Davenport RJ, Law MP, Pike VW, Osman S, Poole KG. Propionyl-L-carnitine: labelling in the N-methyl position with carbon-11 and pharmacokinetic studies in rats.
Nucl Med Biol 1995;
22:699-709. [PMID:
8535330 DOI:
10.1016/0969-8051(95)00010-u]
[Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The prospective therapeutic, propionyl-L-carnitine, was labelled in the N-methyl position with the positron-emitter, carbon-11 (t1/2 = 20.4 min), with a view to studying its pharmacokinetics in humans using PET. Labelling was achieved by methylating nor-propionyl-L-carnitine hydrochloride with no-carrier-added [11C]iodomethane (produced from cyclotron-produced [11C]carbon dioxide) in ethanol in the presence of 1,2,2,6,6-pentamethylpiperidine. HPLC of the reaction mixture on a strong cation exchange column provided high purity [N-methyl-11C]propionyl-L-carnitine in 62% radiochemical yield (decay-corrected from [11C]iodomethane), ready for intravenous administration within 35 min from the end of radionuclide production. [N-methyl-11C]Propionyl-L-carnitine, given intravenously to rats, cleared rapidly from plasma. A slow uptake of radioactivity into myocardium and striated muscle was observed. In plasma, unchanged tracer represented 84% of the radioactivity at 2.5 min and 2.5% of the radioactivity at 60 min. In heart, unchanged tracer represented 18% of radioactivity at 2.5 min and 2.4% at 15 min. The remainder of radioactivity detected in plasma and heart was identified as [N-methyl-11C]L-carnitine and [N-methyl-11C]acetyl-L-carnitine.
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