ABSTRACT
The oral route is considered to be most convenient for administration of drugs to patients. The selection of polymers is an important thing in case of colon-specific drug delivery. Drugs which show poor absorption from the stomach and intestine including proteins and peptides are most suitable for colon-specific drug delivery system. The choice of drug carrier depends on the functional groups of drug molecule. Studies of colonic motility in vivo usually rely on measurement of changes in muscle electrical activity that may determine contractions. In the stomach, pH ranges between 1 and 2 during fasting but increases after eating. The colonic transit may be important in the absorption of some poorly water soluble drugs and sustained release dosage forms. The passage of drug from stomach to small intestine is called gastric emptying and the time required for this process to take place is known as gastric emptying time. Coating is one of the simplest formulation technologies used for colon-specific delivery.
