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Slynd: does a drospirenone progestogen-only pill offer an advantage?

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What you need to know

  • Slynd is a progestogen-only pill (POP) consisting of twenty-four tablets containing drospirenone 4mg and four inactive tablets in each 28-day cycle.

  • Drospirenone is derived from spironolactone and has antiandrogenic and antimineralocorticoid properties.

  • Clinical trials in Europe have shown that a drospirenone POP is an effective contraceptive with a pooled Pearl Index <1.

  • If a single tablet is taken up to 24 hours late, contraceptive protection is not reduced.

  • Commonly reported adverse effects include acne, metrorrhagia, headache and breast pain.

  • The risk of venous thromboembolism with drospirenone POP is not known.


Progestogen-only contraceptives are available in a variety of forms, including injections, subdermal implants, intrauterine systems and progestogen-only pills (POPs).1 POPs make up the bulk of prescriptions for progestogen-only contraceptives dispensed in England each year.2 Out of 4.2 million primary care prescriptions (£41 million) for progestogen-only contraceptives dispensed in England during 2023, over 3.1 million prescriptions (£16 million) were for POPs.2 POPs marketed in the UK contain desogestrel or levonorgestrel or norethisterone, and are supplied as blister strips of 28 active tablets (desogestrel and norethisterone) or 35 active tablets (levonorgestrel) that are taken continuously. If a tablet is delayed for ≥3 hours (levonorgestrel, norethisterone) or ≥12 hours (desogestrel) beyond the usual time of taking the POP, it should be regarded as a ‘missed pill’.1 In the UK, Slynd has recently been marketed as the first oestrogen-free drospirenone contraceptive and the only POP with a 24-hour missed pill window.3 Here, we review the evidence for this new POP.

Contraceptive efficacy

In the assessment of contraceptive efficacy, the Pearl Index (PI) is defined as the number of unintended pregnancies per 100 women-years of using a contraceptive and ranges from 0 (no pregnancies) to 1200 (all participants became pregnant in the first month).4 5 The unadjusted or overall PI (‘user and method failure’) represents the failure rate …

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  • Competing interests None declared. Refer to the online supplementary files to view the ICMJE form(s).

  • Provenance and peer review Commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.