Overcoming hydrolytic degradation challenges in topical delivery: non-aqueous nano-emulsions

Recent Research Advances in Nano-Based Drug Delivery Systems for Local Anesthetics

From a clinical perspective, local anesthetics have rather widespread application in regional blockade for surgery, postoperative analgesia, acute/chronic pain control, and even cancer treatments. However, a number of disadvantages are associated with traditional local anesthetic agents as well as routine drug delivery administration ways, such as neurotoxicity, short half-time, and non-sustained release, thereby limiting their application in clinical practice. Successful characterization of drug delivery systems (DDSs) for individual local anesthetic agents can support to achieve more efficient drug release and prolonged duration of action with reduced systemic toxicity. Different types of DDSs involving various carriers have been examined, including micromaterials, nanomaterials, and cyclodextrin. Among them, nanotechnology-based delivery approaches have significantly developed in the last decade due to the low systemic toxicity and the greater efficacy of non-conventional local anesthetics. Multiple nanosized materials, including polymeric, lipid (solid lipid nanoparticles, nanostructured lipid carriers, and nanoemulsions), metallic, inorganic non-metallic, and hybrid nanoparticles, offer a safe, localized, and long-acting solution for pain management and tumor therapy. This review provides a brief synopsis of different nano-based DDSs for local anesthetics with variable sizes and structural morphology, such as nanocapsules and nanospheres. Recent original research utilizing nanotechnology-based delivery systems is particularly discussed, and the progress and strengths of these DDSs are highlighted. A specific focus of this review is the comparison of various nano-based DDSs for local anesthetics, which can offer additional indications for their further improvement. All in all, nano-based DDSs with unique advantages provide a novel direction for the development of safer and more effective local anesthetic formulations.

Non-aqueous formulations in topical ocular drug delivery - a paradigm shift?

Topical eyedrop application is the preferred route for drug delivery to anterior segment tissues; however, the challenge of overcoming the eye's anatomical and physiological barriers while minimising tissue toxicity has restricted developments in this field. Aqueous vehicles have traditionally been used, which typically require several additives and preservatives to achieve physiologically compatible and sterile eyedrops, elevating their toxicity potential. Non-aqueous vehicles have been suggested as efficient alternatives for topical drug delivery as they can address many of the limitations associated with conventional aqueous eyedrops. However, despite their obvious advantages, non-aqueous eyedrops remain poorly researched and few non-aqueous formulations are currently available in the market. This review challenges the conventional hypothesis that aqueous solubility is a prerequisite to ocular drug absorption and establishes a rationale for using non-aqueous vehicles for ocular drug delivery. Recent advances in the field have been detailed and future research prospects have been explored, pointing towards a paradigm shift in eyedrop formulation in the near future.

Expanding Arsenal against Neurodegenerative Diseases Using Quercetin Based Nanoformulations: Breakthroughs and Bottlenecks

Quercetin (Qu), a dietary flavonoid, is obtained from many fruits and vegetables such as coriander, broccoli, capers, asparagus, onion, figs, radish leaves, cranberry, walnuts, and citrus fruits. It has proven its role as a nutraceutical owing to numerous pharmacological effects against various diseases in preclinical studies. Despite these facts, Qu and its nanoparticles are less explored in clinical research as a nutraceutical. The present review covers various neuroprotective actions of Qu against various neurodegenerative diseases (NDs) such as Alzheimer's, Parkinson's, Huntington's, and Amyotrophic lateral sclerosis. A literature search was conducted to systematically review the various mechanistic pathways through which Qu elicits its neuroprotective actions and the challenges associated with raw Qu that compromise therapeutic efficacy. The nanoformulations developed to enhance Qu's therapeutic efficacy are also covered. Various ongoing/completed clinical trials related to Qu in treating various diseases, including NDs, are also tabulated. Despite these many successes, the exploration of research on Qu-loaded nanoformulations is limited mostly to preclinical studies, probably due to poor drug loading and stability of the formulation, time-consuming steps involved in the formulation, and their poor scale-up capacity. Hence, future efforts are required in this area to reach Qu nanoformulations to the clinical level.

Topical non-aqueous nanoemulsion of Alpinia galanga extract for effective treatment in psoriasis: in vitro and in vivo evaluation

Non-aqueous nanoemulsion (NANE) of Alpinia galanga extract (AGE) was prepared using Palmester 3595 (MCT oil) as oil phase, Cremophor RH 40-Transcutol P® as surfactant-co-surfactant (S_mix), and glycerin as non-aqueous polar continuous phase. The composition was optimized by applying three-level, four factor Box-Behnken design (BBD). The mean droplet size and zeta potential of the optimized AGE NANE was found to be 60.81 ± 18.88 nm and -7.99 ± 4.14 mV, respectively. The ex vivo permeation studies of AGE NANE and AGE per se on porcine skin reported flux of 125.58 ± 8.36 µg/cm² h^-1 and 12.02 ± 1.64 µg/cm²h^-1, respectively. Therefore, the enhancement ratio has shown 10-folds increase in the flux for AGE NANE when compared to extract per se. Later, confocal laser scanning microcopy confirmed that AGE NANE were able to penetrate into skin's stratum by trans-follicular transport mechanism. The stability studies of AGE NANE confirmed its stability at 30 ± 2℃ /75 ± 5 % RH and 5 ± 3℃. The efficacy of AGE NANE was evaluated in vivo on imiquimod (IMQ) induced mouse model. The mice treated with low and high doses of AGE NANE (groups VI and VII) showed significant (p<0.05) amelioration of psoriasis. Results of histopathology indicated reduction in psoriasis area severity index in AGE NANE treated mice (group VI and group VII).