A Cochrane review included 12 trials comparing depot medroxyprogesterone acetate (MPA) given at a dose of 150 mg IM every 3 months and norethisterone oenanthate (NET) given at a dose of 200mg IM every 2 months (n=3 572 after 6 months on treatment and n=2 376 after 2 years of treatment). There was no significant difference between the two treatment groups for the frequency of discontinuation, although the women on NET were 4% more likely to discontinue for personal reasons than those on PMA. Discontinuation because of accidental pregnancy did not differ between the groups. Bleeding and spotting events as well as mean changes in body weight and blood pressure did not differ. However, women on PMA were 21% more likely to develop amenorrhoea.
Comment: The quality of evidence is downgraded by limitations in study quality (blinding to the intervention is not possible).