First Author: E.Flores Villalobos MEXICO
Co Author(s): J. Ramirez Estudillo
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To determine the effect of the silicone oil tamponade medium on the dexamethasone intravitreal implant.
Hospital de Nuestra Señora de La Luz, Mexico City, Mexico.
The dexamethasone (DEX) implant was placed in a 5mL test tube filled with 4mL of each tamponade medium: 1000cS, 5000cS and heavy silicone oil; basic saline solution (BSS) was used as the control medium. colour photographs were taken weekly for 12 months. 200µL samples were taken from each medium at 24 hour intervals, 1 week, 2 weeks and monthly for 12 months since implant placement. ELISA test was performed to quantify dexamethasone release in every sample. We cultured and stimulated peripheral blood mononuclear cells (PBMC) to create an inflammatory stimulus and later exposed it to every sample in order to test their anti-inflammatory capacity by cytokine analysis using cytometric bead array (CBA). Results were analyzed with descriptive statistics and later subject to analysis of normality. Comparisons between different groups of study were made with one way ANOVA. Statistically significant results were obtained with p<0.05.
Photographic follow-up showed disintegration of the implant in BSS starting at month 9 to be fully dissolved at month 12. The implants in silicone oil suffered no changes during the 1 year follow-up. DEX levels in BSS showed stability from month 2 to 12, keeping an average concentration of 8.85.± 0.39ng/mL. Silicone oil mediums showed an average DEX concentrations from the second month of: SO-1000cS: 4.84±1.68ng/mL; SO-500: 3.81±2.30ng/mL; D-68: 3.77±3.10ng/mL. DEX implant in BSS had inhibitory effects on TNF-α starting at 24 hours (31.46±12.68) (p<0.001) and maintained during the complete follow-up period. DEX implant in 1000cS SO showed inhibitory effects on TNF-α starting at month 2 (35.71±11.82pg/mL) (p<0.001) and remained only until month 6 (26.38±8.61pg/mL) (p<0.001). DEX implants in silicone oils of 5000cS and D-68 showed no inhibitory effect on TNF-α levels in any of the samples.
Denser tamponade mediums altered the DEX implant pharmacokinetics. Also, denser silicone oils showed no anti-inflammatory effects even when DEX concentrations were quantified at levels similar to control medium.