Abstract
Estetrol/drospirenone is a combined oral contraceptive (COC) with a plant-synthesised foetal oestrogen (estetrol) and a well-established progestin (drospirenone). In preclinical models, estetrol has lower binding affinity for the oestrogen receptor-α (ER-α) in contrast to estradiol and has antagonistic properties against membrane ER-α in several tissues, including the breast, while retaining agonistic activity on receptors located in the nucleus. The low oestrogenicity of estetrol may potentially contribute to reduced thrombotic risk. Estetrol/drospirenone was an effective contraceptive in phase II and III clinical trials, with regular and predictable bleeding cycles maintained in the majority of women. Estetrol/drospirenone was generally well-tolerated with metrorrhagia reported as the most common treatment-related adverse event, which is consistent with other COCs. Cases of migraines with aura (or severe migraines), deep vein thrombosis, hyperkalaemia and depression were rarely reported during the phase III trials. Overall, estetrol/drospirenone is an effective and generally well-tolerated COC, with a potentially reduced risk of thrombosis.