Biotinylated methotrexate loaded erythrocytes for enhanced liver uptake. 'A study on the rat'

To serve as liver specific delivery system, methotrexate (MTX) loaded erythrocytes were modified by attachment with N-hydroxysuccinimide ester of biotin (NHS-biotin) and in vitro macrophage uptake and in vivo studies were carried out in the rat. Surface bound biotin was quantitated indirectly using an avidin support and measuring the change in absorbance at 500 nm by the interaction with 2-(4' hydroxyazobenzene) benzoic acid (HABA). A concentration course study of biotin binding reaction showed biotin molecules bound to the erythrocytes as a function of the NHS-biotin concentration. Glycerol lysis time study revealed enhanced stability of biotinylated cells (BT) compared with nonbiotinylated drug loaded cells (NB). These surface modified erythrocytes were characterized for in vitro macrophage uptake. The macrophage uptake and phagocytic index of these modified erythrocytes were enhanced by more than two-fold compared with NB cells (P<0.05). In vivo organ localization was assessed by recording amount of drug present in different organs. The modified carrier induces substantial liver targeting as drug therapeutic index in liver was found to be 3.1. These findings support the use of carrier erythrocytes, exploiting the targeting properties imparted by biotinylation. Consequently, it can spare surgical intervention to place hepatic arterial catheters for locoregional treatment of liver neoplasms.