Prophylactic administration of subantimicrobial dose doxycycline to prevent unscheduled bleeding in continuous oral contraceptive pill users

Effect of oral contraceptives and doxycycline on endometrial MMP-2 and MMP-9 activity

OBJECTIVES

To describe the effect of combined oral contraceptives (COCs) on matrix metalloproteinases MMP-2 and MMP-9 activity and compare MMP activity in women taking a COC with or without doxycycline.

STUDY DESIGN

Subjects (n=20) underwent endometrial biopsies (1) in the late luteal phase of a baseline cycle prior to initiating COCs, (2) on days 19-21 while taking COCs in a standard 28-day cycle (7-day hormone-free interval) and (3) on days 26-28 while taking active COCs continuously for a 28-day cycle. During the continuous COC cycle, they were randomized to receive daily subantimicrobial dose doxycycline 40mg or placebo.

RESULTS

Compared to baseline, COC treatment increased MMP-2 (p<.001) and MMP-9 (p<.001). MMP activity was lower in subjects taking a COC with doxycycline compared to those receiving placebo although only significantly lower for MMP-2 latent form (p=.002).

CONCLUSIONS

Unscheduled bleeding with COCs may be the result of increased endometrial MMPs. Sample size limitations prevent us from determining how doxycycline affects MMP activity in COC users.

Unscheduled bleeding with continuous oral contraceptive pills: a comparison of progestin dose

BACKGROUND

Although the use of continuous oral contraceptive pills (OCPs) eliminates scheduled uterine bleeding, unscheduled bleeding is common. The objective of this study was to determine whether progestin dose influences bleeding with use of continuous OCPs.

STUDY DESIGN

This was a secondary data analysis of two other studies of continuous OCPs. Women were eligible if they were switching from a cyclic hormonal contraceptive to a continuous OCP. Women took a 20-mcg ethinyl estradiol (EE)/100-mcg levonorgestrel (LNG) pill or a 20-mcg EE/90-mcg LNG pill for 112 days. The number of bleeding/spotting days was compared between groups using a t test. Sample size was adequate to detect a difference of 8 days of bleeding/spotting over the 112 day study period (β=0.80, α=0.05).

RESULTS

Sixty-six subjects were enrolled, 33 in each group. There were no differences in baseline characteristic, missed OCPs or side effects. There were no differences in the mean number of bleeding/spotting days in the first 84 days of the study (90 mcg LNG mean 20.8 (SE 3.6) days versus 100 mcg LNG 17.8 (SE 2.3) days, p=.48), nor was there a difference in the time to amenorrhea (p=.35).

CONCLUSION

Our results do not support the use of one LNG dose over another to decrease the amount of unscheduled bleeding women experience when initiating a continuous OCP.