Carboxylated high amylose starch as pharmaceutical excipients: Structural insights and formulation of pancreatic enzymes

Carboxymethyl high amylose starch (CM-HAS) and succinate high amylose starch (S-HAS) were proposed as pharmaceutical excipients for oral drug delivery, providing a significant gastroprotection to dosage forms of pancreatic enzymes (alpha-amylase, lipase and trypsin) compared to unprotected enzymes. In acidic medium, carboxylic groups are protonated (at least in tablet surface) ensuring local buffering properties and giving a compact shape of the tablets. The enzymes were formulated individually or in association as three enzymes formulation. After the first hour of incubation (over a 2 h experiment) in simulated gastric fluid (SGF), the three pancreatic enzymes retained an overall (average of the three enzymes) activity of 72% when formulated as tablets with CM-HAS excipient and 77% when formulated with S-HAS excipient. Furthermore, after incubation in SGF, the delivery of 75% of the total remaining enzymatic activity in the simulated intestinal fluid (SIF) taken 180 and 170 min for CM-HAS and S-HAS, respectively. Both formulations with carboxylated starch as excipient have a high loading capacity (up to 70–80% enzymes), which is of interest for pancreatic enzymes replacement therapy of pancreatitis. An advantage of these formulations is that gastroprotection is afforded by the carboxylated matrices (carboxylic groups), without enteric coating.