Abstract
Purpose: :
To design and validate an LC/MS/MS method for fluocinolone acetonide (FA) analysis in rabbit eye tissues and to assess tissue distribution of FA in excised pigmented rabbit eyes after intravitreal injection.
Methods: :
A sensitive and rapid isocratic liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed for the quantification of FA in rabbit eye tissues. Excised Dutch-belted rabbit eyes received posterior intravitreous injection of 1 µg of FA. After maintenance in PBS buffer (PH7.4) at 37 ºC for 4 h, the eyes were dissected and cornea, aqueous humor, lens, vitreous, iris, trabecular meshwork, ciliary body, retina, choriod, and sclera were dissected and determined by LC/MS/MS.
Results: :
The calibration curve for FA was linear over the range 2.5-1280 ng/mL with coefficients of correlation > 0.999. The precision of analysis was < 6% (relative standard deviation), and accuracy ranged from 92 to 108%. Although more variable with respect to drug levels among the tissues assessed, trabecular meshwork exhibited the highest concentration of FA (1301 ng/g). The lowest concentration of 239 ng/g was found in lens among the tissues assessed. The tissue concentration of FA decreased in the individual tissues in the following order: trabecular meshwork > cornea > aqueous humor ciliary body iris retina > choriod vitreous > sclera >lens.
Conclusions: :
A highly sensitive LC/MS/MS method was developed for the determination of FA in tissues following a low dose drug injection. In general, FA has high affinity for tissues compared to the ocular fluids, with the distribution being the highest in the trabecular meshwork. These distributions patterns need to be further assessed in vivo in the presence of viable dynamic and static barriers and clearance mechanisms.
Keywords: corticosteroids • trabecular meshwork • vitreous