Novel drug delivery systems for the treatment of glaucoma
Authors: Vanrell Rocio Herrero 
Published: December 2022

Glaucoma is a group of chronic irreversible neuropathies in which a progressive death of retinal ganglion cells (RGC) and a glaucomatous optic disc neuropathy occurs leading to an irreversible visual field alteration. Intraocular pressure (IOP) increase is a major risk factor strongly associated with the onset and progression of the disease although a non IOP‐dependent neurodegeneration also occurs. Taking all this into account, the glaucoma therapy is based on two different targets: lowering the IOP and neuroprotection.

The treatment of choice in patients with high IOP values is topical administration of hypotensive active agents on the ocular surface. The chronicity of the pathology, together with the low bioavailability of the antiglaucomatous drugs applied topically, make it necessary daily instillations, which are associated, in many cases, with the appearance of surface eye alterations and dry eye disease (DED). For these reasons, the development of therapeutic platforms able to increase the bioavailability of the drug while being soft with the ocular surface is getting special attention. Novel formulations involve pharmaceutical systems such as liposomes, nanoemulsions and microemulsions including also compounds with protective activity on the corneal surface (osmoprotective, antioxidants and/or bioadhesive polymers)(1–3).

It is well known that therapies lowering IOP does not address neurodegeneration. Moreover, pathophysiological studies of glaucoma have shown that even in patients presenting IOP values within the normal limits, neuronal degeneration occurs. For this reason, the use of neuroprotective therapy in the treatment of glaucoma alone or simultaneously with the therapy based on the control of IOP results of great interest. Treatments destined to lower IOP, in which the target is the anterior segment of the eye are administered topically. By the contrary, neuroprotective therapies require the administration of the drugs near to the retinal target as well as their maintenance during long term Due to the multifactorial nature of the disease there is special interest in the design of novel drug delivery systems able to include a combination of active agents in the same formulation and provide long term effects with a single administration(4).

Acknowledgements: Acknowledgements‐ Grant: Fondo Europeo de Desarrollo Regional (FEDER‐CICYT), grant: FIS‐PI17/00079 and PI17/00466, Research Group UCM 920415 ‘Innovation, Therapy and Pharmaceutical Development in Ophthalmology (InnOftal)’ and the ISCII‐FEDER RETICS (OFTARED) (RD16/0008/0004 and RD16/0008/0009)PID2020‐113281RB‐C21 funded by MCIN/AEI/ 10.13039/501100011033.

References.

1. López‐Cano J.J, González‐Cela‐Casamayor M.A., Andrés‐Guerrero V.,Herrero‐Vanrell R. Molina‐Martínez I.T. “Liposomes as vehicles for topical ophthalmic drug delivery and ocular surface protection”. Expert Opinion on Drug Delivery. 2021. 18(7):819–847. DOI: 10.1080/17425247.2021.1872542.

2. M. Gómez‐Ballesteros; J. López‐Cano; I. Bravo‐Osuna; R. Herrero‐Vanrell; I.T. Molina‐Martínez. “Osmoprotectants in Hybrid Liposome/HPMC Systems as Potential Glaucoma Treatment”. Polymers. 2019; 11(6): 929. DOI: 10.3390/polym11060929

3. I Bravo‐Osuna; V Andrés‐Guerrero; P Pastoriza Abel; IT Molina‐Martínez; R Herrero‐Vanrell. Pharmaceutical microscale and nanoscale approaches for efficient treatment of ocular diseases. Drug Deliv Translational Research.2016. 6(6):686–707.

DOI: 10.1007/s13346‐016‐0336‐5.

4. R Herrero‐Vanrell; I. Bravo‐Osuna; V. Andrés‐Guerrero; M. Vicario‐de‐la‐Torre; I.T. Molina‐Martínez. The potential of using biodegradable microspheres in retinal diseases and other intraocular pathologies. Progress in Retinal and Eye Research. 2014. 42; 27–43. DOI: 10.1016/j.preteyeres.2014.04.002.