ABSTRACT
Worldwide, opioids remain the mainstay for the treatment of moderate to severe acute pain. An opioid is any substance with a pharmacological action at the opioid receptor; an opiate is a naturally occurring opioid. Opioid pharmacodynamic and pharmacokinetic variables vary widely between patients and the therapeutic index is narrow. This necessitates the need for close observation and titration of dose to effect in every patient receiving opioids for acute pain. Nausea and vomiting are predictable and significant side effect of opioids when used to treat opioid-naive patients in acute pain; prophylactic antiemetics are often administered routinely. Traditionally, opioids have been classified as strong, intermediate, and weak, according to their perceived analgesic properties and propensity to addiction. Some opioids have mixed actions because they are also active at other receptors or systems. Nausea and vomiting is a predictable and significant side effect in many patients, especially in acute pain when prophylactic antiemetics are often administered routinely.
