The use of intravenous fentanyl during general anesthesia was permitted, but was not to exceed 250 micrograms. The intraoperative use of morphine was prohibited. Postoperatively, subjects had access to both opioid and non-opioid supplemental pain medication under general guidelines. Blood samples for the determination of plasma bupivacaine concentrations were obtained at Baseline and at specified time points through 96 hours.