TOPIRAMATE PILLS 100MG

International non-proprietary name:

topiramate

Dosage Form:

film coated tablets

PHARMACOLOGICAL PROPERTIES

Pharmacodynamics: Topiramate is an antiepileptic agent, belongs to the class of sulfate-substituted monosaccharides. It blocks sodium channels and suppresses the occurrence of repeated action potentials against the background of prolonged depolarization of the neuron membrane. Increases the activity of gamma-aminobutyric acid (GABA) with respect to some subtypes of GABA receptors (including GABABUT-receptors), and also modulates the activity of GABABUTreceptors, prevents the activation of kainate / AMPK (a-amino-3-hydroxy-5-methylisoxazole-4-propionic acid) - receptors for glutamate, does not affect the activity of N-methyl-D-aspartate (NMDA) in relation to the subtype NMDA- receptors. These effects of topiramate are dose-dependent at plasma concentrations of topiramate 1 to 200 μmol / L, with a minimum activity ranging from 1 to 10 μmol / L.

In addition, topiramate inhibits the activity of some isoenzymes of carbonic anhydrase (II-IV).In terms of the severity of this pharmacological effect, topiramate is significantly inferior to acetazolamide, a known inhibitor of carbonic anhydrase, therefore this action of topiramate is not the main component of its antiepileptic activity.

Pharmacokinetics.

After oral administration, topiramate is rapidly and well absorbed from the gastrointestinal tract. Bioavailability is about 81%. After ingestion of 400 mg of topiramate, the maximum plasma concentration (Cmax) of 1.5 mcg / ml is achieved within 2 hours. Eating does not have a clinically significant effect on the bioavailability of topiramate. After repeated ingestion of 100 mg of topiramate twice a day, the average Cmax was 6.76 mcg / ml.

The pharmacokinetics of topiramate is linear, plasma clearance remains constant, and the area under the concentration / time curve (AUC) in the dose range from 100 to 400 mg increases in proportion to the dose.

Communication with plasma proteins for topiramate is 13-17% in the range of concentrations in the blood plasma 0.5-250.0 mcg / ml. After a single dose of up to 1200 mg, the average volume of distribution is 0.55-0.8 l / kg. The magnitude of the distribution depends on gender: in women - about 50% of the values ​​observed in men, which is associated with a higher content of adipose tissue in the body of women. Equilibrium concentration when taking topiramat in patients with normal renal function is achieved after 4-8 days. Penetrates into breast milk and through the placental barrier.

After ingestion, about 20% of the accepted dose is metabolized. Metabolized by hydroxylation, hydrolysis and glucuronidation. However, in patients receiving concomitant therapy with antiepileptic drugs (AEP), which are inducers of microsomal enzymes, the metabolism of topiramate increased to 50%. Six practically inactive metabolites were isolated and identified from blood plasma, urine and feces. With simultaneous intake of cytochrome P450 isoenzyme inductors, the metabolism level of topiramate is up to 50%.

The main route of elimination of unchanged topiramate (about 70%) and its metabolites are the kidneys. After ingestion, plasma clearance of topiramate was 20-30 ml / min. After repeated ingestion of 50 and 100 mg twice a day, the elimination half-life (T1 / 2) of topiramate from blood plasma averages 21 hours. Removed from plasma by hemodialysis.

Pharmacokinetics in special clinical situations. The renal and plasma clearance of topiramate with mild renal failure (creatinine clearance (CK) of more than 70 ml / min) is not changed. With a moderate degree of renal failure (CK 30-69 ml / min), the renal and plasma clearance of topiramate is reduced by 42%, and with severe renal insufficiency (CK less than 30 ml / min), the renal and plasma clearance of topiramate is reduced by 54% or more.

With moderate and severe liver failure, plasma clearance of topiramate is reduced by 20-30%.

In elderly patients without renal and hepatic insufficiency, the clearance of topiramate is unchanged.

The pharmacokinetics of topiramate in children, as in adults, is linear with dose-independent clearance; the equilibrium concentration of topiramate in the blood plasma increases in proportion to the dose increase. In children, the clearance of topiramate is increased, and T1 / 2 is reduced, therefore, with the same dose per 1 kg of body weight, the concentration of topiramate in the blood plasma in children will be lower than in adults. In children, as in adults, antiepileptic drugs that induce liver microsomal enzymes cause a decrease in the concentration of topiramate in the blood plasma and increase its metabolic rate.

INDICATIONS FOR USE

In monotherapy in adults and children from 6 years of age with partial (with secondary generalization or without) or primary generalized tonic-clonic convulsions.

As part of complex therapy in adults and children older than 3 years with partial with secondary generalization, or without or generalized tonic-clonic seizures, as well as for the treatment of seizures caused by Lennox-Gastaut syndrome.

Prevention of migraine attacks in adults after a thorough evaluation of all possible alternatives. Topiramate is not intended to treat acute migraine attacks.

CONTRAINDICATIONS

Hypersensitivity to topiramate or any other component of the drug; children's age up to 6 years with monotherapy, up to 3 years as part of combination therapy for epilepsy;

Children under 18 years of age when used for the prevention of migraine.

Migraine prevention in pregnant women or women of childbearing age who do not use effective contraception.

Carefully

Renal failure, liver failure, hypercalciuria, nephrourolithiasis (including a history or family history).

Use during pregnancy and lactation

Special controlled studies in which topiramate was used to treat pregnant women have not been conducted. There is evidence of a possible connection between the use of topiramate during pregnancy and congenital malformations (for example, craniofacial defects (cleft lip / cleft palate), hypospadias, underweight of the fetus and newborn). These malformations were recorded both with monotherapy with topiramate and with its simultaneous use with other antiepileptic drugs (PEP). The records of pregnancies and the results of studies of monotherapy with topiramate indicate an increase in the probability of having children with underweight (less than 2500 g). The relationship of these cases with the reception of topiramata has not been established. Data from other studies suggest that the risk of teratogenic effects in combination therapy with other antiepileptic drugs may be higher than in monotherapy.

The use of topiramate during pregnancy is contraindicated. At the time of drug treatment is necessary to use effective methods of contraception.

A limited number of patient observations suggests that topiramate is excreted in breast milk, so breastfeeding should be discontinued during use of the drug.

Women with childbearing potential are advised to use effective contraceptive methods and consider alternative therapies. If topiramate is used during pregnancy, or if the patient became pregnant while taking this drug, the doctor should warn her of the potential risk to the fetus.

METHOD OF ADMINISTRATION AND DOSES

Inside, regardless of the meal. pills should not be divided.

For optimal control of seizures, it is recommended to start treatment with low doses followed by an increase to the effective dose. When used as monotherapy, it is necessary to take into account the possible effect of the abolition of concomitant anti-epileptic drugs (AEDs) on the frequency of seizures. In cases where there is no need to abruptly cancel the probe, it is recommended to reduce their dose gradually, reducing the dose by 1/3 every 2 weeks.With the abolition of drugs that are inducers of microsomal liver enzymes, the concentration of topiramate in the blood plasma will increase, which should be taken into account in the therapy.

Monotherapy

Adults:

Adults at the beginning of monotherapy - 25 mg 1 time per day at night for 1 week. Then the dose is increased with an interval of 1-2 weeks at 25-50 mg / day (the daily dose is divided into 2 doses). In case of intolerance to such a treatment regimen, the dose is increased by a smaller amount or at large intervals. The dose is selected depending on the effectiveness and tolerability of the therapy. The recommended initial target dose is 100-200 mg / day, the maximum daily dose should not exceed 500 mg in monotherapy. Dosing recommendations apply to all adults, including elderly patients who do not have kidney disease.

Children older than 6 years with monotherapy in the first week of treatment - at 0.5-1 mg / kg body weight before bedtime. Then the dose is increased with an interval of 1-2 weeks by 0.5-1 mg / kg per day (the daily dose is divided into two doses). In case of intolerance to such a treatment regimen, the dose is increased more smoothly or at large intervals between dose increases. The magnitude of the dose and the rate of its increase are determined by clinical efficacy and tolerability of therapy. The recommended dose range for monotherapy with topiramate in children is 100 mg / day and depends on the clinical efficacy (in children 6–16 years old, it is about 2 mg / kg / day).

As part of combination therapy

Adults:

When prescribed as part of combination therapy with other anticonvulsant drugs in adults, the initial dose is 25-50 mg once a day for a night for 1 week. Further, the dose is increased by 25-50 mg every week until the effective dose is reached. The minimum effective dose is 200 mg / day, the average daily dose is 200-400 mg, the dose is 2 times a day. Doses of more than 1600 mg per day have not been studied. The criterion for the selection of the dose is the clinical effect and tolerability, in some patients this effect can be achieved when taking the drug 1 time per day. Dosing recommendations apply to all adults, including elderly patients who do not have kidney disease.

Children:

When administered as part of combination anticonvulsant therapy in children over 3 years old, the recommended total daily dose is 5–9 mg / kg in 2 doses.Selection of the dose begins with 25 mg / day (at the rate of 1-3 mg / kg / day) at night for 1 week. In the future, the dose can be increased by 1-3 mg / kg for 1-2 weeks and taken in 2 doses. The criterion for the correct dose is a stable clinical effect and good tolerability. Daily dosages up to 30 mg / kg are usually well tolerated.

Migraine Prevention

The recommended total daily dose of 100 mg in 2 doses. Begin treatment with a dose of 25 mg or less at bedtime for 1 week. Then the dose is increased by 25 mg / day with an interval of 1 week. In case of intolerance to such a regimen, the dose is increased by a smaller amount or at large intervals of time. The dose is selected depending on the clinical effect. In some patients, a positive result is achieved with a daily dose of 50 mg / day. When applying a daily dose of more than 100 mg / day, there is no additional effect as a prevention of migraine.

Patients with renal failure. For patients with moderate (QC less than 70 ml / min) and severe (QC less than 30 ml / min) degree of renal failure, the recommended initial dose should be reduced by 2 times, and it should be increased by a smaller amount or at large intervals of time. The dose is selected depending on the clinical effect. It should be borne in mind that the achievement of the equilibrium concentration will take more time and will be from 10 to 15 days after each increase in the dose of Topiramate.

Patients in need of hemodialysis. Since topiramate can be removed by hemodialysis, the daily dose of the drug should be increased by 50% on the days it is administered. The additional dose is divided into 2 parts and is administered before hemodialysis and after its termination. Additional dose may vary depending on the characteristics of the dialysis and equipment used. The dose is selected depending on the clinical effect.

In patients with hepatic impairment Topiramate should be taken with caution under medical supervision because of reduced clearance of topiramate.

In elderly patients dose adjustment is not required.

CANCELLATION OF PREPARATION

Antiepileptic drugs, including topiramate, should be discontinued gradually to minimize the possibility of increasing the frequency of seizures, reducing the dose by 50-100 mg every 1 week when treating epilepsy and 25-50 when using Topiramate for preventing migraine. Children cancel within 2-8 weeks. If for medical reasons you need a quick cancellation of topiramate, it is recommended to carry out appropriate monitoring of the patient's condition.The main route of excretion of topiramate and its metabolites unchanged is excretion by the kidneys. The rate of kidney excretion depends on the kidney function and does not depend on age. In patients with moderate or severe renal impairment, it may take 10–15 days to achieve equilibrium plasma concentrations compared with 4–8 days in patients with normal renal function.

As with other AEDs, the topiramate dosage regimen should focus on therapeutic efficacy (that is, the degree of seizure reduction, no side effects) and should take into account the fact that patients with impaired renal function to establish an equilibrium concentration of topiramate in the blood plasma for each dose may take a longer time.

SIDE EFFECT

The frequency of side effects is classified in accordance with the recommendations of the World Health Organization: very often - at least 10%; often not less than 1%, but less than 10%; infrequently - not less than 0.1%, but less than 1%; rarely - not less than 0.01%, but less than 0.1%; very rarely - not less than 0.01%, including single messages.

The most common adverse reactions (with a frequency of ³5% compared with the placebo group, noted in at least 1 double-blind controlled study): anorexia, loss of appetite, mental retardation, depression, slurred speech, insomnia, impaired coordination of movements, impaired attention, dizziness, dysarthria, impaired taste, hypoesthesia, lethargy, memory loss, nystagmus, paresthesia, drowsiness, tremor, diplopia, visual impairment, diarrhea, nausea, fatigue, irritation itelnost, weight loss.

Children

Adverse reactions that, according to the results of double-blind clinical studies, were ³2 times more common in children than in adults: loss of appetite, increased appetite, hyperchloremic acidosis, hypokalemia, behavioral disturbance, aggression, apathy, sleep disturbance, suicidal thoughts, impaired attention, drowsiness , violation of the daily rhythm of sleep, poor quality of sleep, increased tearing, sinus bradycardia, poor general condition, violation of gait.

Adverse reactions occurring in clinical studies exclusively in children: eosinophilia, psychomotor agitation, vertigo, vomiting, hyperthermia, fever, impaired learning.

Table number 1. Adverse Topiramate Reactions

* Identified by the results of spontaneous messages in the post-registration period. The frequency is calculated according to clinical studies.

OVERDOSE

Signs and symptoms of overdose: convulsions, drowsiness, speech and vision disorders, diplopia, thinking disorders, coordination disorders, dizziness, lethargy, stupor, arterial hypotension, abdominal pain, dizziness, agitation and depression, metabolic acidosis. In most cases, the clinical consequences were not severe, but deaths were noted after an overdose using a mixture of several drugs, including topiramate. There is a known case of an overdose of topiramate at a dose of up to 110 g, which led to a coma within 20-24 hours, and further after 3-4 days full recovery.

Treatment: there is no specific antidote, if necessary symptomatic therapy is carried out.It is necessary to immediately induce vomiting and flush the stomach, increase water intake. In vitro studies have shown that Activated carbon adsorbs topiramate.

Hemodialysis is the most effective way to remove topiramate from the body. Patients are recommended an adequate increase in fluid intake.