Ligand conjugation: An emerging platform for enhanced brain drug delivery

The drug delivery across the brain has always been problematic due to the tight junction present namely the blood brain barrier (BBB). BBB only allows selected pharmaceutical drugs to get across it and reach the brain via lipid free diffusion process and exert their therapeutic effect. This leads to the decrease in drug accessibility to brain. More recently, various approaches were employed to allow larger molecules to cross BBB by reengineering them and conjugating them with ligands which could facilitate their entry across BBB. Therefore literature was explicitly exploited to deduce various ligands employed to enhance the drug delivery across brain via transcytosis. As per established literature, there are evidences that ligand conjugated drug formulations have substantially improved brain uptake. The review presents numerous ligands employed along with the receptor targeted to improve drug uptake by the brain, its anticipated effects and the outcome derived.