The effect of timing of dexamethasone administration on its efficacy as a prophylactic antiemetic for postoperative nausea and vomiting

We evaluated the timing effect of a 10-mg IV administration of dexamethason e on its efficacy as a prophylactic antiemetic on post-operative nausea and vomiting (PONV). One hundred twenty women (n = 40 in each of three groups) undergoing abdominal total hysterectomy under general anesthesia were enro lled in this randomized, double-blinded, placebo-controlled study. Group 1 received dexamethasone before the induction of anesthesia, Group 2 received dexamethasone at the end of anesthesia, and Group 3 received placebo (sali ne). The incidence of PONV was evaluated. During the postoperative period o f 0-2 h, patients in Group 1 reported a less frequent incidence of PONV (15 %) than those in Groups 2 and 3 (45% and 53%, respectively). Patients in Gr oup 1 also requested less rescue antiemetic (8%) than those in Groups 2 and 3 (30% and 35%, respectively). During the postoperative period of 2-24 h,p atients in both Groups 1 and 2 reported less frequent incidences of PONV (2 5% and 28%) and requested fewer rescue antiemetics (13% and 15%) than those in Group 3 (55% and 38%, respectively). In conclusion, the prophylactic IV administration of dexamethasone immediately before the induction, rather t han at the end of anesthesia, was more effective in preventing PONV.