[en] The syntheses of [19,20-3H2]- and [3,3,4,4,5,5,6,6-2H8]-(17R)-17,20-dimethyl-7-thiaprostaglandin E1 methyl esters (3 and 5) are described. The di-tritiated compound 3 was prepared from its protected (Z)-δ19-precursor via catalytic reduction with tritium gas having a specific activity of 49 Ci / mmol. The octa-deuterated compound 5 was prepared from tetrahydrofuran-d8. (author)