What is Memantine?
Memantine is an amantadine derivative which is used for mild to severe Alzheimer's disease. The disease Alzheimer's is not curable but it can be managed by this specific drug. It works to minimize the symptoms of Alzheimer's condition. The drug is not very common since not many of the people are diagnosed with this degenerative disease. Its effect on Alzheimer's disease was not known until in the 1980s. Since its discovery, the drug had been used as a diabetic drug.
Class / Categories of Memantine Hydrochloride
Adamantane, Excitatory Amino Acid Antagonists, NMDA Receptor Antagonists, OCT2 Substrates, Psychoanaleptics, Amantadine, Anti-Alzheimer's Drugs, Anti-Dyskinesia Agents, Cytochrome P-450 CYP2A6 Inhibitors, Cytochrome P-450 CYP2A6 Inhibitors (weak), Cytochrome P-450 CYP2B6 Inhibitors, Anti-Parkinson Drugs, Central Nervous System Agents, Cycloparaffins, Miscellaneous Central Nervous System Agents, N-methyl-D-aspartate Receptor Antagonist, Cytochrome P-450 Enzyme Inhibitors, Nervous System, Neurotransmitter Agents, Cytochrome P-450 CYP2B6 Inhibitors (moderate), Excitatory Amino Acid Agents, Cytochrome P-450 CYP2C19 Inhibitors, Dopamine Agents.
Mode of action
Memantine has a moderate affinity to NMDA receptors. When ingested it targets the glutamatergic pathway by curbing the NMDA receptors. Memantine is not a competitive antagonist rather a non-competitive. It binds specifically to the cation NMDA receptor channels. It completely blocks the action of glutamate which leads to neuronal dysfunction.
Memantine Hydrochloride has other names in different countries. It is also known as 1-Amino-3,5-dimethyladamantane, Memantina, 3,5-Dimethyl-1-adamantanamine, Memantinum, 3,5-Dimethyltricyclo(22.214.171.124(3,7))decan-1-amine, 1,3-Dimethyl-5-adamantanamine, Memantine and 3,5-Dimethyl-1-aminoadamantane.
Memantine is taken orally and the drug is absorbed perfectly and able to reach the maximum bioavailability of 100%. It reaches peak plasma concentrations in four to seven hours. It can be taken between meals or not since meals have no effect it memantine hydrochloride absorption. The protein binding of memantine hydrochloride is 45% and the volume of distribution is about 10l/kg. Memantine is excreted unchanged. When in the body, the one-fifth of the drug is metabolized to 3-amino-1-hydroxy-5,7-dimethyl-adamantane and 1-amino-3-hydroxymethyl-5-methyl-adamantane.
The drug undergoes metabolism in the liver. As stated above about half of the drug is excreted in urine in unchanged form. The remaining half is changed to three metabolites which have a moderate affinity to the NMDA receptors as antagonists. These three metabolites include the 6-hydroxy memantine, N-glucuronide conjugate and 1-nitroso-deaminated memantine. All of these are excreted in urine in unchanged form. The drug half-life is two to five days. The toxicity aspect of the drug has been discussed in the last part of this article (Memantine Overdose)
How To Use And Dosage
Just like any other drug, upon receiving memantine drug, check the patient information leaflet that is usually placed inside the drug packet. Read it carefully and understand what it means. In most cases, this drug is usually ordered by relatives of people who have already been diagnosed with dementia of Alzheimer's type. This means the patient can't read this information but you can read and understand it for the patient. In case you do not understand the leaflet, contact your doctor or pharmacist on the same.
Memantine is a drug not affected by meals hence you can take it between meals or with meals as directed. The dosage is based on your body's reaction to the management and also the severity of your medical condition.
In most cases, this drug is taken OD meaning Once on a daily basis. Most doctors start by directing the patient to start by a lower than normal dosage to assess the side effects after which the dose is raised as per the condition.
For those who are taking the liquid form of memantine, it is vital to read and understand how Memantine is taken using the oral syringe that comes with the bottle. in case you use another means to deliver the drug through the oral cavity, you will either have underdosed or overdosed yourself. As said before, this drug does not cure but when taken consistently, it helps reduce the effect of dementia of Alzheimer's type. Hence, you should take the medicine regularly so as the stated effect above can be achieved. Ensure to follow the prescribed dose.
Memantine has very minimal side effects and if they occur, they are not that serious or something one should worry about. However, if the symptoms get worse, you need to seek medical review from a professional doctor.
These effects include generalized body pains, drowsiness, Constipation (which might be worse especially for elderly patients) and headaches. In case after the administration of Memantine, you note a sudden rash, scratching or swelling of the face and tongue, seek medical help as soon as possible. It could be a sign of a severe allergic reaction.
To begin with, Memantine contains inactive ingredients especially after it is metabolized in the hepatic system. These ingredients might be allergic to some people hence proper analysis should be done before taking this drug. Inform your doctor about the allergies you have and your previous health issues.
Also, drug interactions with other medication occur when memantine is used concomitantly with other drugs. (This information is discussed in the next subtopic) Ensure you inform your doctor the current medications that you are using to enable them to give you a better drug.
Those who have kidney problems or severe UTIs can have problem excreting this drug which will delay the secretion of the drug. This delay, in turn, increases the presence of the drug in plasma leading to higher levels of memantine in the blood. In a few days, it could lead to memantine overdose.
This drug has a synergistic effect with alcohol and marijuana. They both cause drowsiness. Hence they should not be taken together especially if you are used to taking medication during the morning hours.
Memantine as any other drugs interacts with certain drugs to bring out a negative effect. The following drugs should not be taken together with memantine. They include:
All drugs that make urine Alkaline such as the carbonic anhydrase inhibitors and sodium bicarbonate. This is an interaction since the clearance of memantine is reduced greatly when urine is alkaline. This could lead to an increase of memantine in the blood circulation which would possibly lead to certain side effects.
An overdose occurs if the patient takes an excess amount of the dosage prescribed in the prescription. To avoid this, kindly stick to the doctors prescription. The signs and symptoms of memantine hydrochloride poisoning include generalized body weakness, hypertension, changes in Electrocardiogram curve, drowsiness, loss of consciousness, bradycardia, stupor, easily agitated, vomiting and asthenia among other neurological symptoms. Some studies have shown memantine leading to hyperkalemia and renal destruction and thus overdosage of this drug should be reported.
In case you take an overdose or have a friend who has taken an overdose or has signs of memantine toxicity, call 1-800-222-1222 which is the emergency poison helpline
Memantine Hydrochloride Pricing
Memantine Hydrochloride cost is very affordable. You can buy Memantine Hydrochloride tablets online on various sites which are accredited to sell drugs through their websites such as FairPriceRX.com