Memantine Review Article
Memantin makes part of a class of medications called NDMA receptor antagonist which works by decreasing the abnormal activity of the brain and it is used to treat the symptoms of Alzheimer's disease. It can help people with Alzheimer's disease to perform daily activities easily and think clearly, but taking this drug will not stop the progression of the disease. This medicine may cause side effects such as: dizziness, confusion, extreme tiredness, headache, sleepiness, pain anywhere in the body. If you develop any of these side effects you must inform your doctor immediately.
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Memantine has been associated with a moderate decrease in clinical deterioration in Alzheimer's disease. A systematic review of randomised controlled trials found that memantine has a small positive effect on cognition, mood, behaviour, and the ability to perform daily activities in moderate to severe Alzheimer's disease, but an unknown effect in mild to moderate disease.
Memantine is also being tested for generalized anxiety disorder, epilepsy, opioid dependence, systemic lupus erythematosus, depression, obsessive compulsive disorder, Tourette Syndrome, problem gambling, attention-deficit hyperactivity disorder (ADHD), glaucoma, tinnitus, neuropathic pain including Complex Regional Pain Syndrome, pervasive developmental disorders, HIV associated dementia, nystagmus,and multiple sclerosis.
Memantine is generally well-tolerated. Common adverse drug reactions (??1% of patients) include: confusion, dizziness, drowsiness, headache, insomnia, agitation, and/or hallucinations. Less common adverse effects include: vomiting, anxiety, hypertonia, cystitis, and increased libido. On the other hand; it has been reported to induce reversible neurological impairment in multiple sclerosis, that led to stop an ongoing clinical trial. Though exceedingly rare, extrapyramidal side effects (such as dystonic reactions, etc) may occur, particularly in the younger population.
Glutamatergic (NMDA receptor)
A dysfunction of glutamatergic neurotransmission, manifested as neuronal excitotoxicity, is hypothesized to be involved in the etiology of Alzheimer's disease. Targeting the glutamatergic system, specifically NMDA receptors, offers a novel approach to treatment in view of the limited efficacy of existing drugs targeting the cholinergic system.
Memantine is a low-affinity voltage-dependent uncompetitive antagonist at glutamatergic NMDA receptors. By binding to the NMDA receptor with a higher affinity than Mg2+ ions, memantine is able to inhibit the prolonged influx of Ca2+ ions which forms the basis of neuronal excitotoxicity. The low affinity and rapid off-rate kinetics of memantine at the level of the NMDA receptor-channel, however, preserves the physiological function of the receptor as it can still be activated by the relatively high concentrations of glutamate released following depolarization of the presynaptic neuron. The interaction of memantine with NMDA receptors plays a major role in the symptomatic improvement the drug produces in Alzheimer's disease. Moreover, there is no evidence as yet that the ability of memantine to protect against NMDA receptor-mediated excitotoxicity has a disease modifying effect in Alzheimer's, although this has been suggested in animal models.
Serotonergic (5-HT3 receptor)
Memantine acts as a non-competitive antagonist at the 5HT3 receptor, with a potency similar to that for the NMDA receptor. The clinical significance of this serotonergic activity in the treatment of Alzheimer's disease is unknown.
Cholinergic (Nicotinic acetylcholine receptor)
Memantine acts as a non-competitive antagonist at different neuronal nicotinic acetylcholine receptors (nAChRs) at potencies possibly similar to the NMDA and 5-HT3 receptors, but this is difficult to ascertain with accuracy because of the rapid desensitization of nAChR responses in these experiments. Notably, Memantine is an antagonist at alpha-7 nAChR, which may contribute to initial worsening of cognitive function during early Memantine treatment. alpha-7 nAChR upregulates quickly in response to antagonism, which could explain the cognitive-enhancing effects of chronic memantine treatment. It has been shown that the number of nicotinic receptors in the brain are reduced in Alzheimer's disease, even in the absence of a general decrease in the number of neurons, and nicotinic receptor agonists are viewed as interesting targets for anti-Alzheimer drugs.
Dopaminergic (D2 receptor)
Memantine acts as an agonist at the dopamine D2 receptor.
Memantine was first synthesized and patented by Eli Lilly and Company in 1968 (as cited in the Merck Index), and then developed by Merz in collaboration with Neurobiological Technologies, Inc. and licensed to Forest for the U.S. and Lundbeck for selected European and international markets.
NAME OF THE MEDICINAL PRODUCT
Ebixa 10 mg film-coated tablets
QUALITATIVE AND QUANTITATIVE COMPOSITION
Each film-coated tablet contains 10 mg of memantine hydrochloride equivalent to 8.31 mg memantine.
The medication may take as long as 12 weeks to begin working and the type and length of response as well as the time it takes for patients to respond to this medication will vary from person to person.
Will this medication cure Alzheimer's disease?
Ebixa is not a cure for Alzheimer's disease as it does not affect the underlying degenerative process of the disease.
Who should take this medication?
The medication is for people who have been diagnosed with moderate to advanced Alzheimer's disease.
How do you obtain this medication?
Ebixa can only be obtained with a prescription from a doctor after a diagnosis of Alzheimer's disease has been made.
A reminder: This medication has been prescribed only for you or for the person you are caring for. It must not be given to anybody else or used for any other illness.
Important! Things to know before taking this medication
Before taking Ebixa, give the doctor the following information:
all medical conditions, including heart problems, uncontrolled hypertension (high blood pressure), history of seizures or kidney disease
any medications, including prescriptions and non-prescriptions which you are currently taking or have
taken within the last 14 days
if you ever had an allergic reaction to any medication
if you have a urinary tract infection, kidney problems, or if you have recently changed your diet substantially (e.g., from a diet including meat to a vegetarian diet)
How do you take this medication?
Take the medication only as instructed by the doctor.
Usually the doctor will prescribe 20 mg per day, which can be taken as two separate doses of 10 mg.
To reduce the risk of undesirable reactions, the 20 mg dose will be achieved gradually, depending on the person’s response and tolerability.
The minimum recommended interval between increasing the dose is one week, as shown in the following table: 10 mg tablet Morning Afternoon
Week 1 ½ tablet None
Week 2 ½ tablet ½ tablet
Week 3 1 tablet ½ tablet
Week 4 and beyond 1 tablet 1 tablet
Do not change the dose of the medication, unless the doctor instructs you to do so.
The medication can be taken with or without food.
Swallow the tablets whole, with some water.Do not chew tablets.
Stop taking the medication and contact the doctor immediately if you experience an allergic reaction or any severe reaction.
Continue to take the medication as long as directed by the doctor and you do not experience any unacceptable reactions. The doctor should monitor and assess the treatment regularly.
If you miss a dose, do not take the missed tablet, but take the next dose when it is due.
What are the possible side effects?
Along with its beneficial effect, Ebixa may cause some undesirable reactions. These may include fatigue, dizziness, sleepiness, headache, hypertension (high blood pressure), constipation, vomiting, anxiety, confusion, hallucinations and sleep disturbance. If you develop any other side effects while taking this medication, consult the doctor. If you suffer from epileptic seizures, there is a slight possibility that the medication may increase the chances of one occurring.Also, as this product may cause sleepiness or dizziness, do not drive or operate machinery under these conditions.
What to do if an overdose is taken
If more medication has been taken than what is prescribed, contact either your doctor, hospital emergency department, or the nearest poison control centre immediately, even if you do not feel sick.
How do you store this medication?
Ebixa tablets contain memantine hydrochloride. The 10 mg tablets are white to off-white.
Keep this medication in a safe place, out of the reach of children.
Store the tablets at room temperature (15°-30° C) and in a dry place.
If the doctor tells you to stop taking the medication, return any leftover tablets to the pharmacist, unless the doctor tells you to keep them.
Anti-Alzheimer's, Anti-Dementia Agents
Memantine Review Article