Effect of Weight and/or Obesity on Sulfamethoxazole and Trimethoprim Concentrations

This study is designed to measure drug concentrations in the blood of volunteers administered a single oral dose of sulfamethoxazole and trimethoprim. The volunteers to be enrolled will not have ear infections, urinary tract infections, bronchitis, traveler's diarrhea, Pneumocystis carinii pneumonia, or any other bacterial infection. This is a single center study. A total of 36 adult volunteers will be consented for the study at the Clinical and Translational Research Center (CTRC). Volunteers will be recruited using IRB approved fliers. Volunteers will be admitted to the CTRC for an overnight stay. Half will be female and half male. Twelve volunteers will have a body mass index (BMI) less than 25 kg/m2, twelve will have a BMI 25-40 kg/m2, and twelve will have a BMI greater than 40 kg/m2. Volunteers will have height and weight measured after they have consented to participate. All volunteers will receive a single oral dose of sulfamethoxazole and trimethoprim of 1600 mg/320 mg. The volunteers will have blood drawn via an intravenous catheter just prior to the dose, and then at 1, 2, 4, 8, 12, and 24h after the drug dose. The intravenous catheter is then removed after the 24h blood draw, and the volunteer is discharged from the study.