The Pediatric Trials Network (PTN), with funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), recently completed a multicenter study of trimethoprim/sulfamethoxazole (TMP/SMX) to determine appropriate dosing for infants and children. The results of the study were published in the journal Antimicrobial Agents and Chemotherapy on Oct. 30.

TMP/SMX is a combination antibiotic used to treat various types of bacterial infections in children, including urinary tract infections, bacterial pneumonia, and skin abscesses caused by methicillin-resistant Staphylococcus aureus (MRSA). Although it is one of the most commonly used drugs for treating infections in infants and children, pharmacokinetic data in children are lacking and appropriate dosing information had never been determined for this population.

“It’s common to extrapolate adult doses to treat children,” said Dr. Michael (Micky) Cohen-Wolkowiez, co-principal investigator for the study. “However, developmental changes during childhood play a significant role in drug dosing, and failure to account for these changes often leads to decreased drug efficacy and safety in young patients.”

During the study, investigators analyzed samples from 153 infants and children who had been given TMP/SMX as part of their treatment. The TMP/SMX combination is one of more than 30 drug therapies given as part of standard care that are being evaluated in POPS, a study that began in 2011 and is expected to have enrolled approximately 3000 patients by 2018.

Only a small percentage of drugs and devices approved by the FDA are actually labeled for pediatric use. As a result, pediatricians must frequently prescribe medical therapies according to their best guess based on dosing information from adult studies.

PTN, a network of more than 100 sites in 5 countries, aims to fill this gap by conducting trials primarily with off-patent drugs that lack data to guide their use in pediatric populations. Since its inception in 2011, it has studied 72 drugs to determine appropriate dosing for children and infants.