Topiramate

Brand Akrikhin

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Available since: 2019-09-19

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Clinical Pharmacology

Antiepileptic drug belongs to the class of sulfate-substituted monosaccharides.

Topiramate reduces the frequency of action potentials characteristic of a neuron in a state of persistent depolarization, which indicates the dependence of the blocking action of the drug on sodium channels on the state of the neuron. Topiramate potentiates the activity of GABA against certain subtypes of GABA receptors (including GABA_A-receptors), and also modulates the activity of GABA itself_A-receptors, prevents the activation of kainate sensitivity of the kainate / AMPK receptors to glutamate, does not affect the activity of N-methyl-D-aspartate towards NMDA receptors. These effects of topiramate are dose-dependent when plasma topiramate concentration is from 1 μM to 200 μM, with a minimum activity ranging from 1 μM to 10 μM.

In addition, topiramate inhibits the activity of some carbonic anhydrase isoenzymes, however, this effect is weaker in topiramate than in acetazolamide and, apparently, is not central to the antiepileptic activity of topiramate.

Indications

Partial or generalized tonic-clonic seizures in adults and children (as monotherapy or in combination with other anticonvulsants); seizures associated with Lennox-Gastaut syndrome in adults and children (as a means of additional therapy).

Topiramate is marketed under different brands and generic names, and comes in different dosage forms:

Brand name	Manufacturer	Country	Dosage form
Topalepsin	Akrikhin	Russia	pills
Topiramate	Canonpharma	Russia	pills
Toreal	Lecco/Pharmstandard	Russia	pills
Topsaver	Teva	Israel	pills
Topamax	Janssen Pharmaceuticals N.V	Belgium	capsules

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Dosage and Administration

The drug is taken orally, regardless of the meal.

Capsules should be carefully opened, mix their contents with a small amount (about 1 teaspoon) of any soft food. This mixture should be swallowed immediately, without chewing. Do not store the drug mixed with food until the next dose. Capsules Topamax^® can be swallowed whole.

To achieve optimal control of epileptic seizures in adults and children, it is recommended to begin treatment with the use of the drug in low doses followed by titration to an effective dose.

Capsules are intended for patients who have difficulty swallowing pills (for example, in children and elderly patients).

Partial or generalized tonic-clonic seizures, as well as seizures against the background of Lennox-Gastaut syndrome

Combined anticonvulsant therapy in adults. The minimum effective dose is 200 mg / day. Typically, the total daily dose ranges from 200 mg to 400 mg and is taken in 2 divided doses. Some patients may need to increase the daily dose to a maximum of 1600 mg. It is recommended to start treatment with a low dose, followed by gradual selection of an effective dose. Selection of the dose begins with 25-50 mg, taking them overnight for 1 week. In the future, at intervals of 1-2 weeks, the dose can be increased by 25-50 mg and take it in 2 doses. The selection of the dose should be guided by the clinical effect. In some patients, the effect can be achieved when taking the drug 1 time / day. For optimum effect treatment with Topamax^® it is not necessary to control its plasma concentration.

These dose recommendations apply to all adult patients, including elderly patients, in the absence of kidney disease.

Combined anticonvulsant therapy in children over 2 years old. Recommended total daily dose of Topamax^® as a means of additional therapy ranges from 5 to 9 mg / kg and is taken in 2 doses. Selection of the dose should be started with 25 mg (or less, based on the initial dose of 1 to 3 mg / kg per day) at night for 1 week. In the future, the dose can be increased with an interval of 1-2 weeks for 1-3 mg / kg and take it in 2 doses. The selection of the dose should be guided by the clinical effect. Daily dosages up to 30 mg / kg are usually well tolerated.

Epilepsy (including first diagnosed)

When canceling concomitant anticonvulsants with the purpose of monotherapy with topiramate, it is necessary to take into account the possible influence of this step on the frequency of seizures. In cases where there is no need to abruptly cancel concomitant anticonvulsants for safety reasons, it is recommended to reduce their doses gradually, reducing the dose of concomitant antiepileptic drugs by 1/3 every 2 weeks.

With the abolition of drugs that are inducers of liver microsomal enzymes, the concentration of topiramate in the blood will increase. In such situations, in the presence of clinical indications, the dose of Topamax^® can be reduced.

With monotherapy in adults at the beginning of treatment Topamax^® prescribed in a dose of 25 mg at bedtime for 1 week. Then the dose is increased with an interval of 1-2 weeks by 25 mg or 50 mg in 2 doses. If the patient does not tolerate such a mode of increasing the dose, you can increase the intervals between dose increases, or increase the dose more smoothly. The selection of the dose should be guided by the clinical effect. The initial dose for monotherapy with topiramate in adults is 100 mg / day, and the maximum daily dose should not exceed 500 mg. Some patients with refractory forms of epilepsy tolerate monotherapy with topiramate in doses up to 1000 mg / day. These dosing recommendations apply to all adults, including elderly patients without kidney disease.

With monotherapy for children over the age of 2 in the first week of treatment, Topamax^® prescribed in a dose of 0.5-1 mg / kg body weight at bedtime. Then the dose is increased with an interval of 1-2 weeks by 0.5-1 mg / kg / day in 2 doses. If the child does not tolerate such a mode of increasing the dose, it is possible to increase the dose more smoothly or increase the intervals between dose increases. The magnitude of the dose and the rate of its increase depends on the clinical effect. The recommended dose range for monotherapy with topiramate in children over the age of 2 years is 100-400 mg / day. Children with newly diagnosed partial seizures can be given up to 500 mg / day.

Migraine

For the prevention of migraine attacks, the recommended daily dose of topiramate is 100 mg in 2 divided doses. At the beginning of treatment, 25 mg is prescribed 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 of therapy, the dose is increased by a smaller amount or at long intervals. The dose is selected depending on the clinical effect. In some cases, a positive result is achieved with a daily dose of topiramate 50 mg. In clinical studies, patients received various doses of topiramate, but not more than 200 mg / day.

Special patient groups

Patients with moderate to severe renal insufficiency may need a dose reduction. The use of half the recommended initial and maintenance dose is recommended.

Hemodialysis: since topiramate is removed from plasma by hemodialysis, an additional dose of Topamax should be administered on the days of hemodialysis.^®equal to about half the daily dose. The additional dose should be divided into two doses taken at the beginning and after completion of the hemodialysis procedure. The additional dose may vary depending on the characteristics of the equipment used during hemodialysis.

In patients with hepatic insufficiency, topiramate should be used with caution.

Adverse reactions

Determination of the frequency of side effects: very often (≥1 / 10), often (≥1 / 100,

On the part of the nervous system: very often - drowsiness, dizziness, paresthesias, in children - apathy, impaired attention; often - nystagmus, lethargy, impaired memory, impaired concentration, tremor, amnesia, hypoesthesia, taste perversion, impaired thinking, speech disorder, cognitive disorders, apathy, mental impairment, psychomotor disorders, sedative action; infrequently - loss of taste sensitivity, akinesia, loss of smell, aphasia, apraxia, aura, burning sensation (mainly on the face and extremities), cerebellar syndrome, circadian rhythm sleep disturbance, impaired coordination of movements, complex partial seizures, convulsions, postural dizziness, increased salivation , dysesthesia, dysgraphia, dyskinesia, dysphasia, dystonia, body chills, tonic-clonic seizures of grand mal type, hyperesthesia, hypogemia, hypokinesia, hyposmia, peripheral neuropathy, parosmia, n red-fainting states, repeated speech, impaired touch, stupor, fainting, lack of response to stimuli, in children - psychomotor hyperactivity.

Mental disorders: often - delayed thinking, confusion, depression, insomnia, aggressive reactions, agitation, disorientation, emotional lability, erectile dysfunction, in children - behavior change; infrequently - anorgasmia, sexual dysfunction, crying, impaired sexual arousal, disfemiya, early awakening in the morning, euphoric mood, auditory and visual hallucinations, hypomania, a decrease in libido, mania, a state of panic, paranoid state, perseveration of thought, impaired reading skills, restlessness , sleep disorders, suicidal ideation or attempt, tearfulness; very rarely - a sense of hopelessness.

On the part of the digestive system: very often - reduction of appetite, anorexia; often - nausea, diarrhea; infrequently - abdominal pain, constipation, dry mouth, sensitivity to the mouth, pancreatitis, increased appetite, gastritis, gastroesophageal reflux, bleeding gums, bad breath, flatulence, glossy, mouth pain, thirst, dyspeptic symptoms ( stomach discomfort, epigastric discomfort, heaviness in the stomach), in children - vomiting.

From the musculoskeletal system: often - myalgia, muscle spasms, muscle cramps, muscle pain in the chest, arthralgia; infrequently - pain in the side, stiffness of muscles; very rarely - swelling of the joints, discomfort in the limbs.

Since the cardiovascular system: infrequently - bradycardia, rapid heartbeat, flushing, orthostatic hypotension, Raynaud's phenomenon.

On the part of the organ of vision: often - diplopia, blurred vision, dry eyes; infrequently - disturbance of accommodation, amblyopia, blepharospasm, transient blindness, unilateral blindness, increased lacrimation, mydriasis, night blindness, photopsia, presbyopia, scotoma (including atrial), reduction of visual acuity; very rarely - angle-closure glaucoma, involuntary movements of the eyeballs, eyelid edema, myopia, conjunctival edema, maculopathy.

From the organ of hearing: often - pain in the ears, ringing in the ears, in children - vertigo; infrequently - deafness (including neurosensory and unilateral), discomfort in the ears, hearing impairment.

On the part of the respiratory system: often - difficulty breathing, nosebleeds; infrequently - hoarseness, shortness of breath on exertion, nasal congestion, hypersecretion in the paranasal sinuses, in children - rhinorrhea; very rarely - nasopharyngitis.

On the part of the skin and subcutaneous tissues: often - rash, alopecia, itching, decrease in the sensitivity of the face; infrequently - lack of sweating, allergic dermatitis, reddening of the skin, impaired skin pigmentation, unpleasant skin odor, urticaria; very rarely - erythema multiforme, paraorbital edema, Stevens-Johnson syndrome, toxic epidermal necrolysis.

From the urinary system: often - nephrolithiasis, dysuria, pollakiuria; infrequently - exacerbation of urolithiasis, hematuria, urinary incontinence, frequent urination, renal colic, pain in the kidneys; very rarely - renal tubular acidosis.

From the hemopoietic system: often - anemia; infrequently - leukopenia, lymphadenopathy, thrombocytopenia, in children - eosinophilia; very rarely - neutropenia.

From the laboratory indicators: infrequently - a decrease in the content of bicarbonate in the blood (on average by 4 mmol / l), crystalluria, leukopenia, hypokalemia (decrease in the level of potassium in the blood serum below 3.5 mmol / l).

General disorders: very often - fatigue, irritability, weight loss; often - asthenia, anxiety, in children - fever; infrequently - facial edema, allergic reactions, hyperchloremic acidosis, increased appetite, metabolic acidosis, polydipsia, cooling of the extremities, fatigue, weakness, calcification; very rarely - generalized edema, flu-like illness, allergic edema, weight gain.

It should be used with caution in case of renal or hepatic insufficiency, nephroluritiasis (including in the past or in the family history), with hypercalciuria.

Application for violations of the liver

Caution should be used when liver failure. In patients with moderately severe and severely impaired liver function, plasma clearance is reduced.

Application for violations of renal function

Drug interactions

Effect of Topamax^® on the concentration of other antiepileptic drugs (PEP)

Simultaneous use of the drug Topamax^® with other probes (phenytoin, carbamazepine, valproic acid, phenobarbital, primidone) does not affect the values of their C_ssin plasma, with the exception of certain patients in whom the addition of the drug Topamax^® to phenytoin may cause an increase in plasma phenytoin concentration. This may be due to the inhibition of a specific polymorphic isoform of the cytochrome P450 enzyme system (CYP2Cmeph). Therefore, in the development of toxic symptoms in patients receiving phenytoin, it is necessary to control the concentration of phenytoin in the blood plasma.

In the pharmacokinetic study of patients with epilepsy, the addition of topiramate to lamotrigine did not affect C_ss the last in blood plasma at doses of topiramate 100-400 mg / day. During and after the abolition of lamotrigine (average dose of 327 mg / day) C_ss topiramata did not change.

The effect of other probes on the concentration of topiramate in plasma

Phenytoin and carbamazepine with simultaneous use with Topamax^®reduce the concentration of topiramate in plasma. Addition or cancellation of phenytoin or carbamazepine during treatment with Topamax^® may require a dose change of the latter. The dose is selected depending on the development of the required clinical effect. Addition or removal of valproic acid does not cause clinically significant changes in the concentration of topiramate in the blood plasma and, therefore, does not require a change in the dose of Topamax^®.

Add PEP	PEP concentration	Topiramate concentration
Phenytoin	lack of effect (increase in plasma concentration in isolated cases)	48% reduction in plasma concentration
Carbamazepine	lack of effect	decrease in plasma concentration by 40%
Valproic acid	lack of effect	lack of effect
Phenobarbital	lack of effect	not investigated
Primidone	lack of effect	not investigated

Interaction with other drugs

In the studies conducted with simultaneous use of the drug Topamax^® in a single dose, the digoxin AUC was reduced by 12%. The clinical significance of this effect has not been established. When prescribing or withdrawing the drug Topamax^® in patients receiving digoxin, it is necessary to monitor the concentration of digoxin in serum.

In clinical studies, the effects of joint use of the drug Topamax^® with drugs that inhibit the function of the central nervous system, as well as with ethanol, have not been studied. The combined use of the drug Topamax^® with drugs that have a depressant effect on the central nervous system, and with ethanol is not recommended.

When co-administering Topamax and Hypericum perforatum preparations based on Hypericum perforatum, the concentration of topiramate in the plasma may decrease and, as a result, the effectiveness of the preparation may also decrease. Clinical research drug interaction Topamax^® and preparations on the basis of Hypericum perforatum was not conducted.

With simultaneous use of oral contraceptive containing norethisterone (1 mg) and ethinyl estradiol (35 mcg), Topamax^® in doses of 50-800 mg / day did not have a significant impact on the effectiveness of norethisterone and in doses of 50-200 mg / day - on the effectiveness of ethinyl estradiol. A significant dose-dependent decrease in the effectiveness of ethinyl estradiol was observed at doses of the drug Topamax^® 200-800 mg / day. The clinical significance of the described changes is not clear. The risk of reducing the effectiveness of contraceptives and enhancing breakthrough bleeding should be considered in patients taking oral contraceptives in combination with Topamax^®. Patients taking estrogen-containing contraceptives should inform the doctor about any changes in the timing and nature of menstruation. The effectiveness of contraceptives can be reduced even in the absence of breakthrough bleeding.

In healthy volunteers, lithium AUC decreased by 18% while taking topiramate at a dose of 200 mg / day.In patients with manic-depressive psychosis, the use of topiramate in doses up to 200 mg / day did not affect the pharmacokinetics of lithium, but at higher doses (up to 600 mg / day), lithium AUC was increased by 26%. With the simultaneous use of topiramate and lithium should monitor the concentration of the latter in the blood plasma.

Studies of drug interactions conducted with a single and multiple administration of topiramate to healthy volunteers and patients with bipolar disorder, gave the same results. With the simultaneous use of topiratam in daily doses of 250 mg or 400 mg of AUC of risperidone taken in doses of 1-6 mg / day, reduced by 16% and 33%, respectively. At the same time, the pharmacokinetics of 9-hydroxyrisperidone did not change, and the total pharmacokinetics of the active substances (risperidone and 9-hydroxyrisperidone) changed insignificantly. Changes in the level of systemic exposure to risperidone / 9-hydroxyrisperidone and topiramate were not clinically significant, and this interaction is unlikely to have clinical significance.

Drug interactions were studied in healthy volunteers with separate and co-administration of hydrochlorothiazide (25 mg) and topiramate (96 mg). The research results showed that while taking topiramate and hydrochlorothiazide, there is an increase in C_max topiramata by 27% and its AUC by 29%. The clinical significance of these studies has not been identified. When administering hydrochlorothiazide to patients taking topiramate, dose adjustment of topiramate may be required. There were no significant changes in the pharmacokinetic parameters of hydrochlorothiazide with concomitant therapy with topiramate.

Drug interactions were studied in healthy volunteers who received metformin or a combination of metformin and topiramate. The results of studies have shown that when taking topiramate and metformin simultaneously, an increase in C occurs._maxand AUC of metformin by 18% and 25%, respectively, whereas the clearance of metformin with simultaneous administration with topiramate decreased by 20%. Topiramate had no effect on T_maxmetformin in plasma. The clearance of a topiramat at joint appointment with metformin decreases. The degree of clearance changes have not been studied. The clinical significance of the effects of metformin on topiramate pharmacokinetics is not clear. In case of addition or withdrawal of the drug Topamax^® in patients receiving metformin, the condition of patients with diabetes should be monitored.

Drug interactions were studied in healthy volunteers with separate and co-administration of pioglitazone and topiramate. A 15% reduction in the AUC of pioglitazone was found, with no change in C_maxdrug. These changes were not statistically significant. A decrease in C was also found for the active hydroxymetabolite pioglitazone._maxand AUC by 13% and 16%, respectively, and a decrease in C was detected for active ketometabolite_max and AUC by 60%. The clinical significance of this data has not been elucidated. When patients are jointly prescribed Topamax^® and pioglitazone should carefully monitor the patient's condition to assess the course of diabetes.

A drug interaction study was conducted to study the pharmacokinetics of glibenclamide (5 mg / day) in an equilibrium state, used alone or simultaneously with topiramate (150 mg / day) in patients with type 2 diabetes. When using topiramate AUC glibenclamide was reduced by 25%. The level of systemic exposure to active metabolites, 4-trans-hydroxy-glibenclamide and 3-cis-hydroxy-glibenclamide, was also reduced (by 13% and 15%, respectively). Glibenclamide did not affect the pharmacokinetics of topiramate in equilibrium. A statistically insignificant decrease in pioglitazone AUC by 15% was found with no change in its C_max. When administering topiramate to patients receiving glibenclamide (or prescribing glibenclamide to patients receiving topiramate), the patient’s condition should be carefully monitored to assess the course of diabetes.

With the simultaneous use of the drug Topamax^® other drugs predisposing to the development of nephrolithiasis may increase the risk of kidney stones. During the period of treatment with Topamax^® The use of such drugs should be avoided, as they can cause physiological changes that contribute to the development of nephrolithiasis.

The combined use of topiramate and valproic acid in patients who tolerate each drug well separately is accompanied by hyperammonemia with or without encephalopathy. In most cases, the symptoms and signs disappear after the cancellation of one of the drugs. This adverse event is not caused by pharmacokinetic interaction. The relationship between hyperammonemia and the use of topiramate alone or in combination with other drugs has not been established.

When combined with topiramate and valproic acid, hypothermia may occur (unintended decrease in body temperature below 35 ° C) in combination with hyperammonemia or independently. This phenomenon can occur both after the start of joint administration of valproic acid and topiramate, and with an increase in the daily dose of topiramate.

Clinical studies have been conducted to evaluate potential options for drug interactions between topiramate and other drugs. The results of this interaction are summarized in the table.

Add drug	Concentration of the added drug *	Topiramate concentration *
Amitriptyline	increase C_maxand AUC of nortriptiline (amitriptyline metabolite) by 20%	not explored
Dihydroergotamine (inside and s / c)	**	**
Haloperidol	increase in metabolite AUC by 31%	not explored
Propranolol	increase C_max 4-OH propranolol by 17% (topiramate 50 mg)	increase C_max by 9% and 16%, an increase in AUC by 9% and 17% (propranolol 40 mg and 80 mg every 12 hours, respectively)
Sumatriptan (inside and s / c)	**	not explored
Pizothyfen	**	**
Diltiazem	reduction of AUC of diltiazem by 25% and desacetyldylthiazem by 18% and ** for N-demethyl-diltiazem	20% increase in AUC
Venlafaxine	**	**
Flunarizin	16% increase in AUC (50 mg every 12 hours)¹	**

* expressed in% of C values_maxand AUC with monotherapy

** no change C_maxand AUC (≤ 15% of raw data)
¹with repeated use of flunarizine (monotherapy), an increase in AUC by 14% was observed, which may be due to the accumulation of the drug in the process of achieving an equilibrium state

Pregnancy and Lactation

Special controlled studies in which Topamax^® used for the treatment of pregnant women, not carried out. Topiramate may have a damaging effect on the fetus when used in pregnant women.

Pregnancy records show that infants exposed to intrauterine topiramate have an increased risk of developing congenital malformations (for example, craniofacial defects such as cleft lip or palate, hypospadias and anomalies of various body systems). These malformations were recorded both in monotherapy with topiramate and in its use in the framework of polytherapy.

Compared with the group of patients who do not take anti-epileptic drugs, the data of registration of pregnancies with monotherapy drug Topamax^®indicate an increased likelihood of low birth weight babies (less than 2500 g). The relationship of the observed phenomena with the drug is not installed. In addition, the records of pregnancies and the results of other studies suggest that the risk of teratogenic effects in the combined treatment with antiepileptic drugs is higher than in monotherapy.

Use of Topamax^® during pregnancy is justified only in the case when the potential benefit of therapy for the mother outweighs the possible risk to the fetus.

When treating and consulting women of childbearing age, the attending physician should weigh the balance of benefits and risks of treatment and consider alternative treatment options.

If Topamax^® used during pregnancy, or if the patient became pregnant while taking the drug, it should be warned of the potential risk to the fetus.

A limited number of observations suggests that topiramate is excreted in breast milk in women. If necessary, use the drug Topamax^® in the period of lactation should decide the issue of termination of breastfeeding or discontinuation of the drug.

Special instructions

Cancel Topamax^® (like other antiepileptic drugs) should be gradual to minimize the possibility of increasing the frequency of seizures. In clinical studies, the dose of the drug was reduced by 50-100 mg 1 time per week - for adults with epilepsy therapy and 25-50 mg - for adults receiving Topamax^® at a dose of 100 mg / day for the prevention of migraine. In children in clinical studies of Topamax^® gradually canceled within 2-8 weeks. If medically necessary to quickly discontinue Topamax^®It is recommended that the patient be monitored accordingly.

As with any disease, the dosage regimen should be set according to the clinical effect (i.e., the degree of seizure control, no side effects) and take into account the fact that patients with impaired renal function can establish need a longer time.

With topiramate therapy, oligohydrosis (reduced sweating) and anhidrosis can occur. Reduced sweating and hyperthermia (increased body temperature) can occur in children exposed to high ambient temperatures. During therapy with topiramate, it is very important to adequately increase the volume of fluid consumed, which helps reduce the risk of developing nephrolithiasis, as well as the side effects that can occur under exercise or elevated temperatures.

In the treatment of topiramate, there is an increased incidence of mood disorders and depression.

When using antiepileptic drugs, including Topamax^®, increases the risk of suicidal thoughts and suicidal behavior in patients taking these drugs for any of the indications.

In double-blind clinical studies, the incidence of phenomena associated with suicide (suicidal thoughts, suicide attempts, suicide) was 0.5% in patients treated with topiramate (46 people out of 8652), which is about 3 times higher than placebo (0.2%; 8 people out of 4045). One case of suicide was recorded in a double-blind study of bipolar disorder in a patient receiving topiramate.

Thus, it is necessary to monitor the condition of patients in order to identify signs of suicidal thoughts and prescribe appropriate treatment. Patients (and, if necessary, caregivers) should be advised to immediately seek medical attention if they show signs of suicidal thoughts or suicidal behavior.

Some patients, especially those with a predisposition to nephrolithiasis, may have an increased risk of kidney stones and associated symptoms, such as renal colic. To reduce this risk, an adequate increase in fluid intake is needed. Risk factors for nephrolithiasis are nephrolithiasis in history (including family), hypercalciuria, concomitant therapy with other drugs that contribute to the development of nephrolithiasis.

Caution must be exercised in the appointment of the drug Topamax.^® patients with renal insufficiency (QC

In patients with impaired liver function Topamax^® should be used with caution because of the possible reduction in clearance of topiramate.

When using the drug Topamax^® described syndrome, including acute myopia with concomitant secondary angle-closure glaucoma. Symptoms include acute reduction of visual acuity and / or pain in the eye. Ophthalmologic examination may show myopia, flattening of the anterior chamber of the eye, hyperemia (redness) of the eyeball, and increased intraocular pressure. Mydriasis may occur. This syndrome may be accompanied by secretion of fluid, leading to the displacement of the lens and the iris forward with the development of secondary angle-closure glaucoma. Symptoms usually appear 1 month after starting Topamax.^®. Unlike primary open-angle glaucoma, which is rarely seen in patients under 40 years of age, secondary angle-closure glaucoma is observed with the use of topiramate in both adults and children. In the event of a syndrome involving myopia associated with angle-closure glaucoma, treatment includes discontinuation of Topamax.^®as soon as the attending physician considers it possible, and appropriate measures aimed at lowering the intraocular pressure. Usually these measures lead to the normalization of intraocular pressure.

Increased intraocular pressure of any etiology in the absence of adequate treatment can lead to serious complications, including loss of vision.

When using topiramate, hyperchloremic, not associated with anion deficiency, metabolic acidosis may occur (for example, a decrease in plasma bicarbonate concentration below the normal level in the absence of respiratory alkalosis). Such a decrease in serum bicarbonate concentration is a consequence of the inhibitory effect of topiramate on renal carbonic anhydrase. In most cases, a decrease in the concentration of bicarbonates occurs at the beginning of the drug intake, although this effect may occur during any period of treatment with topiramate. The level of reduction is usually mild or moderate (the average value is 4 mmol / l when used in adult patients at a dose of more than 100 mg / day and about 6 mg / kg / day when used in pediatric practice). In rare cases, patients had a decrease in concentration below 10 mmol / l. Some diseases or treatments that predispose to the development of acidosis (for example, kidney disease, severe respiratory diseases, status epilepticus, diarrhea, surgical interventions, ketogenic diet, taking certain medications) can be additional factors that enhance the bicarbonate-reducing effect of topiramate.

In children, chronic metabolic acidosis can lead to stunted growth. The effect of topiramate on growth and possible complications associated with the skeletal system have not been systematically studied in children and adults.

In connection with the foregoing, in the treatment with topiramate it is recommended to conduct the necessary studies, including the determination of the concentration of bicarbonate in serum. If metabolic acidosis occurs and persists, it is recommended to reduce the dose or stop taking Topamax^®.

If against the background of the drug Topamax^® if the patient's body weight decreases, then the question of the advisability of enhanced nutrition should be considered.

Influence on ability to drive motor transport and control mechanisms

Topamax^® acts on the central nervous system and may cause drowsiness, dizziness, blurred vision and other symptoms. These adverse effects can be dangerous for patients driving a car and moving machinery, especially during the period until the patient's reaction to the drug is established. <