Memantine

Memantine is a prescription drug used to treat moderate to severe confusion (dementia) related to Alzheimer's disease. It does not cure Alzheimer's disease, but it may improve memory, awareness, and the ability to perform daily functions. This medication works by blocking the action of a certain natural substance in the brain (glutamate) that is believed to be linked to symptoms of Alzheimer's disease.

• Memantine is available under the following different brand names: Namenda XR, and Namenda.

Dosages of Memantine:

Tablet

• 5 mg
• 10 mg

Capsule, extended-release

• 7 mg
• 14 mg
• 21 mg
• 28 mg

Oral solution

• 2 mg/ml

Not indicated for pediatric use

Dosage Considerations – Should be Given as Follows:

Alzheimer-Type Dementia

• Treatment of moderate-to-severe dementia
• Tablet: 5 mg orally once daily initially; increased by increments of 5 mg/day each week; maintenance target dosage (more than 5 weeks): 20 mg/day orally divided every 12 hours
• Extended-release capsule: 7 mg orally each day initially; may be increased by increments of 7 mg/day each week; maintenance target dose is 28 mg orally each day

Dosage Modifications

Renal impairment

• Mild or moderate: No dosage adjustment is required
• Severe: (creatinine clearance of 5-29 mL/min): Not to exceed 14 mg/day (extended-release) or 5 mg twice daily (prompt-release)

Hepatic impairment

• Mild or moderate (Child Pugh A/B): No dosage adjustment required
• Severe (Child Pugh C): Caution

Administration

• May take with or without food
• Consume entire capsule contents, do not divide the dose
• Swallow the capsule whole or open and sprinkle on a spoonful of applesauce; do not chew or crush
• Do not mix the oral solution with any other liquid
• Missed dose: Do not double next dose, the next dose should be taken as scheduled; if missed for several days, dosing may need to be resumed at lower doses and re-titrated as described above

Mild-to-Moderate Vascular Dementia (off-label)

• 5 mg (immediate-release) orally daily; titrate by 5 mg every 7 days to target dose 10 mg twice daily

Side effects of memantine include:

• dizziness
• confusion
• headache
• constipation
• cough
• high blood pressure (hypertension)
• backache
• pain
• sleepiness
• fainting
• vomiting
• shortness of breath
• fatigue
• acute kidney failure
• blockage in the brain (cerebral infarction)
• stroke (cerebrovascular accident)
• deep venous thrombosis
• hepatitis, liver failure
• intracranial hemorrhage
• neuroleptic malignant syndrome ([NMS] fever, altered mental status, muscle rigidity, and autonomic dysfunction)
• seizure (including grand mal)
• Stevens-Johnson syndrome
• disruption of blood supply to the brain or eye (transient ischemic attack, or mini-stroke)

Postmarketing side effects of memantine reported include:

• Blood and lymphatic system disorders: vulnerability to infection (agranulocytosis); reduced white blood cells (leukopenia, neutropenia); deficiency of red blood cells, white blood cells, and platelets (pancytopenia); low platelets (thrombocytopenia); blood clots (thrombotic thrombocytopenic purpura [TTP])
• Cardiac disorders: cardiac failure congestive
• Gastrointestinal disorders: pancreatitis
• Hepatobiliary disorders: inflammation of the liver (hepatitis)
• Psychiatric disorders: suicidal ideation
• Renal and urinary disorders: Acute kidney failure (including increased creatinine and kidney insufficiency)
• Skin disorders: Stevens-Johnson syndrome

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

• Memantine has no known severe interactions with other drugs.
• Serious interactions of memantine include:
  • dextromethorphan
  • ketamine
• Moderate interactions of memantine include:
  • acetazolamide
  • aluminum hydroxide
  • amantadine
  • amiodarone
  • calcium carbonate
  • cimetidine
  • digoxin
  • dofetilide
  • procainamide
  • quinidine
  • ranitidine
  • sodium bicarbonate
  • sodium citrate/citric acid
  • sodium lactate
  • tenofovir DF
  • vandetanib
• Mild Interactions of memantine include:
  • diltiazem
  • hydrochlorothiazide
  • metformin
  • methyclothiazide
  • midodrine
  • ofloxacin
  • pramipexole
  • quinine
  • sulfamethoxazole
  • triamterene
  • trimethoprim
  • verapamil

This information does not contain all possible interactions or adverse effects. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns, or for more information about this medicine.

Warnings

• This medication contains memantine
• Do not take Namenda XR or Namenda if you are allergic to memantine or any ingredients contained in this drug
• Keep out of reach of children
• In case of overdose, get medical help or contact a Poison Control Center immediately

Contraindications

• Hypersensitivity to product or components

Effects of Drug Abuse

• No information available

Short-Term Effects

• See "What Are Side Effects Associated with Using Memantine?"

Long-Term Effects

• See "What Are Side Effects Associated with Using Memantine?"

Cautions

• Not evaluated in patients with a seizure disorder; seizures occurred in 0.2% of patients
• Conditions that raise urine pH may decrease urinary elimination and increase plasma levels of memantine
• Use caution in cardiovascular disease, seizure disorder, ophthalmic disease, liver and/or kidney impairment

Pregnancy and Lactation

• Use of memantine during pregnancy may be acceptable
• Either animal studies show no risk but human studies are not available or animal studies showed minor risks and human studies were done and showed no risk
• It is unknown whether memantine is excreted into breast milk; use with caution if breastfeeding