EVALUATION OF PANCREATIC LIPASE ACTIVITY BY SIMPLE URINE ANALYSIS AFTER ORAL-ADMINISTRATION OF A NEW IODINE-131-LABELED TRIGLYCERIDE

A new iodine-131-labeled triglyceride analogue called ''MIPAG'' [1,2-d ipalmitoyl-3-[(15-p-iodophenyl) pentadecan-1-oyl]rac-glycerol] has bee n prepared in which 15-(p-iodophenyl)pentadecanoic acid (IPPA) is atta ched to position-3. MIPAG has been developed for the evaluation of pan creatic exocrine function by simple urine analysis and has been evalua ted in rats and humans. After oral administration, IPPA is released fr om the triglyceride by the action of pancreatic lipases followed by in testinal absorption and the principal IPPA metabolite (p-iodobenzoic a cid, IBA) is primarily excreted in the urine. Excretion in the urine a nd feces was evaluated in rats, as well as the biodistribution in vari ous organs over 21 days. Twenty patients without pancreatic disease (n ormals) and four patients with pancreatic insufficiency were also inve stigated. Following oral administration of 30 mu Ci of MIPAG, urine wa s collected for two successive 24-h periods. Blood samples were drawn and thin-layer chromatographic (TLC) analysis was performed on the ser um lipid extracts. Urine from normals contained 44.9%+/-7.7% and 61.8% +/-8.4% of the administered activity after 24 and 48 h, respectively. The patients with pancreatic insufficiency excreted 13.1%+/-5.6% and 1 8.9%+/-6.2%, respectively, which was significantly decreased (P<0.001) compared with normals. The TLC profiles showed an increasing proporti on of IBA with time. Urine analysis after oral administration of MIPAG thus appears to be an attractive new technique for the evaluation of pancreatic lipase activity by a simple urine analysis.