Purpose: The contraceptive pill is an effective and safe method of preventing pregnancy. The progestins used for contraception either are components of a combined hormonal contraceptive (tablets, patches or vaginal rings) or are used alone in progestin-only formulations. Progestin-only contraceptives are available as daily oral preparations, subcutaneous or intramuscular injectables (every 1-3 months), subdermal implants (every 3-5 years) and intrauterine systems (every 3-5 years). Long-acting progestins are highly effective in typical use and have a very low risk profile and few contraindications.Material and Methods: A new progestin-only, oestrogen-free contraceptive, drospirenone, in a dosage of 4 mg/day in a 24/4 regimen, has received regulatory approval in the USA and the EU. The molecule has antigonadotropic, antimineralocorticoid, antiestrogenic and antiandrogenic properties.Results: The regimen was chosen to improve the bleeding profile; maintain plasma oestradiol levels at those of the early follicular phase, to avoid hypoestrogenism; and preserve efficacy even with a missed pill, as drospirenone has a half-life of 30-34 h.Conclusions: Clinical studies have shown good efficacy, very low cardiovascular side effects and a favourable bleeding pattern, as well as maintenance of ovulation inhibition after scheduled 24 h delays in pill intake.
Keywords: Drospirenone; oestrogen-free contraception; progestins; spirolactone derivative.