Namenda (memantine) is a brand-name drug that’s prescribed for Alzheimer’s disease. Namenda has interactions with some other drugs. Examples include dextromethorphan and acetazolamide.

Namenda is prescribed for moderate to severe dementia due to Alzheimer’s disease in adults.

An interaction occurs when one substance causes another substance to have a different effect than expected.

Namenda comes in different forms, and they have the same interactions. The forms are:

  • immediate-release oral tablets
  • extended-release* oral capsules (Namenda XR)

To learn more about Namenda’s interactions, keep reading. For additional information about Namenda, including details about its uses, see this article.

Note: As Alzheimer’s disease progresses, a person may need help reading or understanding information regarding their circumstances. This article contains information that may help caregivers learn more about Namenda interactions.

* Extended-release means the drug is slowly released into your body over a long period of time.

Before you start treatment with Namenda, tell your doctor and pharmacist which prescription, over-the-counter, and other medications you take. By sharing this information with them, you may help prevent possible interactions. (To learn whether Namenda interacts with supplements, herbs, or vitamins, see the “Namenda and other interactions” section below.)

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Here’s a table of drugs that can interact with Namenda. Keep in mind that this table doesn’t include all drugs that may interact with Namenda. Some of these interactions are described in detail just below in “Drug interactions in depth.”

Drug class or drug nameDrug examplesInteraction result with Namenda
other N-methyl-D-aspartate (NMDA) antagonists• amantadine (Gocovri)
• dextromethorphan (Delsym, others)
• ketamine (Ketalar)
may increase the risk of side effects of Namenda and other NMDA antagonists
carbonic anhydrase
inhibitors
• acetazolamide
• methazolamide
can increase the risk of side effects of Namenda
urinary alkalinizing agents• potassium citrate (Urocit-K)can increase the risk of side effects of Namenda
dopaminergic drugs• bromocriptine (Parlodel, Cycloset)
• ropinirole
• rotigotine (Neupro)
may increase the risk of side effects of dopaminergic drugs
sodium bicarbonatecan increase the risk of side effects of Namenda

In some cases, factors or conditions could prevent your doctor from prescribing Namenda due to the risk of harm. These are known as contraindications. The contraindications of Namenda include:

Having had an allergic reaction to Namenda or any of its ingredients

If you have had an allergic reaction to Namenda or any of its ingredients, your doctor will likely not prescribe Namenda. Taking the drug could cause another allergic reaction. You can ask them about other treatments that may be better choices for you.

Note: Before you start treatment with Namenda, it’s important to tell your doctor if this contraindication applies to you. They can determine whether to prescribe Namenda.

There aren’t any known interactions between Namenda and alcohol. However, your doctor may advise you to avoid or limit alcohol consumption during Namenda treatment.

This is because drinking alcohol while taking the drug may worsen some of Namenda’s side effects. For example, you may experience headache or dizziness.

Alcohol can also worsen the condition you’re receiving Namenda to treat. For example, if you have Alzheimer’s disease, drinking alcohol may worsen your symptoms.

If you have questions about drinking alcohol while taking Namenda, talk with your doctor.

Here’s a closer look at certain drug interactions of Namenda.

Other N-methyl-D-aspartate (NMDA) antagonists

Namenda belongs to a class of drugs called N-methyl-D-aspartate (NMDA) antagonists. It can interact with other drugs from this class, which have several different uses.

Interaction result: Taking Namenda with other NMDA antagonists can raise the risk of side effects of Namenda and other NMDA antagonists.

Interaction explained: Namenda and other NMDA antagonists can both cause some similar side effects, such as agitation, dizziness, and sleepiness. So taking these drugs together may increase these side effects or make them more likely to occur.

Examples of NMDA antagonist drugs: Here are some NMDA antagonists that may interact with Namenda:

  • the Parkinson’s disease drug amantadine (Gocovri)
  • the cough suppressant dextromethorphan (Delsym, others)
  • the anesthetic drug ketamine (Ketalar)

Steps you or your doctor may take: Your doctor will likely avoid prescribing Namenda with other drugs that are NMDA antagonists.

If you take Namenda with one of these drugs, tell your doctor if you have any new or increased side effects.

Note that the NMDA antagonist dextromethorphan is an ingredient in some over-the-counter (OTC) cough remedies. You shouldn’t take these with Namenda unless your doctor recommends it. Be sure to check the ingredients of OTC cough remedies before using them with Namenda, or ask your pharmacist for advice.

Carbonic anhydrase inhibitors

Namenda can interact with carbonic anhydrase inhibitors, which are used to treat glaucoma.

Interaction result: Taking Namenda with carbonic anhydrase inhibitors can raise your risk of Namenda side effects, such as dizziness and headache.

Interaction explained: Your kidneys filter Namenda out of your blood and into your urine. This clears the drug from your body. If your urine is more alkaline than usual, your kidneys filter less Namenda into your urine. This can make Namenda build up in your blood, which can raise your risk of its side effects. Carbonic anhydrase inhibitors make your urine more alkaline.

Examples of carbonic anhydrase inhibitors drugs: Here are some carbonic anhydrase inhibitors that may interact with Namenda:

  • acetazolamide
  • methazolamide

Steps you or your doctor may take: If you take Namenda with a carbonic anhydrase inhibitor, your doctor may monitor you more closely. Tell your doctor if you have any new, increased, or bothersome Namenda side effects.

Urinary alkalinizing agents

Namenda can interact with urinary alkalinizing agents, such as potassium citrate (Urocit-K), which are used to treat or prevent kidney stones.

Interaction result: Taking Namenda with urinary alkalinizing agents can raise your risk of Namenda side effects, such as dizziness and headache.

Interaction explained: Your kidneys filter Namenda out of your blood and into your urine. This clears the drug from your body. If your urine is more alkaline than usual, your kidneys filter less Namenda into your urine. This can make Namenda build up in your blood, which can raise your risk of its side effects. Urinary alkalinizing agents make your urine more alkaline.

Steps you or your doctor may take: If you take Namenda with a urinary alkalinizing agent, your doctor may monitor you more closely. Tell your doctor if you have any new, increased, or bothersome Namenda side effects.

Namenda may have other interactions, such as with supplements, foods, vaccines, or even lab tests. You’ll find details below. Keep in mind that the following information does not include all other possible interactions with Namenda.

Namenda interactions with supplements

Before you start treatment with Namenda, tell your doctor and pharmacist which supplements, herbs, and vitamins you take. By sharing this information with them, you may help prevent possible interactions.

Namenda can interact with sodium bicarbonate (baking soda) supplements. These may be used to treat indigestion. Some people also take them to improve exercise performance. Taking sodium bicarbonate supplements with Namenda can make Namenda build up in your body. This can raise your risk of Namenda side effects, such as headache and dizziness.

If you have questions about other interactions that may affect you, ask your doctor or pharmacist.

Namenda and herbs

There are no specific reports of herbs interacting with Namenda. However, that doesn’t mean herbal interactions won’t occur or be recognized in the future. Because of this, it’s important to check with your doctor or pharmacist before taking any of these products during Namenda treatment.

Namenda and vitamins

There are no specific reports of vitamins interacting with Namenda. However, that doesn’t mean vitamin interactions won’t occur or be recognized in the future. Because of this, you should talk with your doctor or pharmacist before taking any vitamin product with Namenda.

Namenda interactions with food

Although sodium bicarbonate (baking soda) supplements may interact with Namenda, there were no reports of food interactions with the drug.

The amount of baking soda in food, such as baked goods, is usually small. The food is also often divided into multiple servings. The quantity of baking soda would be much less than what’s in a sodium bicarbonate supplement.

If you have additional questions or want more information about eating certain foods during Namenda treatment, talk with your doctor.

Namenda and vaccines

There aren’t any known interactions between Namenda and vaccines. Talk with your doctor or pharmacist to see whether you’re due for any vaccines.

Namenda and lab tests

Namenda isn’t known to interact with any lab tests. If you have concerns about this medication interacting with lab tests, talk with your doctor.

NAMENDA INTERACTION WITH CANNABIS OR CBD

Cannabis (often called marijuana) and cannabis products, such as cannabidiol (CBD), have not been specifically reported to interact with Namenda. However, as with any drug or supplement, talk with your doctor before using cannabis in combination with Namenda. The impact of cannabis may affect how well you stick to your Namenda treatment plan.

Note: Cannabis is illegal at a federal level but is legal in many states to varying degrees.

Certain medical conditions and other factors may increase the risk of interactions with Namenda. Before you take this drug, be sure to talk with your doctor about your health history. Namenda may not be the right treatment option if you have certain medical conditions or other factors affecting your health.

Health conditions or factors that might interact with Namenda include:

  • Kidney problems: If you have severe kidney problems such as chronic kidney disease, your doctor may prescribe a dosage of Namenda that’s lower than usual.
  • Liver problems: Namenda has not been studied in people with severe liver problems. If you have severe liver problems such as cirrhosis, talk with your doctor about whether Namenda is right for you.
  • History of seizures: Namenda has not been studied in people with a seizure disorder. If you have a history of seizures, talk with your doctor about whether Namenda is right for you.
  • Allergic reaction: If you’ve had an allergic reaction to Namenda or any of its ingredients, your doctor will likely not prescribe Namenda. Taking the drug could cause another allergic reaction. You can ask them about other treatments that may be better choices for you.
  • Breastfeeding: It’s not known whether it’s safe to use Namenda while breastfeeding. There isn’t enough information to determine whether the drug passes into breast milk or what effects Namenda may have on a child who is breastfed. If you’re breastfeeding or planning to, talk with your doctor before using Namenda. They can talk with you about nursing considerations, including treatment options and ways to feed your child.
  • Pregnancy: There haven’t been enough clinical trials to determine whether Namenda is safe to use while pregnant. If you’re pregnant or planning to become pregnant, tell your doctor before starting Namenda. They can advise you on the right treatment plan for you.

You can take certain steps to help prevent interactions with Namenda. Your doctor and pharmacist are key resources, so reach out to them before starting treatment. For example, you should plan to do the following:

  • Let them know if you drink alcohol or use cannabis.
  • Tell them about any other medications you take, as well as any supplements, herbs, and vitamins.
  • Create a medication list, which your doctor and pharmacist can help you fill out.

It’s also important to read the Namenda label and other paperwork that may come with the drug. The label may have colored stickers that mention an interaction. And the paperwork, sometimes called the medication guide or patient package insert, may contain details about interactions.

If Namenda doesn’t come with paperwork, you can ask your pharmacist to print a copy. If you need help reading or understanding this information, ask your doctor or pharmacist.

You can also help prevent interactions with Namenda by taking it exactly as your doctor prescribes.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.