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Therapeutic Category
- ANTIPARKINSONSIM DRUGS
- Pharmaceutical Form : Film coated tablets
- Composition : Memantine HCl 10 mg /Tab
- Active Substance : Memantine HCl
DESCRIPTION
Persistent activation of central nervous system N-methyl-D-aspartate (NMDA) receptors 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 uncompetitive (open-channel) NMDA receptor antagonist which binds preferentially to the NMDA receptor-operated cation channels. There is no evidence that memantine prevents or slows neurodegeneration in patients with Alzheimer’s disease.
Memantine showed low to negligible affinity for GABA, benzodiazepine, dopamine, adrenergic, histamine and glycine receptors and for voltage-dependent Ca2+, Na+ or K+ channels.
Following oral administration memantine is highly absorbed with peak concentrations reached in about 3-7 hours, Memantine undergoes partial hepatic metabolism. The hepatic microsomal CYP450 enzyme system does not play a significant role in the metabolism of memantine. It is excreted predominantly in the urine, unchanged, and has a terminal elimination half life of about 60-80 hours. Food has no effect on the absorption of memantine.
INDICATIONS AND USAGE
MEMA (memantine hydrochloride) is indicated for the treatment of moderate to severe dementia of the Alzheimer’s type.
CONTRAINDICATIONS
MEMA (memantine hydrochloride) is contraindicated in patients with known hypersensitivity to memantine hydrochloride.
WARNINGS
Neurological Conditions:
Seizures: MEMA has not been systematically evaluated in patients with a seizure disorder.
In clinical trials of MEMA, seizures occurred in 0.2% of patients treated with MEMA and 0.5% of patients treated with placebo.
Genitourinary Conditions: Conditions that raise urine pH may decrease the urinary elimination of memantine resulting in increased plasma levels of memantine.
Hepatic Impairment: MEMA should be administered with caution to patients with severe hepatic impairment.
Renal Impairment: A dosage reduction is recommended in patients with severe renal impairment.
Pregnancy Category B:
Memantine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Nursing Mothers:
It is not known whether memantine is excreted in human breast milk. Because many drugs are excreted in human milk, caution should be exercised when memantine is administered to a nursing mother.
INDICATIONS
MEMA (memantine hydrochloride) is indicated for the treatment of moderate to severe dementia of the Alzheimer’s type.
DRUG INTERACTIONS:
– N-methyl-D-aspartate (NMDA) antagonists: The combined use of MEMA with other NMDA antagonists (amantadine, ketamine, and dextromethorphan) has not been systematically evaluated and such use should be approached with caution.
– Acetylcholinesterase (ACHE) inhibitors: Co-administration of MEMA with the AChE inhibitor donepezil HCl did not affect the pharmacokinetics of either compound. In a 24-week controlled clinical study in patients with moderate to severe Alzheimer’s disease, the adverse event profile observed with a combination of memantine and donepezil was similar to that of donepezil alone.
– Drugs eliminated via renal mechanisms: Because memantine is eliminated in part by tubular secretion, co-administration of drugs that use the same renal cationic system, including hydrochlorothiazide (HCTZ), triamterene (TA), metformin, cimetidine, ranitidine, quinidine, and nicotine, could potentially result in altered plasma levels of both agents.
– Drugs that make the urine alkaline: The clearance of memantine was reduced by about 80% under alkaline urine conditions at pH 8. Therefore, alterations of urine pH towards the alkaline condition may lead to an accumulation of the drug with a possible increase in adverse effects
DOSAGE:
First weak: 5 mg once daily
Second weak: 10mg (5 mg twice a day)
Third weak: 15 mg (5 mg and 10 mg as separate doses)
Forth weak: 20 mg (10 mg twice a day)
–patients with severe renal impairment: A target dose of 5 mg BID is recommended.
– MEMA can be taken with or without food.
OVER DOSAGE
Signs and symptoms associated with memantine overdosage in clinical trials and from worldwide marketing experience include agitation, confusion, ECG changes, loss of consciousness, psychosis, restlessness, slowed movement, somnolence, stupor, unsteady gait, visual hallucinations, vertigo, vomiting, and weakness.
OVERDOSAGE MANAGEMENT:
As in any cases of overdose, general supportive measures should be utilized, and treatment should be symptomatic. Elimination of memantine can be enhanced by acidification of urine.
HOW SHOULD I STORE MEMA?
Store MEMA at room temperature, under 30 ºC. Away from light and moisture.
Keep MEMA out of the reach of children.
PACKING : Box of 30 coated tablets.