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Memantine: profile and news
Memantine Shows Promise In Treating Alzheimer's 07 Mar 2006 Drug May Help Patients With Severe Alzheimer's 07 Mar 2006 Healthy lifestyle lowers risk of dementia caused by white matter ... 07 Mar 2006 Alzheimer’s Disease Questions and Answers Feb 28, 2006 Update on major health topics Feb 19, 2006 Neurobiological Technologies Inc. Receives $1.4 Million Quarterly ... Feb 1, 2006 Alzheimer's drug maker gets $1.37M payment Feb 1, 2006 Replidyne and Forest Laboratories Announce FDA Acceptance for ... Feb 23, 2006 Improving Alzheimer’s treatment Feb 6, 2006 Immune to Fear Feb 14, 2006 Neurobiological Technologies Reports Fiscal 2006 Second Quarter ... Feb 9, 2006 Evotec completes Phase I component for Alzheimer’s drug Feb 8, 2006 Alzheimer's Drugs Offer Modest Improvements, Equal Effectiveness Feb 5, 2006 Trapeze expands in Europe Feb 1, 2006 (PRN) - Salesforce.com Delivers Japanese AppExchange, Further ... Feb 1, 2006 Other information Indication For the treatment of moderate to severe dementia of the Alzheimer's type. Pharmacology Memantine is an orally active NMDA receptor antagonist indicated for the treatment of moderate to severe dementia of the Alzheimer's type. 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. Mechanism Of Action Memantine exerts its action through uncompetitive NMDA receptor antagonism, binding preferentially to the NMDA receptor-operated cation channels. Prolonged increased levels of glutamate in the brain of demented patients are sufficient to counter the voltage-dependent block of NMDA receptors by Mg2+ ions and allow continuous influx of Ca2+ ions into cells and ultimately neuronal degeneration. Studies suggest that memantine binds more effectively than Mg2+ ions at the NMDA receptor, and thereby effectively blocks this prolonged influx of Ca2+ ions through the NMDA channel whilst preserving the transient physiological activation of the channels by higher concentrations of synaptically released glutamate. Thus memantine protects against chronically elevated concentrations of glutamate. Drug Category Dopamine Agents; Antiparkinson Agents; Antidyskinetics; Excitatory Amino Acid Antagonists; Central Nervous System Agents; ATC:N06DX01 Brand Names/Synonyms CHEMBANK733; D 145; D-145; DMAA; DRG 0267; DRG-0267; Ebixa; M183; M9292; MEMANTINE HYDROCHLORIDE; Memantina; Memantina [Inn-Spanish]; Memantine; Memantine Hydrochloride; Memantine [Inn]; Memantinum [Inn-Latin]; Namenda Dosage Forms TABLET Absorption Well absorbed orally, peak plasma concentrations are reached in 3-7 hours Interactions -->Interactions for Memantine: N-methyl-D-aspartate (NMDA) antagonists: The combined use of NAMENDA with other NMDA antagonists (amantadine, ketamine, and dextromethorphan) has not been systematically evaluated and such use should be approached with caution. Effects of NAMENDA on substrates of microsomal enzymes: In vitro studies conducted with marker substrates of CYP450 enzymes (CYP1A2, -2A6, -2C9, -2D6, -2E1, -3A4) showed minimal inhibition of these enzymes by memantine. In addition, in vitro studies indicate that at concentrations exceeding those associated with efficacy, memantine does not induce the cytochrome P450 isozymes CYP1A2, CYP2C9, CYP2E1 and CYP3A4/5. No pharmacokinetic interactions with drugs metabolized by these enzymes are expected. Effects of inhibitors and/or substrates of microsomal enzymes on NAMENDA: Memantine is predominantly renally eliminated, and drugs that are substrates and/or inhibitors of the CYP450 system are not expected to alter the metabolism of memantine. Acetylcholinesterase (AChE) inhibitors: Coadministration of NAMENDA 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 Alzheimerís 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, coadministration 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. However, coadministration of NAMENDA and HCTZ/TA did not affect the bioavailability of either memantine or TA, and the bioavailability of HCTZ decreased by 20%. In addition, coadministration of memantine with the antihyperglycemic drug GlucovanceÒ (glyburide and metformin HCl) did not affect the pharmacokinetics of memantine, metformin and glyburide. Furthermore, memantine did not modify the serum glucose lowering effect of GlucovanceÒ. 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. Urine pH is altered by diet, drugs (e.g. carbonic anhydrase inhibitors, sodium bicarbonate) and clinical state of the patient (e.g. renal tubular acidosis or severe infections of the urinary tract). Hence, memantine should be used with caution under these conditions. Chemical IUPAC Name 3,5-dimethyladamantan-1-amine Chemical Formula C12H21N Half Life 60-80 hours Drug Type Approved Drug # Accession No APRD00221 CAS Registry Number 19982-08-2 |
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