Flibanserin

Female sexual complaints are so, so common, and some of the best data we have say that somewhere between 40% and 50% of women across the spectrum have some kind of complaint of sexual dysfunction. It’s hugely common in one form or another, and there has not been much success in drug development for that.

At the hearing for the advisory committee, the Even the Score group brought in 20 women to provide testimony about the degree of suffering and how their sexual dysfunction was really affecting their lives, their relationships and their sense of well-being.

How serious is female sexual dysfunction and the concerns that women have regarding their libido?

It’s really prevalent across populations. I see mostly peri-menopausal and post-menopausal women but also women in their 20s and 30s as well. [Note: The best study, she said, is a 1999 study in JAMA that found 43% of women and 31% of men complained of some form of sexual dysfunction.] It is very distressful for women, and the FDA has approved the drug specifically for “a lack of sexual desire that causes distress to the woman or in her relationship.” I have a lot of patients who never have sex, and they’re okay with that. The only time it’s a problem is if it’s a problem for the woman or her partner. By definition, it’s a condition that’s causing distress.

What exactly does flibanserin (Fliban) do? How does it act on the body?

That’s what’s really interesting about this. People are hyping this as the female Sildenafil, but it’s really different from Sildenafil in a couple of important ways. Number one, Sildenafil works almost 100% of time for men. But only 1 in 10 women is going to benefit from flibanserin, so it’s much less effective than Sildenafil. Number two, Sildenafil works by increasing blood flow to the penis, whereas flibanserin works on neurotransmitters in the brain, almost like antidepressants. [Flibanserin is actually a failed antidepressantwhose mechanism on mice was to act on serotonin in a way different than other antidepressants and to increase dopamine.]

Number three, with Sildenafil, men just take it when they want to have sex. Women have to take flibanserin every day, and it takes about four weeks to begin to see an effect. Peak effects aren’t seen until eight weeks. How many women want to take a drug every day that affects their brain to improve their libido?

What are the possible side effects of flibanserin (Fliban)? Can you discuss the interaction with alcohol in particular?

It has pretty significant side effects. The big ones are nausea, dizziness and fainting. [According to the FDA, the “most common adverse reactions associated with the use of Fliban are dizziness, sleepiness, nausea, fatigue, insomnia and dry mouth.”] It’s designed to be taken at night. We have to be very careful not to give it to women who have conditions that could make a problem from the drug worse. Say a woman already has a blood pressure condition. Then you add this drug, and she’s fainting at work or while driving.

How effective is it really? How well does it work, and how many women could benefit?

That’s the other thing — in the women we think might be candidates for this drug, does it work? In the trials, they found that women at baseline were having 2.7 “sexually satisfying events” per month. Sexually satisfying events were defined as “intercourse, manual sex, oral sex, or masturbation, with or without orgasm.” Women taking the placebo went to 3.7 events per month, and women taking flibanserin went to 4.5 per month. [So, women are getting not quite one whole additional “sexually satisfying event” — potentially without orgasm — than on placebo.]

These were well designed trials, and the effect seemed to be real, but it’s small, and it only occurred in about 10% of women. One could argue that what we have here is a minor aphrodisiac with scary side effects. How many women are going to be eligible for the drug and how effective are they going to feel that it is?

How much data do we have about long-term risks of using flibanserin?

We don’t have any long-term data. Any time a new drug is brought to market, it’s on the basis of short-term studies, and it remains to be seen how it’s going to be tolerated over time. Again, this drug is designed to be taken every day like an antidepressant and presumably a person would be maintained on it, so that’s an unanswered question right now.

What’s considered “normal” or typical levels of desire in women?

I spend a fair amount of time talking to my patients about what’s normal. The traditional model of sexual response (research by Masters and Johnson) is that sexual activity starts with desire, goes up through arousal, then plateaus a little bit, there is an orgasm (or several orgasms), and then there’s resolution. This is an up and down model. That actually has turned out not to be the case for most women.