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Cory Silverberg

Meet Your New Experimental Sex Drug: Flibanserin

By November 17, 2009

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Pharmaceutical maker Boehringer Ingelheim (BI) is looking to create a lot of pre-emptive buzz for its gamble on the female sex drug market, flibanserin. Flibanserin is being developed as a non-hormonal treatment for low sexual desire in women, a market that's thought to be more financially lucrative than even the $2 billion dollar erectile dysfunction market.

On Monday they orchestrated several media releases, webcasts, and a presentation at a major sexual medicine conference in Europe, all to release data from Phase III trials on pre-menopausal women labeled with low sex drive (also known as hypoactive sexual desire disorder, or HSDD). The next few days and weeks will reveal how effective this first of many blitzes is likely to be.

All of this has everything to do with marketing and little to do with science. The data hasn't been released and no breakthroughs have been discovered. Still it's an opportunity to get a little more acquainted with a drug that changes brain chemistry and they hope will change, or direct, the global conversation on female sexuality.

Defining Sexual Desire
Sexual desire is a difficult thing to define, as even researchers involved in the flibanserin studies acknowledge. The model presented by BI researchers involves breaking down desire into three elements, which include:

Drive, referring to spontaneous sexual interest that is somehow biological or hardwired (what that actually looks like is only a guess).

Belief & values, including social, cultural, ethnic, religious, and other factors that impact how often we might feel sexual desire, how intensely we feel it, and how comfortable we are with it.

Motivation, which considers all the psychological and interpersonal factors creating a willingness to be sexual and feel sexual desire.

The pitch from BI researchers is that while good treatments exist for low sexual desire caused by beliefs, values, and motivation, we don't have anything to treat the drive component (which they call the "biologic" component). They believe that flibanserin treats the drive component of sexual desire.

How It Works
What they don't know is how flibanserin is supposed to achieve this. They know that the drug reduces serotonin levels, and their current guess is that it impacts sexual desire by reducing inhibitory effects in the brain (basically it's removing whatever is stopping you from feeling desire). But this is just a guess.

What It Does
On Monday November 15 the company did a major media push, releasing some of the data from their clinical trials with pre-menopausal women who had been diagnosed with HSDD. They released data at a sexual medicine conference, through media releases, and via phone/webcasts (one of which I listened in on). Here's a summary of what they have released:

BI conducted several studies in North America and Europe involving over 5,000 pre-menopausal women who had been diagnosed with HSDD. In their publicity campaign, they focus on the North American studies (more on that below) and included just over 1300 women. The average age was 35 and most of the women were married and the average length of relationships was over 10 years.

The women were assessed for both desire and distress caused by desire and then followed for 6 months. Every day the women were asked to record their subjective evaluation of their own sexual desire and their sexual activities, defined as Satisfying Sexual Events (SSEs). One particularly nice aspect of the study was that sexual events weren't defined solely as intercourse or orgasm. An SSE was defined as sexual intercourse, oral sex, masturbation or genital stimulation by the partner, which was subjectively evaluated by the woman as satisfying (with prompts like gratifying, fulfilling, satisfactory and/or successful).

Comparing the women taking daily doses of flibanserin with women taking a placebo, the pooled data show: Women taking flibanserin increased their SSEs by 1.7 per month while on the drug. Women taking the placebo had 1 more satisfying sexual event per month while taking the placebo.

Women taking flibanserin reported an increase in sexual desire and a reduction in distress about sexual desire. Women taking the placebo also reported increase desire and decreased distress, but the difference between the two groups was statistically significant.

Notably, in the European study there wasn't a significant increase in sexually satisfying events.

Questions Remain
To be fair, BI hasn't completed it's research. At the same time they are making the calculated business decision to get publicity for this data, so it also seems fair to start raising questions now about what they are reporting.

They haven't offered any rationale for why the drug produced statistically significant results in the "biologic" component in North American but not in Europe. I suspect the answer to that question may be messy as it would likely refer back to non-"biologic" elements of sexual desire, thus pointing out a problem with the premise of the research.

After the six month study there were participants who stopped taking the drug reported that their sexual desire did not diminish. Whether this suggests that the drug is having a permanent effect on brain chemistry, or that brain chemistry is not in fact a significant factor in most cases of low sexual desire remains to be explained.

Finally, I was interested to hear one of the researchers say that most women in the study reported that their low sexual desire crept up on them over a period of time. If, as the researchers argue, problems with low desire are drive related, hard-wired or biological, why would they appear slowly? Are they suggesting there are precipitating factors influencing low sexual desire? If so, would effective treatment not want to address those factors before they go altering the brain chemistry of otherwise healthy women? One consideration in a low desire creep may be age, but these studies were of pre-menopausal women with an average age of 35. These seem like pretty important questions to consider.

What What We Don't Know
Currently the only safety data we have is for women who have been on flibanserin for six months. They have been following women for over a year (after the studies are done women are given the option of continuing on the drug) but haven't released data on those women. In a telephone media presentation researchers propose that no significant safety risk is expected to emerge. This seems a little like hubris given the "unexpected" discoveries of risks associated with long term use of SSRIs, which weren't found in clinical testing.

We also don't know when flibanserin would be an appropriate treatment. Is it meant to be a first line treatment or used only when safer, more proven treatment options have been exhausted? Once the media and a splashy BI advertising campaign create the myth of a pill that'll make you want sex, how prepared are physicians going to be to explain the actual complicated nature of desire, never mind finding the time to do it versus the time it takes to write a prescription.

The Bottom Line (for now):
In truth, it's much too early to be evaluating the potential benefit versus harm of flibanserin. It's a smart strategy on the part of pharmaceutical companies to generate press for a drug that's not yet approved as a way of mobilizing a lazy media, generating a public buzz and setting the terms of the public discussion on the topic. Unfortunately what's good for business isn't always good for public health.

Read more - Petra Boynton Offers a Behind the Scenes Look at the Flibanserin Release

Related - Bloomberg News: Desire Drug May Prove Sex Really Is All in Her Head

Boehringer Ingelheim Press Release - Boehringer Ingelheim Announces Pivotal Phase III Data of Flibanserin in Pre-Menopausal Women with Hypoactive Sexual Desire Disorder

Guardian Comment is Free - Pill-popping approach to female libido

Neuroskpetic - One Pill Makes Your Libido Larger

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Comments
November 18, 2009 at 1:45 pm
(1) Neuroskeptic says:

Thanks for this, very informative. I blogged about this here from a scientific perspective.

“Finally, I was interested to hear one of the researchers say that most women in the study reported that their low sexual desire crept up on them over a period of time.”

Clinical depression tends to creep up on you too. Hmm. The patients in these study were excluded if they had

“a history of MDD within 6 months prior the Screen Visit or a score of 14 on the Beck Depression Inventory© II, or a history of suicide attempt according to the Beck Scale for Suicide Ideation.”

according to the clinical trials register however a BDI score of up to 14 is still quite high. In my experience most mentally healthy people score 0-3, while 20 is full-blown “moderate depression”.

Given that this drug may be an antidepressant – it failed clinical trials but that doesn’t mean it doesn’t have a small effect – the sexual benefits could just be reflecting a mood improvement.

Also, according to the side effects chart it causes fatigue and sleepiness, so it’s a sedative – and as we all know sedatives, e.g. alcohol, can increase desire!

November 19, 2009 at 7:21 pm
(2) Cory says:

Thanks for the link and your great piece. Reading your article just highlights for me that it’s actually not fair to be expecting BI or any company to have answers that they simply won’t be able to produce. So the final question for me then is, do the benefits outweigh the risks/harm? My problem with this is that a couple hundred million dollars in marketing has such an influence on expectation, perception, and eventually reporting, that I don’t think we’ll ever get a good answer precisely because of the aggressive way pharmaceutical companies market this stuff.

December 30, 2009 at 4:33 pm
(3) David says:

Seems the critics and dissidents have cited various psychological reasons for the effectiveness of Flibanserin in increasing a woman’s libido. However, what explanation do they have for the observed increase in sex which was observed in animal tests. Do animals suffer from depression or does Flibanserin actually increase a desire for sex in both animals and humans, if that distinction can be made?

March 5, 2010 at 12:31 pm
(4) Girosa says:

I wonder if the fact that Flibanserin decreases the amount of serotonin in the brain has any affect on increasing sexual desire. Flibanserin was tested to work as an anti-depressant as we know, but it is an unusual type as most anti-depressants (SSRI) increase serotonin (blocking the reabsorption) SSRI’s can tend to lessen ones sexual drive, so I wonder if it has something to do with the opposite. This of course is just a minor part of the overall equation.

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