Preclinical characterization of water-free cyclosporine eye drops – Factors impacting ocular penetration ex vivo and in vivo

Although the efficacy of Cyclosporine A (CsA) in the management of ocular inflammation is well-demonstrated, ocular delivery remains challenging due to its hydrophobic nature. The semifluorinated alkane, perfluorobutylpentane (F4H5) has previously been suggested as an efficient vehicle for preparation of CsA eyedrops. Here we evaluated the influence of drop volume and the formulation aid, ethanol (EtOH), on ocular penetration of CsA and compared it to that of the commercial eyedrop, Ikervis, ex vivo and in vivo. Moreover, conjunctival and corneal tolerability after EtOH addition were evaluated ex vivo. The F4H5/EtOH vehicle was well tolerated and resulted in better corneal CsA penetration (AUC(0-4h): 63,008 ± 3,946 ng.h.g-1) than Ikervis (AUC(0-4h): 10,328 ± 1,462 ng.h.g-1) or F4H5 alone (AUC(0-4h): 50,734 ± 3,472 ng.h.g-1) ex vivo. Interestingly, in vivo the CsA concentration in cornea, conjunctiva and lacrimal glands observed after administration of the F4H5 formulation (AUC(0.133-24h): 7,741 ± 1,334 ng.h.g-1, 1,313 ± 291 ng.h.g-1, 48.2 ± 26.3 ng.h.g-1) and F4H5/EtOH, both at a reduced dose of 11 µl (AUC(0.133-24h): 9,552 ± 1,738 ng.h.g-1, 1,679 ± 285 ng.h.g-1, 50.3 ± 21.1 ng.h.g-1) was similar or even greater than that observed on administration of 50 µl Ikervis (AUC(0.133-24h): 9,943 ± 1,413 ng.h.g-1, 2,069 ± 263 ng.h.g-1, 30.6 ± 18.4 ng.h.g-1). Thus, F4H5-based eyedrops were shown to deliver CsA more efficiently to anterior ocular tissues at a reduced dose in comparison to Ikervis, reducing dose wastage and minimizing any potential systemic side effects.