Namenda and Gastrointestinal Side Effects
Yes, Namenda (memantine) can cause gastrointestinal side effects, with constipation being the most common GI adverse reaction reported in clinical trials, occurring in ≥5% of patients at rates higher than placebo. 1
Primary GI Side Effects from Clinical Trials
Constipation is the predominant gastrointestinal side effect documented in controlled clinical trials of memantine, appearing as one of only four adverse reactions occurring in ≥5% of patients at higher rates than placebo (alongside dizziness, headache, and confusion). 1
Additional GI adverse reactions reported in ≥2% of memantine-treated patients at higher frequencies than placebo include:
Serious Postmarketing GI Adverse Events
While less common, pancreatitis has been reported in postmarketing surveillance of memantine, though the exact frequency cannot be reliably estimated due to voluntary reporting from populations of uncertain size. 1
Clinical Context and Comparative Safety
The overall GI tolerability profile of memantine appears favorable compared to cholinesterase inhibitors. When memantine was combined with rivastigmine in patients with moderate Alzheimer's disease, the incidences of nausea (30%) and vomiting (13%) were substantially lower than those reported for rivastigmine monotherapy alone (47% and 31%, respectively), suggesting memantine may actually ameliorate GI side effects when used in combination therapy. 2
Practical Management Considerations
Memantine can be taken with or without food, providing flexibility for patients who experience mild GI symptoms. 1
If a patient develops constipation on memantine, this is an expected adverse effect that may require standard management with increased fluid intake, dietary fiber, or stool softeners, as constipation was specifically identified in clinical trials. 1
Important Monitoring Caveat
While GI side effects are generally mild with memantine, any patient presenting with severe abdominal pain should be evaluated for pancreatitis, given its inclusion in postmarketing adverse event reports. 1