MONDAY, June 29 (HealthDay News) -- Despite positive results treating preoperative anxiety in adults, oral melatonin is not effective in reducing preoperative anxiety in children, according to a study in the July issue of Anesthesiology.

Zeev N. Kain, M.D., of the University of California in Irvine, and colleagues randomized 148 children (ages 2 to 8 years) who were about to undergo surgery to receive preoperative oral does of the sedative midazolam (0.5 mg/kg) or oral melatonin (0.05 mg/kg, 0.2 mg/kg or 0.4 mg/kg, depending on body weight). The preoperative anxiety of the children was assessed by blinded evaluators using the Yale Preoperative Anxiety Scale. Secondary outcomes included the subject's compliance with induction, behavior at emergence, and parental anxiety.

The researchers found that the children who took melatonin were more anxious than those who took midazolam, regardless of melatonin dose. However, the children who took melatonin had less emergence delirium than those who took midazolam. This effect was dose-dependent with the incidence of delirium 25 percent, 8.3 percent, and 5.4 percent, respectively for the 0.05 mg/kg, 0.2 mg/kg, and 0.4 mg/kg melatonin doses.

"In conclusion, we found that oral melatonin in doses up to 0.4 mg/kg (max 20 mg) administered to children before surgery is not as effective as oral midazolam in reducing preoperative anxiety. We did find, however, that melatonin is effective in reducing the incidence of emergence delirium in children undergoing general anesthesia," the authors write.

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