New drospirenone pill is an effective POP option
Kimble T, Burke AE, Barnhart KT, et al. A 1-year prospective, open-label, single-arm, multicenter, phase 3 trial of the contraceptive efficacy and safety of the oral progestin-only pill drospirenone 4 mg using a 24/4-day regimen. Contracept X. 2020;2:100020.
Palacios S, Colli E, Regidor PA. Multicenter, phase III trials on the contraceptive efficacy, tolerability and safety of a new drospirenone-only pill. Acta Obstet Gynecol Scand. 2019;98:1549-1557.
In a prospective, single-arm, multicenter phase 3 trial in the United States, Kimble and colleagues evaluated the efficacy and safety of an oral drospirenone POP in a cyclic 24-day hormone/4-day placebo regimen. The trial included 1,006 users. No BMI cutoff was used, and about one-third of study participants were obese (BMI >30.0 kg/m2). Women were instructed to take a missed tablet as soon as remembered if within 24 hours or with the next scheduled dose if more than 24 hours late.
Contraceptive effectiveness
The Pearl Index for nonbreastfeeding users aged 35 years or younger with pregnancies confirmed by a quantitative serum ß-human chorionic gonadotropin test (915 users) was 2.9 (95% CI, 1.5-5.1). Of note, 2 out of 15 on-treatment pregnancies were excluded from this calculation because of protocol site violations, as were 3 pregnancies that were unconfirmed. In the modified full analysis set of 915 users, 36% were obese (BMI≥30 kg/m2), and the Pearl Index was noted to be unaffected by BMI (TABLE 2).
While 61% of women reported adverse effects, more than 95% of these were mild or moderate in intensity, including headache, nausea, dysmenorrhea, metrorrhagia, and breast pain. No VTE occurred. The frequency of hyperkalemia was 0.5%, and there was no evidence of hypotension, which is significant due to the antimineralocorticoid activity of drospirenone. All cases of hyperkalemia were considered mild, and all women were asymptomatic. There were no clinically relevant changes in body weight, gynecologic exam, or other laboratory values.
With increased cycles of use, the number of days with bleeding or spotting generally decreased and amenorrhea increased. However, in cycles 11 to 13, 41.6% of users still had unscheduled bleeding (reduced from 57.0% at cycles 2-4), and 29.0% had scheduled bleeding (decreased from 44% at cycles 2-4) (FIGURE 2). With these bleeding patterns, 86.2% of users agreed or strongly agreed that they were satisfied with the product.
European multicenter study of drospironene
In a European investigation, Palacios and colleagues pooled and analyzed data from 2 phase 3 multicenter trials to assess the efficacy, tolerability, and safety of the same drospirenone-only pill (24 days of drospironene 4 mg and 4 days of placebo) in 1,571 users. No BMI cutoff was used, but overall only 71 participants (4.6%) were obese. One study included desogestrel 0.075 mg (in a regimen of 28 active pills) as a comparator for safety.
The overall Pearl Index for users 35 years or younger (1,251 users) was 1.0 (95% CI, 0.4-2.0). The "method failure Pearl Index" in users 35 years or younger, which included all pregnancies during "perfect medication cycles," was 1.3 (95% CI, 0.5-2.5).
The most common adverse effects were acne (6.6% in study 1 and 4.4% in study 2), headache (4.5% in study 1), and irregular bleeding (4.4% in study 2). No cases of VTE occurred; there was 1 case of asymptomatic hyperkalemia. Additional laboratory values and vital signs showed no significant changes. The trend in bleeding was similar to that in the US studies, but it is interesting to note that there were significantly lower rates of unscheduled bleeding or spotting in drospirenone users than in desogestrel users (67.9% vs 86.5%, respectively; P<.001).
WHAT THIS EVIDENCE MEANS FOR PRACTICE
In the US study, the higher Pearl Index compared with that found in the European study (2.9 vs 1.0) likely reflects an increased proportion of study participants with a BMI of 30 kg/m2 or higher, a younger average age of participants, and a historical tendency toward better contraceptive efficacy in European than in US study participants. Kimble and colleagues’ finding of a Pearl Index of 2.9 is similar to that seen with other CHCs and POPs, and the data from the US study are potentially more generalizable.
Among the 2,257 participants in 3 studies, 423 (19%) were obese. No VTE events occurred with drospirenone use, as compared with 4 events in the SA/EE CVS study with 2,308 participants in the phase 3 studies.
Historically, POPs were associated with more days of bleeding than CHCs and require stricter adherence to daily use within a narrow window for missed pills. The new drospirenone-only pill may provide women with more flexibility since it maintains contraceptive efficacy even with 24-hour delayed or missed-pill errors. Although intermenstrual bleeding rates are high, participants still had a very favorable assessment, and the profile may be more tolerable compared with other POPs. Clinicians prescribing this new POP should counsel patients that the cyclic regimen does not always result in regular bleeding patterns.
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