Purpose: To determine the penetration of orally administered trimethoprim (TMP)-sulfamethoxazole (SMX) into the aqueous and vitreous cavity of noninflamed human eyes.
Methods: Nine adult patients undergoing cataract surgery and 10 adult patients undergoing pars plana vitrectomy were given 3 doses of oral TMP-SMX every 12 hours before the surgery. Aqueous and blood samples were collected from patients undergoing cataract surgery; vitreous and blood samples were collected from patients undergoing vitrectomy. The levels of TMP and SMX were analyzed using high-performance liquid chromatography and were compared with the mean minimum inhibitory concentrations (MIC90) of potential ocular pathogens.
Results: TMP-SMX was present in all samples. Among eyes undergoing cataract surgery, the mean concentrations of TMP in aqueous and blood were 0.341 ± 0.141 μg/mL (mean ± SD) and 1.501 ± 0.433 μg/mL and of SMX were 5.259 ± 0.929 μg/mL and 11.835 ± 2.100 μg/mL, respectively. Among eyes undergoing vitrectomy, the mean concentrations of TMP in vitreous and blood were 1.864 ± 0.807 μg/mL and 4.591 ± 2.979 μg/mL and of SMX were 5.910 ± 2.705 μg/mL and 39.289 ± 15.469 μg/mL, respectively. MIC90 levels were achieved against many bacterial pathogens, including methicillin-resistant Staphylococcus aureus.
Conclusions: TMP-SMX penetrates both the aqueous and vitreous cavities when given orally. The components reach therapeutic inhibitory concentrations in the ocular cavity against many potential pathogens.
*Department of Ophthalmology, University of California, Davis Medical Center, Sacramento, CA;
†Department of Ophthalmology, University of Texas Health Science Center at San Antonio, San Antonio, TX;
‡Department of Pathology and Laboratory Medicine, University of California, Davis Medical Center, Sacramento, CA; and
§Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT.
Reprints: Majid Moshirfar, 65 Mario Capecchi Drive, Salt Lake City, UT 84132 (e-mail: firstname.lastname@example.org).
Supported by the Research to Prevent Blindness Foundation (New York, NY).
The authors have no conflicts of interest to disclose.
Received September 17, 2012
Accepted April 17, 2013