Latanoprost-loaded phytantriol cubosomes for the treatment of glaucoma

•Latanoprost-loaded phytantriol cubosomes (CubLnp) were prepared using a top-down method and displayed an average size around 200 nm.•CubLnp showed a double-diamond surface, Pn3m cubic-phase structure, which was not affected by drug loading.•Latanoprost release from cubosomes was very slow evidencing a sustained release profile.•A single subconjunctival application of CubLnp induced greater reduction in IOP of around 30% at 24 hours.•CubLnp at low concentrations showed a hypotensive effect for 9 days with a reduction in IOP of 20%. Glaucoma is a degenerative optic neuropathy characterized by increased intraocular pressure that if untreated can result in blindness. Ophthalmological drug therapy is a challenge of great clinical importance due to the diversity of ocular biological barriers which commonly causes limited or no effectiveness for drugs delivered through the eye. In this work, we proposed the development of nanosized cubic liquid crystals (cubosomes) as a new drug carrier system for latanoprost, an anti-glaucoma drug. Latanoprost-loaded phytantriol cubosomes (CubLnp) were prepared using a top-down method. Latanoprost concentration in the formulations ranged from 0.00125% to 0.02% w/v. All cubosomes displayed an average size around 200 nm, a low polydispersity index of 0.1 and zeta potential values around –25 mV, with an encapsulation efficiency of about 90%. Structural studies revealed that cubosomes displayed a double-diamond surface, Pn3m cubic-phase structure, and was not affected by drug loading. Calorimetric studies revealed a fast and exothermic interaction between latanoprost and cubosomes. According to in vitro essays, latanoprost release from cubosomes was slow in time, evidencing a sustained release profile. Based on this behavior, the in vivo hypotensive intraocular effect was evaluated by means of the subconjunctival administration of CubLnp in normotensive rabbits. We obtained promising results in comparison with a marketed latanoprost formulation (0.005% w/v). [Display omitted]