Optimal Dose of Prophylactic Naloxone in Reducing Opioid-Induced Side Effects in Children/Adolescents

This is an investigator initiated dose finding study designed to determine the optimal dose of naloxone to prevent or minimize the most common side effects induced by opioids, namely itching, nausea, and vomiting. Male and female inpatients of the Children's Center of the Johns Hopkins Hospital, who are greater than 6 and less than 18 years of age with acute, moderate to severe pain, and who are to be treated with intravenous Patient controlled analgesia (IVPCA) morphine will be eligible for inclusion in this study. Patients will be recruited by a study investigator prior to the initiation of IVPCA therapy. The majority of patients will be post operative patients, and will start therapy and the investigational drug in the Post Anesthesia Care Unit or the Pediatric Intensive Care Unit. The investigators plan on studying between 10 and 99, male and female patients over a 2 year period.