Approaches in Barriers, Modifications, Route of Administrations, and Formulations of Therapeutic Agents for Brain Delivery

The barriers in the delivery of the therapeutic agent to brain diseases are blood–brain barrier (BBB), blood-cerebrospinal fluid barrier, and cellular barriers. The above mentioned barriers limit the distribution of the therapeutic agent or drug delivery system, thereby affects the therapeutic efficacy. The route of administration is also an important factor in the drug delivery to the brain diseases. Therefore, there is unmet need for the development of drug delivery systems which will overcome the barriers and delivers the therapeutic agent to the brain diseases. This chapter is focused on various strategies used to overcome the barriers in drug delivery to the brain diseases. The application of energy and chemical substances such as osmotic agent and permeation enhancers has been studied. Other strategies, such as developing the prodrug and inclusion complex of therapeutic agents, have been explained. The application and limitations of the different routes of administration such as intravenous, intra-arterial, intranasal, intracerebral, and intracerebroventricular have been described. The drug delivery system in the nanoscale such as liposomes, nanoemulsion, polymeric nanoparticles, and dendrimer have been explored to overcome the limitations associated with drug delivery to the brain diseases. Specific examples are described in this chapter. Lastly, various ongoing clinical trials for drug targeting to the brain are listed.