1. From the University of Tennessee College of Medicine, Department of Pediatrics, Memphis, Tennessee;
2. Children's Hospital of Philadelphia, Department of Pediatrics, Division of Clinical Pharmacology and Therapeutics, Philadelphia, Pennsylvania;
3. Arkansas Children's Hospital Research Center, Inc, Section of Clinical Pharmacology, Little Rock, Arkansas;
4. Louisiana State University Medical School, Department of Pediatrics, Shreveport, Louisiana; and the
5. Section of Pharmacology and Toxicology, Children's Hospital Research Foundation, Columbus, Ohio.