Lamitor

Lamitor is an effective anticonvulsant used in various convulsive syndromes.

Indications Lamitor

Lamitor is indicated for both monotherapy and combined treatment courses for adults and children aged 12+ for the following disorders:

• simple or complex partial seizures;
• secondary or primary form of generalized tonic-clonic seizures;
• simple and complex absences;
• myoclonic seizures;
• seizures that are resistant to other anticonvulsants.

In addition, the medicine can be used as an adjuvant for children aged 2-12 years.

Release form

Available in tablets of 25, 50 or 100 mg. One blister contains 10 tablets. One pack contains 3 or 5 blister strips.

Pharmacodynamics

Lamotrigine is an effective blocker of voltage-dependent sodium channels located in presynaptic neuronal membranes. It eliminates the excess of released 2-aminopentanedioic acid (a neurotransmitter involved in the development of epileptic seizures) and the associated propagation of transmitted impulses.

Pharmacokinetics

Lamotrigine is absorbed from the intestines quite quickly and is almost not involved in the presystemic process of metabolism of the so-called "first pass". The substance reaches its peak concentration in the plasma approximately 2.5 hours after taking the drug.

The peak concentration period is prolonged if the drug is taken with food, but the absorption rate remains the same. Significant interindividual variations in peak equilibrium concentration are possible, but such variations are quite rare for each individual patient. The plasma protein binding index is about 55%. The distribution volume is 0.92-1.22 l/kg.

The enzyme UDP-GT is involved in metabolism. Depending on the dosage, lamotrigine may slightly increase its own metabolism. The equilibrium coefficient of clearance of the active substance in adults is 39±14 ml/min (average value).

Metabolized to glucuronides, which are then excreted primarily in the urine (less than 10% of the substance is excreted unchanged). Another 2% is excreted in the feces.

The half-life (in adults, 24-35 hours on average) and the clearance rate are independent of dosage. The clearance rate of the active substance is reduced by 32% in patients with constitutional hyperbilirubinemia, but does not exceed the standard values. The half-life of lamotrigine is strongly affected by drugs taken in combination with Lamitor.

The active substance is excreted in breast milk (the concentration is 40-60% of the plasma levels). Sometimes, in infants, plasma concentration levels reached therapeutic levels.

The clearance rates of the active ingredient in children (according to weight) exceed the similar level in adults. The highest coefficient is observed in children under 5 years of age. The half-life is shorter than in adult patients. The average rate is 7 hours (in case of combination with drugs inducing glucurone) and can increase to 45-50 hours (in case of combination with valproates).

Dosing and administration

Initially, the dosage of the drug for children 12+, as well as adults (not taking sodium valproate, but taking other anticonvulsants that induce isoenzymes) is 50 mg once (per day) - the first 2 weeks, and then 100 mg 2 times (per day) for the next 2 weeks. After this, the dosage should be increased to 200-400 mg (twice a day).

Initially, the dosage of the drug for patients taking sodium valproate, combined with other anticonvulsants that induce isoenzymes, is 25 mg every day for 2 weeks, and then 25 mg daily for the next 2 weeks. Then the dosage is increased until the optimal therapeutic effect is achieved. The maintenance dosage is 100-200 mg (in 1 or 2 doses).

The initial dosage for patients aged 2-12 years (with Lamitor monotherapy) is 2 mg/kg twice a day (2-week treatment), and then 5 mg/kg twice a day for another 2 weeks. The maintenance dose is 5-15 mg/kg twice a day.

The initial dosage of the drug for children (combination course of treatment) is 0.2 mg/kg daily for 2 weeks, and then 0.5 mg/kg daily for the next 2 weeks. Then the dosage is increased until the optimal therapeutic effect is achieved. The maintenance dose is 1-5 mg/kg (1-2 times per day).

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Use Lamitor during pregnancy

Prescribing the drug during pregnancy is prohibited (except in cases where the possible benefit of treatment outweighs the potential risk to the child).

Contraindications

Among the contraindications:

• severe liver dysfunction;
• lactation period;
• age under 3 years;
• individual intolerance to lamotrigine or other components of the drug.

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Side effects Lamitor

Side effects that occur when taking the drug in monotherapy:

• CNS organs: headaches with dizziness, sleep disorders or drowsiness, as well as increased fatigue;
• Digestive system: nausea;
• Allergy: measles-like skin rash (2%), which is usually observed in the first month after the start of the course of treatment and disappears after discontinuation of the drug. Rarely, malignant exudative erythema, Lyell's syndrome or Quincke's edema may develop.

Side effects when taking Lamitor as an adjuvant treatment during treatment with standard antiepileptic drugs:

• CNS organs: in addition to the above – aggressiveness and irritability, imbalance, confusion and tremor;
• organs of vision: visual acuity disorder, as well as diplopia;
• organs of the hematopoietic system: neutro- and leukopenia;

Digestive system: dyspeptic symptoms and vomiting with nausea.

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Overdose

Signs of overdose include: in the case of a single dose that exceeds the maximum permissible limit by 10-20 times, ataxia, impaired consciousness, nystagmus, and a comatose state may develop.

To eliminate symptoms, hospitalization is required with supportive treatment depending on the clinical picture.

Interactions with other drugs

As a result of combination with drugs that stimulate the glucuronidation process (phenytoin or carbamazepine), the average half-life period is reduced (to approximately 14 hours). When combined with valproates, this indicator increases to 70 hours.

Valproates have a powerful inhibitory effect on the process of glucuronidation of the active substance of Lamitor.

Drugs such as phenytoin, carbamazepine, as well as phenobarbital and primidone, as well as ethinyloestradiol/levonorgestrel and rifampicin stimulate the process of glucuronidation of the substance lamotrigine.

Valproate, which inhibits the process of glucuronidation of lamotrigine, is capable of slowing down its metabolism and also prolonging the average half-life by almost 2 times.

Some of the above-mentioned antiepileptic drugs (for example, phenobarbital with phenytoin, as well as carbamazepine with primidone), which have a stimulating effect on metabolizing liver enzymes, accelerate the processes of glucuronidation and metabolism of lamotrigine.

When carbamazepine was combined with lamotrigine, adverse reactions such as ataxia, nausea, and loss of visual acuity, as well as dizziness and diplopia, were observed. These manifestations usually disappeared after decreasing the dosage of carbamazepine.

Alanzapine at a dosage of 15 mg reduces the peak concentration and AUC values by 20% and 24% on average, respectively. However, such changes generally do not affect the clinical picture of treatment.

Inhibition of lamotrigine by drugs such as fluoxetine, amitriptyline, clonazepam, haloperidol, bupropion, or lorazepam has little effect on the formation of the primary breakdown product of lamotrigine, 2-N-glucuronide.

When using combined oral contraceptives (containing 30 mcg of ethinyloestradiol and 150 mcg of levonorgestrel), the lamotrigine clearance coefficient increases by approximately 2 times (after oral administration), resulting in a decrease in the AUC and peak concentration of lamotrigine by 52% and 39%, respectively (on average).

When combined with lamotrigine, a slight increase in the clearance rate of levonorgestrel is observed, resulting in a 19% and 12% decrease in its AUC and peak concentration, respectively.

Rifampicin increases the clearance rate of lamotrigine and shortens its half-life because this drug stimulates the activity of liver enzymes that carry out the glucuronidation process. Patients taking rifampicin as a concomitant drug should be prescribed a special regimen for taking lamotrigine - in accordance with the regimen prescribed when combining lamotrigine with drugs that stimulate the glucuronidation process.

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Storage conditions

The medicine must be kept in a place protected from moisture, sunlight, and children. Temperature conditions – no more than 30°C.

Shelf life

Lamitor is permitted to be used for 3 years from the date of manufacture of the drug.

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