AIDS and
Cancer are two main diseases which face humankind today. There is need for innovation and a scientific approach
to find a cure for these diseases. Thus,
erythrocytes can be used as drug delivery systems which can carry the drug to the active site and release it which will help to cure these diseases.Erythrocytes are not toxic nor immunogenic and are biodegradable. They are easy to obtain, their cellular volume is large enough to load high quantities of active substances and their half life is well defined. Due to their physiological role they have access to most parts of the body and can be used as drug carriers to deliver the drug to the active site.Interleukin2 , a lymphocytotropic hormone secreted exclusively by stimulated T-cells has been characterized of major importance in both cell mediated and humoral immunity. Lymphokine therapy is being used in high dose regimes to treat
cancer.The clinical trials have shown that IL2 administration can mediate the regression of established tumors especially cell carcinoma and malignant carcinoma and thus treat cancer.IL2 has very rapid clearance from the circulation which means a shorter duration of action for the drug.Due to rapid clearance of the drug from the body higher doses of IL2 administration is required which leads to toxicity.Erythrocytes coated with recombinant IL2 (rIL2) provides a means of delivering IL2 in a continuous low dose manner which in turn maintains a low potentially non-toxic IL2 concentration. At the same time results indicate that rIL2 retains its biological activity when bound to RBC`s and have a longer duration of action which leads to lower frequency of dose and thus could prove useful as therapeutic delivery system for cancer treatment. Nucleoside analogues such as Azidothymidine (AZT) , Dideoxycytidine (ddc) and Dideoyinosne (ddi) are most common drugs for treatment of HIV. These drugs are first phosporylated by the cellular kinases present in the body and then they get activated and inhibit the infectivity and replication of HIV virus.The enzymes needed for phosporylation are present in small quantities in quiescent cells . Moreover, AZT, ddc and ddi have low permeability through cerebrospinal fluid (CSF) and low half life in plasma. Thus, high doses and greater frequency of administration are necessary to obtain therapeutic efficiency with consequent enhancement of toxicity for the organism.A new nucleoside analogue di (thymidine-3`-azido-2`,3`-di-deoxy-D-riboside) -5`,5`-p1-p2 pyrophosphate ( AZTp2AZT) has been designed. This was encapsulated in human erythrocytes and it showed a remarkable stability and slow conversion to 5`-monophosphate(AZT-MP) and to AZT. This azidothymidine homonucleotide seems to have chemical and biochemical properties enabling its profitable utilization in erythyrocyte encapsulated form in order to treat AIDS.Erythrocyte carrier systems are very unique and are useful specific targeting agents with a prolonged , sustained action with minimal toxic effects. The stability of this carrier system provides greater applications especially of enzymes and proteins by minimizing immunological reactions and enhance stability. Its application reduces the toxicity so that higher doses of IL2 can be used to treat cancer and the use of more drugs such as 3`-azidothymidine homonucleotide as an anti-HIV drug.