Richard Dickey’s book “Managing contraceptive pill patients” lists the androgenic activity for levonorgestrel as 8.3 but only 1.0 for norethindrone (norethisterone) 1.6 for norethindrone acetate.2 These results were obtained from a rat ventral prostate assay in which testosterone was 50.
norethisterone has the same increased risk of thrombosis as levonorgestrel.
Any current use of combined OCs has a 3-fold increased risk of idiopathic venous thromboembolism compared with no use in the past year. Risks doubled for newer progestogens with desogestrel (x4.28), gestodene (x4.27), drospirenone (4.12) and cyproterone (4.27) compared with levonorgestrel (2.38), norethisterone (2.56) and norgestimate (2.53).3
all effective hormonal contraceptives must be predominantly progestogenic to avoid pregnancy.
Progesterone and progestogens increase the monoamine oxidase levels which is a major cause of depressive mood changes and loss of libido.
Some women did complain of increased libido and even violence; “ My husband was exhausted”, or, “ I wanted to sexually assault the bus driver”, or, “ I threw a frozen chicken at my husband”.
Note: With norethisterone acetate combinations containing higher doses of oestrogen than are used now.