Compendium of pH-sensitive polymers in gastroenterology drugs: focus on enteric coatings

Abstract

This compendium for gastroenterologists and hepatologists contains information about pH-sensitive polymers used in dosage forms for oral administration and delivery of drugs to certain parts of the gastrointestinal tract. There is more information here on pH-insensitive polymers in laxatives, hepatology antivirals and rectal agents. There is also background information on the chemical, spatial structure and properties of pH-sensitive and individual pH-insensitive polymers, the physiological basis for their transformations under certain characteristics of the environment in the lumen of the gastrointestinal tract. These are aspects of their use in targeted drug delivery systems, use as active ingredients or “increasers” of the molecular weight of other active ingredients. The main attention is paid to polymers used in the production of enteric coatings for tablets and granules (pellets). The material is illustrated with examples of drugs registered in the Russian Federation and promising drugs with dosage forms for diffuse application of antibiotics to the gastric mucosa, for targeted delivery of drugs to the duodenum and other parts of the small and large intestines. Chitosan-based hydrogels, a liposomal form of doxycycline, enteric dosage forms with pH-sensitive polymers, more complex delivery systems with two drug release triggers, and dosage forms with thermosensitive polymers have been described. Thus, polymers, which are an essential component of the environment and living conditions of modern humans, entered the pharmacotherapeutic field as active substances or components that increase the the local pharmacodynamic effect, bioavailability or slow down the excretion of drugs. Knowledge of the chemical and structural features of high-molecular compounds, their changes in certain environmental conditions is necessary for making the right decisions in those areas of medicine where drugs with polymers of different properties are used, in particular, in gastroenterology, proctology and hepatology.