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Clinical Trial
. 2025 Jun;51(6):e16340.
doi: 10.1111/jog.16340.

Efficacy and safety of drospirenone as a progestin-only pill in Japanese women: A phase III study

Kunio Kitamura  1 , Enrico Colli  2 , Ryoko Kikuyama  3 , Yumiko Kurihara  3 , Rieko Azuma  3 , Tomoya Kagawa  3
Affiliations
Clinical Trial

Efficacy and safety of drospirenone as a progestin-only pill in Japanese women: A phase III study

Kunio Kitamura et al. J Obstet Gynaecol Res. 2025 Jun.

Abstract

Aim: To evaluate the efficacy and safety of 4 mg of drospirenone (DRSP), a progestin-only pill (POP), for contraception in Japanese women.

Methods: This was a multicenter, open-label, single-arm study. The dosing period of DRSP was 13 cycles, each lasting for 28 days. In one cycle, 4 mg of DRSP was administered orally once daily for the first 24 days, followed by a placebo for 4 days.

Results: Data from 276 subjects were analyzed, with a total of 3319 DRSP exposure cycles. Pregnancy occurred in one subject. The overall Pearl Index [95% CI] was 0.39 [0.01, 2.18], and the cumulative pregnancy rate [95% CI] was 0.40% [0.06, 2.81]. Of the 276 subjects, 273 (98.9%) experienced treatment-emergent adverse events (TEAEs) and 264 (95.7%) experienced adverse drug reactions. All TEAEs were mild or moderate, with no severe events. The most common TEAE was intermenstrual bleeding (irregular uterine bleeding) (89.5%). Although 31.9% of the subjects had risk factors for venous thromboembolism (VTE), no VTE-related TEAEs were observed. The incidence of unscheduled bleeding [95% CI] across all cycles was 91.6% [87.7, 94.3].

Conclusions: DRSP, the first POP in Japan, is effective and safe as a contraceptive in Japanese women. It provides a new contraceptive option for Japanese women, including those at risk of VTE for whom combined oral contraceptives are contraindicated.

Keywords: contraception; drospirenone; efficacy; progestin‐only pill; safety.

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Conflict of interest statement

Kunio Kitamura received lecture fees from ASKA Pharmaceutical Co., Ltd. and Fuji Pharma Co., Ltd. Enrico Colli is an employee of Exeltis. Ryoko Kikuyama, Yumiko Kurihara, Rieko Azuma, and Tomoya Kagawa are employees of ASKA Pharmaceutical Co., Ltd.

Figures

FIGURE 1
FIGURE 1
Subjects disposition. Of the 286 subjects enrolled, 276 received the study drug, and 241 completed 13 cycles of treatment.
FIGURE 2
FIGURE 2
Return of menstrual bleeding. The cumulative menstrual recovery rate was 100.0%.
See this image and copyright information in PMC

References

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