Rectal administration of tacrolimus protects against post-ERCP pancreatitis in mice

There is an unmet clinical need for effective, targeted interventions to prevent post-ERCP pancreatitis (PEP). We previously demonstrated that the serine-threonine phosphatase, calcineurin (Cn) is a critical mediator of PEP and that the FDA-approved calcineurin inhibitors, tacrolimus (Tac) or cyclosporine A, prevented PEP. Our recent observations in preclinical PEP models demonstrating that Cn deletion in both pancreatic and hematopoietic compartments is required for maximal pancreas protection, highlighted the need to target both systemic and pancreas-specific Cn signaling. We hypothesized that rectal administration of Tac would effectively mitigate PEP by ensuring systemic and pancreatic bioavailability of Tac. We have tested the efficacy of rectal Tac in a preclinical PEP model and in cerulein-induced experimental pancreatitis.

C57BL/6 mice underwent ductal cannulation with saline infusion to simulate pressure-induced PEP or were given seven, hourly, cerulein injections to induce pancreatitis. To test the efficacy of rectal Tac in pancreatitis prevention, a rectal Tac suppository (1 mg/kg) was administered 10 min prior to cannulation or first cerulein injection. Histological and biochemical indicators of pancreatitis were evaluated post-treatment. Pharmacokinetic parameters of Tac in the blood after rectal delivery compared to intravenous and intragastric administration was evaluated.

Rectal Tac was effective in reducing pancreatic injury and inflammation in both PEP and cerulein models. Pharmacokinetic studies revealed that the rectal administration of Tac helped achieve optimal blood levels of Tac over an extended time compared to intravenous or intragastric delivery.

Our results underscore the effectiveness and clinical utility of rectal Tac for PEP prophylaxis.