The effect of esterases on 17α-hydroxyprogesterone caproate

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Objective: The aim of this investigation is to determine whether 17α-hydroxyprogesterone caproate is hydrolyzed, in vitro, to 17α-hydroxyprogesterone and caproate. Study Design: The in vitro hydrolysis of dual radioactively labeled 17α-hydroxy-[3H] progesterone [14C] caproate by human plasma, hepatic and placental S9 fractions as well as recombinant esterases was investigated. The formation of [3H]-17α-hydroxyprogesterone and [14C]-caproate were determined with the use of high-performance liquid chromatography equipped with an online radioactivity detector. The presence and activity of carboxylesterase and butyrylcholinesterase in the human-derived preparations was confirmed by the hydrolysis of their prototypic substrates p-nitrophenyl acetate, p-nitrophenyl butyrate, and butyrylthiocholine, respectively. Results: The aforementioned human-derived preparations hydrolyzed p-nitrophenyl acetate, p-nitrophenyl butyrate, and butyrylthiocholine. However, when 17α-hydroxyprogesterone caproate was incubated with the human-derived preparations under identical experimental conditions neither [3H]-17α-hydroxyprogesterone nor [14C]-caproate was detected. Conclusion: 17α-hydroxyprogesterone caproate is not hydrolyzed in vitro by the esterase enzymes present in human plasma, liver, preterm, or term placenta.

Original languageEnglish (US)
JournalAmerican Journal of Obstetrics and Gynecology
Issue number2
StatePublished - Feb 2008



  • 17α-hydroxyprogesterone caproate
  • hydrolysis
  • spontaneous preterm labor

ASJC Scopus subject areas

  • Medicine(all)
  • Obstetrics and Gynecology

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