Preformulation Studies of a Liposomal Formulation Containing Sirolimus for the Treatment of Dry Eye Disease

Abstract

Purpose: The aim of this study was to develop and characterize a liposomal product containing sirolimus to be administered subconjunctivally for the treatment of nonresponsive keratoconjunctivitis sicca (KCS) or dry eye. Methods: Formulations were prepared using an ethanol injection method and an adaptation of the heating method in pursuance of the most suitable methodology for future industrial production. Liposomes were loaded with either a high dose of 1 mg/mL of sirolimus or a less toxic dose of 0.4 mg/mL. The effects of critical process and formulation parameters were investigated. Liposomes were characterized in terms of size, zeta potential, polydispersity, differential scanning calorimetry, morphology, entrapment efficiency, phospholipid content, thermal stability, and sterility. The formulation was evaluated clinically in dogs with spontaneous KCS. Results: Sterile liposomal dispersions with sizes ranging from 140 to 211 nm, were successfully obtained. High entrapment efficiency of 93%-98% was achieved. The heating method allowed an easier production of liposomes with high entrapment efficiency, to significantly shorten production time and the elimination of the use of alcohol. The poor stability of the obtained liposomes in aqueous dispersion made the inclusion of a lyophilization step necessary to the manufacturing process. In vivo testing of the liposomal sirolimus formulations in the spontaneous KCS dog model have produced promising results, particularly with a sirolimus dose of 1 mg/mL, indicating the need for further development and study of proposed formulations in the treatment of canine KCS. Clinical improvement in tear production in dogs with spontaneous KCS treated with the 1 mg/mL dose product was observed. Conclusions: The heating method allowed easier production of high entrapment efficiency liposomes to significantly shorten production time and the elimination of the use of alcohol. Tear production was increased in dogs administered with the formulation.

Nanomedicine approaches for sirolimus delivery: a review of pharmaceutical properties and preclinical studies

“…The proposed mechanisms for this efficient multifunctional carrier were as follow: (1) through enhanced permeability and retention (EPR) as well as folate mediated active targeting effects, the formulation was selectively accumulated at the tumour site and efficiently internalized into endothelial and tumour cells; (2) this theranostic probe precisely tracked the tumour tissue, focused the laser beam on the tumour region and converted NIR laser light energy to hyperthermia; (3) hyperthermia generated by activation of ICG under NIR irradiation mediated photothermal therapy and triggered sirolimus release from the thermosensitive liposomes; and (4) through blocking the regulation effect of mTOR by the released drug, antiproliferative and antiangiogenic effects were observed [47]. In vitro/in vivo [56] DOPE: dioleoylphosphatidylethanolamine; DPPC: dipalmitoylphosphatidylcholine; DSPC: distearoylphosphatidylcholine; DSPE-PEG: pegylated distearoylphosphatidylethanolamine; DSPG: distearoyl-sn-glycerophosphoglycerol; EPC: egg phosphatidylcholine; PC: phosphatidylcholine; SPC: soybean phosphatidylcholine.…”

Comparative efficacy of topical oclacitinib 0.1% and tacrolimus 0.01% in canine keratoconjunctivitis sicca

“…The treatment aims to reestablish tear production, avoiding the complications of KCS . Alternative and supporting treatments have been sought to achieve better overall results, for use in refractory cases, and to reduce costs and improve owner compliance with treatment …”

“…13,18,[24][25][26]33 Alternative and supporting treatments have been sought to achieve better overall results, for use in refractory cases, and to reduce costs and improve owner compliance with treatment. 37,38 Oclacitinib is a novel drug for the treatment of pruritus related to allergic skin diseases and atopic dermatitis in dogs. 43 It is a janus kinase (JAK) inhibitor, with JAK1 selectivity, and is well tolerated by dogs.…”

The effects of topical aqueous sirolimus on tear production in normal dogs and dogs with refractory dry eye

“…Commercial sirolimus (Rapamune ® Pfizer Inc., New York NY, USA) is FDA approved for immunosuppressive therapy in human renal transplantation to help prevent organ rejection. Regarding ocular tissue, sirolimus has been evaluated in human, rat, mice, pig, equine, and rabbit tissue . Sirolimus has shown, experimentally, to have positive effects in ameliorating sequelae of various ocular disease processes, including choroidal and retinal neovascularization, macular degeneration, anterior and posterior uveitis, KCS, and glaucoma.…”

“…Results showed a significant decrease in inflammatory cell infiltrate of murine lacrimal glands compared to controls; however, there were no efforts to evaluate lacrimal gland function. The next study evaluated a subconjunctival liposome encapsulated 1 mg/mL sirolimus solution in dogs with refractory KCS . While an increase in tear production was observed, the study did not contain a control population and included only four dogs.…”