders: 100-200 mg for 0.5-1 h before bedtime. The duration of the hypnotic effect is 6-8 hours;

- with chorea, psychomotor agitation, anxiety - 50 mg 2-3 times a day. Usually the drug is used in combination with spasmolytic, vasodilating and other means;

- as an anticonvulsant for 50-100 mg 2 times a day and gradually increasing the dose until the seizures stop, but not more than 600 mg per day;

- in the treatment of spastic paralysis - the maximum single dose of 200 mg, the maximum daily dose of 500 mg.

The action of the drug upon its cancellation

Cancellation should be carried out gradually, by reducing the dose for a long time to reduce the risk of developing the "withdrawal" syndrome. Abstinence syndrome can develop within 8-12 hours after the last dose and is usually manifested in the following sequence with minor symptoms: anxiety, muscle twitching, hand tremors, progressive weakness, dizziness, visual disturbances, nausea, vomiting, sleep disorders, orthostatic hypotension ( dizziness, fainting). In severe cases, there may be more significant symptoms (convulsions, delirium) that occur within 16 hours and last up to 5 days after the abrupt withdrawal of the drug. The severity of the "withdrawal" syndrome gradually decreases over a period of about 15 days.

A sudden discontinuation of the drug with epilepsy can cause an epileptic fit or status epilepticus.

Side effects:

From the nervous system: asthenia, dizziness, general weakness, ataxia, nystagmus, paradoxical reaction (especially in elderly and weakened patients - arousal), hallucinations, depression, nightmares, sleep disorders, fainting.

From the side of the musculoskeletal system: with prolonged use - violation of osteogenesis and development of rickets.

From the digestive system: nausea, vomiting, constipation, with prolonged use - a violation of liver function.

On the part of the organs of hematopoiesis: agranulocytosis, interregional anemia, thrombocytopenia.

From the side of the cardiovascular system: lowering blood pressure.

Allergic reactions: skin rashes, hives, swelling of the eyelids, face and lips, shortness of breath, exfoliative dermatitis, malignant exudative erythema (Stevens-Johnson syndrome).

Other: with prolonged use - drug dependence.

Overdose:

Symptoms: in acute toxicity (receiving 1 g) - dizziness, headache, severe weakness, ataxia, marked drowsiness or arousal (euphoria, mood enhancement, volubility, emotional explosion), raising or lowering the body temperature, dyspnea, cardiac failure, arrhythmia (tachy or bradycardia), nystagmus, slurred speech, the attenuation or loss of reflexes, blood pressure, pupillary (alternating paralytic expansion) block,oliguria, cyanosis, confusion, respiratory depression, pulmonary edema, coma; with chronic toxicity - irritability, weakening the ability to critically assess their own actions, sleep disorders, confusion; when taking 2-10 g - a lethal outcome.

In case of a life-threatening overdose it is possible to suppress electrical brain activity (the electroencephalogram can be "flat"), which should not be regarded as a clinical death, this effect is completely reversible if the damage associated with hypoxia has not developed.

Treatment: there is no specific antidote. Gastric lavage, reception of activated charcoal, conduct of detoxification therapy, symptomatic treatment, maintenance of vital body functions.

Interaction:

Phenytoin and valproate increase the content of phenobarbital in the blood serum.

Anticonvulsant effect of phenobarbital decreases with simultaneous reception with reserpine, increases with combination with amitriptyline, nialamide.

Phenobarbital accelerates the metabolism of diazepam and chlordiazepoxide and leads to faster release of drugs.In addition, with the combined use of phenobarbital with these drugs, its anticonvulsant effect is enhanced.

Reduces the effectiveness of oral contraceptives and salicylates.

Reduces the blood levels of indirect anticoagulants, glucocorticosteroids, doxycycline, estrogens and other drugs metabolized by microsomal enzymes of the liver.

With simultaneous application with griseofulvin, it is possible to reduce the absorption of griseofulvin in the intestine.

Strengthens the effect of alcohol, neuroleptics, narcotic analgesics, muscle relaxants, sedatives and hypnotics.

Acetazolamide, alkalinizing urine, reduces the reabsorption of phenobarbital in the kidneys and weakens its effect.

The hypnotic effect of phenobarbital decreases with simultaneous reception with atropine, belladonna extract, dextrose, thiamine, nicotinic acid, analeptics and psychostimulating drugs.

Reduces the antibacterial activity of antibiotics, sulfonamides.

Phenobarbital is a potent inducer of cytochrome P450 (mainly isoenzyme CYP3A4).

Special instructions:

The drug is used with caution in weakened patients (high risk of paradoxical arousal, depression and confusion, even with normal doses).

Avoid prolonged use of the drug due to the possibility of its cumulation in the body.

With prolonged intake of phenobarbital exceeding the usual therapeutic dose, sexual disinhibition, aggressive and suicidal behavior are observed.

In patients with acute and / or chronic pain syndrome: paradoxical stimulation is possible.

To avoid the development of the withdrawal syndrome (anxiety, muscle twitching, trembling of hands, progressive weakness, dizziness, visual disturbances, nausea, vomiting, sleep disturbances, orthostatic hypotension (dizziness, fainting), convulsions, delirium), treatment should be discontinued gradually.

It is unacceptable to drink alcoholic beverages.

Effect on the ability to drive transp. cf. and fur:During treatment, it is not recommended to manage vehicles, mechanisms, and also to engage in activities requiring rapidity of psychomotor reactions.

Form release / dosage:

Tablets, 100 mg.

Packaging:

For 6 tablets in a contour non-cellular package of paper with a polyethylene coating or 10 tablets in a contour mesh box made of polyvinyl chloride film and foil of aluminum printed lacquered.

1, 2, 3 contour non-jawed or contour mesh packages together with the instruction for use are placed in a pack of cardboard.

For hospitals, 1000 contour non-jammed packages, together with an equal number of instructions for use, are placed in a box of corrugated cardboard.

Storage conditions:

List of potent substances BKKN.

In a dry, protected from light place at a temperature of no higher than 25 ° C.

Keep out of the reach of children.

Shelf life:

5 years.

Do not use after the expiration date printed on the package.

Terms of leave from pharmacies:On prescription

Registration number:LS-001694

Date of registration:14.05.2012

The owner of the registration certificate:DALHIMFARM, OJSC DALHIMFARM, OJSC Russia

Manufacturer: & nbsp

DALHIMFARM, OJSC Russia

Representation: & nbspDALHIMFARM, OJSCDALHIMFARM, OJSC

Information update date: & nbsp19.09.2015

Illustrated instructions

Instructions

Phenobarbital (Phenobarbital)