Memantine hydrochloride is used for the treatment of patients with moderate to severe Alzheimer's disease.
Persistent activation of N-methyl-D-aspartate (NMDA) receptors in Central Nervous System by the excitatory amino acid glutamate has been hypothesized to contribute to the symptomatology of Alzheimer's disease. Memantine is postulated to exert its therapeutic effect through its action as a low to moderate affinity as an uncompetitive (open-channel) NMDA receptor antagonist which binds preferentially to the NMDA receptor-operated cation channels.
Memantine is well absorbed after oral administration and has linear pharmacokinetics over the therapeutic dose range. It is excreted predominantly unchanged in the urine and has a terminal elimination half-life of about 60-80 hours. Following oral administration, Memantine is highly absorbed with peak concentrtions reached in about 3-7 hours. Food has no effect on the absorption of Memantine. The mean volume of distribution of Memantine is 9-11 L/kg and the plasma protein binding is low (45%). emantine undergoes partial hepatic metabolism. About 48% of administered drug is excreted unchanged in urine; the remainder is converted primarily to three polar metabolites which possess minimal NMDA receptor antagonistic activity: the N-glucuronide conjugate, 6-hydroxy Memantine and 1-nitroso-deaminated Memantine. A total of 74% of the administered dose is excreted as the sum of the parent drug and the N-glucuronide conjugate. The hepatic microsomal CYP-450 enzyme system does not play a significant role in the metabolism of Memantine.
Moderate to severe dementia in Alzheimer’s disease BY MOUTH Adult: Initially 5 mg once daily, then increased in steps of 5 mg every week; usual maintenance 20 mg daily; maximum 20 mg per day
Due to the pharmacological effects and mechanism of action of memantine suggests that the effects of L-dopa, dopaminergic agonists, and anticholinergics may be enhanced by concomitant treatment with NMDA-antagonists such as memantine. The effects of barbiturates and neuroleptics may be reduced. Concomitant administration of mematine with the antispasmodic agents, dantrolene or baclofen, can modify their effects and a dosage adjustment may be necessary. Memantine should not be used with amantadine, ketamine, dextromethorphan, phenytoin, cimetidine, ranitidine, procainamide, quinidine, quinidine, quinine & nicotine.
Epilepsy . history of convulsions . risk factors for epilepsy
Common or very common Balance disorders . constipation . dizziness . drowsiness . dyspnoea . headache . Hypertension Uncommon Abnormal gait . confusion . fatigue . hallucinations . heart failure . thrombosis . vomiting Very rare Seizures Frequency not known Depression . hepatitis . pancreatitis . psychosis . suicidal ideation
PREGNANCY Manufacturer advises avoid unless essential?no information available. BREAST FEEDING Manufacturer advises avoid?no information available.
Store in a cool and dry place, protected from light. Keep this medication out of reach of children.
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