In a parallel single-blinded randomized clinical trial , ninety 1-7 y-old uncooperative kids who were referred to Pediatric Neurology Clinic of Shahid Sadoughi University , Yazd , Iran from April through August 2012 , were randomly assigned to receive 40mg/kg of chloral hydrate or 40mg/kg of chloral hydrate and 1mg/kg of promethazine or 40mg/kg of chloral hydrate and 2mg/kg of hydroxyzine .