Classification: N-methyl-D-aspartate (NMDA) receptor antagonist.
Common usage: Memantine is indicated for the treatment of moderate to severe dementia of the Alzheimer’s type. There is no evidence that memantine prevents or slows the underlying disease process in patients with Alzheimer’s disease.
Important side effects: Side effects reported with memantine include dizziness, headache, confusion, constipation, hypertension, coughing, pain (especially back pain), sleepiness, and fatigue. The following symptoms are not common, but if the patient experiences shortness of breath or hallucinations (hearing, seeing, or tasting something that does not really exist) while taking memantine, call the patient’s doctor immediately.
This is not a complete list of all known or potential adverse effects. Notify the prescriber or pharmacist of any symptoms that have started since beginning this medication, changing its dose, or adding or changing other medication or diet. Care should be taken when performing any task that requires attention (such as driving or operating machinery) until the patient has experience with this drug and you are confident that the patient can perform the task safely.
Contraindications: Memantine should not be taken by any patients who are allergic to memantine or have had a bad reaction to memantine or to any of its ingredients. Memantine is not recommended for patients with severe renal (kidney) impairment. Memantine should be used with caution in patients with severe hepatic (liver) impairment.
Before taking memantine, tell the doctor if the patient has or ever had asthma, seizures, kidney disease, liver disease, or repeated urinary tract infections. Tell the doctor if the patient is pregnant, planning to become pregnant, or is breastfeeding. If the patient is planning to have surgery, including dental surgery, tell the doctor or dentist that he/she is taking memantine.
Interactions with other medications: Certain drugs, such as sodium bicarbonate (Alka-Seltzer), and certain medical conditions, such as severe urinary tract infections, can change the urine so that it becomes more alkaline. This may result in accumulations of memantine in the body that may lead to an increase in side effects. Under these conditions, memantine should be used with caution. Memantine also should be used with caution in combination with certain other drugs. Tell the doctor if the patient is using any of the following: cimetidine (Tagamet); ketamine; cold or cough medicines containing dextromethorphan (Coricidin, Delsym, Vicks, Robitussin); drugs containing nicotine to help quit smoking (Commit, Habitrol, Nicoderm, Nicotrol, Nicorette); ranitidine (Zantac); quinidine (Cardioquin, Quinadex, Quinaglute); or antiviral medications such as amantadine (Symmetrel) or rimantadine (Flumadine).
Tell the doctor if the patient is a vegetarian, or normally eats large amounts of citrus fruits, such as oranges, or large amounts of vegetables or legumes, such as beans and peas. The doctor will determine if the patient needs to change his/her diet while taking memantine.
This is not a complete list of all known or potential drug interactions. To help prevent problems, always make sure that the pharmacist and all prescribers know about all medications the patient is taking, including over-the-counter drugs; dietary herbal supplements; folk or home remedies; or unusual foods, drinks, or dietary habits.
Common dosages: Memantine should be taken with a full glass of water, with or without food. The recommended starting dose of immediate-release memantine tablets is 5 mg once a day, gradually increased over a period of 4 weeks to a maximum recommended dose of 20 mg daily. The recommended dosing schedule for the immediate-release formulation is as follows:
- Week 1 — Starting on day 1, take one 5-mg tablet in the morning, every day.
- Week 2 — Starting on day 8, take one 5-mg tablet in the morning and one 5-mg tablet at night, every day.
- Week 3 — Starting on day 15, take one 10-mg tablet in the morning and one 5-mg tablet at night, every day.
- Week 4 — Starting on day 22, take one 10-mg tablet in the morning and one 10-mg tablet at night, every day.
Once the target dose (10 mg, twice a day) is reached, that daily regimen can be continued unless instructed otherwise by the doctor. The patient should not take more of this medication than what the doctor has prescribed.
For patients with severe renal impairment, the recommended dose is 5 mg twice daily (5 mg in the morning and 5 mg at night).
Memantine is also available as an oral solution with the same dosage recommendation as for tablets. This formulation may be useful for patients who prefer taking a liquid or who have difficulty swallowing tablets. A patient instruction sheet on how to use the oral solution dosing device is enclosed with the product. If you have any questions regarding use of the oral solution, consult the doctor or pharmacist.
Identification: Memantine is available as Namenda in tan-colored, capsule-shaped, film-coated 5-mg tablets with “5” printed on one side and “FL” on the other side. The 10-mg tablets are gray, capsule-shaped, and film-coated, with “10” printed on one side and “FL” on the other side. The tablets are available in bottles of 60, 200, and 2,000.
Namenda is also available as a Titration Pak in a blister package containing 49 tablets (28 tablets of 5 mg and 21 tablets of 10 mg).
The oral solution, available in a 12-ounce bottle, is clear and peppermint-flavored, and contains no alcohol or sugar.
Storage: Store this medication at 77°F (permitted temperature range: 59°F to 86°F) in a tightly closed, child-, light-, and moisture-resistant container. If you have difficulty opening child-resistant containers, the pharmacist can provide you with a container that is easier to open. Keep the medication out of direct sunlight and avoid storing it in a warm and humid area, such as the bathroom or kitchen, to avoid deterioration. To prevent accidental poisoning, keep all medications out of the reach of children or adults with dementia. Expired medication should not be taken. Do not transfer medication from one container to another. Carefully discard discontinued medication where children or adults with dementia cannot find it.