Liposomes as vehicles for topical ophthalmic drug delivery and ocular surface protection

Abstract

Introduction:The development of ophthalmic formulations able to deliver hydrophilic and hydrophobic drugs to the inner structures of the eye and restore the preocular tear film has been a leading topic of discussion over the last few years. In this sense, liposomes represent a suitable strategy to achieve these objectives in ocular drug delivery. Areas covered: Knowledge of the different physiological and anatomical structures of the eye, and specially the ocular surface are critical to better understanding and comprehending the characteristics required for the development of topical ophthalmic liposomal formulations. In this review, several features of liposomes are discussed such as the essential materials used for their fabrication, basic structure and preparation methods, from already established to novel techniques, allowing the control and design of special characteristics. Besides, physicochemical properties, purification processes and important strategies to overcome delivery or encapsulation challenges are also presented. Expert opinion: Regarding ocular drug delivery of liposomes, there are some features that can be re-designed. Specific biocompatible and biodegradable materials presenting therapeutic properties, such as lipidic compounds or polymers significantly change the way of tackling ophthalmic diseases. Besides, liposomes entail an effective, safe and versatile strategy for the treatment of diseases in the clinical practice.

Topical Pirfenidone-Loaded Liposomes Ophthalmic Formulation Reduces Haze Development after Corneal Alkali Burn in Mice

“…Moreover, the use of liposomes remarkably improved these effects. The use of new delivery systems such as liposomes is part of novel strategies to avoid early degradation of drugs and regulate their release into the stroma, reducing the frequency of application [21,22,43].…”

“…Liposomes, small vesicles (approximate size of 30-1000 nm) which are prepared with phospholipids, offer an efficient option for PFD drug delivery. Previously, liposomes have been evidenced to increase drug penetration, extend the time in contact with the ocular surface, and to improve the therapeutic effect of topical ophthalmic drugs, thus reducing the frequency of application [21,22]. We anticipate that due to these nanoparticles, PFD penetration will increase the time of interaction with the ocular surface and would improve the therapeutic effect by reducing the frequency of application.…”

Diabetic eye: associated diseases, drugs in clinic, and role of self-assembled carriers in topical treatment

“…Self-assembled drug carriers that can be prepared in few steps and can encapsulate both small and large active substances, while providing a highly biocompatible, stealth interface are gaining increasing attention for ocular delivery. Although a plethora of novel self-assembled carriers are being tested, polymeric micelles, liposomes, and niosomes have already demonstrated in vivo promising performances [13,16,99,107]. Below, first the variables that drive the formation of these carriers and the main preparation protocols are revisited.…”

“…Liposomes have been widely used as carriers since several decades ago because of their dual capability to simultaneously host hydrophilic and hydrophobic drugs plus the general advantages of passive and active targeting [134,135]. Usefulness of liposomes for topical ophthalmic drug delivery, and especially management of ocular surface diseases, has been recently reviewed [13]. Importantly, the bioinspired structure and composition of liposomes facilitate the fusion with cell membrane at the cornea and conjunctiva surface and drug transfer to cell cytoplasm.…”

“…Polymeric micelles have outstanding capability to encapsulate hydrophobic drugs increasing apparent drug solubility, although concerns about premature disassembly may arise [12]. Lipid-based vesicles, such as liposomes, may host both hydrophobic and hydrophilic active substances [13], but the constituent lipids may be prone to chemical degradation [14,15]. In this context, niosomes as vesicles made of self-assembled nonionic surfactants may gather the advantages of both micelles and liposomes while providing improved physical and chemical stability.…”