Convolutions in the rendition of nose to brain therapeutics from bench to bedside: Feats & fallacies.

Brain, a subtle organ of multifarious nature presents plethora of physiological, metabolic and bio-chemical convolutions that impede the delivery of biomolecules and thereby resulting in truncated therapeutic outcome in pathological conditions of central nervous system (CNS). The absolute bottleneck in the therapeutic management of such devastating CNS ailments is the BBB. Another pitfall is the lack of efficient technological platforms (due to high cost and low approval rates) as well as limited clinical trials (due to failures of neuro­leads in late-stage pipelines) for CNS disorders which has become a literal brain drain with poorest success rates compared to other therapeutic areas, owing to time consuming processes, tremendous convolutions and conceivable adverse effects. With the advent of intranasal delivery (via direct N2B or indirect nose to blood to brain), several novel drug delivery carriers viz. unmodified or surface modified nanoparticle based carriers, lipid based colloidal nanocarriers and drysolid/liquid/semisolid nanoformulations or delivery platforms have been designed as a means to deliver therapeutic agents (small and large molecules, peptides and proteins, genes) to brain, bypassing BBB for disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), epilepsy, schizophrenia and CNS malignancies primarily glioblastomas. Intranasal application offers drug delivery through both direct and indirect pathways for the peripherally administered psychopharmacological agents to CNS. This route could also be exploited for the repurposing of conventional drugs for new therapeutic uses. The limited clinical translation of intranasal formulations has been primarily due to existence of barriers of mucociliary clearance in the nasal cavity, enzyme degradation and low permeability of the nasal epithelium. The present review literature aims to decipher the new paradigms of nano therapeutic systems employed for specific N2B drug delivery of CNS drugs through in silico complexation studies using rationally chosen mucoadhesive polymers (exhibiting unique physicochemical properties of nanocarrier's i.e. surface modification, prolonging retention time in the nasal cavity, improving penetration ability, and promoting brain specific delivery with biorecognitive ligands) via molecular docking simulations. Further, the review intends to delineate the feats and fallacies associated with N2B delivery approaches by understanding the physiological/anatomical considerations via decoding the intranasal drug delivery pathways or critical factors such as rationale and mechanism of excipients, affecting the permeability of CNS drugs through nasal mucosa as well as better efficacy in terms of brain targeting, brain bioavailability and time to reach the brain. Additionally, extensive emphasis has also been laid on the innovative formulations under preclinical investigation along with their assessment by means of in vitro /ex vivo/in vivo N2B models and current characterization techniques predisposing an efficient intranasal delivery of therapeutics. A critical appraisal of novel technologies, intranasal products or medical devices available commercially has also been presented. Finally, it could be warranted that more reminiscent pharmacokinetic/pharmacodynamic relationships or validated computational models are mandated to obtain effective screening of molecular architecture of drug-polymer-mucin complexes for clinical translation of N2B therapeutic systems from bench to bedside.

Bio-Inspired Strategies against Diabetes and Associated Complications: A Review.

Bio-molecules are the most important target to be considered while designing any drug delivery system. The logic lies in using such bio-sensing or bio-mimicking systems in their formulations that can mimic the active site of those receptors to which the drug is going to bind. Polymers mimicking the active site of target enzymes are regarded as bio-inspired polymers and can be used to ameliorate many diseased conditions. Nowadays, this strategy is also being adopted against diabetes and its complications. Under hyperglycemic conditions, many pathways get activated which are responsible for the progression of diabetes-associated secondary complications viz. retinopathy, neuropathy, and nephropathy. The enzymes involved in the progression of these complications can be mimicked for their effective management. For an instance, Aldose Reductase (ALR2), a rate-limiting enzyme of the polyol pathway (downstream pathway) which gets over-activated under hyperglycemic condition is reported to be mimicked by using polymers which are having same functionalities in their structure. This review aims at critically appraising reports in which target mimicking bio-inspired formulations have been envisaged against diabetes and its complications. The information summarized in this review will provide an idea about the bio-sensing approaches utilized to manage blood glucose level and the utility of bio-inspired polymers for the management of diabetic complications (DC). Such type of information may be beneficial to pharmaceutical companies and academia for better development of targeted drug delivery systems with sustained-release property against these diseased conditions.