MODERN STATE OF CREATION, PRODUCTION AND RESEARCH OF DRUGS. Message 23. Characteristic of development, research and application of new therapeutic colon target delivery systems

Abstract

Introduction. The oral aspect is considered to be most convenient for administration of drugs to patients.

Nowadays it was developed a number of therapeutic colon target delivery systems (CTDS) in order to solve the problem of drug delivery in the colon. At the time, colon can be as a target of local action and / or location systemic absorption of medications. The advantage of that system is that the active substances can be selectively absorbed just in the colon and not in others parts of gastrointestinal tract. A colonic targeted approach found to be effected in minimizing uncertain side effects.

The main purpose of searching new drug delivery technologies is to keep control under the processes of the active substance in the body with the ability to manage this process to maintain an effective concentration of the drug in plasma or tissues for a long time.

Investigation methods. The review of foreign literature of the development, research and application of new therapeutic colon target delivery systems was conducted.

Results and discussion. In general, seven primary approaches have been proposed for targeted colon delivery, namely:

• Transit time dependent colonic drug delivery system (CDDS);
• pH Dependent CDDS;
• pH- and time-dependent CDDS;
• Bacterial enzyme dependent CDDS;
• pH and bacterial enzyme dependent CDDS;
• Colonic pressure controlled DDS;
• Osmotic pressure controlled CDDS.

Drugs which show poor absorption from the stomach as intestine including peptide are most suitable for CDDS. The drugs used in treatment of inflammatory bowel diseases, ulcerative colitis, diarrhea and colon cancers are ideal candidates for local colon delivery.

The selection of carrier for particular drug candidate depends on the physiochemical nature of the drug as well as the disease for which the system is to be used. The factors such as chemical nature, stability and partition coefficient of drug and the type of absorption enhancers chosen influence the carrier selection.Matrix tablets containing various excipients and polysaccharide were prepared by wet granulation technique using different binder systems.

Some study confirms that dextrin is a good carrier for Paracetamol to deliver it in colon specifically. Based on other results, selective delivery of Tramadoli hydrochloride to the colon could be achieved using almond gum as release modifier. Other study confirms that dextrin can act as good carrier in the form of matrix tablet for Aceclofenac to deliver it in colon specifically by using ethyl cellulose as binder.

So, colon specificity is more likely to be achieved with systems that utilize natural materials that are degraded by colonic bacterial enzymes. Considering the sophistication of colon-specific drug delivery systems, and the uncertainty of current dissolution methods in establishing possible in-vitro/in-vivo correlation, challenges remain for pharmaceutical scientists to develop and validate a dissolution method that incorporates the physiological features of the colon, and yet can be used routinely in an industry setting for the evaluation of CDDS.

Conclusions. The basic features, classification and approaches for development of the colon target delivery systems were considered. The instances of preparation peroral CTDS that have durable action in colon was reported. It should be noted that the theme of the development of CTDS is still actual for further study and comprehensive research. The concept of targeting the delivery of specific drugs to colon is quite self explanatory and sufficient scientific rationale is available to support the justification.