Study of the gastrointestinal bioavailability of a pancreatic extract product (Zenpep) in chronic pancreatitis patients with exocrine pancreatic insufficiency

Introduction: The Food and Drug Administration in 2006 required that all pancreatic enzyme products demonstrate bioavailability of lipase, amylase, and protease in the proximal small intestine.

Methods: In this phase I open-label, randomized, crossover trial, 17 adult chronic pancreatitis (CP) patients with severe exocrine pancreatic insufficiency (EPI) underwent two separate gastroduodenal perfusion procedures (Dreiling tube suctioning and [¹⁴C]-PEG instillation by an attached Dobhoff tube in the duodenal bulb). Patients received Ensure Plus® alone and Ensure Plus with Zenpep (75,000 USP lipase units) in random order. The bioavailability of Zenpep was estimated by comparing the recovery of lipase, amylase, chymotrypsin activity in two treatment conditions. ¹⁴C-PEG was used to correct duodenal aspirates volume. The primary efficacy endpoint was lipase delivery in the duodenum after Zenpep administration under fed conditions. Secondary efficacy endpoints included chymotrypsin and amylase delivery, serum CCK levels, and measuring duodenal and gastric pH.

Results: Zenpep administration with a test meal was associated with significant increase in duodenal aspiration of lipase (p = 0.046), chymotrypsin (p = 0.008), and amylase (p = 0.001), compared to the test meal alone, indicating release of enzymes to the duodenum. Lipase delivery was higher in the pH subpopulation (the efficacy population with acid hypersecretors excluded) (p = 0.01). Recovery of [¹⁴C]-PEG was 61%. Zenpep was generally well tolerated. All adverse events were mild and transient.

Conclusions: In CP patients with severe EPI, lipase, chymotrypsin and amylase were released rapidly into the duodenum after ingestion of Zenpep plus meal compared to meals alone. Results also reflected the known pH threshold for enzyme release from enteric coated products.

Keywords: Bioavailability; Chronic pancreatitis; Efficacy; Exocrine pancreatic insufficiency; Zenpep.