Engineering prolonged-acting prodrugs employing an albumin-binding probe that undergoes slow hydrolysis at physiological conditions

Abstract Here we describe the design and application of OSu–FMS–MAL–S–(CH 2 ) 15 –COOH, an agent that associates with albumin while linked to a peptide or a protein with sufficient affinity (Ka = 2 to 2.6 × 10 5  M - 1 ) to protract the action of short- lived peptides and proteins in vivo. Under physiological conditions this probe undergoes spontaneous hydrolysis with the concomitant reactivation of inactive conjugates. Intravenously administered 125 I-labeled-Insulin–FMS–MAL–S–(CH 2 ) 15 –COOH to rats shows half-life of 17 ± 2 h, exceeding 5.2 times that obtained with intravenously administered 125 I-labeled Insulin. In mice this derivative facilitates glucose-lowering effect over a period of 24 h, yielding AUC five times greater than that obtained by a similar dose of insulin-detemir. Similarly, subcutaneous administration of Exendin-4–FMS–MAL–S–(CH 2 ) 15 –COOH into mice facilitated prolonged and stable reduction in glucose level, yielding a t ½ value of 28 ± 2 h, exceeding the effect of exendin-4 4.7 folds. The inactive derivative gentamicin–FMS–MAL–S–(CH 2 ) 15 –COOH regained its full antibacterial potency upon incubation at physiological conditions yielding a t½ value of 7.1 ± 0.2 h. In conclusion, the albumin-binding probe we introduced enables to prolong the action of any amino containing molecule in vivo, without the drawback of inactivation that often occurs upon such derivatization.