Serum medroxyprogesterone acetate levels in new and repeat users of depot medroxyprogesterone acetate at the end of the dosing interval.

In the absence of published data on serum medroxyprogesterone acetate (MPA) levels in South African users, this study examines such levels in new and repeat users of depot medroxyprogesterone acetate at the end of the dosing interval. The study was undertaken at three family-planning clinics in Durban, South Africa. Serum MPA levels were measured in 94 Black African, Indian and White women returning between 11 and 14 weeks after their last injection. The median serum MPA level was 0.88 (range, <0.04-1.77) ng/mL and wide interindividual variability was observed. Levels in all but one woman were higher than 0.1 ng/mL, the level at which ovulation is reported to resume. MPA levels were not found to vary according to weight, body mass index or ethnicity. Although there was a slight tendency towards higher MPA levels with longer duration of use (r = 0.13), the wide interindividual variability precluded the possibility of determining whether this was a real trend. A prospective study, using standardized assay techniques and following individual women, is required to further clarify this issue.