The risk of deep venous thrombosis with oral contraceptives containing drospirenone

Drospirenone is a synthetic progestogen, derived from the aldosterone blocker spironolactone. It is structurally related to progesterone and has antiandrogenic and anti-mineralocorticoid properties. It has been marketed in oral contraceptive preparations, combined with 30 mg of ethinylestradiol, since about 2000. The contraceptive efficacy of such pills is undoubted, but their adverse effect profile is the subject of controversy, particularly the potential to cause venous thromboembolism. Two linked studies add to this debate (doi:10.1136/bmj.d2139; doi:10.1136/bmj.d2151).1 2 Both are observational database studies and produce remarkably similar results, which support another two studies published in the BMJ in 2009.3 4 All of these studies suggest that drospirenone increases the risk of venous thromboembolism compared with the progestogen, levonorgestrel. However, at least two other studies disagree.5 6

The two new papers analyse …