Memantine and Postoperative Pain

Phase 4

Terminated

Brief Summary: Memantine is associated with improvement in pain relief after surgery.

Detailed Description: This prospective, randomized, controlled trial will investigate whether perioperative memantine has a postoperative analgesic effect following radical retropubic prostatectomy (RRP). 100-110 patients scheduled to undergo RRP at Duke will be assessed preoperatively for allodynia using Von Frey filaments, then stratified into two groups based on the presence or absence of allodynia. Patients in each group will then be randomized to receive either memantine 20 mg or placebo 30-60 minutes preoperatively, followed on postoperative day 1 with either memantine 10 mg in the morning and 10 mg in the evening for memantine patients, or placebo at the same intervals for placebo patients. Data such as morphine consumption, patient satisfaction and pain scores, opioid-related side effects, and the area of hyperalgesia around the surgical incision will be recorded for the initial 48 hours postoperatively, and patient satisfaction with their postoperative analgesia will be assessed after 1 week. At 1, 3, and 6 months postoperatively, patients will be asked about the presence and intensity of any persistent pain related to surgery.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Chronic pain conditions or taking regular analgesics
Taking psychotropic medications
Parkinson's disease
Narrow-angle glaucoma
Known gastroduodenal ulcer
History of seizure disorder
Renal insufficiency, as defined by serum creatinine greater than 2 mg/dL
Liver disease, including liver failure, cirrhosis, or acute hepatitis
Significant coronary vascular disease or cardiac conduction system disease, as noted by ECG or history of cardiac symptoms, or cardiac ejection fraction less than 30%
American Society of Anesthesiologists (ASA) score of 4 or higher
Allergy to ketorolac or memantine

Arm && Interventions

Group	Intervention	Description
Placebo	Placebo	Placebo
Memantine	Memantine	-

Primary Outcome Measures

Name	Time	Method
24 hr Opioid Consumption	24 hr

Secondary Outcome Measures

Name	Time	Method
Pain Scores	48 hours	Pain score (0=no pain, 10= worst possible pain)
Chronic Post-surgical Pain	1 month, 3 month, 6 month
Opioid Related Side Effects	0-24 h	Number of participants with postoperative nausea and vomiting.
Opioid Related Side Effects: Pruritus	0-24 h	Number of participants who experienced pruritus.
Hyperalgesia	Within 48 h	Stimulation with a Von Frey hair filament at 396 mN of force will be started from outside the hyperalgesic area, where no pain sensation is experienced toward the incision until the patient reports a distinct change in perception. The first point where a "painful," "sore," or "sharper" feeling occurs will be marked, and the distance to the incision measured. The surface area will be measured in cm2 around the surgical incision.
Patient Satisfaction	48 hours	Number of participants who reported "very satisfied" or "somewhat satisfied"