The risk comes from the Goodpoint report.
Persistence. No data.
Bioaccumulation. No data.
Toxicity. No data.
Risk. Low environmental risk.
Environmental information is missing on fass.se for memantine (2021-04-07). It is voluntary for manufacturers to provide information on environmental impact on fass.se.
Since 2006, an Environmental Risk Assessment (ERA) for the active pharmaceutical substance shall accompany an application for a marketing authorisation in EU for a medicinal product for human use. Parts of environmental data can be found in the public investigation report (PAR/EPAR for medicinal product through a centralized procedure). Since the benefit/risk assessment for human medicinal products at present does not include environmental effects, an update of the environmental risk assessment is not required for renewals of marketing authorizations. There is thus no requirement for companies to stay informed about the development of their substances from an environmental point of view and consequently to update the environmental risk assessment as new data are published.
"Memantine is administered to humans at doses of usually 20 mg/day. 70% of the ingested drug are excreted unmetabolized in the urine. The metabolites are water-soluble and not biologically active or toxic. From their chemical structures no persistence in the environment can be assumed for the parent compound or its derivatives. Therapeutic used of memantine is estimated to lead to concentrations below one part per billion at the point of entry into the aquatic environment. An environmental risk can be excluded."
Similar information can be found in the various assessment reports for generic medical products with memantine. The following information comes from the Memantine Accord assessment report, 19 September 2013, EMA/610378/2013: "No Environmental Risk Assessment was submitted. It can be assumed that there will be no significant increase of the amount of the active substance on the market and, therefore, no significant increase of environmental exposure. The proposed justification for omission of any further environmental risk assessment was considered acceptable by the CHMP."
Memantine has been detected in treated wastewater and surface water in Region Stockholm in 2020.
Comparative assessment of environmental risk when using medicinal products in the treatment of Alzheimer's disease/dementia (memantine, donepezil, rivastigmine, galantamine) from a Swedish perspective.
All investigated substances are likely to occur in concentrations close to or below 20 ng/L in Swedish aquatic environments exposed to treated wastewater. The environmental risk is very low for galantamine and rivastigmine, based on expected water exposure in relation to both potential for bioconcentration and potency in humans (fish plasma model) as well as available ecotoxicological data. The environmental risk is also low for memantine, although the ecotoxicity information is more scarce. However, the use of donepezil is associated with a certain environmental risk. [...] The use of galantamine, rivastigmine and memantine is not considered to pose an environmental risk. There is an increased risk of donepezil, but due to the lack of ecotoxicity studies, the scientific support is not currently considered strong enough to recommend an exchange. Continued measurements of donepezil in treated wastewater are recommended together with measurements in exposed aquatic biota.
Author: Health and Medical Care Administration, Region Stockholm