What is the half-life of clodronate (liposomes)?

The half-life (t1⁄2) of clodronate released from dead macrophages is in the order of minutes[3], since free clodronate is rapidly cleared from the circulation by the renal system. Free clodronate molecules will not easily enter into cells due to difficulty in passing cell membranes, including liposomal phospholipid bilayers. However, if they remain in the surrounding medium, they may slowly accumulate into cells[4].

The half-life of clodronate liposomes is difficult to determine. Liposomes are difficult to isolate from blood and their distribution in the animal is not even. Further, the half-life of clodronate liposomes depends on the time it takes to be ingested and digested by macrophages, which is determined by many factors, such as: immunocompetence of the animal model, route of administration, dose of administration.

1. Fleisch, H. (2000). Bisphosphonates in bone disease: from the laboratory to the patient. Elsevier.
2.Claassen, I., Van Rooijen, N., & Claassen, E. (1990). A new method for removal of mononuclear phagocytes from heterogeneous cell populations in vitro, using the liposome-mediated macrophage ‘suicide’ technique. Journal of immunological methods, 134(2), 153-161.