Molecule of the Day

If you take or are close to someone who takes antidepressant medication, you’re probably aware that one class, the SSRIs, is particularly prone to causing sexual side effects. These effects can run the gamut from inhibition of libido, to erectile dysfunction, to a diminished or complete inability to achieve orgasm. It’s that last one that we take a look at today – a SSRI went on sale in Britain this week that is touted as inhibiting orgasm – on purpose!


This SSRI, dapoxetine, is marketed to treat premature ejaculation. Previously sold in a few European countries, it has just gone on the market in the UK as a product called Priligy.

This compound is a rather short-acting SSRI, with a half-life (that is, the time it takes your body to eliminate it) of just under two hours. Contrast that with, say, Prozac, which has a half-life of several days. Additionally, one of the compounds your body metabolizes Prozac is also an antidepressant, with a half-life of up to about two weeks. Half-lives are an important part of designing and prescribing a drug – if you have something you want around constantly (like an antidepressant), it can be nice to have something that sticks around quite awhile. That way, if you miss a dose, your brain chemistry won’t return to the bad old days before you started taking the drug – the effect of the missed dose is blunted by the fact that you’re still carrying a fair amount around in your body. That said, if your long-half-life pill isn’t working for you, and you want to switch to a new antidepressant, it can take awhile to get it all eliminated from your system. For a pill intended to be used for something episodic (like having sex), a short half-life isn’t a liability at all – in fact, it can be a desirable feature.

Back after a long hiatus – thanks for reading!

Comments

  1. #1 lukas
    April 29, 2010

    Welcome back, hope all is well with you!

  2. #2 mitch
    April 29, 2010

    Good post and welcome back. :)

    Mitch

  3. #3 Rosiecee
    April 29, 2010

    There are other side-effects to worry about more than sexual dysfunction.

    The Physicians Desk Reference states that SSRI antidepressants and all antidepressants can cause mania, psychosis, abnormal thinking, paranoia, hostility, etc. These side effects can also appear during withdrawal. Also, these adverse reactions are not listed as Rare but are listed as either Frequent or Infrequent.

    Go to http://www.SSRIstories.com where there are over 3,800 cases, with the full media article available, involving bizarre murders, suicides, school shootings/incidents [54 of these] and murder-suicides – all of which involve SSRI antidepressants like Prozac, Zoloft, Paxil, etc, . The media article usually tells which SSRI antidepressant the perpetrator was taking or had been using.

  4. #4 PhilD
    April 29, 2010

    Welcome back!

  5. #5 Ian Musgrave
    May 2, 2010

    G’Day! Great to have you back!

  6. #6 organic chemistry
    May 3, 2010

    welcome back. I guess my first question about this would be if one could build a tolerance to the drug and how quickly it would happen

  7. #7 Priligy
    May 24, 2010

    I have been reading more about this product, looks like the FDA a few years back actually rejected it, any ideas why?

  8. #8 Neighborcat
    June 12, 2010

    Rosiecee:

    So you don’t trust SSRIs or other antidepressants. Great, don’t take them. As with everything else in life, antidepressants have benefits and costs, good effects and bad effects. Are you offering an alternative that has no down side? SSRIs have literally given me my life back.

    As for the incidents “involving” SSRIs, all I can say is that correlation does not equal causation, and with only 3800 cases out of the tens of millions taking SSRIs, offering this statistic as evidence of harmful effects is laughable.

  9. #9 Kevin Allie
    June 14, 2010

    I feel it’s important to note that a drug’s half life is not the amount of time it takes to be eliminated– it’s the time required for something to fall to half its initial value.

  10. #10 sync
    May 23, 2011

    I know people who have taken these and they really helped. The thing is, you have to find the right one. it’s like birth control pills- lived happily on Ortho-Novum 1/35-28 for years, then someone put me on 7-7-7 and I became violent and irrational until put back. It’s a matter of finding one that works. They don’t call them ‘Selective’ serotonin reuptake inhibitors for no reason. They’re tools, things that might help, but you have to read the directions and pay attention a little. I am happy for anyone who has got a better life from something as simple as a pill they can take. That’s what I think.