AmantadineEffects of N-Methyl-D-Aspartate (NMDA)-Receptor Antagonism on Hyperalgesia, Opioid Use, and Pain After Radical Prostatectomy

Inclusion Criteria:

1. Able to read and write English;
2. Age 18-59 or >= 60 years;
3. American Society of Anesthesiologists Class 1 to 3;
4. Scheduled for elective radical prostatectomy;
5. Body weight between 50-110 kg, body mass index (BMI) <= 30.

Exclusion Criteria:

1. Significant central nervous system (CNS), respiratory, cardiac, hepatic, renal or endocrine dysfunction and/or any significant sequelae;
2. Contraindications, allergies to, and/or past adverse reactions to opioid analgesics, amantadine or nonsteroidal anti-inflammatory drugs (NSAIDS);
3. Current Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM IV) Axis I disorder or cognitive dysfunction or history of this within the last year;
4. History of epilepsy or other seizures;
5. History of chronic pain of at least 6 months duration;
6. History of long term opioid use for chronic pain of at least 6 months duration;
7. History of long term use of amantadine or other antiparkinsonian drug;
8. Ingestion of antitussive medication (dextromethorphan) within the 48 hours before surgery;
9. History of alcohol or drug dependency/abuse of at least 6 months duration