Pharmacologic class (EPC) · 3 drug pages

N-methyl-D-aspartate receptor antagonist: adverse event reports filed with FDA

5,879 reports list a drug in this class as a suspect or interacting product, 2004–2026.

Read first · FDA's statement on these data

Adverse event reports submitted to FDA do not undergo extensive validation or verification. Therefore, a causal relationship cannot be established between product and reactions listed in a report. While a suspected relationship may exist, it is not medically validated and should not be the sole source of information for clinical decision making or other assumptions about the safety or efficacy of a product. Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product. openFDA, FDA

FDA adds: "There is no certainty that the reported event (adverse event or medication error) was actually due to the product. FDA does not require that a causal relationship between a product and event be proven, and reports do not always contain enough detail to properly evaluate an event." The information in these reports "cannot be used to estimate the incidence of these events."

Do not rely on openFDA to make decisions regarding medical care. While we make every effort to ensure that data is accurate, you should assume all results are unvalidated.

Not medical advice. This site counts what was reported to FDA. Questions about a medicine or device belong with a pharmacist or clinician.

5,879
reports across the class: 0% of all reports; 299
reports, 12 months to June 2026: 390 in the 12 months before; 92.6%
marked serious by the reporter: 57.4% across all reports; 3
drugs with a page: brand and generic names counted separately

N-methyl-D-aspartate receptor antagonist is a pharmacologic class (an FDA Established Pharmacologic Class) with 3 drug pages on this site. Together those drugs are listed as a suspect or interacting product in 5,879 adverse event reports received by FDA, 0% of the database, from January 2004 to June 2026.

299 reports arrived in the 12 months to June 2026, down 23% from 390 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. 92.6% of the class's reports are marked serious, 12.8% record death among the outcomes and 48.5% record hospitalisation, as reported.

Across the class the reactions recorded most often are drug ineffective (7.1%), fall (6.8%) and off label use (6.5%). The class median share shown beside each term is the middle value across the member drugs; it is the comparison used on every drug page in this class.

The members table is ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Drugs in the class

Drug	Name type	Reports	Latest 12 months	Marked serious	Top term recorded
Memantine	generic	3,485	246	92.4%	Drug ineffective
Memantine hydrochloride	generic	1,324	53	91%	Fatigue
Memantine hcl	generic	1,070	0	95.3%	Fall

Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Reports by month, five years

FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

Reactions recorded across the class

share of class reports recording the termmedian drug in the class

Drug ineffectivethe medicine did not work as expected7.1%416
Falla fall6.8%400
Off label useused for a purpose or in a way not on the label6.5%385
Confusional stateconfusion5.6%332
Condition aggravatedthe condition being treated got worse5.4%318
Agitationrestlessness4.7%279
Somnolencedrowsiness4.3%254
Dizzinesslight-headedness or unsteadiness4.1%242
Fatiguetiredness3.9%227
Astheniaweakness or lack of energy3.6%209
Drug interactionan interaction between medicines3.5%205
Nauseafeeling sick3.4%198
Bradycardiaslow heart rate3.2%191
Vomitingbeing sick2.8%163
Aggressionaggressive behaviour2.8%162
Headachehead pain2.5%147
Hallucinationseeing or hearing things that are not there2.4%143
Hypertensionhigh blood pressure2.3%133
Deliriumsudden confusion2.1%125
Dyspnoeashortness of breath2.1%125
Insomniadifficulty sleeping2%120
Pulmonary embolisma blood clot in the lung2%119
Toxicity to various agentspoisoning or toxic effect of one or more substances2%117
Gait disturbancedifficulty walking1.9%114
Abnormal behaviourunusual behaviour1.9%113

Solid bar: share of all class reports. Hollow bar: the median share across the 3 member drugs, the reference used on each member's page. One report can record several terms.

Outcomes, patients and reporters

Outcomes recorded

Death12.8%755

Life-threatening5.3%310

Hospitalisation (initial or prolonged)48.5%2,851

Disability3.9%229

Congenital anomaly0%0

Other serious47.4%2,788

Not serious7.4%435

Patient age

Under 20.1%7

2 to 110.9%54

12 to 170.4%26

18 to 445.1%302

45 to 6410.5%620

65 to 7411.9%699

75 and over46.3%2,722

Age not given24.6%1,449

Who reported

Physician23.9%1,404

Pharmacist10.6%626

Other health professional44.2%2,597

Lawyer0%2

Consumer or non-health professional13.4%789

Not given7.8%461

Grey bar: all 20,646,523 reports in the database. Outcome flags are as the reporter set them and are not verified by FDA.

Questions about N-methyl-D-aspartate receptor antagonist reports

Which drugs are in the N-methyl-D-aspartate receptor antagonist class on this site?

Memantine, Memantine hydrochloride and Memantine hcl. Class membership comes from the pharmacologic class (EPC) on the drug's FDA label.

How many reports does the class have?

5,879 reports through June 2026, 299 of them in the latest 12 months. A report listing two drugs of the class counts once for each.

What reactions are recorded most often?

drug ineffective (7.1%), fall (6.8%), off label use (6.5%), confusional state (5.6%) and condition aggravated (5.4%).

Can the members table be used to rank the drugs?

No. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." Drugs differ in how many people take them, in the conditions they treat, in time on the market and in how diligently reports are collected.

How do I report an adverse event?

Through FDA MedWatch (Form FDA 3500, or 1-800-FDA-1088) or to the manufacturer. See the guide on how to report.

Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A class is the Established Pharmacologic Class most often attached to a drug's reports by openFDA's label harmonisation, or from the NDC Directory where reports carry none. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.

Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.