Improved radioiodination of 1,2-dipalmitoyl-3-IPPA via a tributyltin intermediate

1,2-Palmitoyl-3-[15-(4-iodophenyl)pentadecan-3-oyl]-rac-glycerol (MIPAG) is a new agent for the clinical evaluation of pancreatic lipase activity and has demonstrated promise in preliminary clinical studies with patients affe cted with pancreatic insufficiency. Iodine-131-MIPAG was initially prepared via thallium-iodide displacement. Because of the need for a simple method which is amendable for the routine clinical use of MIPAC we have investigat ed the preparation and radioiodination of MIPAG utilizing the tributyltin p recursor, 1,2-palmitoyl-3-[15-(4-tributylstannylphenyl)pentadecan-3-oyl] (T BT-MIPAG, 2). Compound 2 was prepared via the condensation of 1,2-palmitoyl -rac-glycerol with 15-(4-tributylstannylphenyl)pentadecanoic acid (TBT-PPA) prepared from 4-bromophenylacetylene. Electrophilic radioiodination using peracetic acid with sodium iodide-125 in ethanol at 80 degrees C for 60 min afforded I-125-MIPAG in (65.9% +/-11.5%) yield and radiochemical purity of 94% (+/-3.0%) after C-18 Sep-Pak purification (n=6). This improved method for radioiodination utilizing TBT-MIPAG now provides radioiodinated MIPAG f or routine clinical evaluation. Published by Elsevier Science Ltd.