Method for Analysis, and Distribution Profile, of Covalently‐linked Ferritin‐daunorubicin Conjugate in the Blood of Trypanosome‐infected Mice

— Daunorubicin is a highly potent trypanocide in-vitro but is inactive in-vivo. When daunorubicin is conjugated to bovine serum albumin or horse spleen ferritin using Schiffs base linkages, the complex is trypanocidal in-vitro and in-vivo. We have developed novel analytical methods, using HPLC with fluorimetric detection, for the quantitation of daunorubicin and doxorubicin in biological samples, either as unconjugated drug, or when covalently linked to macromolecules or particles. Ferritin-daunorubicin conjugate (25 mg kg−1) was administered intraperitoneally to mice infected with monomorphic Trypanosoma brucei rhodesiense; peak plasma levels occurred after 1·5 h, and were 5 times higher than those resulting from administration of an equivalent amount of unconjugated daunorubicin. Plasma levels then declined rapidly (t½ for 1–6 h period was 0·58 and 0·86 h respectively for conjugated and unconjugated daunorubicin). However, higher plasma levels were seen 24 h after treatment, suggesting the distribution profile of daunorubicin when conjugated to ferritin is multiphasic with resultant high levels of daunorubicin obtained for a prolonged time period.