DL-[CARBOXYL-C-11]TRYPTOPHAN, A POTENTIAL AGENT FOR PANCREATIC IMAGING - PRODUCTION AND PRE-CLINICAL INVESTIGATIONS

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  • 1 January 1979
    • journal article
    • research article
    • Vol. 20  (8) , 857-864
Abstract
In animal studies, DL-[carboxyl-14C]tryptophan [DL-Try(C-14)] showed a high specificity for the pancreas, which suggested the potential of DL-[carboxyl-11C]tryptophan [DL-Try(C-11)] for clinical pancreatic imaging. The blood clearance and tissue uptake of the amino acid were rapid and no carrier effect was seen through a dose of 5 mg/kg. None of 3 transplanted hamster pancreatic adenocarcinomas that were studied showed a selective uptake of DL-Try(C-14) by the tumor, and none of the 3 enzymatic regimens studied gave significant enhancement of the pancreatic specificity. Commercial L-Try(C-14) gave slightly better pancreatic specificity than the analogous racemic compound, but without enough improvement to warrant attempts at optical resolution. DL-Try(C-11) was synthesized in amounts up to 325 mCi using a rapid, high-temperature, high-pressure modification of the Buecherer-Strecker amino acid synthesis. Yields ranged from 30-60%, and 40 min was required for synthesis and chromatographic purification. DL-Try(C-11) appears to have significant potential as a clinical pancreas-imaging agent, particularly when used in conjunction with positron computerized transaxial tomography.