Primidon
Primidone: instructions for use and reviews
- 1. Release form and composition
- 2. Pharmacological properties
- 3. Indications for use
- 4. Contraindications
- 5. Method of application and dosage
- 6. Side effects
- 7. Overdose
- 8. Special instructions
- 9. Application of pregnancy and lactation
- 10. Use in childhood
- 11.disorders of renal function
- 12.abnormal liver function
- 13. Use in the elderly
- 14. Drug interactions
- 15. Analogs
- 16. Terms and conditions of storage
- 17. Terms of dispensing from pharmacies
- 18. Reviews
- 19. Price in pharmacies
Latin name: Primidone
ATX code: N03AA03
Active ingredient: primidone (Primidone)
Producer: JSC "KhFK AKRIKHIN" (Russia)
Description and photo update: 2019-28-11
Primidone is an antiepileptic drug.
Release form and composition
The drug is available in the form of tablets: flat-cylindrical, white, beveled; tablets with a dosage of 0.25 g are at risk (10 pcs. in blisters, in a cardboard box 1, 2, 3, 4 or 5 blisters; 10, 20, 30, 40 or 50 pcs. in dark glass jars, in a cardboard box 1 can and instructions for the use of Primidon).
Composition for 1 tablet:
- active substance: primidone (hexamidine) - 0.125 g or 0.25 g;
- auxiliary components: sodium starch glycolate, calcium stearic acid, potato starch, polyvinylpyrrolidone type "Kollidon 90F".
Pharmacological properties
Pharmacodynamics
In terms of chemical structure, hexamidine is close to phenobarbital, but its anticonvulsant effect is more pronounced. Unlike phenobarbital, Primidone does not cause a clear hypnotic effect and a depressing effect on the central nervous system (central nervous system).
The mechanism of action of the drug is associated with the suppression of the transmission of nervous excitement from segmental and pyramidal pathways to motor neurons located in the spinal cord.
Pharmacokinetics
Absorption of hexamidine after oral administration is rapid and almost complete. The maximum concentration in blood plasma is observed after about 3 hours. Bioavailability is more than 90%, the volume of distribution is from 0.64 to 0.86 l / kg.
Undergoes hepatic metabolism with the formation of two active metabolites - FEMA (phenylethylmalonamide) and phenobarbital. About 20% of primidone and 50% of phenobarbital bind to plasma proteins. The association of FEMA with plasma proteins is insignificant.
Hexamidine and its metabolites in sufficiently large quantities penetrate into breast milk (the average concentration in the milk of a nursing woman is 75% of the stable plasma concentration). The half-life for primidone is 3-23 hours, for FEMA - 10-25 hours and phenobarbital - 75-126 hours. The main part of the dose taken is excreted by the kidneys in the form of primidone (about 64%), about 6.6% of the drug is excreted in the form of FEMA and 5.1% in the form of phenobarbital.
Indications for use
Primidone is used for large convulsive seizures and epilepsy. In patients with mild abortive seizures and mental equivalents, the drug is less effective. It does not have a permanent effect in patients with small forms, but in some cases some therapeutic effect is observed.
Contraindications
Absolute:
- severe renal failure;
- severe liver failure;
- diseases of the hematopoietic system (leukopenia, anemia);
- acute intermittent porphyria;
- the period of pregnancy and breastfeeding;
- children under 3 years old;
- hypersensitivity to the main or auxiliary ingredients of the drug.
Relative (Primidone is used with caution):
- impaired renal and / or liver function;
- respiratory dysfunction;
- children over 3 years old and old age (possible motor and paradoxical excitement).
Primidone, instructions for use: method and dosage
Primidon tablets are taken orally, after meals.
Treatment is usually individualized. Some patients with epilepsy may need primidone monotherapy, while others require combined anticonvulsant therapy.
The drug is usually prescribed twice a day. The initial dose is 0.125 g once at night. Then every 3 days the dose is increased by 0.125 g until the total daily dose is 0.5 g (0.25 g twice a day). In the future, the dose of the drug continues to increase every 3 days by 0.25 g in children over 9 years of age and adults and by 0.125 g in children aged 3–9 years. The dose is increased until control of seizures or the maximum tolerated dose is achieved. For children over 9 years old and adults, the maximum tolerated dose of Primidone is 1.5 g per day, for children aged 3-9 years - 1 g per day.
Average maintenance doses of the drug:
- children aged 3-6 years - 0.5-0.75 g per day;
- children aged 6-9 years - 0.75-1 g per day;
- children over 9 years old and adults - 0.75-1.5 g per day.
The daily dose of Primidone is usually divided into two equal parts and taken twice a day (morning and evening).
For some patients, during periods when seizures occur more often, it is advisable to increase the single dose. For example, if convulsions appear at night, give all or most of the daily dose in the evening. If seizures occur due to certain periods or circumstances (for example, with menstrual bleeding), a small increase in the daily dose during this period can be very beneficial.
Side effects
At the beginning of treatment with Primidone, the most common adverse reactions of the drug include drowsiness, headache, nausea, apathy, dizziness and ataxia. These phenomena usually go away on their own.
During the use of the drug, especially with prolonged therapy, unwanted side effects from the following systems and organs are possible:
- digestive system: often - nausea; infrequently - vomiting;
- hepatobiliary system: rarely - increased activity of hepatic enzymes;
- central and peripheral nervous system: often - visual disturbances, apathy, nystagmus, anxiety, ataxia; rarely, psychotic reactions and personality disorder;
- musculoskeletal system: often - osteomalacia, arthralgia; isolated cases - Dupuytren's contracture (palmar fibromatosis);
- lymphatic system and blood: rarely - blood disorders, B 12 - deficiency anemia, lymphocytosis, leukopenia;
- skin and subcutaneous fat: infrequently - measles, scarlet fever and maculopapular rash; rarely - toxic epidermal necrolysis, exfoliative dermatitis, lupus-like syndrome, Stevens-Johnson syndrome;
- other reactions: often - drowsiness; infrequently - dizziness, headache, folic acid deficiency, drug dependence.
Overdose
In case of an overdose of Primidone, the patient may feel nausea and dizziness, he has ataxia and depression of the central nervous system (including loss of consciousness and ataxia). In severe cases, respiratory depression and coma may occur. One of the diagnostic signs of drug overdose is crystalluria.
The patient's stomach is washed, activated carbon is prescribed. Further treatment is symptomatic, if necessary, the therapy is carried out in a hospital setting.
special instructions
Primidone tablets can be used as part of a complex anticonvulsant treatment.
Long-term use of the drug increases the risk of drug dependence and resistance, as well as withdrawal symptoms in case of abrupt cessation of therapy.
If during treatment the patient develops megaloblastic anemia, the drug should be discontinued and the patient should be prescribed vitamin B 12 and / or folic acid.
Since the side effects of Primidone can be quite serious and pronounced, it is recommended to use other antiepileptic drugs if possible, for example, carbamazepine, valproic acid, etc.
Like other drugs for epilepsy, Primidone can cause manifestations of suicidal activity, suicidal ideation and behavior. All patients during treatment should be under the supervision of a doctor so that behavioral changes and mental disorders that threaten their health and life can be identified in a timely manner.
The drug can only be used as directed by a specialist. If you experience any unusual reactions, you should see your doctor.
Influence on the ability to drive vehicles and complex mechanisms
During the period of therapy with antiepileptic drugs, it is necessary to refrain from driving vehicles and other work, the performance of which requires an increased concentration of attention and a quick reaction.
Application during pregnancy and lactation
Primidone is contraindicated in pregnant women, as it can cause serious fetal malformations (cleft palate, heart defects, anencephaly and microcephaly). During pregnancy, the drug is used for the treatment of epilepsy only on strict indications, if other methods of treatment are unavailable or impossible.
In newborns whose mothers took primidone in the third trimester, especially in the later stages, withdrawal symptoms and bleeding disorders may occur. Throughout pregnancy, a woman should receive additional supplements of folic acid and vitamin B 12 (to prevent folate deficiency). In the later stages (during the last month of pregnancy), it is recommended to additionally take vitamin K 1.
During the period of breastfeeding, the drug is also contraindicated. If it is necessary to use Primidone during breastfeeding, it is necessary to monitor the baby (possibly sedative).
Pediatric use
The drug should not be administered to children under 3 years of age.
With impaired renal function
In patients with severe renal failure, Primidone is not used.
In case of impaired renal function, the drug is prescribed with caution.
For violations of liver function
Primidone is contraindicated in patients with severe hepatic impairment.
In case of violations of liver function, the drug is used with caution.
Use in the elderly
Elderly patients with reduced renal function should be monitored during treatment.
Drug interactions
Primidone enhances the effects of sleeping pills, methotrexate, cyclophosphamide and sulfonylurea derivatives; accelerates metabolism and weakens the action of indirect anticoagulants, paracetamol, chloramphenicol, digitalis glycosides, doxycycline, metronidazole, quinidine, vitamin D, oxtriphylline, oral contraceptives, mineralocorticosteroids and glucocorticosteroids, cyclopiraxidine, amyloxylinet, levioxylamide, phenylamine dacarbazine and caffeine.
In combination with ethanol and drugs with a central inhibitory effect, the suppression of the central nervous system is enhanced.
Carbonic anhydrase inhibitors can increase the impairment of osteogenesis caused by primidone.
Amphetamine slows down the absorption of phenobarbital (one of the metabolites) in the digestive tract.
With the simultaneous use of drugs for general anesthesia (halothane, enflurane, methoxyflurane), their hepatotoxicity increases.
Primidone reduces the absorption of griseofulvin, which leads to a decrease in its antifungal action.
Guanethidine, loxapine, molindone, thioxanthenes, guanadrel, haloperidol, maprotiline and phenothiazines reduce the seizure threshold and act depressively on the central nervous system. Large doses of leucovorin weaken the anticonvulsant effect of primidone. Methylphenidate increases the plasma concentration of primidone and increases its toxicity.
When combined with phenylbutazone, a mutual weakening of the therapeutic effects is observed; with hormones of the posterior lobe of the pituitary gland - the risk of coronary insufficiency and arrhythmias increases.
Stimulants of microsomal liver enzymes (carbamazepine, phenobarbital, ethanol, rifampicin) accelerate the metabolism of the drug and reduce its effectiveness.
Analogs
Analogues of Primidone are Benzonal, Valproic acid, Depakine, Hexamidine, Zeptol, Misolin, Phenobarbital, Benzonal, etc.
Terms and conditions of storage
Keep out of the reach of children. Store in a place protected from moisture at a temperature not exceeding 25 ° C.
The shelf life of the tablets is 5 years.
Terms of dispensing from pharmacies
Dispensed by prescription.
Reviews about Primidon
To date, there are few actual reviews about Primidone. Basically, both doctors and patients respond well to the drug. It has been shown to be effective for essential tremors and seizures. However, due to the high frequency and severity of side effects, this antiepileptic drug is increasingly being replaced by more modern and safer drugs for epilepsy.
The price of Primidone in pharmacies
The drug is currently not available in pharmacies. The last price of Primidone on sale in the form of tablets of 0.25 mg (50 pcs. In a package) was about 400 rubles.
Maria Kulkes Medical journalist About the author
Education: First Moscow State Medical University named after I. M. Sechenov, specialty "General Medicine".
Information about the drug is generalized, provided for informational purposes only and does not replace the official instructions. Self-medication is hazardous to health!
