Thus, if topical prednisolone acetate can predict the IOP response of an intravitreal steroid like IVTA, then it can possibly be extrapolated in its predictive utility with FAc as well. If we compare the aqueous concentrations of prednisolone acetate or difluprednate with FAc, we find that both topical difluprednate and prednisolone acetate are more than 100 times higher in aqueous concentration as compared with the intravitreal implant with FAc.10-11
Therefore, these topical preparations of steroids provide more than sufficient aqueous concentrations to determine the effects of steroid compounds on the trabecular meshwork. Finally, if we look at chemical structure (see Figure 1), difluprednate appears to have the most similar chemical structure to FAc given the difluorinated chemical structure.
Overall, determining the best agent prior to FAc for predicting IOP rise with corticosteroid treatments remains the decision of each individual retinal specialist.
In my practice, I continue to utilize dexamethasone as a good predictor however I am starting to implement the utilization of topical difluprednate or prednisolone acetate (one drop four times a day for 4-6 weeks) as an acceptable alternative steroid challenge based on current evidence.
While dexamethasone continues to be a helpful predictor of the possible clinical response to intravitreal steroids prior to the FAc implant, this article provides significant evidence and assurances that a topical steroid challenge with either difluprednate or prednisolone acetate can be a very effective predictor and represents a new paradigm shift.
1) Mali, Joshua. Selecting the right DME patients for long-term steroidal implants. Opthalmology Times, September 2016.
2) ILUVIEN prescribing information
3) Ozurdex prescribing information
4) O'Neil, M.J. (ed.). The Merck Index, 13 th Edition, 2001., p. 518
5) Analytical Profiles of Drug Substances, Vol 11, K Florey (ed.). Academic Press 1982.p. 620
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7) ALOGPS, also reported to have extremely low water solubility in patent EP0878197 A1
8) ALOGPS, also reported as practically insoluble in water in patent EP1909798 A2
9) Hollands, H. et al. A trial of topical prednisolone acetate before intravitreal triamcinolone acetonide decreases intraocular pressure spikes. Can J Ophthalmol 2010;45:484-8.
10) McGhee CN, Watson DG, Midgley JM et al. Penetration of synthetic corticosteroids into human aqueous humour. Eye 1990; 4:526-30.
11) Tetsuya Tajika, Akiharu Isowaki,Hideyuki Sakaki. Ocular Distribution of Difluprednate Ophthalmic Emulsion 0.05% in Rabbits. Journal of Ocular Pharmacology and Therapeutics. Vol. 27, No. 1, 2.
12) Durezol prescribing information