Memantine

GENERIC NAME: memantine

DRUG CLASS AND MECHANISM
Memantine is an oral medication for treating patients with Alzheimer's disease. Other medications used for Alzheimer's disease affect acetylcholine, one of the neurotransmitter chemicals that nerve cells in the brain use to communicate with one another. These drugs - galantamine (Razadyne - formerly known as Reminyl), donezepil (Aricept), rivastigmine (Exelon), and tacrine (Cognex)-- inhibit the enzyme acetylcholinesterase that destroys acetylcholine and thereby increases the effects of acetylcholine. Memantine's effects are independent of acetylcholine and acetylcholinesterase.

Glutamate is the main excitatory neurotransmitter in the brain. It is believed that too much stimulation of nerve cells by glutamate may be responsible for the degeneration of nerves that occurs in some neurological diseases such as Alzheimer's disease. Like other neurotransmitters, glutamate is produced and released by nerve cells in the brain. The released glutamate then travels to nearby nerve cells where it attaches to a receptor on the surface of the cells called the N-methyl-D-aspartate (NMDA) receptor. Memantine blocks the receptor and thereby decreases the effects of glutamate. It is thought that by blocking the NMDA receptor and the effects of glutamate, memantine may protect nerve cells from excess stimulation by glutamate. Memantine was approved by the FDA in October, 2003.

PRESCRIPTION: Yes.

GENERIC AVAILABLE: No.

PREPARATIONS: Tablets: 5 mg (tan) and 10 mg (gray).

PRESCRIBED FOR
Memantine is used for the treatment of moderate to severe dementia of the Alzheimer's type. Dementia can be categorized into three levels of severity. Mild: Patients are alert and sociable, but forgetfulness begins to interfere with daily living. Moderate: This is often the longest stage of the disease with deterioration of intellect, logic, behavior, and function. Severe: Loss of long-term memory and language skills. Patients may require 24-hour care and can no longer complete basic self-care tasks including washing, eating, and using the bathroom.

DOSING
The usual starting dose of memantine is 5 mg once daily. The dose usually is increased to 5 mg twice daily, then 5 mg and 10 mg as separate doses daily, and finally 10 mg twice daily. Memantine can be taken with or without food.

DRUG INTERACTIONS
Medicines that make the urine more alkaline (for example, carbonic anhydrase inhibitors such as acetazolamide (Diamox) and sodium bicarbonate would be expected to reduce the elimination of memantine by the kidneys and might increase the blood levels and the risk of side effects of memantine. Combining memantine with other NMDA receptor antagonists (for example, amantadine (Symmetrel), ketamine, and dextromethorphan) has not been evaluated and should be approached cautiously.

USES
This medication is used to treat moderate to severe Alzheimer's disease. It works by blocking a chemical in the brain (glutamate) that is involved with the development of Alzheimer's disease. Memantine does not cure the disease, but patients on this medication may show improvement with certain daily functions and may have better awareness.

HOW TO USE
Take this medication by mouth with or without food. This medication is usually taken once daily when first started. As your dose is gradually increased, take the medication on a twice daily schedule as directed by your doctor. The dosage is based on your medical condition and response to therapy. Use this medication regularly in order to get the most benefit from it.

SIDE EFFECTS
Fatigue, pain, dizziness, headache, or joint pain may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly. Tell your doctor immediately if any of these unlikely but serious side effects occur: mental/mood changes (e.g., depression, agitation, anxiety), swelling of hands or feet, trouble breathing. If you notice other effects not listed above, contact your doctor or pharmacist.

PRECAUTIONS
Before taking memantine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney disease, liver disease, severe urinary tract infections. This drug may make you dizzy; use caution engaging in activities requiring alertness such as driving or using machinery. Limit alcoholic beverages. This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor. It is not known whether this drug passes into breast milk. Consult your doctor before breast-feeding.

OVERDOSE
If overdose is suspected, contact your local poison control center or emergency room immediately. US residents can call the US national poison hotline at 1-800-222-1222. Canadian residents should call their local poison control center directly. Symptoms of overdose may include restlessness, personality change, hallucinations, drowsiness, or loss of consciousness.

MISSED DOSE
If you miss a dose, use it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

STORAGE
Store at room temperature at 77 degrees F (25 degrees C) away from light and moisture. Brief storage between 59-86 degrees F (15-30 degrees C) is permitted. Do not store in the bathroom. Keep all medicines away from children and pets.

Note : This product information is intended only for residents of the India. Taj Pharmaceuticals Limited, medicines help to treat and prevent a range of conditions—from the most common to the most challenging—for people around the world.