Memantine
Memantine: 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 during pregnancy and lactation
- 10. Use in childhood
- 11. In case of impaired renal function
- 12. For violations of 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: Memantin
ATX code: N06DX01
Active ingredient: memantine (memantin)
Manufacturer: OZON, LLC (Russia); VERTEX, JSC (Russia); PHARMZASCHITA SPC, FSUE (Russia)
Description and photo update: 2018-21-11
Prices in pharmacies: from 417 rubles.
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Memantine is a drug used to treat dementia.
Release form and composition
Memantine is produced in the form of film-coated tablets: biconvex; depending on the manufacturer: round, almost white or white, with a line on one side / engraving in the form of a circle (20 mg) / engraving in the form of a triangle (10 mg); or oblong, white (10 mg) and yellow (20 mg) in color, with a risk on each side; in all tablets, the core on a cross section is almost white or white (10 pcs. in blisters, 3 or 9 blisters in a cardboard box; 10, 25, 30 or 50 pcs. in a blister contour packaging, 1-6, 9 or 10 packages in a cardboard box; 15 pcs. in a blister contour packaging, 2, 4 or 6 packages in a cardboard box; 10, 25, 30, 40, 50, 60, 90 or 100 pcs. in cans, 1 can in a cardboard box) …
1 tablet contains:
- active substance: memantine hydrochloride - 10 or 20 mg;
- auxiliary components (depending on the manufacturer): microcrystalline cellulose, colloidal silicon dioxide, magnesium stearate; additionally - pregelatinized starch or lactose monohydrate (milk sugar), croscarmellose sodium, povidone-K25 or calcium hydrogen phosphate dihydrate, talc, hyprolose (hydroxypropyl cellulose);
- film casing (depending on the manufacturer): OPADRAY II 85F19250 Transparent (OPADRY II 85F19250 Clear) [polysorbate 80, talc, polyvinyl alcohol, macrogol 4000 (20 mg) or macrogol (10 mg) (polyethylene glycol)]; or hypromellose, titanium dioxide, additionally - macrogol-4000 or hyprolose (hydroxypropyl cellulose), talc, iron oxide yellow (20 mg yellow).
Pharmacological properties
Pharmacodynamics
Memantine is a derivative of adamantane, an antagonist of N-methyl-D-aspartate (NMDA) -receptors (including in the substantia nigra), which allows it to reduce the excessive stimulating effect on the neostriatum of cortical glutamate neurons, which occurs with insufficient release of dopamine. The substance, regulating the flow of ions, blocks calcium channels, contributes to the normalization of the membrane potential and the efficiency of the process of transmission of nerve impulses.
The drug provides improved cognitive functions and increased daily activity.
Pharmacokinetics
After oral administration, the active substance is rapidly and completely absorbed from the gastrointestinal tract (GIT). The maximum concentration of memantine in blood plasma is observed on average 3–8 hours after administration. The drug is characterized by absolute bioavailability - up to 100%. Food intake does not have any effect on its absorption.
Pharmacokinetics of the drug in the dose range of 10–40 mg is linear. The use of memantine in a daily dose of 20 mg provides an equilibrium plasma concentration of 70–150 ng / ml with significant individual variations. The ratio of the average concentration of the agent in the cerebrospinal fluid to its concentration in the blood plasma when taking a daily dose of 5–30 mg is 0.52. The volume of distribution is approximately 10 l / kg, approximately 45% of the active substance binds to blood plasma proteins. Against the background of normal kidney function, no cumulation of the drug was observed.
About 80% of the circulating substance in the blood is represented by the parent compound. The main metabolites of memantine are: isomeric mixture of 4- and 6-hydroxymemantine, N-3,5-dimethylgludantane and 1-nitroso-3,5-dimethyl-adamantane. None of the above substances exhibit NMDA receptor antagonistic activity. During in vitro experiments, the participation of cytochrome P450 in the metabolism of the drug was not revealed.
The drug is excreted mainly by the kidneys, excretion is carried out in one phase, the half-life is 60-100 hours. The total clearance in healthy volunteers with normal renal function is 170 ml / min / 1.73 m² and is partially achieved by tubular secretion. Renal excretion also includes tubular reabsorption, which is thought to be mediated by cationic transport proteins.
In a study with oral administration of labeled 14 C-memantine, over 84% of the dose was excreted within 20 days, over 99% was eliminated by the kidneys.
When urine is alkalized, the excretion of memantine is reduced (by about 80% at a urine pH of 8).
Indications for use
According to the instructions, Memantine is recommended for the treatment of moderate to severe dementia in Alzheimer's disease.
Contraindications
Absolute:
- severe liver failure (class C according to the Child-Pugh classification);
- age up to 18 years;
- pregnancy and lactation;
- syndrome of glucose-galactose malabsorption, lactase deficiency, lactose intolerance (if the drug contains lactose monohydrate);
- hypersensitivity to any of the constituents of the drug.
Relative (it is necessary to take memantine with extreme caution under close medical supervision):
- heart failure III-IV functional class according to the classification of the New York Association of Cardiologists (NYHA);
- myocardial infarction (history);
- uncontrolled arterial hypertension;
- convulsions (including a history of indications);
- epilepsy, predisposition to its development;
- thyrotoxicosis;
- severe course of urinary tract infections caused by bacteria of the genus Proteus spp.;
- renal tubular acidosis;
- renal failure;
- the presence of factors leading to an increase in urine pH, including sudden dietary changes (for example, switching to a vegetarian diet), frequent use of alkaline gastric buffers;
- liver failure (class A and B according to the Child-Pugh classification);
- a combination with dextromethorphan, ketamine, amantadine (NMDA receptor antagonists), since these drugs and memantine affect the same receptor system, which can aggravate the occurrence of adverse reactions, mainly from the central nervous system (CNS).
Instructions for use of Memantine: method and dosage
Treatment with Memantine is required to begin and continue under the supervision of a physician experienced in the diagnosis and treatment of Alzheimer's dementia. The diagnosis is made based on current recommendations. During the course, the person involved in the constant care of the patient must ensure regular monitoring of the drug intake by the patient.
During the first 3 months of therapy, it is required to systematically assess the tolerance and adequacy of the dose of Memantine. In the future, the clinical efficacy of the drug and its tolerance to patients should be reviewed according to current recommendations.
Maintenance therapy can be carried out for a long time, provided that the drug is well tolerated and a positive therapeutic result, otherwise the drug should be discarded.
Memantine is recommended to be taken orally, once a day, constantly at the same time, regardless of the meal.
The course of treatment should be started with the use of the minimum effective doses, the maximum daily dose is 20 mg.
In order to reduce the risk of adverse events during the first 21 days of the course, the maintenance dose is selected by sequentially increasing it by 5 mg every 7 days. Recommended doses:
- 1-7 days - 5 mg;
- 8-14 days - 10 mg;
- 15-21 days - 15 mg;
- Day 22 and beyond - 20 mg.
The recommended maintenance dose of Memantine is 20 mg per day.
Side effects
- nervous system: often - headache, drowsiness, dizziness, imbalance; infrequently - gait disturbance; rarely - increased fatigue; extremely rare - convulsions, epileptic seizures; with an unknown frequency - muscle hypertonicity, increased intracranial pressure;
- mental disorders: infrequently - sleep disturbance, hyperexcitability, depression, agitation, confusion, hallucinations (mainly in patients with severe dementia of the Alzheimer's type); with an unknown frequency - suicidal thoughts, psychotic reactions;
- infections: infrequently - fungal infections; with an unknown frequency - candidiasis;
- digestive system: often - constipation, infrequently - vomiting, nausea; with an unknown frequency - pancreatitis, hepatitis;
- cardiovascular system: often - increased blood pressure (BP); infrequently - thromboembolism / venous thrombosis, heart failure, heart defects;
- genitourinary system: with an unknown frequency - cystitis, acute renal failure, increased libido;
- respiratory system: often - shortness of breath;
- skin: with an unknown frequency - thrombocytopenic purpura;
- allergic reactions: often - hypersensitivity to the components of the drug; with an unknown frequency - Stevens-Johnson syndrome;
- laboratory parameters: often - increased activity of liver enzymes; with an unknown frequency - pancytopenia, leukopenia (including neutropenia), agranulocytosis, thrombocytopenia.
Overdose
There is limited information on memantine overdose.
In this condition, the administration of adsorbents (activated carbon), gastric lavage, acidification of urine is prescribed, after which symptomatic treatment is carried out. If necessary, a forced diuresis is prescribed. Memantine has no specific antidote.
While taking Memantine at a dose of 200 mg once or at a dose of 105 mg for 3 days, there were no symptoms of overdose or the appearance of diarrhea, weakness, fatigue.
When using the drug at a dose of less than 140 mg or taken in an unknown amount, the following undesirable effects were observed: diarrhea, vomiting, vertigo, dizziness, agitation, anxiety, drowsiness, confusion, hallucinations, gait disturbance.
The most severe overdose was recorded when using memantine at a dose of more than 2000 mg, with the manifestation of such reactions as coma within 10 days, with further agitation and diplopia. In this case, the patient was prescribed symptomatic therapy and plasmapheresis. After carrying out these measures, the patient recovered without further development of complications.
A serious overdose with a single dose of 400 mg of the drug with the occurrence of disorders mainly from the central nervous system is also described: drowsiness, anxiety, stupor, visual hallucinations, psychosis, unconsciousness, seizures. The patient survived and recovered without adverse effects.
special instructions
It is necessary to carefully monitor the condition of patients in the presence of an alkaline reaction of urine or factors that cause an increase in its pH, due to a decrease in the rate of excretion of memantine. These factors may include abrupt changes in diet (including replacing a diet that includes many meat dishes with a vegetarian one) or intensive use of antacid stomach drugs. Renal tubular acidosis (RTA) or a severe form of urinary tract infections caused by Proteus spp. Can also cause an increase in urine pH.
Influence on the ability to drive vehicles and complex mechanisms
In the presence of moderate to severe dementia of the Alzheimer's type, in most cases, the ability to drive vehicles and other complex mechanisms is impaired. Memantine therapy can also lead to a change in the reaction rate, therefore, during the period of taking the drug, it is necessary to refuse to perform any potentially hazardous activities, including working with complex structures and mechanisms (including vehicles).
Application during pregnancy and lactation
Since there are no clinical data on the effect of the drug on the course of pregnancy, its use is contraindicated in pregnant women. According to the results obtained in experimental studies on animals, it can be assumed that memantine can lead to intrauterine growth retardation when used in concentrations identical to therapeutic ones or slightly higher than the latter. The potential risk to humans is unknown.
During preclinical studies of male and female fertility, the negative effect of the drug was not established.
Since there is no data confirming the penetration of the drug into breast milk, if therapy is necessary during lactation, it is required to stop breastfeeding.
Pediatric use
For patients under 18 years of age, the drug is contraindicated, since the safety profile of memantine in this category of patients has not been studied.
With impaired renal function
In patients with severe renal failure, with a creatinine clearance (CC) of 5-29 ml / min, the daily dose of memantine should not exceed 10 mg. In patients with CC 30–49 ml / min, the initial dose should not exceed 10 mg; if therapy is well tolerated, an increase in the dose to 20 mg is allowed, carried out according to the standard selection scheme. Patients with moderate renal impairment (CC 50–80 ml / min), as a rule, are not prescribed dose adjustment.
For violations of liver function
In the presence of severe hepatic impairment (class C according to the Child-Pugh classification), Memantine is contraindicated. In the case of mild to moderate liver dysfunction (class A and B according to the Child-Pugh classification), it is not necessary to change the dosage regimen.
Use in the elderly
In patients over 65 years of age, there is no need for dose adjustment of Memantine.
Drug interactions
- barbiturates, antipsychotics: the effect of these drugs decreases;
- dextromethorphan, ketamine, phenytoin, amantadine: the risk of pharmacotoxic psychosis is aggravated (with these combinations, special care should be taken);
- anticholinergics, dopamine receptor agonists, levodopa drugs: their effect is enhanced;
- antispasmodics, dantrolene, baclofen: there may be an increase or decrease in their effect (the dose must be selected individually);
- quinidine, ranitidine, quinine, cimetidine, procainamide, nicotine: the threat of an increase in the plasma concentration of memantine in the blood increases (due to the use of the cationic transport system of the kidneys by these substances);
- indirect anticoagulants (warfarin): there is a possibility of an increase in the international normalized ratio (INR) (prothrombin time or INR should be monitored);
- antidepressants, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors: it is required to carefully monitor the patient's condition due to the risk of interaction of these drugs;
- hydrochlorothiazide: a decrease in the concentration of this substance in the blood plasma is possible due to an increase in its excretion;
- glibenclamide, donepezil, metformin: no drug interaction was noted (with a single use with memantine);
- galantamine: no effect on the pharmacokinetics of this drug was found;
- isozymes of cytochrome P450 CYP isoforms 1A2, 2D6, 2C9, 2A6, 2E1, 3A; epoxide hydrolase; monooxygenase containing flavin: no inhibitory effect of memantine on these substances has been found in in vitro studies.
Analogs
Memantine analogs are Memantine-Alvogen, Alzeim, Akatinol Memantine, Memantal, Memantine-Richter, Memaneirin, Maruksa, Memantine Sandoz, Memantine Canon, Memorel, Memantinol, Noodzheron, Memikar, Noodzheron-Teva, Memantin-TL, Tingrex.
Terms and conditions of storage
Store in a place protected from moisture and light, out of reach of children, at a temperature not exceeding 25 ° C.
The shelf life is 3 years.
Terms of dispensing from pharmacies
Dispensed by prescription.
Reviews about Memantine
According to the few reviews of Memantine, it is an effective treatment for moderate to severe dementia and cognitive impairment. According to doctors, the drug stops the progress of Alzheimer's disease at the initial stages, and also shows good results when used in pediatric practice for the treatment of intellectual development disorders, and attention deficit hyperactivity disorder (ADHD). Treatment is recommended, especially at the beginning of the course, under constant supervision.
In some reviews, patients, however, note the lack of effect from taking Memantine. The most commonly reported adverse reactions during therapy are sleep disorders, loss of appetite, anxiety, agitation, and irritability in elderly patients. There are references to severe disorders such as the onset of delirium-type psychotic symptoms. The disadvantages of the drug are also attributed to its high cost.
Memantine price in pharmacies
The average price for Memantine can be approximately:
- tablets 10 mg: 30 pcs. - 600 rubles, 60 pcs. - 1160 rubles, 90 pcs. - 1700 rubles;
- tablets 20 mg: 30 pcs. - 1580 rubles, 60 pcs. - 3060 rubles, 90 pcs. - 4190 rubles.
Memantine: prices in online pharmacies
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Anna Kozlova Medical journalist About the author
Education: Rostov State Medical University, 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!
