The currently predominant means of controlling postoperative pain is the peri-operative administration of opioid or non-opioid (acetaminophen) analgesics, alone or in combination, and non-steroidal anti-inflammatory drugs (NSAIDs). However, anti-inflammatory drugs are contraindicated for many patients because they may impair renal function, interact with platelet aggregation, and increase the risk of gastrointestinal damage and bleeding. The spectrum of available options is narrow.