Nose to Brain Drug Delivery: A Directed Approach for Delivering Drug into Brain

Abstract

Poor/delayed bioavailability and hepatic first pass metabolism are the major concern when most common oral
route is chosen for the delivery of drug, which is why alternate therapies are constantly sought for. Oral route
known to have first dissolution of drugs in stomach followed by absorption in systemic circulation which may lead
to delay in the effect of drug and reduce the efficacy and potency of the drug. When it is a matter of targeting to
the brain, less lipophilic drugs have limited accessibility to the brain and thereby delays therapeutic effect. These
limitations about brain targeting system suggest the requirement for the development of delivery system that will
transport the medication in to the brain with adequate concentration to get pharmacological action. Drug delivery
to brain through nasal mucosa is nowadays emerging way of transport of drug. This method devotes of first pass
effect, improves absorption and requires minimal dose. Nasal in situ gel, after administration, converts rapidly
into gel from liquid after contact with nasal mucosal region allowing adhering of drug in to nasal region. Nasal
epithelium allows molecular mass up to 500 Da to pass and thus, the rapid drug accumulation in brain. This review
focuses on nasal administration of medicines as a new method of drug transport into the brain. The mechanism of
drug absorption through the mucous membrane of the nose, different types of nasal drug administration, methods
of production, and polymers required are all described in this paper.