In particular, PECs formed between pectin and chitosan are considered as promising candidates for colon-targeted delivery of therapeutically-active moieties because of its physiological inertness and relatively higher resistance to enzymatic degradation . Microspheres based on this complex were proven to have better protective effect against immature drug release in the stomach as the interaction between pectin or and chitosan is more favored at low pH values . Preparation of chitosan PECs The preparation of such PECs is a mild and reversible process requiring only the reacting species. It requires no auxiliary molecules as initiators or catalysts, no additional purification steps, and is almost done in aqueous medium . Therefore, this electrostatic interaction was found to be superior to the chemical (covalent) crosslinking reaction, with respect to the safety and avoidance of organic solvents and chemical cross-linkers thereby, reducing toxicity and undesirable side-effects . Two methods were reported for the formation of chitosan PEC. The single step method is a simple and efficient one in which, an aqueous solution of the polyanion is added dropwise into the crosslinking medium containing chitosan . Alternatively, a two-stage method is available which involves coating of the preformed Ca-pectinate or Ca-alginate beads with an external membrane of chitosan . Drugs formulated as chitosan microspheres for colonic targeting: Various categories of drugs could be targeted to the colon, including drugs which are unabsorbed in the upper GIT or those required for treatment of local colonic pathologies. Moreover, the colonic delivery is also beneficial for systemic absorption of some drugs. Chitosan-based microspheres were extensively investigated for various classes of drugs, such as anticancer drugs including Fluorouracil , Cisplatin , Mitoxantrone , Methotrexate and Taxol ; anti-inflammatory drugs including Indomethacin , Diclofenac sodium , Prednisolone , cardiovascular drugs Ketoprofen , Piroxicam and Sulfasalazine ; including Diltiazem , antibiotics Nifedipine , Propranolol and Isosorbide mononitrate ; including Amoxycillin ,
In particular, PECs formed between pectin and chitosan are considered as promising candidates for colon-targeted delivery of therapeutically-active moieties because of its physiological inertness and relatively higher resistance to enzymatic degradation . Microspheres based on this complex were proven to have better protective effect against immature drug release in the stomach as the interaction between pectin or and chitosan is more favored at low pH values . Preparation of chitosan PECs The preparation of such PECs is a mild and reversible process requiring only the reacting species. It requires no auxiliary molecules as initiators or catalysts, no additional purification steps, and is almost done in aqueous medium . Therefore, this electrostatic interaction was found to be superior to the chemical (covalent) crosslinking reaction, with respect to the safety and avoidance of organic solvents and chemical cross-linkers thereby, reducing toxicity and undesirable side-effects . Two methods were reported for the formation of chitosan PEC. The single step method is a simple and efficient one in which, an aqueous solution of the polyanion is added dropwise into the crosslinking medium containing chitosan . Alternatively, a two-stage method is available which involves coating of the preformed Ca-pectinate or Ca-alginate beads with an external membrane of chitosan . Drugs formulated as chitosan microspheres for colonic targeting: Various categories of drugs could be targeted to the colon, including drugs which are unabsorbed in the upper GIT or those required for treatment of local colonic pathologies. Moreover, the colonic delivery is also beneficial for systemic absorption of some drugs. Chitosan-based microspheres were extensively investigated for various classes of drugs, such as anticancer drugs including Fluorouracil , Cisplatin , Mitoxantrone , Methotrexate and Taxol ; anti-inflammatory drugs including Indomethacin , Diclofenac sodium , Prednisolone , Ketoprofen , Piroxicam and Sulfasalazine ; cardiovascular drugs including Diltiazem , Nifedipine , Propranolol and Isosorbide mononitrate ; antibiotics including Amoxycillin ,
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