RESEALED ERYTHROCYTES AS A POTENTIAL DRUG CARRIER SYSTEMAbstract
Novel drug delivery system has been introduced to overwhelm the drawback of fluctuating drug levels associated with conventional dosage forms. Out of various cellular carrier systems, erythrocytes (red blood cells, RBC) have been the most widely investigated and found to possess great potential for the delivery of drugs and drug-loaded microspheres. These cellular carriers, having remarkable biocompatibility, biodegradability, and life-span in circulation, can be loaded by a wide spectrum of compounds of therapeutic value using different chemically, as well as physically, based methods. Most of the characteristics of the erythrocytes, including shape, membrane fragility, deformability, and hematologic indices undergo some degree of irreversible changes during the loading procedure. Carrier erythrocytes are prepared simply by collecting blood sample from the organism of interest, separating erythrocytes from plasma, then by using various physical and chemical methods the cells are broken. The drug is entrapped into the erythrocytes and finally resealing the resultant cellular carriers. Hence these carriers are suitably known as Resealed erythrocytes. Surface modification with glutaraldehyde, antibodies, carbohydrates like sialic acid and biotinylation of loaded erythrocytes (biotinylated erythrocytes) is possible to achieve various levels of targeting and increased circulation half-life. Upon reinjection the drug loaded erythrocytes serve as slow circulation depots, targets the drug to the reticuloendothelial system (RES), prevents degradation of loaded drug by endogenous chemicals, attain steady state concentration of drug and decrease the toxic-effects of loaded drug.