title: Intraocular and systemic pharmacokinetics of triamcinolone acetonide after a single 40-mg posterior subtenon application.
abstract: OBJECTIVE
  To characterize the pharmacokinetics of triamcinolone acetonide (TA) in aqueous, vitreous, and systemic circulation after a single subtenon injection.
  
  
  METHODS
  Prospective interventional case series.
  
  
  METHODS
  Thirty-six patients (36 eyes) who received a single posterior subtenon injection of TA (40 mg in 0.4 ml).
  
  
  METHODS
  Aqueous, vitreous, and blood samples were obtained at 1-hour, 1-day, 3-day, 5-day, 10-day, 14-day, 21-day, and 28-day time points after the posterior subtenon TA injection. At each time point, there were 3 to 6 eyes (patients). The concentrations of TA in the aqueous, vitreous, and plasma were analyzed using ultra-performance liquid chromatography coupled with tandem mass spectrometry.
  
  
  METHODS
  Triamcinolone acetonide concentration in the samples was measured, and pharmacokinetic parameters were calculated.
  
  
  RESULTS
  The TA concentration-time profile in aqueous consisted of a fast distribution phase during the first 24 hours and a slow elimination phase thereafter. In contrast, the TA concentration-time profile in vitreous consisted of an absorption phase during the first 24 hours followed by a slow elimination phase. The TA in plasma followed a mono-exponential elimination during the study course. The TA concentration peak time for aqueous and plasma was at 1 hour and 24 hours, for vitreous after subtenon injection. The terminal elimination half-life in aqueous, vitreous, and plasma was 11.8, 17.1, and 25 days, respectively. The integral of the area under the concentration time curve (AUC(0-∞)) was 862 ng/day/ml for aqueous, 1262 ng/day/ml for vitreous, and 17.4 ng/day/ml for plasma. The total TA exposure to vitreous was 46% more than total TA exposure to the aqueous. The TA concentration in vitreous was 70- to 98-fold higher than that in plasma.
  
  
  CONCLUSIONS
  Posterior subtenon TA application can provide a sustained high local ocular TA level while also resulting in a very low systemic TA level, which may be well below the normal glucocorticoid level in humans.
authors.affiliation: Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical College, Wenzhou, Zhejiang, China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Shen
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: You
authors.forename: Shumao
authors.initials: S
authors.lastname: Sun
authors.forename: Yiqi
authors.initials: Y
authors.lastname: Chen
authors.forename: Jia
authors.initials: J
authors.lastname: Qu
authors.forename: Lingyun
authors.initials: L
authors.lastname: Cheng
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001082:Aqueous Humor / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005938:Glucocorticoids / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006207:Half-Life; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D053719:Tandem Mass Spectrometry; D058475:Tenon Capsule / Q000378:metabolism; D014222:Triamcinolone Acetonide / Q000008:administration & dosage / Q000493:pharmacokinetics*; D014822:Vitreous Body / Q000378:metabolism*; D055815:Young Adult
chemical_list: D005938:Glucocorticoids; D014222:Triamcinolone Acetonide