Sciencebase has a short article on a potential new aphrodisiac. It’s called PT-141, or bremelanotide, or Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH (“PT-141” is the useful search term if you want to hit up PubMed), and it’s a melanocortin agonist that works directly on the brain. It can be delivered as a nasal spray. It works on men, promoting erections, and it also seems to be effective on women, increasing sexual appetite.

“A dose of PT-141 results, in most cases, in a stirring in the loins in as little as 15 minutes,” reports Julian Dibbell, “Women, according to one set of results, feel ‘genital warmth, tingling and throbbing’, not to mention ‘a strong desire to have sex’.”

Wow. Makes me want to run out and buy stock in Palatin Technologies, the manufacturer.

But the story bugs me, and I have to dash a little cold water on it all. I just have my doubts that it can work as well as they claim.

This is a compound that stimulates receptors in the brain, receptors that are associated with the regulation of various kinds of appetites. If they are that easy to manipulate, as the article suggests, then evolution would have ‘noticed’ long ago—we ooze odorants all the time, we produce melanocortin, I’d be very surprised if there were not selection for secretion of a substance that has that kind of effect on prospective mates. And to complement that, of course, there would be selection for an ability to resist that kind of chemical manipulation. It makes me very suspicious that this compound is being over-hyped.

That doesn’t mean it doesn’t work, of course. Lean in close to your lover sometime, and take a deep breath; oh, yeah, it works. Lots of subtle phenomena can elicit arousal, smells included, but also such things as novelty, language, security, and trust. A chemical signal like PT-141 can be a part of the stimulus, but you hygienically-challenged mouth-breathing dullards of the world should sit back down: giving a lady at a bar a snort of a melanocortin agonist isn’t going to override her revulsion.

Besides, I thought the most provocative and significant part of the story was buried near the end of the Observer article.

The funny thing is, it appears there’s a certain humanlike subjectiveness to the sex life of lab animals as well. When Jim Pfaus tested PT-141 on his female rats, he based his experimental design partly on the work of Raul Paredes, a fellow rat sexologist testing the effects of something more elusive: personal autonomy. That’s a tricky thing to measure, but it can be done. Paredes did it like this: first, he looked at rat couples living in standard, box-shaped cages and recorded the details of their sexual behaviour. Then, he altered the cages in only one particular: he divided them into two chambers with a clear wall broken only by one opening, too small for the males to get through but just right for the females. Architecturally it was a minor change, but what it did for the females was huge. It let them get away from the males whenever they chose to, and thereby made it entirely their choice whether to have sex. Paredes then observed the rats’ behaviour in this altered setting. Here’s what he found: the effects of giving a female rat greater personal control over her sex life are essentially the same as those of giving her PT-141. Autonomy, in other words, is as real an aphrodisiac as any substance known to science.

Unfortunately, freedom isn’t something that a pharmaceutical company can market and sell, and it’s not quite as easy to carry as a pocket inhaler. I have a dream, though, that someday everyone will realize that you can’t manipulate people into love and lust, and that autonomy and mutual trust are the sexiest part of a relationship.

I’m also thinking that there’s a lesson here that our neighbor state to the west could learn (new slogan: “South Dakota is not for lovers” or maybe “South Dakota: the anti-libido state”).


  1. says

    2,5-dimethoxy-4-bromophenethylamine has the same effectiveness and lets you see weird stuff too. To quote Alex Shulgin in PiHKAL:

    A generalized spectrum of 2C-B action can be gleaned from the many reports that have been written describing its effects. (1) There is a steep dose response curve. Over the 12 to 24 milligram range, every 2 milligrams can make a profound increase or change of response. Initially, one should go lightly, and increase the dosage in subsequent trials by small increments. A commonly used term for a level that produces a just perceptible effect is “museum level.” This is a slightly-over-threshold level which allows public activities (such as viewing paintings in a museum or scenery watching as a passenger in a car) to be entered into without attracting attention. There can be considerable discomfort associated with being in the public eye, with higher doses. (2) The 2C-B experience is one of the shortest of any major psychedelic drug. Wherever you might be, hang on. In an hour or so you will be approaching familiar territory again. (3) If there is anything ever found to be an effective aphrodisiac, it will probably be patterned after 2C-B in structure.

    Emphasis added.

  2. Blake Stacey says

    The Sciencebase article calls PT-141 an “odourless and colourless synthetic chemical” (paragraph four). Uh-oh. Why do I feel a moral panic brewing about “the next date-rape drug”?

  3. George Cauldron says

    Wasn’t PT-141 that boat JFK was on during WW2? COINCIDENCE? I think not!

    Thank you, thank you, I’m here all week!

  4. Com$tock says

    I seem to recall hearing about this drug 2 or 3 years ago. I might be mistaken. Maybe it was another, similarly named sex drug. In any case, I’m wondering: if it works so well, why isn’t al the rage? I get the sense this is going to be one of those things that you can find on the counter at gas stations, promising a bigger, longer, thinnner, happier you, but really just some huckster’s attempt to spur an impulse purchase. I guess I’ll believe it when I see it.

  5. rrt says

    I’m a bit confused by the latter excerpt. What effect did giving the females autonomy have that was similar to PT-141? They had more sex?

    And, assuming it works, I don’t see this being hyped much as a date-rape drug. I see it being marketed much like Viagra, Levitra, etc.

  6. says

    A relevant course reading is the recent PLoS Medicine special collection on “disease mongering”. In this collection, the most pertinent essays are probably “Bigger and Better: How Pfizer Redefined Erectile Dysfunction” by Joel Lexchin and “Female Sexual Dysfunction: A Case Study of Disease Mongering and Activist Resistance” by Leonore Tiefer. The take-home message, as far as I can judge, is that yes, ConHugeCo Pharmaceuticals are out to get your money by turning everything we can fix with a pill into a disease; however, this works best when the public is particularly vulnerable. I can think of few aspects of human behavior less susceptible to this technique than sexuality.

    Take a broken free-market economy, mix it with an abysmal lack of science education, a pervasive media culture which steeps the population in insecurity, omnipresent advertising fine-tuned to appeal to the most reptilian parts of the human brain, and a few other risk factors — and the current situation seems inevitable.

    (Disclaimer for our friends at the Department of Fatherland Security now joining our program already in progress: no, just because I mention an exotic psychotropic substance, that doesn’t mean I know where to find it or have tried it myself. The written word is my anti-drug, or more accurately, my drug of choice.)

  7. says

    They were assaying the effect in female mice by measuring female pre-coital behavior — nose-twitching, ear-nibbling, etc. — and those responses were similarly elicited by autonomy. They had their refuge, and they would spontaneously emerge from it looking for sex.

  8. rrt says

    Thanks, PZ…interesting, and cool. I wonder if there are differences in, say, reproductive success of the females who were given the autonomy?

    I don’t see anything necessarily “wrong” with the drug (if it works), but I do see Blake’s point about disease-mongering and marketing.

  9. DeafScribe says

    PZ’s view on autonomy as aphrodisiac is also bolstered by the recently published Global Study of Sexual Attitudes and Behaviours, published in April’s Archives of Sexual Behaviour.

    USAToday has a bit on it:

    Basically, countries where partners have more autonomy and equality report greater levels of sexual satisfaction.

    Ironically, the study was sponsored by Pfizer, the Viagra people.

  10. George Cauldron says

    I am sad that in my schooling they didn’t teach us how to tell when a female mouse is turned on.

    I bet in Japan they learn that by the fourth grade.

  11. says

    If I read that some complicated chemical turns rats on I say so what!…I am not a rat. If I read that freedom to respond or not turns rats on, I accept the extrapolation to humans. And I consider the findings consistent with my understanding of at least one mind-body connection I know of. Being in control of your fate is less stressful whereas cortisol and other stress induced substances probably supress sensitivity to these putative aphrodesiacs.

    Just a neat finding and thanks for the usual excellent PZM hightlighting.

  12. MattXIV says

    If they are that easy to manipulate, as the article suggests, then evolution would have ‘noticed’ long ago–we ooze odorants all the time, we produce melanocortin, I’d be very surprised if there were not selection for secretion of a substance that has that kind of effect on prospective mates. And to complement that, of course, there would be selection for an ability to resist that kind of chemical manipulation. It makes me very suspicious that this compound is being over-hyped.

    But the levels that could be delivered dissolved in a nasal spray are fair higher than what could practically be diffused through the air. We would have evolved resistance based on the later levels, since we don’t go around squirting our musk up each other’s noses, so a concentrated nasal spray may be illiciting a response by using a dose far higher than what we’d encounter naturally.

  13. says

    An ideal test platform: feed the stuff into the ventilation system at the next meeting of the S. Dakota legislature. (You could tell it was working when everyone’s heads explode)

  14. G. Tingey says

    Sorry, I thought it was …

    “Sex, and Drugs and Rock’n Roll is all my brain and body need” ????

    ( Ooh – errr missus! )

  15. Azkyroth says

    Anecdotal evidence in possible support of the rat thing (or, at least, of its applicability to humans): my observations of and conversations with female acquiantances suggest a correlation of libido with independence (as a personality trait as well as as as condition). More specifically, I’ve observed that my wife’s emphatically not into it when she feels like she’s not in control of her life…

  16. ferrellms says

    It is surprising that you find this result not credible. As Matt points out, the levels from a spray could be much higher than that emitted by a person. The fact that autonomy has a similar effect is irrelevant to whether this spray works or not. I am surprised that a scientist would offer such irrelevant and anecdotal dismissal of anothers’ work.

  17. older and better says

    Oh, PZ! I know, you are a squid guy, not a rodent guy, but please!! Rats and mice are not the same folks! Not at all. Yes, they look sort of alike, but they are only a few of the species that use that body style, all of them different in many other ways. Sorry to complain, I love your stuff, mostly.

  18. mofoman says

    its funny our ancestors had no problem with sexual disfunction we are liveing proof of that, but in an age where our food is radiaited crops manipulated by cloneing and chemical pest control, in all has been used in every facet of our lifes its no wonder we need viagra ETAL to boost our sexual gratification, i am not one to condem anything that could help enhance our lifes, out of curiosity i cant wait until human testing gos full bore to make that yea or nea on this stuff,. and john kenedy was on pt 109 and the crew lived remember that?