title: Preparation, characterization, and in vivo evaluation of triamcinolone acetonide microspheres after intravitreal administration.
abstract: OBJECTIVE
  The aim of this study was to evaluate the intraocular pressure (IOP) increasing effect and bioavailability of triamcinolone acetonide (TA) microspheres, as a novel drug delivery system, after intravitreal administration.
  
  
  METHODS
  Microspheres loaded by TA were prepared by the solvent evaporation method. After encapsulation, the final microspherical formulation was tested in an animal model. The left eyes of rabbits received microspherical TA and the right eyes were injected with conventional TA suspension. The drug concentration in the vitreous samples at days 7, 14, 28, and 56 after the injection was determined by high-performance liquid chromatography. The IOP was also checked at the same days with the Schiotz tonometer.
  
  
  RESULTS
  There was no statistically significant (P>0.05) difference between mean concentration of TA in the vitreous of right and left eyes at the different sampling times except day 56. Mean IOP of eyes that received microspherical TA was increased less than that of the eyes injected with TA suspension, and the difference was statistically significant (P<0.05) for each measurement day. TA was detectable in both eyes after 8 weeks. Both TA microsphere and suspension showed the sustained release profile.
  
  
  CONCLUSIONS
  The results of this study showed less IOP increasing effect of triamcinolone microspheres in comparison with suspension form.
authors.affiliation: Department of Ophthalmology, Eye Research Center, Khatam-al-Anbia Eye Hospital, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Siamak
authors.initials: S
authors.lastname: Zarei-Ghanavati
authors.forename: Bizhan
authors.initials: B
authors.lastname: Malaekeh-Nikouei
authors.forename: Reza
authors.initials: R
authors.lastname: Pourmazar
authors.forename: Sajad
authors.initials: S
authors.lastname: Seyedi
mesh_terms: D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid; D004339:Drug Compounding; D016503:Drug Delivery Systems; D007429:Intraocular Pressure / Q000187:drug effects*; D058449:Intravitreal Injections; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010316:Particle Size; D011817:Rabbits; D013499:Surface Properties; D014018:Tissue Distribution; D014222:Triamcinolone Acetonide / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics; D014822:Vitreous Body / Q000378:metabolism
chemical_list: D014222:Triamcinolone Acetonide