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Background:Human brain is amongst the most complex organs in human body, and delivery of therapeutic agents across the brain is a tedious task. Existence of blood brain barrier (BBB) protects the brain from invasion of undesirable substances; therefore it hinders the transport of various drugs used for the treatment of different neurological diseases including glioma, Parkinson's disease, Alzheimer's disease, etc. To surmount this barrier, various approaches have been used such as the use of carrier mediated drug delivery; use of intranasal route, to avoid first pass metabolism; and use of ligands (lactoferrin, apolipoprotein) to transport the drug across the BBB. Ligands bind with proteins present on the cell and facilitate the transport of drug across the cell membrane via. receptor mediated, transporter mediated or adsorptive mediated transcytosis.Objective:The main focus of this review article is to illustrate various studies performed using ligands for delivering drug across BBB; it also describes the procedure used by various researchers for conjugating the ligands to the formulation to achieve targeted action.Methods:Research articles that focused on the used of ligand conjugation for brain delivery and compared the outcome with unconjugated formulation were collected from various search engines like PubMed, Science Direct and Google Scholar, using keywords like ligands, neurological disorders, conjugation, etc.Results and Conclusion:Ligands have shown great potential in delivering drug across BBB for treatment of various diseases, yet extensive research is required so that the ligands can be used clinically for treating neurological diseases.

The structure of the eye is very complex in nature which makes it a challenging task for pharmaceutical researchers to deliver the drug at the desired sites via different routes of administration. The development of the nano-based system helped in delivering the drug in the desired concentration. Improvement in penetration property, bioavailability, and residence time has all been achieved by encapsulating drugs into liposomes, dendrimers, solid lipid nanoparticle, nanostructured lipid carrier, nanoemulsion, and nanosuspension. This review puts emphasis on the need for nanomedicine for ocular drug delivery and recent developments in the field of nanomedicine along with recent patents published in the past few years.

Abstract: At present, people and patients worldwide are relying on the medicinal plant as a therapeutic agent over pharmaceuticals because the medicinal plant is considered safer, especially for chronic disorders. Several medicinal plants and their components are being researched and explored for their possible therapeutic contribution to CNS disorders. Thymoquinone (TQ) is one such molecule. Thymoquinone, one of the constituents of Plant Nigella Sativa, is effective against several neurodegenerative diseases like, Alzheimer's, Depression, Encephalomyelitis, Epilepsy, Ischemia, Parkinson's, and Traumatic. This review article presents the neuropharmacological potential of TQ's, their challenges, and delivery prospects, explicitly focusing on neurological disorders along with their chemistry, pharmacokinetics, and toxicity. Since TQ has some pharmacokinetic challenges, scientists have focused on novel formulations and delivery systems to enhance bioavailability and ultimately increase its therapeutic value. In the present work, the role of nanotechnology in neurodegenerative disease and how it improves the bioavailability and delivery of a drug to the site of action has been discussed. There are a few limitations to developing novel drug formulations, including solubility, pH, and compatibility of nanomaterials. Since here we are targeting CNS disorders, the bloodbrain barrier (BBB) becomes an additional challenge. Hence, the review summarized the novel aspects of delivery and biocompatible nanoparticles-based approaches for targeted drug delivery into CNS, enhancing TQ bioavailability and its neurotherapeutic effects.