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Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

A new principle of injectable depot contraceptives. I Drug selection and studies in monkeys.

The aim of the investigations was to develop a long-acting depot contraceptive on the basis of norethisterone or levonorgestrel. Disappointing results with levonorgestrel nonanoate and levonorgestrel undecylate showed that elongation of the fatty acid, esterified with the steroid, decreased the bioavailability of the latter due to incomplete hydrolysis of the ester. Therefore, several new compounds were synthesized which contained a bifunctional molecule between the steroid and the fatty acid. In vivo studies showed an increase in hydrolysis when glycolic acid was taken as the "bridge", compared to the hitherto known esters. Due to the new principle of the steroid-fatty acid connection, in the case of norethisterone, it was possible to introduce tridecanoic acid as lipophilic release controlling substituent without a loss of bioavailability in the baboon. This compound (called: "norethisterone glycotridecanoate") and the corresponding levonorgestral derivative were chosen for a pharmacokinetic-clinical study in women.[1]


  1. A new principle of injectable depot contraceptives. I Drug selection and studies in monkeys. Hümpel, M., Schulze, P.E., Speck, U. Contraception. (1979) [Pubmed]
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