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F. Y. Chien, Y. Murakami, R. F. Gariano; Intraocular Levels of Triamcinolone Acetonide After Periocular Injection Assessed by Tandem Liquid Chromatography and Mass Spectroscopy. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5609.
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To determine the concentration of triamcinolone acetonide (TA) in the vitreous and aqueous humors using tandem liquid chromatography and mass spectroscopy, and to investigate the mechanism of uptake of TA after subtenon and subconjunctival injections.
Patients scheduled to undergo surgery for complications of proliferative diabetic retinopathy received a subtenon or subconjunctival injection of TA (40mg in 1.0ml). Subtenon injections were given in the posterior superotemporal quadrant of the globe. Vitreous and aqueous humor samples were subsequently collected during vitreous surgery. The degree to which TA was delivered to the subtenon and/or subconjunctival space was confirmed by direct visualization of the depot site at the time of surgery. Aqueous humor samples (via anterior chamber paracentesis) and vitreous specimens (via "dry" biopsy) were obtained 10 to 36 days after TA injection. Vitreous and aqueous humor concentrations of TA were determined by tandem high-performance liquid chromatography and mass spectroscopy.
Twenty five paired specimens have been collected, and ten have been analyzed. All contained measurable levels of TA. Mean TA concentration in the aqueous humor was approximately twice that in the vitreous (0.033 vs. 0.016 ug/ml; p=0.02). There was a trend for aqueous TA levels to be greater in patients in whom the TA depot was predominantly located in the subconjunctival space (0.045 ug/ml) compared to the subtenon space (0.031 ug/ml).
Tandem liquid chromatography and mass spectroscopy measurement of TA yields intraocular concentrations more consistent and less variable than those reported using liquid chromatography alone, and indicates that uptake of TA after periocular injection is more predictable than previously thought. By measuring both aqueous and vitreous concentrations, and localizing the site of injection, this ongoing study addresses the mechanism of intraocular uptake of TA after periocular injection. Preliminary results suggest that posteriorly injected TA in part enters the eye via the anterior segment. This may relate to the effectiveness in posterior segment disease and the high anterior segment complication rate of posteriorly injected TA.
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