INTRODUCTION: {1} Now-a-days research is being carried out for the development of drug delivery system with maximum therapeutic effects. Introduction of a probe into the existing delivery system results in the development of a new safe drug delivery system with maximum therapeutic effects and minimal side effects. Erythrocytes otherwise called as red blood cells are being used as carriers and drug-loaded microspheres as well. WHY ARE THESE CALLED RESEALED ERYTHROCYTES,...?{1} Carrier erythrocytes are prepared by collecting the blood samples from the selected organism, separating the RBC from the plasma, entrapping the drug in the erythrocytes and resealing the resultant carrier. Based on the procedure of their preparation they are hence termed as resealed erythrocytes. METHODS OF DRUG LOADING: {1} Several methods have been developed for the preparation of these carrier erythrocytes like physical osmosis based systems (e.g: electrical pulse method) and chemical methods (e.g: chemical perturbation of the erythrocyte membrane) etc. But whatever may be the process employed the drug being sealed should possess certain properties for its successful entrapment. They are: 1.Considerable degree of water solubility. 2.It should not have any physical or chemical interactions with the erythrocyte membrane. 3.It should be resistant against the degradation within erythrocytes. 4.It should possess well-defined pharmacokinetic and pharmacodynamic properties. The methods employed for the preparation of resealed erythrocytes can be classified as follows: 1. Hypo-osmotic lysis method: a. Dilution method b. Dialysis method c. Preswell method d. Isotonic osmotic lysis method 2. Electrical breakdown method 3. Endocytosis method 4. Membrane perturbation method ADVANTAGES OF ERYTHROCYTES AS CARRIERS: {1} 1. Their ability to circulate through out the body. 2. Uniform size and shape of the carrier. 3. Their biodegradability with no generation of toxic products. 4. A wide variety of chemicals can be entrapped. 5. Possibility of ideal zero-order kinetics. 6. Attainment of steady state plasma concentration decreases fluctuations in concentration etc... LIMITATIONS: {1} 1.Limited potential as carrier to non-phagocytic target tissue. 2.Possible clumping of RBC and there by dose dumping may occur. CONCLUSION: {1} Use of resealed erythrocytes has gained massive importance in modern day research. It looks promising for safe delivery of various drugs. However, the concept of resealed erythrocytes needs further optimization to become a routine drug delivery system. RERFERENCES: {1}PHARMA BUZZ, AN ASSEMBLAGE OF PHARMACEUTICAL RESOURSES, A NATIONAL PHARMA MONTHLY MAGAZINE, MAY 2011, VOLUME 6, ISSUE 05. "THIS BLOG DOES NOT CONTAIN ANY PLAGIARISED MATERIAL"