Rationale for drug selection Pain from the surgical incision and tissue manipulation associated with the surgical procedure is instigated immediately. This gives way to inflammatory pain that follows inflammatory cell recruitment to the injured area within the course of several hours. Inflammatory pain generally continues for several days, depending on the nature of the surgical procedure. As a consequence of tissue damage and release of neurogenic inflammatory mediators, there is activation of specific receptors and pathways that can contribute to central sensitization and development of hyperalgesia and persistent pain. While various pharmacological strategies, including the use of opioids, provide adequate attenuation of pain, their use is associated with undesirable side effects, drug interactions, pharmacokinetic variability, and often inadequate dosing, all of which can lead to ineffective analgesia and prolonged suffering. Opioids do not interrupt the inflammatory component of pain.