Application of chitosan and its derivatives in drug delivery

Drug delivery is a method of delivering drug to the patients in a way which increases the concentration of drug to the relevant site by directing the drug to the specific site of action. Polymeric drug delivery systems are mostly preferred to take the drug to the specific site of action and achieve the therapeutic effect. Among different types of biocompatible polymers, carbohydrate-based polymers or polysaccharides are the most common natural polymers with complex structures consisting of long chains of monosaccharide or disaccharide units bound by glycosidic linkages. One such polymer is chitosan which is used in drug delivery. Chitosan’s appealing properties, especially of natural origin, may mediate the protection against degradation of the biologically active substance, control the release of the drug, boost the absorption, increase the physiological action and result in a consequent reduction in the rate of administration. Another advantage of using chitosan is its chemical structure that could be modified easily which makes chitosan derivatives used for different applications. The main objective is to provide an overview on chitosan and its derivatives applications in drug delivery.

In-Situ Forming Polymeric Drug Delivery Systems for Ophthalmic Use: An Overview

Delivery of drug into the ocular region is hindered by the protective layers that encapsulate the eyes, it has always been a major problem to get an effective bioavailability of the active drug in the ocular region due to the low precorneal resident time of most of the ocular delivery systems specifically convention once such as ointment, solution and suspension, as a result, most of the delivery systems are not capable of effectively treating ocular diseases. Several works have and are being carried out to overcome this problem one of which is using in-situ forming polymeric systems. Ocular In-situ gelling systems are a novel class of ocular drug delivery systems that are initially in a solution form but instantaneously gets converted into a viscous gel upon introduction or installation in the ocular cavity from which the active drugs get released in a sustained manner. This sol-to-gel phase transition depends upon various factors like change in pH, ion presence and change in temperature. Gel formed after the transformation has preferred viscosity along with bio-adhesive property, which increases the gel’s resident time in the ocular area and also releases the drug in a prolonged and sustained manner unlike conventional eye drops and ointments. This review emphasizes various ocular in-situ systems namely, pH triggered, Ion activated, and Temperature triggered systems which have prolonged residence time in the cul-de-sac area of the eye, hence increasing the ocular bioavailability. Keywords: In-situ gel, Ocular Drug delivery, Ocular Bioavailability, Polymer

Polymeric Drug Delivery Systems Bearing Cholesterol Moieties: A Review

This review aims to provide an overview of polymers comprising cholesterol moiety/ies designed to be used in drug delivery. Over the last two decades, there have been many papers published in this field, which are summarized in this review. The primary focus of this article is on the methods of synthesis of polymers bearing cholesterol in the main chain or as side chains. The data related to the composition, molecular weight, and molecular weight distribution of polymers are presented. Moreover, other aspects, such as forms of carriers, types of encapsulated drugs, encapsulation efficiency and capacity, are also included.