Licarin A as a Novel Drug for Inflammatory Eye Diseases.

Purpose: This study investigated the safety and therapeutic efficacy of licarin A (LCA) in the treatment of intraocular inflammation. Methods:In vitro safety of LCA in retinal pigmented epithelial cells (ARPE-19) and human embryonic stem cell derived-retinal pigmented epithelial cells (hES-RPE) was evaluated using CellTiter-Blue® kit. The chorioallantoic membrane (CAM) assay was used to investigate LCA safety and antiangiogenic activity. In vivo safety of intravitreal LCA was accomplished by clinical examination (including assessment of intraocular pressure), electroretinography (ERG), and histopathology. Uveitis was induced in rats by subcutaneous and intravitreal injection of bacillus Calmette-Guérin (BCG) antigen of Mycobacterium bovis. Intraocular inflammation was graded by slit-lamp and fundus examination, ERG, and histopathology. Results: LCA was safe to cells and to the CAM at concentration below 12.0 µM. LCA significantly reduced the percentage of blood vessels in the CAM. Retinal safety and anti-inflammatory efficacy of intravitreal injection of LCA 6.0 µM were confirmed through clinical, functional, and histopathological evaluation. Significant reduction of inflammatory cytokines (tumor necrosis factor-α and interleukin-6) was also found, when compared to untreated animals. Conclusion: The results suggest that LCA is a potential new drug for the treatment of inflammatory eye disease.

Delay of neuropathic pain sensitization after application of dexamethasone-loaded implant in sciatic nerve-injured rats

Neuroimmune interactions underlying the development of pain sensitization in models of neuropathic pain have been widely studied. In this study, we evaluated the development of allodynia and its reduction associated with peripheral antineuroinflammatory effects induced by a dexamethasone-loaded biodegradable implant. Chronic constriction injury (CCI) of the sciatic nerve was performed in Wistar rats. The electronic von Frey test was applied to assess mechanical allodynia. The dexamethasone-loaded implant was placed perineurally at the moment of CCI or 12 days after surgery. Dorsal root ganglia (DRG; L4-L5) were harvested and nuclear extracts were assayed by Western blot for detection of nuclear factor (NF)-κB p65/RelA translocation. Dexamethasone delivered from the implant delayed the development of allodynia for approximately three weeks in CCI rats when the implantation was performed at day 0, but allodynia was not reversed when the implantation was performed at day 12. NF-κB was activated in CCI rat DRG compared with naïve or sham animals (day 15), and dexamethasone implant inhibited p65/RelA translocation in CCI rats compared with control. This study demonstrated that the dexamethasone-loaded implant suppresses allodynia development and peripheral neuroinflammation. This device can reduce the potential side effects associated with oral anti-inflammatory drugs.

Drug repositioning: playing dirty to kill pain.

The number of approved new molecular entity drugs has been decreasing as the pharmaceutical company investment in research and development is increasing. As we face this painful crisis, called an innovation gap, there is increasing awareness that development of new uses of existing drugs may be a powerful tool to help overcome this obstacle because it takes too long, costs too much and can be risky to release drugs developed de novo. Consequently, drug repositioning is emerging in different therapeutic areas, including the pain research area. Worldwide, pain is the main reason for seeking healthcare, and pain relief represents an unmet global clinical need. Therefore, development of analgesics with better efficacy, safety and cost effectiveness is of paramount importance. Despite the remarkable advancement in research on cellular and molecular mechanisms underlying pain pathophysiology over the past three decades, target-based therapeutic opportunities have not been pursued to the same extent. Phenotypic screening remains a more powerful tool for drug development than target-based screening so far. It sounds somewhat heretical, but some multi-action drugs, rather than very selective ones, have been developed intentionally. In the present review, we first critically discuss the utility of drug repositioning for analgesic drug development and then show examples of 'old' drugs that have been successfully repositioned or that are under investigation for their analgesic actions. We conclude that drug repositioning should be more strongly encouraged to help build a bridge between basic research and pain relief worldwide.