Progesterone or progestogen or progestin; which is it?
This editorial refers to combination oestrogen-progestin
contraceptives but in the concluding sentences implies that levonorgestrel
and norethisterone are types of progesterone. Stephenson in her letter 
refers to the etonogestrel containing implant as a progesterone implant.
Progesterone appears to have been used as a synonym for progestin. The
British Pharmacopeia  lists the action and use of progesterone and
progestins such as levonorgestrel and norethisterone as progestogen. There
appears to be a lot of confusion around the group name for progestational
agents. In 1976 Dalton  argued that progesterone should not be confused
with or considered the same as progestins (synthetic progestogens). Yet in
2009 it appears they are still being confused.
The confusion possibly arises because of the use of oestrogen and
progesterone to represent the female sex hormones. Oestrogen is a generic
term for oestrogenic agent, and there are three primary oestrogens in the
human body; oestrone (E1), oestradiol (E2), and oestriol (E3). On the
other hand progestogen is the generic term for a progestational agent and
progesterone (P4) is a single chemical entity and the primary
progestogenic hormone synthesised by the human body. The term
progestin can be used to refer to synthetic progestational agents.
It appears that the difference between progesterone, progestogens,
and progestins is still not appreciated. Confusion associated with
interpreting research findings with regard to progesterone and progestins
would be reduced if a consistent name, other than progesterone, was used
to represent synthetic progestogens.
1. Stephenson V. Migraine and risk of stroke: For contraception try
IUDs BMJ 2009;339:b4841.
2. British Pharmacopoeia Commission. British Pharmacopoeia. London:
The Stationery Office, 2009.
3. Dalton K. Progesterone or progestogens? BMJ 1976;2(6046):1257.
4. Dorland's illustrated medical dictionary. 29th ed. Philadelphia:
W.B. Saunders Company, 2000.
Competing interests: No competing interests