Catena (Gabapentin) 400 mg, 50 pcs.

Anticonvulsant drug. Gabapentin is similar in structure to the neurotransmitter GABA (GABA), but its mechanism of action is different from some other similar drugs that interact with GABA receptors, including valproate, barbiturates, benzodiazepines, GABA transaminase inhibitors, GABA uptake inhibitors, GABA agonists and GABA forms: it does not have GABA-ergic properties and does not affect the uptake and metabolism of GABA.

The results of preliminary studies showed that gabapentin binds to the α ₂ -δ subunit of voltage-dependent calcium channels and inhibits the flow of calcium ions, which plays an important role in the occurrence of neuropathic pain.

Other mechanisms involved in the action of gabapentin in neuropathic pain are: a decrease in glutamate-dependent death of neurons, an increase in GABA synthesis, and suppression of the release of neurotransmitters of the monoamine group.

Clinically significant concentrations of gabapentin do not bind to receptors of other common drugs or neurotransmitters, including GABA _A , GABA _B , benzodiazepine, glutamate, glycine or N-methyl-D-aspartate receptors.

Unlike phenytoin and carbamazepine, gabapentin does not interact with sodium channels.

• treatment of neuropathic pain in adults (18 years and older). Efficacy and safety in patients under the age of 18 have not been established;
• monotherapy of partial seizures in epilepsy with and without secondary generalization in adults and children over the age of 12 years. The effectiveness and safety of monotherapy in children under 12 years of age have not been established;
• as an additional tool in the treatment of partial seizures in epilepsy with and without secondary generalization in adults and children 3 years of age and older. The safety and effectiveness of additional gabapentin therapy in children under the age of 3 years have not been established.

There are no data on the safety and effectiveness of the drug during pregnancy, therefore, the use of gabapentin during pregnancy is possible only if the intended benefit to the mother justifies the possible risk to the fetus.

Gabapentin is excreted in breast milk, so breast-feeding should be abandoned during treatment.

Use in children

Contraindicated in children under 3 years of age.

• children under 3 years old;
• hypersensitivity to gabapentin or auxiliary components of the drug.

With caution, a drug should be prescribed for renal failure.

Use for impaired renal function

With caution, the drug should be prescribed for renal failure.

For hemodialysis patients who have not previously taken gabapentin, the drug is recommended to be prescribed in a saturating dose of 300-400 mg, and then 200-300 mg every 4 hours of hemodialysis is used.

From the cardiovascular system: symptoms of vasodilation, hypertension.

From the digestive system: dyspepsia, flatulence, nausea, vomiting, abdominal pain, constipation, diarrhea, dry mouth or throat, anorexia, gingivitis, dental diseases, increased appetite, increased activity of hepatic transaminases.

From the musculoskeletal system: myalgia, arthralgia, back pain, increased fragility of bones.

From the nervous system: drowsiness, dizziness, ataxia, amnesia, confusion, impaired coordination, increased fatigue, impaired thinking, tremors, hypesthesia, depression, dysarthria, insomnia, nervousness, nystagmus, increased, weakened or absent reflexes, asthenia, anxiety, hostility, hyperkinesia, emotional lability.

From the respiratory system: pharyngitis, rhinitis, shortness of breath, cough, pneumonia, bronchitis, respiratory infections.

From the genitourinary system: urinary tract infections, impotence.

From the sensory organs: impaired vision, amblyopia, diplopia.

From the hemopoietic organs: leukopenia, purpura (most often it is described as bruising that occurred during physical trauma).

Allergic reactions: skin rash, itching, acne.

Other: fever, viral infection, weight gain, pain of various localization, peripheral edema, swelling of the face, headache.

Post-Registration Application Experience

Cases of sudden unexplained death have been reported, the relationship of which with the treatment with gabapentin has not been established.

Other adverse events: acute renal failure, allergic reactions, including urticaria, alopecia, angioedema, generalized edema; fluctuations in the blood glucose concentration in patients with diabetes mellitus, chest pain, an increase in the volume of the mammary glands, gynecomastia, an increase in liver function indices, erythema multiforme exudative (including Stevens-Johnson syndrome), hallucinations, motor disorders, such as choreoathetosis , dyskinesia and dystonia, palpitations, pancreatitis, tinnitus, thrombocytopenia, urinary incontinence, myoclonus.

With the simultaneous use of gabapentin and morphine, when morphine was taken 2 hours before gabapentin, an average AUC of gabapentin was increased by 44% compared with gabapentin monotherapy, which was associated with an increase in the pain threshold (cold pressor test). The clinical significance of this change has not been established; the pharmacokinetic characteristics of morphine have not changed. Side effects of morphine when taken together with gabapentin did not differ from those when taking morphine in conjunction with placebo.

The interaction between gabapentin and phenobarbital, phenytoin, valproic acid and carbamazepine was not observed. The pharmacokinetics of gabapentin in equilibrium are the same in healthy people and patients receiving other anticonvulsants.

The simultaneous use of gabapentin with oral contraceptives containing norethisterone and / or ethinyl estradiol was not accompanied by changes in the pharmacokinetics of both components.

The simultaneous use of gabapentin with antacids containing aluminum and magnesium is accompanied by a decrease in the bioavailability of gabapentin by about 20%. Gabapentin is recommended to be taken approximately 2 hours after taking antacid.

Probenecid does not affect renal excretion of gabapentin.

A slight decrease in renal excretion of gabapentin while taking cimetidine probably does not have clinical significance.

The drug Catena ^{® is}  prescribed inside, regardless of the meal. If it is necessary to reduce the dose, cancel the drug or replace it with an alternative agent, this should be done gradually over a period of at least one week.

Neuropathic pain in adults

The initial daily dose is 900 mg (in 3 divided doses); if necessary, depending on the effect, the dose is gradually increased to a maximum of 3.6 g / day. Treatment can begin immediately with a dose of 900 mg / day (300 mg 3 times / day) or during the first 3 days the dose can be gradually increased to 900 mg per day according to the following scheme:

• 1st day: 300 mg 1 time / day;
• 2nd day: 300 mg 2 times / day;
• 3rd day: 300 mg 3 times / day.

Partial cramps

Adults and children over 12 years old

The effective dose is from 900 mg to 3.6 g per day. Therapy can be started with a dose of 300 mg 3 times / day on the 1st day or gradually increased to 900 mg according to the scheme described above (see the section Neuropathic pain in adults). Subsequently, the dose can be increased to a maximum of 3.6 g / day in 3 divided doses. The maximum interval between doses when taking the drug three times should not exceed 12 hours in order to avoid the resumption of seizures. Good tolerability of the drug in doses up to 4.8 g / day was noted.

Children aged 3-12

The initial dose of the drug varies from 10 to 15 mg / kg / day, which is prescribed in equal doses 3 times / day and increased to effective within about 3 days. The effective dose of gabapentin in children aged 5 years and older is 25-35 mg / kg / day in equal doses in 3 divided doses. The effective dose of gabapentin in children aged 3 to 5 years is 40 mg / kg / day in equal doses in 3 divided doses. Good tolerability of the drug in doses up to 50 mg / kg / day with prolonged use was noted. The maximum interval between doses of the drug should not exceed 12 hours in order to avoid the resumption of seizures.

There is no need to control the concentration of gabapentin in plasma. The Katena ^® preparation  can be used in combination with other anticonvulsants without taking into account changes in its plasma concentration or the concentration of other anticonvulsants in serum.

Dose selection for renal failure

For patients with renal failure, a dose reduction of gabapentin is recommended according to the table.

* The daily dose should be prescribed in 3 divided doses.

** Prescribe 300 mg every other day.

For hemodialysis patients who have not previously taken gabapentin, the drug is recommended to be prescribed in a saturating dose of 300-400 mg, and then 200-300 mg every 4 hours of hemodialysis is used.

Symptoms:  dizziness, double vision, speech impairment, drowsiness, lethargy and diarrhea.

Treatment:  gastric lavage, intake of activated carbon, symptomatic therapy. Patients with severe renal failure may be shown hemodialysis.

Suction

The bioavailability of gabapentin is not proportional to the dose; with increasing doses, it decreases. After ingestion of C _max,  gabapentin in plasma is achieved after 2-3 hours. The absolute bioavailability of gabapentin in capsules is about 60%. Food, including high in fat, does not affect pharmacokinetics. The elimination of gabapentin from plasma is best described using a linear model.

Distribution

Pharmacokinetics does not change with repeated use. C _ss  in plasma can be determined based on the results of a single dose of the drug. Gabapentin practically does not bind to plasma proteins (d - 57.7 l.

Metabolism

No signs of metabolism in humans.

The drug does not induce oxidative liver enzymes with a mixed function involved in the metabolism of drugs.

Breeding

T _{1/2 of}  plasma is dose-independent and averages 5-7 hours. It is excreted exclusively by the kidneys unchanged.

Pharmacokinetics in special clinical cases

The clearance of gabapentin from plasma is reduced in the elderly and patients with impaired renal function. Excretion rate constant, plasma clearance, and renal clearance are directly proportional to creatinine clearance. Gabapentin is removed from plasma by hemodialysis. In patients with impaired renal function and patients receiving hemodialysis treatment, a dose adjustment is recommended.

It has been established that plasma concentrations of gabapentin in children aged 4 to 12 years are generally similar to those in adults.

With joint therapy with morphine, an increase in the concentration of gabapentin may occur in patients. At the same time, it is necessary to carefully monitor patients for the development of such a sign of central nervous system depression as drowsiness. In this case, the dose of gabapentin or morphine should be adequately reduced.

With the combined use of gabapentin and other anticonvulsants, false-positive results were recorded in the determination of protein in urine using Ames N-Multistix SG ^® test strips . To determine the protein in the urine, it is recommended to use a more specific method of precipitation with sulfosalicylic acid.

Influence on the ability to drive vehicles and control mechanisms

During the treatment period, it is necessary to refrain from driving vehicles and engaging in potentially dangerous activities that require an increased concentration of attention and speed of psychomotor reactions.