Application of a glyceride-mimetic prodrug strategy to deliver protease inhibitors to gut lymph to alleviate organ failure

Gut-derived "toxic factors," including proteolytic enzymes such as trypsin, can disseminate via the mesenteric lymphatics and drive multiorgan failure in acute pancreatitis (AP) and other acute and critical illnesses (ACIs). Delivery of protease inhibitors into gut lymph could thus present a strategy to mitigate organ failure in ACIs. We thus synthesised a series of gut lymph directing glyceride-mimetic prodrugs of 4-(4-guanidinobenzoyloxy) phenylacetic acid (GBPA), the active metabolite of the serine protease inhibitor camostat, and tested their pharmacokinetics and therapeutic utility in a rat model of AP. GBPA was esterified at the sn-2 position of a 1,3-dioleoyl-glycerol backbone through either a C6 linker (CAM-C6-TG) or a β-methyl C8 linker (CAM-C8β-TG). A prodrug employing the same C8β linker but where the GBPA guanidino group was capped with two tert-butyloxycarbonyl (Boc) groups to increase lipophilicity was also synthesised (diBoc-CAM-C8β-TG). The stability of all prodrugs was tested in vitro in simulated intestinal fluid, plasma and lymph and pharmacokinetic studies were performed in carotid artery and mesenteric lymph duct cannulated rats. CAM-C6-TG was less stable in in vitro stability studies in simulated intestinal fluid compared to the C8 prodrugs and displayed relatively low exposure in in vivo pharmacokinetic studies. Both CAM-C8β-TG and di-Boc-CAM-C8β-TG were relatively stable, increased plasma exposure of GBPA compared with camostat and achieved substantial lymphatic transport of GBPA related substances (5-12% of dose). In the sodium taurocholate-induced rat AP model, CAM-C8β-TG significantly reduced biomarkers of cardiac, renal and hepatic dysfunction, whereas camostat showed more limited protective effect. These findings demonstrate that lymph-targeted glyceride prodrugs of GBPA can attenuate organ injury in experimental AP. Future studies will determine the efficacy of the prodrugs in other ACIs such as hemorrhagic shock and sepsis.