Over the past two decades, nanoemulsions have gained significant scientific attention because of their unique features such as high solubilization capacity, spontaneous formation, enhanced thermodynamic stability, ability to load both hydrophilic and hydrophobic drug molecules, enhanced stability of the encapsulated therapeutic molecule, and high diffusion/absorption rates. Further, they have applications in dermal and epidermal targeting for various skin disorders. The materials used in nanoemulsion formulations can greatly influence the in vitro and in vivo performance of the therapeutic moiety. This review describes various lipid materials used in the preparation of nanoemulsions for topical and transdermal drug delivery. The lipids are classified as vegetable oils, fatty acids, fatty alcohols, medium chain glycerides, and fatty acid esters.

The delivery of drugs and cosmetic actives to the skin by nanoparticle formulations has a number of advantages over conventional formulations. Nanoparticle formulations offer protection of incorporated active compounds against chemical degradation, more flexibility in modulating the release of the compound, the use of well-tolerated excipients, and feasibility of large scale production. The materials used in the nanoparticle synthesis and formulation can influence product stability, active ingredient properties and delivery to the intended site of action. This review describes the characteristics and application of various polymeric and lipid materials in the preparation of nanoparticles for topical and transdermal drug delivery.

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Recent coronavirus pandemic and its global socio-economic impact has re-emphasized the need for safe, fast, and efficient delivery of vaccines for humankind. With advent of technological advances, and to improve patient acquiescence, several techniques for fast, effective, and safe delivery of vaccines have been researched and published in the literature in last three decades. These delivery enhancement techniques include but are not limited to electroporation, microneedles (MN), ultrasound, iontophoresis, etc. This review aims at discussing the current research undergoing in vaccine delivery, specifically focusing on microneedles assisted, the historical background of microneedles and their introduction to drug delivery area, and a special focus on formulation challenges and stability in these systems. The review also sheds light on regulatory challenges one must keep in mind for bringing a successful microneedles-based vaccine delivery into market as well as a snapshot of current commercially available microneedles-based products in cosmetic and pharmaceutical industry.

Purpose Exogenous melatonin (MT) has significant neuroprotective roles in Alzheimer’s and Parkinson’s diseases. This study investigates the delivery MT to brain via nasal route as a polymeric gel suspension using central brain microdialysis in anesthetized rats. Methods Micronized MT suspensions using polymers [carbopol, carboxymethyl cellulose (CMC)] and polyethylene glycol 400 (PEG400) were prepared and characterized for nasal administration. In vitro permeation of the formulations was measured across a three-dimensional tissue culture model EpiAirway™. The central brain delivery into olfactory bulb of nasally administered MT gel suspensions was studied using brain microdialysis in male Wistar rats. The MT content of microdialysis samples was analyzed by high performance liquid chromatography (HPLC) using electrochemical detection. The nose-to-brain delivery of MT formulations was compared with intravenously administered MT solution. Results MT suspensions in carbopol and CMC vehicles have shown significantly higher permeability across Epiairway™ as compared to control, PEG400 (P < 0.05). The brain (olfactory bulb) levels of MT after intranasal administration were 9.22, 6.77 and 4.04-fold higher for carbopol, CMC and PEG400, respectively, than that of intravenous MT in rats. In conclusion, microdialysis studies demonstrated increased brain levels of MT via nasal administration in rats.