Liposomes in Enzyme Carriers

Introduction

Enzyme drugs are all biological macromolecules. Their common feature is that they are unstable in the body and are easily degraded by proteolytic enzymes. Therefore, their half-life in vivo is short, and most of them are not suitable for oral administration. These problems can be solved by using liposomes as enzyme carriers.

Application

The natural targeting of liposomes makes the enzyme-encapsulated liposomes mainly taken up by the liver, so liposomes are good drug carriers for the treatment of enzyme storage diseases. In addition, liposomes have also been used to treat other enzymatic diseases.

Superoxide dismutase (SOD) can scavenge excess superoxide anion free radical damage in the body, but it is easily destroyed by proteolytic hydrolysis in the body. After encapsulation with liposomes, the in vivo half-life is significantly improved, and liposomes can increase the uptake of SOD by cells, thereby better protecting cells from free radical damage.

Amylo-glucose-encapsulated multi-chambered liposomes have been used in the treatment of type II glycogen storage disease (Pompe disease), resulting in a significant reduction in the size of the patient's liver. Liposomes are also used to treat lysozyme storage disease, which is Gaucher disease in adults. In the past, free enzymes have been used to treat this disease. Due to the destruction and inactivation of enzymes in the body and the lack of targeting, the patient develops disease after taking the drug. There was little or no change in clinical indicators. If the enzyme was injected into a patient encapsulated in liposomes and clinical indicators were examined, the formulation was found to be effective within 48 hours of injection.

The results of Anderson et al. showed that the half-life of free IL-2 was only 6 minutes when injected subcutaneously, whereas the half-life of liposome-encapsulated IL-2 was 68 minutes, and the distribution and pharmacokinetics of liposome-encapsulated IL-2 were significantly altered. After oral administration of insulin, the bioavailability is low due to the destructive effects of gastric enzymes and gastric acid. These drawbacks can be overcome with liposome-encapsulated IL-2, and the blood glucose of the animals decreased significantly after oral administration.

Reference

1. Finkelstein; et al. The introduction of enzymes into cells by means of liposomes. Journal of Lipid Research. 1978 19: 289-302.