Polymer coatings are used to control the release of drugs from oral solid dosage forms. They are used to enhance systemic delivery by directing the release of the API to specific areas of the small intestine or colon, and targeted delivery in this way may be important for several reasons.
Active ingredients that are labile or that may irritate the stomach can be coated to pass through the stomach intact. For the treatment of local diseases such as ulcerative colitis, Crohn’s disease or irritable bowel syndrome, drugs can be released at the local area of the disease. Coatings can also be used to mask unpleasant tastes and odours.
We have enormous expertise in the three principal approaches of targeting release by using coating technologies.
pH-controlled release We can use pH-controlled release. These systems use polymer coatings that respond to the reduction in acidity as they pass from the stomach to the small intestine. We use polymer profiles that are insoluble at the lower pH values in the stomach but soluble in the higher pH environment of the small or large intestine.
Enzymatic release These systems use coatings that are essentially polysaccharide based. They are resistant to digestion in the stomach but are degraded by the microbial enzymes of the normal gut flora once they reach the lower gastrointestinal tract.
Timed release In these systems, the dosage form is designed to release the API at a specific time after ingestion by using an erodible coating, possible in combination with manipulating the formulation to assist the effect.