**Author details**

*Role of Novel Drug Delivery Vehicles in Nanobiomedicine*

by liposomes [158, 159].

TA-LF for macular edema.

been approved (liposomes and CDs among them).

**8. Conclusion**

For example, fluorescent probes used as drug models, such as coumarin-6 and 5(6)-carboxyfluorescein, have efficiently been released into the posterior segment of the eyeball by liposomes [155, 157, 161, 162]. On the other hand, drugs like edaravone and diclofenac were successfully released into the vitreous and the retina

Special mention is reserved for the study performed by Davis BM et al. This group demonstrated that the topical instillation of eye drops containing annexin A5 associated with liposomes loaded with bevacizumab is able to deliver physiologically significant concentrations of this large therapeutic protein (monoclonal antibody against vascular endothelial growth factor A) into the posterior segment of the eye in animal models (rats and rabbits) [156]. Moreover, liposomes can

Lastly, a topical triamcinolone acetonide-loaded liposomes formulation (TA-LF) was used to successfully deliver TA into the vitreous and the retina of rabbits. Besides the authors report that TA-LF was well tolerated by the study animals and that no toxicity was observed in cell culture assays and no adverse events like corneal and conjunctival erosions were observed [150]. Recently, Jin Li et al. [164] validated in animal models (mice) that eye drops containing chitosan-coated liposomes carrying TA are an efficient method to deliver this drug into the posterior segment of rabbit eyeballs, supporting the previous findings published by Altamirano-Vallejo et al. Even though Li et al. reached superior TA entrapment efficiency in their TA-loaded liposomes prepared through the calcium acetate gradient method, it seems that this characteristic does not compromise the therapeutic activity of TA-LF. TA-LF has been tested in clinical assays where its efficiency and safety profile have satisfactorily been demonstrated. In a recent report, TA-LF was efficient in the management of refractory pseudophakic cystoid macular edema [20], where the use of this formulation was associated with the improvement of best corrected visual acuity and central foveal thickness with no reports of adverse events. At this time, phase II trials are underway to demonstrate the efficacy of

Although there has been great interest in the development of new topical ocular delivery systems, the topical administration of drugs is not as effective as intravitreal delivery in treating retinal diseases. During topical delivery, drug molecules must cross several anatomic and physiologic barriers before reaching the posterior segment of the eye. Consequently, very low concentrations, with almost no clinical effect, are usually obtained. However, dramatic changes have been observed in the field of ocular drug delivery over the last decade, and nanomedicine is one of the most promising technologies for efficient drug delivery into intraocular tissues. Nanocarriers have a great potential to solve the challenge of releasing drugs into the posterior segment of the eyeball and reaching deeper intraocular tissues. Different nanocarriers, such as NPs, LPs, micelles, dendrimers, cyclodextrin nanoparticles, and liposomes, have been developed for the safe and effective drug delivery to the vitreous and the retina. Nevertheless, only a few of these particles have clinically

Liposomes have lately been of great interest as carriers for advanced drug delivery in medicine and, especially, in ophthalmology due to their potential to avoid sophisticated ocular barriers when they are topically used. Liposomal drug delivery systems have a bright future in ophthalmology and, particularly, for the retina for several reasons. First, features such as the passive-targeting effect may substantially

release genetic material into the vitreous and the retina [160, 163].

**46**

Arturo Santos1,2\*, Juan C. Altamirano-Vallejo1,2, José Navarro-Partida1,2, Alejandro González-De la Rosa1,2 and Jane H. Hsiao3

1 Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Zapopan, Jalisco, México

2 Centro de Retina Médica y Quirúrgica S.C., Centro Médico Puerta de Hierro, Zapopan, Jalisco, México

3 OPKO Health Inc., Miami, Florida, United States of America

\*Address all correspondence to: asantos@e-retina.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
