Phenifren

INSTRUCTIONS FOR MEDICAL USE OF THE MEDICINAL PRODUCT FENIFREN (FENIFREN)

Composition:

Active substance: phenibut;

1 capsule contains phenibut 250 mg;

Excipients: lactose monohydrate, potato starch, calcium stearate;

Capsule shell: gelatin, titanium dioxide (E 171).

Dosage form. Capsules.

Main physicochemical properties: hard gelatin capsules of white color. The capsule contents are white or almost white powder.

Pharmacotherapeutic group.

Other psychostimulants and nootropic agents. Phenibut.

ATC code N06B X22.

Pharmacological Properties

Pharmacodynamics

Phenibut, the active ingredient of the drug Phenifren, is a derivative of γ-aminobutyric acid (GABA) and phenylethylamine.

Phenibut exhibits both nootropic and anxiolytic (tranquilizing) activity, typical of GABA derivatives. Phenibut does not affect cholinoreceptors or adrenoreceptors. It reduces anxiety, restlessness, fear, and improves sleep; therefore, the drug can be used for the treatment of neuroses as well as prior to surgical procedures. Phenibut prolongs and enhances the effects of hypnotics, narcotic agents, neuroleptics, and antiparkinsonian drugs. It does not possess anticonvulsant activity.

Phenibut prolongs the latent period of nystagmus and reduces its duration and intensity. Phenibut significantly reduces manifestations of asthenia and vasovegetative symptoms, including headache, sensation of heaviness in the head, sleep disturbances, irritability, and emotional lability, while increasing mental performance. Under the influence of phenibut, psychological parameters improve—attention, memory, speed and accuracy of sensorimotor reactions. In patients with asthenia and emotional lability, phenibut improves subjective well-being from the first days of therapy, increases interest and initiative, and motivation for action, without causing excessive sedative effect or excitation. In terms of antiasthenic activity (weakness, fatigability, hypodynamia, mental and physical asthenia), phenibut is more active than piracetam.

Pharmacokinetics

Absorption and Distribution

After oral administration, the drug is well absorbed from the gastrointestinal tract and penetrates into all tissues of the body, easily crossing the blood-brain barrier (approximately 0.1% of the administered dose reaches brain tissue, and to a significantly greater extent in both young and elderly individuals). About 80% of phenibut is bound in the liver; this binding is non-specific.

Biotransformation and Elimination

80−95% of phenibut is metabolized in the liver into pharmacologically inactive metabolites. Approximately 5% of the dose is excreted unchanged in urine. No accumulation occurs with repeated administration.

Clinical characteristics.

Indications.

Asthenic and anxious-neurotic states: restlessness, anxiety, and fear; in elderly patients – insomnia and nocturnal restlessness; stress prophylaxis prior to surgery.

Meniere's disease and vertigo associated with vestibular dysfunction of various origins.

Prophylaxis 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 medicinal product.

Pregnancy and breastfeeding period.

Interaction with other medicinal products and other forms of interaction.

Phenifren can be combined with psychotropic medicinal products, reducing the doses of Phenifren and the concomitantly used medicinal products.

Phenifren enhances and prolongs the effects of sedatives, narcotics, neuroleptics, and antiparkinsonian medicinal products.

Special precautions for use.

The medicinal product should be used with caution in patients with peptic ulcer of the stomach and/or intestine. To protect mucous membranes from the irritating effect of phenibut, lower doses should be prescribed to these patients.

In case of prolonged treatment, blood parameters and liver function tests should be monitored.

The medicinal product contains lactose and therefore should not be administered to patients with rare hereditary forms of galactose intolerance, complete lactase deficiency, or glucose-galactose malabsorption.

Use during pregnancy or breastfeeding.

Animal studies have not revealed mutagenic, teratogenic, or embryotoxic effects of phenibut. There are no well-controlled and adequate studies on the safety of phenibut use in pregnant or breastfeeding women. Therefore, the use of Phenifren during pregnancy or breastfeeding is contraindicated.

There is no information available on the effect of phenibut on fertility.

Ability to influence reaction rate when driving or operating machinery.

Patients who experience drowsiness or other central nervous system disorders during treatment should refrain from driving or operating machinery.

Dosage and Administration

For asthenic and anxiety-neurotic conditions:
The recommended dose for adults is 250–500 mg (1–2 capsules) three times daily. Maximum single dose: 750 mg for adults; 500 mg for patients over 60 years of age.

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

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

For infectious-origin functional disorders of the vestibular analyzer and during exacerbations of Meniere’s disease, Phenyphren is prescribed at 750 mg (3 capsules) three times daily for 5–7 days. When vestibular symptoms subside, the dose is reduced to 250–500 mg (1–2 capsules) three times daily for 5–7 days, followed by 250 mg once daily for 5 days. In milder cases, Phenyphren is administered at 250 mg (1 capsule) twice daily for 5–7 days, then 250 mg once daily for 7–10 days.

For relief of dizziness and vestibular dysfunction of vascular or traumatic origin:
Phenyphren is prescribed at 250 mg three times daily for 12 days.

For prevention of kinetosis:
The drug should be taken once at a dose of 250–500 mg one hour before the expected onset of motion sickness or at the first symptoms of discomfort. The drug is poorly effective if symptoms are severe (e.g., vomiting).

For management of alcohol withdrawal syndrome:
In the initial days of treatment, Phenyphren is prescribed at 250–500 mg three times daily and 750 mg at bedtime, 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 liver dysfunction. The lowest effective dose should be used in this patient group.

Patients with renal impairment:
There are no data on adverse effects of Phenyphren in patients with impaired renal function when the drug is used at therapeutic doses.

Children aged 8 to 14 years:
The recommended dose is 250 mg (1 capsule) three times daily.

The duration of treatment is 2–6 weeks.

Phenyphren should be taken orally after meals. Swallow the capsules with sufficient amount of water.

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

Overdose.

No cases of overdose have been reported.

Phenyphren is a low-toxicity medicinal product.

Symptoms:
Drowsiness, nausea, vomiting, dizziness.

With prolonged use of high doses, eosinophilia, arterial hypotension, fatty liver degeneration, and impaired renal function may develop.

Treatment:
Symptomatic therapy.

There is no specific antidote.

Side effects.

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

Adverse reactions are listed according to the MedDRA system organ classification and frequency classification: 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).

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

Nervous system disorders: frequency not known: somnolence (at the beginning of treatment), headache and dizziness (at doses above 2 g per day; adverse effects decrease when the dose is reduced).

Gastrointestinal disorders: frequency not known: nausea (at the beginning of treatment).

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

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

There are isolated reports that in children, failure to follow the instructions for use of the medicinal product may lead to emotional lability and sleep disturbances.

If any adverse reactions occur during treatment that are not listed in this leaflet, or if any of the listed adverse reactions are particularly severe, please consult your physician.

Shelf life. 3 years.

Do not use after the expiry date.

Storage conditions.

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

Keep out of reach and sight of children.

Packaging.

10 capsules in a blister, 2 blisters in a cardboard box.

Prescription status.

Prescription only.

Manufacturer.

JSC "CHEMICAL PHARMACEUTICAL PLANT "CHERVONA ZIRKA".

Manufacturer's address and place of business.

1, Gordienkovskaya Street, Kharkiv, Kharkiv region, 61010, Ukraine.