A progestogen ester is an ester of a progestogen or progestin (a synthetic progestogen). The prototypical progestogen is progesterone, an endogenous sex hormone. Esterification is frequently employed to improve the pharmacokinetics of steroids, including oral bioavailability, lipophilicity, and elimination half-life.[1] In addition, with intramuscular injection, steroid esters are often absorbed more slowly into the body, allowing for less frequent administration.[1] Many (though not all) steroid esters function as prodrugs.
Esterification is particularly salient in the case of progesterone because progesterone itself shows very poor oral pharmacokinetics and is thus ineffective when taken orally.[2][3] Unmodified, it has an elimination half-life of only 5 minutes, and is almost completely inactivated by the liver during first-pass metabolism.[3] Micronization, however, has allowed for progesterone to be effective orally, although oral micronized progesterone was not developed until recent years.[2]
Examples of important progestogen esters include the 17α-hydroxyprogesterone derivatives medroxyprogesterone acetate, megestrol acetate, cyproterone acetate, and hydroxyprogesterone caproate, the 19-norprogesterone derivative nomegestrol acetate, and the 19-nortestosterone derivatives norethisterone acetate and norethisterone enanthate.
- ^ a b Fraser, Ian S. (1998). Estrogens and Progestogens in Clinical Practice. Churchill Livingstone. p. 13. ISBN 978-0-443-04706-0.
- ^ a b Lobo, Roger; Crosignani, P.G.; Paoletti, Rodolfo (31 October 2002). Women's Health and Menopause: New Strategies – Improved Quality of Life. Springer Science & Business Media. pp. 91–. ISBN 978-1-4020-7149-2.
- ^ a b Korolkovas, Andrejus (16 August 1988). Essentials of Medicinal Chemistry. Wiley. p. 1021. ISBN 978-0-471-88356-2.