Long-term tolerability of ethinylestradiol 20 µg/drospirenone 3 mg in a flexible extended regimen: results from a randomised, controlled, multicentre study

BACKGROUND: This study was designed to assess the long-term safety and tolerability of a new flexible extended regimen of ethinylestradiol (EE) 20 μg/drospirenone (DRSP) 3 mg, which allows management of intracyclic (breakthrough) bleeding [flexible management of intracyclic (breakthrough) bleeding (MIB)], in comparison to conventional 28-day and fixed extended regimens. STUDY DESIGN: In this Phase III, multicentre, open-label study, women (aged 18–35 years) were randomised to EE/DRSP in the following regimens: flexible(MIB) (24–120 days' active hormonal intake followed by a 4-day tablet-free interval), conventional 28-day (24 days' active hormonal intake followed by a 4-day hormone-free interval) or fixed extended (120 days' uninterrupted active hormonal intake followed by a 4-day tablet-free interval) during a 1-year comparative phase. Thereafter, women entered a 1-year safety extension phase in which the majority received the flexible(MIB) regimen. Safety/tolerability outcomes were measured over 2 years. A separate analysis of certain safety parameters (endometrial, hormonal, lipid, haemostatic and metabolic variables) was conducted at two of the study centres. RESULTS: Results were analysed in 1067 and 783 women in the comparative and safety extension phases. Overall, 56.3% of women experienced ≥1 adverse event (AE) in the safety extension phase. Serious AEs occurred in 3.0%, 1.4% and 3.3% of women receiving the flexible(MIB), conventional and fixed extended regimens, respectively. No unexpected endometrial, hormonal, lipid, haemostatic or metabolic findings occurred with any of the three regimens. CONCLUSIONS: EE/DRSP in a flexible extended regimen with management of intracyclic (breakthrough) bleeding is well-tolerated and, when administered for up to 2 years, has a good safety profile comparable to other estrogen/progestogen oral contraceptives.