title: The effect of esterases on 17alpha-hydroxyprogesterone caproate.
abstract: OBJECTIVE
  The aim of this investigation is to determine whether 17alpha-hydroxyprogesterone caproate is hydrolyzed, in vitro, to 17alpha-hydroxyprogesterone and caproate.
  
  
  METHODS
  The in vitro hydrolysis of dual radioactively labeled 17alpha-hydroxy-[3H] progesterone [14C] caproate by human plasma, hepatic and placental S9 fractions as well as recombinant esterases was investigated. The formation of [3H]-17alpha-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 17alpha-hydroxyprogesterone caproate was incubated with the human-derived preparations under identical experimental conditions neither [3H]-17alpha-hydroxyprogesterone nor [14C]-caproate was detected.
  
  
  CONCLUSIONS
  17Alpha-hydroxyprogesterone caproate is not hydrolyzed in vitro by the esterase enzymes present in human plasma, liver, preterm, or term placenta.
authors.affiliation: Department of Obstetrics & Gynecology, University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: Ru
authors.initials: R
authors.lastname: Yan
authors.forename: Valentina
authors.initials: V
authors.lastname: Fokina
authors.forename: Gary D V
authors.initials: GD
authors.lastname: Hankins
authors.forename: Mahmoud S
authors.initials: MS
authors.lastname: Ahmed
authors.forename: Tatiana N
authors.initials: TN
authors.lastname: Nanovskaya
mesh_terms: D000077713:17 alpha-Hydroxyprogesterone Caproate; D002851:Chromatography, High Pressure Liquid; D004950:Esterases / Q000494:pharmacology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D006908:Hydroxyprogesterones / Q000097:blood / Q000378:metabolism*; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism; D007752:Obstetric Labor, Premature; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy
chemical_list: D006908:Hydroxyprogesterones; D000077713:17 alpha-Hydroxyprogesterone Caproate; D004950:Esterases