title: Effects of oral administration of trimethoprim-sulfamethoxazole on tear production in clinically normal guinea pigs.
abstract: OBJECTIVE
  To determine the effects of short-term oral administration of trimethoprim-sulfamethoxazole on tear production in clinically normal guinea pigs.
  
  
  METHODS
  Thirty-two healthy adult Abyssinian guinea pigs were used in this study.
  
  
  METHODS
  One day before the start of the trial, the pretreatment baseline phenol red thread test (PRTT) values were recorded. Sixteen guinea pigs in the treated group received 25 mg/kg trimethoprim-sulfamethoxazole orally twice a day for 14 days. The other sixteen guinea pigs were used as untreated controls and received a placebo during the study. All the ophthalmic tests were performed without chemical restraint. PRTT values were evaluated in both eyes of all the guinea pigs using a commercial PRTT strip of a single lot number on days 0 (baseline), 15, and 21 after starting the trial.
  
  
  RESULTS
  The pretreatment baseline mean ± SD PRTT values for the treatment and control groups were 11.12 ± 3.82 mm/15 s and 11.93 ± 2.73 mm/15 s, respectively. After 14 days of drug administration, the mean ± SD PRTT values for the treatment and control groups were 10.87 ± 3.11 mm/15 s and 13.00 ± 2.47 mm/15 s, respectively. On Day 21, the mean ± SD PRTT values for the treatment and control groups were 12.62 ± 4.05 mm/15 s and 12.87 ± 2.99 mm/15 s, respectively. Significant decreases in the PRTT values, compared with the pretreatment baseline values, were not observed in the treatment group on Day 15 (P = 0.14) and Day 21 (P = 0.31).
  
  
  CONCLUSIONS
  Trimethoprim-sulfamethoxazole did not decrease tear production in the guinea pigs in this study.
authors.affiliation: Faculty of Veterinary Medicine, University of Semnan, Semnan, Iran. Annaasadii@gmail.com.
authors.forename: Faezeh
authors.initials: F
authors.lastname: Asadi
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Karaj Branch, Islamic Azad University, Alborz, Iran.
authors.forename: Seyed Mehdi
authors.identifier: http://orcid.org/0000-0002-5065-8025
authors.initials: SM
authors.lastname: Rajaei
authors.affiliation: Veterinary Medicine Faculty, University of Tehran, Tehran, Iran.
authors.forename: Salar
authors.initials: S
authors.lastname: Golabdar
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D006168:Guinea Pigs; D013666:Tears / Q000378:metabolism*; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D015662:Trimethoprim, Sulfamethoxazole Drug Combination
keywords: Co-trimoxazole; guinea pigs; phenol red thread test; tear production; trimethoprim-sulfamethoxazole