Osphena (ospemifene) is an oral medication recently approved by the FDA for painful sex (dyspareunia) due to vaginal dryness for menopausal women. As typically happens when a new drug gets FDA approval the PR machine for the company goes into overdrive flooding the media with press releases. Since sex sells, well, Osphena received a fair amount of air time and print space. Headlines like FDA-Approved “Female” Viagra might lead someone to believe that Osphena is freaking amazing. Which, of course, it is not.
What is Osphena? It is an estrogen agonist/antagonist, meaning on some tissues it acts like an estrogen and on other tissues it acts like an anti-estrogen. It acts like estrogen on the vaginal tissues and the lining of the uterus, but it acts like an anti-estrogen on the breast (note; this is in animal studies). There are 3 other drugs on the market in the same class (tamoxifen, toremifene, and raloxifene), however, ospemifene is the only one that works on vaginal tissue.
As estrogen levels drop during menopause (and sometimes a few years before) the vaginal tissues often become fragile and secretions decrease. The vagina may feel dry and sandpaper-like and the tissues may be unable to withstand the friction of intercourse even with a ton of lube. This discomfort is typically treated very effectively with topical estrogen (cream, vaginal tablet, or a ring) which increases secretions and improves the thickness and elasticity of the vaginal tissues. Many women who want to have sex after menopause will need vaginal estrogen, there is just no way around it.
But what about this new drug, Osphena?
First of all, Osphena should only ever be used when the cause of painful sex is low estrogen (the clinical term is atrophy). In other words, this pill is definitely not a Jill of all trades for sexual difficulties.
Secondly, Osphena has a lot of drawbacks and potential problems, many or which are very serious, including the following:
- It will stimulate the lining of the uterus and if not prevented this could lead to cancer of the uterus. Women with a uterus will need to take an oral drug called progesterone or a progesterone like drug to prevent this cancer (although a Mirena IUD would also do this).
- An increased risk of blood clots
- Hot flashes as Osphena as like an antiestrogen on some tissues. Not everyone reports hot flashes, but it is definitely listed as an adverse effect.
- Drug interactions. Osphena is metabolized by several liver enzymes that are responsible for the metabolism of other drugs. When two drugs use the same enzyme system side effects and serious adverse reactions are more common. On the flip side, this interaction can also cause a drug to be metabolized so quickly that it becomes less effective. A prescription for Osphena should prompt an review of your medications with a pharamcist.
Vaginal estrogen therapy is the standard of care for pain with sex due to menopausal changes. It is not absorbed to any significant degree and does not affect the lining of the uterus, increase the risk of blood clots, or have drug interactions. With vaginal estrogen women don’t have to take a second medication to prevent uterine cancer. Also, Osphena has not been around very long so there could be unknown long-term side effects.
Osphena has never been studied head-to-head against vaginal estrogen, so while it may be better than placebo no one knows how it might perform against vaginal estrogen. Vaginal estrogen replacement for the majority of women will be the safest option with fewest systemic effects.
Is Osphena the new female Viagra? Not by a long shot. In fact, it seems to be a drug looking for an indication as it is hard to imagine a clinical scenario where Osphena would be the first line treatment for vaginal atrophy.