Iopentol (Imagopaque 250) compared with diatrizoate (Urografin 219) in endoscopic retrograde cholangio-pancreatography (ERCP). A clinical trial assessing safety (adverse events and S-pancreatic iso-amylase) and diagnostic information (VAS)

Effects of contrast media on the hepato-pancreato-biliary system

AIM: To determine the effects of high osmolarity contrast media (HOCM) and iso-osmolar contrast media (CM) application, with or without pressure, on hepato-pancreato-biliary (HPB) system.

METHODS: Sixty rats were divided into six equal groups as follows: Group 1: (0.9% NaCl, control), Group 2: (diatrizoate meglumine Na, ionic HOCM, Urographin^®), Group 3: (iodixanol, iso-osmolar non-ionic CM, Visipaque^®); each of which was applied without pressure, whereas the animals of the remaining three groups (1p, 2p, 3p) were subjected to the same CM with pressure. We performed a duodenal puncture and introduced a catheter into the ampulla. After the catheterization, 0.2 mL CM or 0.9% NaCl was injected with or without pressure. Blood samples were taken for biochemical evaluations. The histopathological examinations of liver, common bile duct, and pancreas were performed.

RESULTS: There were no significant differences between the six groups for blood amylase, alanine aminotransferases, aspartate aminotransferases, bilirubin levels (P > 0.05). Alkaline phosphatase and γ glutamyl transaminase levels were higher (P < 0.05) in the Urographin^® groups (2, 2p) than the Visipaque^® groups (3, 3p), or control groups (1, 1p). Hepatocyte necrosis, portal area inflammation, and Kupffer’s cell hyperplasia were higher (P < 0.05) in the study groups than the control group. However, there were no significant differences (P > 0.05) between HOCM (2, 2p) and iso-osmolar CM (3, 3p) groups. Bile duct proliferation and regeneration in the Urographin^® groups (2, 2p) were significantly higher (P < 0.05) than the Visipaque^® groups (3, 3p) or the control groups (1, 1p). Although CM caused minor damage to the pancreas, there were no statistically significant differences (P > 0.05) between the groups. Application of the CM with pressure did not cause additional damage to the HPB system.

CONCLUSION: Iso-osmolar, non-ionic CM could be more reliable than the ionic HOCM, whereas the application of pressure during the CM application had no effect on the HPB system.

Protection against acute pancreatitis by activation of protease-activated receptor-2

Protease-activated receptor-2 (PAR-2) is a widely expressed tethered ligand receptor that can be activated by trypsin and other trypsin-like serine proteases. In the exocrine pancreas, PAR-2 activation modulates acinar cell secretion of digestive enzymes and duct cell ion channel function. During acute pancreatitis, digestive enzyme zymogens, including trypsinogen, are activated within the pancreas. We hypothesized that trypsin, acting via PAR-2, might regulate the severity of that disease, and to test this hypothesis, we examined the effect of either genetically deleting or pharmacologically activating PAR-2 on the severity of secretagogue-induced experimental pancreatitis. We found that experimental acute pancreatitis is more severe in PAR-2(-/-) than in wild-type mice and that in vivo activation of PAR-2, achieved by parenteral administration of the PAR-2-activating peptide SLIGRL-NH2, reduces the severity of pancreatitis. In the pancreas during the early stages of pancreatitis, the MAPK ERK1/2 is activated and translocated to the nucleus, but nuclear translocation is reduced by activation of PAR-2. Our findings indicate that PAR-2 exerts a protective effect on pancreatitis and that activation of PAR-2 ameliorates pancreatitis, possibly by inhibiting ERK1/2 translocation to the nucleus. Our observations suggest that PAR-2 activation may be of therapeutic value in the treatment and/or prevention of severe clinical pancreatitis, and they lead us to speculate that, from a teleological standpoint, PAR-2 may have evolved in the pancreas as a protective mechanism designed to dampen the injurious effects of intrapancreatic trypsinogen activation.

Role of osmolality of contrast media in the development of post-ERCP pancreatitis: a metanalysis

The role of osmolality of contrast media (CM) in the development of post-ERCP pancreatitis (PEP) is debated. We therefore performed a metanalysis to determine whether osmolality affects the incidence of PEP. A literature search of English-language studies was performed using computerized databases and manual searching of abstracts and article bibliographies. Randomized controlled trials comparing the incidence of PEP associated with high- and low-osmolality contrast media (HOCM, LOCM) were considered. The outcome assessed was clinical pancreatitis as evidenced by both elevation of pancreatic enzymes and pain. Data were analyzed using logistic regression with terms for study and osmolality. Fisher's exact test was done to compare PEP rates. Homogeneity between studies was indicated by the nonsignificance of the study effect in the logistic regression model. Logistic regression also indicated no difference in PEP rates between LOCM and HOCM (P = 0.399). Comparison of PEP rates in both groups using Fisher's exact test did not indicate a difference in any individual study (all P values > 0.05). Due to the large variation of study sample sizes, we repeated the analysis by creating three study groups. The effect of osmolality was invariant to how the data were combined. The results of this metanalysis indicate that there is no significant difference between HOCM and LOCM with respect to clinical PEP.