Introduction to Volume 2 of JOPT Special Issue

Volume 2 of this Special Issue of Journal of Ocular Pharmacology and Therapeutics (JOPT) addresses a variety of topics dealing with drug delivery, dry eye, ocular surface, and retinal diseases, along with various aspects connected with ocular safety testing of drugs. As a unique and important organ for sight, studies of the pharmacology of drugs and other biological agents designed to produce a therapeutic effect on the eye face numerous challenges due to its unique anatomy and physiology. Ocular barriers that serve a protective role against the entry of pathogens and noxious agents have been found to also prevent the penetration of therapeutic drugs and biologics into both anterior and posterior segments of the eye. Several articles in Volume 2 provide information on the different modes of administration of small and large molecule drugs and their pharmacodynamics and pharmacokinetic profiles. In a review article by Hartman and Kompella, a discussion of the historical use of intravitreal, subretinal, and suprachoroidal injections is provided that is followed by the description of various types of needles and procedures for these modes of drug administration.

Therapeutic approaches to the alleviation of symptoms of dry eye disease (DED) such as corneal epithelial lesions, increased osmolarity of the tear film, inflammation, and ocular discomfort are discussed in a couple of reviews in which pharmacodynamic studies on the utility of amitriptyline (Gallar et al.) and taurine/sodium hyaluronate (Bucolo et al.) in animal models of this disease are described. Furthermore, pharmacokinetic studies are described for lifitegrast (Welty et al.), a recently approved drug for DED treatment, which blocks key mediators of the inflammatory process associated with DED. Diquafosol delivery from silicone hydrogel contact lenses using in vitro and in vivo animal models of DED is discussed by Pintor et al. In another study, Singh et al. demonstrate that tazocin, an antibiotic, can find utility in the treatment of Pseudomonas aeruginosa as their study shows using a rabbit model of keratitis.

The use of intraocular implants as tools for delivery of drugs is described in an article by Verhoeven et al., in which ENV905 (difluprednate) is shown to be effective in reducing inflammation and pain in animal models of ocular surgery. Likewise, Waterbury presents evidence for an alternative delivery method for phenylephrine/ketorolac irrigation solution to reduce inflammation during lens replacement surgery in beagle dogs when compared with topical administration of this anti-inflammatory drug combination. In terms of preclinical safety profiles, Bantseev et al. describe results from toxicity studies in a primate model in which multiple intravitreal injections of an antifactor D antibody (lampalizumab) was found to be well tolerated, indicating a potential safe use in patients with age-related retinal disease such as geographic atrophy. In an interesting review article, Patil et al. provide compelling evidence for the role of aquaporins (especially AQP1) as novel targets for the treatment of ocular diseases such as glaucoma and age-related macular degeneration.

In conclusion, the wide scope of articles and review articles presented in Volume 2 of this Special Issue of JOPT will enable the readers to appreciate the numerous challenges faced by investigators in delivering both small molecule drugs and large antibody biologics to the anterior and posterior segments of the eye. Equally important is the awareness of appropriate safety issues associated with the development and utility of new therapeutic agents, and deployment of novel procedures and devices in combating the numerous ocular diseases afflicting animals and humans.