The Mirena Migraine - A Review of the Pharmacodynamics of Levonorgestrel and Its Implications in Women's Health

Abstract

The new progestin, levonorgestrel, delivered via an intrauterine system or subdermal implant is showing promising signs of preventing pregnancy, decreasing excessive bleeding with menstruation, and returning fertility when removed (Backman, 2004). As promising as the levonorgestrel parental systems are, side effects are a common cause for concern and are a large reason for premature removal (Coukell & Balfour, 1998). Other than prolonged bleeding from insertion, and heavier periods for some women, other side effects have been observed such as weight gain, mood changes, dizziness and persistent, headache (Backman, 2004). With headache being one of the primary reasons for premature removal, previous literature has shown strong antiestrogenic activity among the pharmacodynamics of levonorgestrel (Schindler, 2003), which in turn may be the causative agent for the headache experienced among users. Given that headaches are mediated by vasodilation and vasoconstriction, the antiestrogenic activity of levonorgestrel is hypothesized to affect estrogen mediated vasodilation (Schindler, 2003). As one of the strongest antagonist of estrogen, levonorgestrel has also been discussed to affect the oxidation of low-density lipoprotein (LDL) cholesterol impacting the endothelium of the cardiac vasculature (Zhu, Bonet, & Knopp, 2000). This review aims to identify how levonorgestrel could be the causative agent for the physiologic phenomenon of a headache experienced among users so that medical professionals and drug manufacturers can be guided towards developing and prescribing a more effective and tolerable birth control option.