PHENIBUT

INSTRUCTION FOR MEDICAL USE OF THE MEDICINAL PRODUCT PHENIBUT (PHENIBUT)

Composition:

Active substance: phenibut;

1 tablet contains phenibut 250 mg;

Excipients: lactose monohydrate; potato starch; calcium stearate.

Pharmaceutical form. Tablets.

Main physicochemical properties: tablets from white to white with a yellowish tint, oval-shaped with a biconvex surface.

Pharmacotherapeutic group.

Other psychostimulants and nootropic agents.

ATC code N06B X22.

Pharmacological properties.

Pharmacodynamics.

Phenibut is a derivative of γ-aminobutyric acid and phenylethylamine.

Its predominant action is anti-hypoxic and anti-amnesic. Phenibut improves memory and attention, facilitates learning processes, and increases physical and mental performance. Psychological parameters (attention, memory, speed and accuracy of sensorimotor reactions) improve under the influence of phenibut. It has been established that phenibut increases the energy potential of neurons by improving mitochondrial function.

Phenibut also has tranquilizing properties: it relieves psychoemotional tension, anxiety, fear, emotional lability, irritability, and improves sleep. It prolongs and enhances the effects of hypnotics, narcotic agents, neuroleptics, and anticonvulsants. Phenibut binds exclusively to GABA-β receptors in the brain, thus exerting a moderate calming effect without causing undesirable sedative effects such as drowsiness, dizziness, or reduced attention and performance. The drug prolongs the latent period and reduces the duration and intensity of nystagmus, and has antiepileptic activity. It does not affect cholinergic or adrenergic receptors.

PHENIBUT significantly reduces manifestations of asthenia and vasovegetative symptoms, including headache and a sensation of heaviness in the head. In patients with asthenia and emotionally labile individuals, phenibut improves well-being without causing excitation.

Pharmacokinetics.

Absorption and distribution

Phenibut is well absorbed after oral administration and readily penetrates all tissues of the body. It crosses the blood-brain barrier effectively (approximately 0.1% of the administered dose reaches brain tissue, with significantly greater penetration observed in both young and elderly individuals). The highest binding of phenibut occurs in the liver (80%), and this binding is nonspecific.

Biotransformation and excretion

80–95% of phenibut is metabolized in the liver; the metabolites are pharmacologically inactive.

Distribution in the liver and kidneys is close to uniform, while in the brain and blood it is lower than uniform. A significant amount of administered phenibut is detectable in urine within 3 hours; simultaneously, the concentration of the drug in brain tissue does not decrease—it remains detectable in the brain for up to 6 hours.

The following day, phenibut is detectable only in urine; it can still be found in urine up to 2 days after administration, although the amount detected constitutes only 5% of the administered dose. With repeated administration, no accumulation is observed.

Clinical characteristics.

Indications.

Asthenic and anxiety-neurotic states: restlessness, fear, anxiety.

Insomnia, nocturnal restlessness in elderly people.

Prevention of stress conditions prior to surgeries or painful diagnostic procedures.

Meniere's disease, dizziness associated with vestibular analyzer dysfunction of various origins.

Prevention of kinetosis (a specific condition characterized by nausea, vomiting, prostration, and vestibular dysfunction caused by being in a moving object, such as a ship or airplane).

Stuttering, tics in children aged 8 to 14 years.

As an adjunctive agent in the treatment of alcohol withdrawal syndrome.

Contraindications.

Hypersensitivity to the components of the drug.

Acute renal failure.

Pregnancy or breastfeeding period.

Interaction with other medicinal products and other forms of interaction.

Phenibut can be combined with other psychotropic medicinal agents, reducing the doses of PHENIBUT and concomitantly administered drugs.

Phenibut enhances and prolongs the effects of hypnotics, narcotics, neuroleptics, and antiparkinsonian agents.

Special precautions.

The medicinal product should be used with caution in patients with gastrointestinal disorders due to the irritant effect of phenibut. To protect the mucosa from the irritating action of phenibut, lower doses should be prescribed to such patients, and the medicinal product should be taken after meals.

During prolonged treatment, blood cell counts and liver function tests should be monitored.

The preparation contains lactose; therefore, it should not be administered to patients with rare hereditary forms of galactose intolerance, lactase deficiency, or glucose-galactose malabsorption syndrome.

Use during pregnancy or breastfeeding.

The use of the medicine PHENIBUT is contraindicated during pregnancy or breastfeeding due to insufficient data on its use during these periods.

Ability to affect reaction speed when driving or operating machinery.

Patients who experience drowsiness, dizziness, or other central nervous system reactions while taking the medicine should refrain from driving vehicles or operating machinery.

Method of administration and dosage.

FENIBUT should be taken orally before meals. Swallow the tablet whole with an adequate amount of water. To reduce the irritating effect of fenibut on the gastrointestinal tract (see section "Special precautions"), the medicinal product may be taken after food.

For asthenic and anxiety-neurotic conditions in adults: administer 250–500 mg (1–2 tablets) three times daily. Maximum single doses: for adults – 750 mg, for elderly patients – 500 mg.

The treatment course lasts 2–3 weeks. If necessary, the treatment course may be extended to 4–6 weeks.

Children aged 8 to 14 years: 250 mg (1 tablet) three times daily.

FENIBUT 250 mg tablets may be used as an alternative dosage form.

The treatment course lasts 2–6 weeks.

Meniere’s disease and dizziness associated with vestibular dysfunction of various origins.

In infectious vestibular dysfunction and Meniere’s disease during exacerbation, administer FENIBUT 750 mg (3 tablets) three times daily for 5–7 days; when vestibular symptoms decrease, reduce to 250–500 mg (1–2 tablets) three times daily for 5–7 days, followed by 250 mg once daily for 5 days. In milder cases, administer FENIBUT 250 mg (1 tablet) twice daily for 5–7 days, then 250 mg once daily for 7–10 days.

For relief of dizziness in vascular and traumatic vestibular dysfunction: administer FENIBUT 250 mg three times daily for 12 days.

For prevention of kinetosis: take the medicinal product in a single dose of 250–500 mg one hour before the expected onset of motion sickness or at the first symptoms of motion discomfort.

For management of alcohol withdrawal syndrome: during the first days of treatment, administer FENIBUT 250–500 mg three times daily and 750 mg at night, with gradual reduction of the daily dose to the standard adult dose.

Patients with hepatic impairment

High doses of the drug may cause hepatotoxicity in patients with hepatic impairment. Lower doses should be prescribed for this patient group.

Patients with renal impairment

There are no data on adverse effects of FENIBUT in patients with renal function disorders when therapeutic doses are used.

Drug dependence and withdrawal syndrome have not been observed during use of this medicinal product.

Information on isolated cases of tolerance to fenibut can be found in the literature.

Children

The drug may be used in children aged 8 years and older.

Overdose

Data regarding overdose are lacking. FENIBUT is a low-toxicity medicinal product; however, daily doses of 7–14 g, especially with prolonged use, may be hepatotoxic. These doses significantly exceed the recommended average therapeutic doses according to patient age (average therapeutic dose is 500–2000 mg).

Symptoms: drowsiness, nausea, vomiting, dizziness.

With prolonged use of high doses of fenibut, arterial hypotension, acute renal failure, eosinophilia, and fatty liver degeneration may develop.

Treatment: gastric lavage. Symptomatic therapy. There is no specific antidote.

Adverse reactions.

FENIBUT, like other medicinal products, may cause adverse reactions, although they do not occur in all patients.

Classification of adverse reactions by frequency of occurrence: very common (≥ 1/10); common (≥ 1/100 to < 1/10); uncommon (≥ 1/1000 to < 1/100); rare (≥ 1/10000 to < 1/1000); very rare (< 1/10000); frequency not known (cannot be estimated from available data).

Central nervous system: frequency not known – drowsiness (at the beginning of treatment), headache and dizziness (when doses above 2000 mg per day are used; reducing the dose decreases the intensity of this adverse effect).

Gastrointestinal disorders: frequency not known – nausea (at the beginning of treatment), vomiting, diarrhea, epigastric pain.

Hepatobiliary disorders: frequency not known – hepatotoxicity (with prolonged use of high doses).

Immune system disorders: frequency not known – hypersensitivity reactions, including urticaria, erythema, rash, angioneurotic edema, facial swelling, tongue swelling.

Skin and subcutaneous tissue disorders: rare – allergic reactions (rash, pruritus).

Psychiatric disorders: frequency not known – emotional lability, sleep disturbances (these adverse reactions may occur in children when the medicinal product is used without following the recommendations of the instructions for medical use).

If any adverse reactions not listed in this instruction appear during treatment, or if any of the listed adverse reactions are particularly severe, medical advice should be sought immediately.

Reporting of suspected adverse reactions.

Reporting of suspected adverse reactions after the medicinal product has been authorized is important. It allows ongoing monitoring of the benefit-risk balance of the medicinal product. Healthcare professionals and patients, as well as their legal representatives, are encouraged to report all suspected adverse reactions and lack of efficacy through the Automated Pharmacovigilance Information System at the following link: https://aisf.dec.gov.ua.

Shelf life.

3 years.

Storage conditions.

Store in the original packaging at a temperature not exceeding 25 °C.

Keep out of reach and sight of children.

Packaging.

10 tablets per blister. 2, 3, 4, 5, 6 or 10 blisters per cardboard box.

Prescription status.

Prescription only.

Manufacturer.

LLC "ASTRAFARM".

Manufacturer's address and place of business.

6, Kyivska Street, Vyshneve, Bucha District, Kyiv Region, 08132, Ukraine