CALCIUM PHOSPHATE COATED LIPOSOMES: A NOVEL APPROACH FOR DRUG TARGETTING

Abstract

Cancer is a major public health problem in the world. Cancer continues to be a major life-threatening disease. The most limiting factors in treatment of cancer are mutation and drug resistance in the cancer cells, poor selectivity and immunosuppressive action, side effect of the anticancer drugs, and low penetration in solid tumor. Liposomes have raised considerable interest as drug carriers in cancer chemotherapy because of their ability to alter the biodistribution by selectively targeting the drug to the tumor and control the release rate of encapsulated drugs. Such formulation and drug targeting strategies enhance the effectiveness of anticancer chemotherapy and reduce at the same time the risk of toxic side-effects. In spite of desirable feature of liposome as carrier, they suffer from disadvantages such as their rapid clearance from systemic circulation leading to short duration of action, less stability and drug leakage resulting into loss of drug before it reaches the target site. Such draw backs can be easily overcome by coating the liposome with materials such as silica and calcium phosphate. Calcium phosphate coated liposome has excellent biocompatibility, absorbability and high binding affinity for variety of molecules. Dissolution Profile of calcium phosphate play an important role in drug release. Calcium phosphate has low solubility at pH 7.4 and thus it is expected that there would be negligible dissolution and hence the drug release from the liposomes while in systemic circulation. Calcium phosphate dissolves to an appreciable extent at acidic pH and thus is expected to dissolve and release the drug at the pH of the tumor interstitium (4.5 to 5.5).