Survival of gentamicin‐loaded carrier erythrocytes in healthy human volunteers

Abstract

Resealed erythrocytes are potential slow release carriers for drugs and enzymes. We have investigated carrier erythrocyte survival in human volunteers using gentamicin (G) as encapsulated cell marker; G was readily incorporated into red cells by hypo-osmotic dialysis (87% efficiency of incorporation) and did not exit from carrier cells in vitro. Six healthy young volunteers were injected with 59 ± 7 ml carrier erythrocytes containing 56 ± 13 mg G. G levels were measured in plasma and haemolysed whole blood by RIA. After an initial phase of cell loss (up to 4·5 h post-injection) the carrier erythrocytes survived in circulation with a half-life of 22 days, as was indicated by intracellular G concentration. G levels were detectable in plasma during the first 90 min after injection. This indicates haemolysis of some carrier cells. In conclusion, carrier erythrocytes appear to circulate longer than any other drug carrier under investigation and may well serve as innocuous slow release system.