Dexamethaone Concentration in Vitreou and erum After Oral Adminitration Original Reearch Article

Purpoe: To determine the dexamethaone concentration in vitreou and erum of patient after oral adminitration of dexamethaone and to compare the reult with the concentration in vitreou and erum found in a previou tudy with peribulbar injection of 5 mg dexamethaone diodiumphophate. Method: In a propective tudy, 54 patient who were cheduled for vitrectomy received 7.5 mg dexamethaone orally at varied time interval before urgery. A vitreou ample wa taken from each patient and erum ample were collected at multiple time point from 32 out of 54 patient. Dexamethaone concentration were meaured by radioimmunoaay. Reult: Dexamethaone concentration in erum ranged from 2.5 to 98.1 ng/ml (median, 61.6 ng/ml) between 1 and 3 hour after oral adminitration of 7.5 mg dexamethaone. erum concentration after peribulbar injection of 5 mg dexamethaone diodiumphophate (containing 3.75 mg dexamethaone) were lower by a factor of 1.5. Concentration in vitreou ranged from 1.7 to 23.4 ng/ml (median, 5.2 ng/ml) between 4 and 10 hour after oral adminitration. After peribulbar injection of 5 mg dexamethaone diodiumphophate, the intravitreal concentration were 3.9 time higher. Concluion: An oral doe of 7.5 mg dexamethaone reulted in an intravitreal corticoteroid concentration with an anti-inflammatory potency that i clearly above phyiological level. Thi concentration, however, i everal time lower than i the intravitreal concentration after a peribulbar injection of 5 mg dexamethaone diodiumphophate, although the two route of adminitration reulted in nearly equal dexamethaone concentration in erum. The higher intravitreal concentration after peribulbar injection i probably caued by diffuion from the erum and additional trancleral diffuion.