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Giving people what they want: violence and sloppy eating

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Up yer bum - rectal microbicides
mini me + poo
Someone asked about this when I last mentioned them...

Rectal microbicides are chemicals which are designed to be put up the anus into the rectum to kill off microbes that cause STIs when having anal sex with an infected partner. Ideally, they'd protect both the receptive and insertive partner.

Much more research is being done on vaginal microbicides, partly because of 'moral' issues (i.e. homophobia and general bigotry) but also because the vagina is a much easier place to get a microbicide to work.

Remember that being on the receiving end of anal sex with an HIV+ man is about fifteen times riskier than being on the receiving end of vaginal sex? Here are some reasons why:

Vagina: thick outer layer of the skin, about forty cells deep
Rectum: one cell layer deep, albeit with thicker cells than the vagina

Vagina: fewer CD4 cells near the surface to be infected by HIV
Rectum: complex and extensive immune structures under surface

Vagina: acidic
Rectum: alkaline

Vagina: an enclosed 'pouch'
Rectum: a long tube, ultimately ending at the mouth. You don't need to go that far, but it's known that lube can be found two feet along, well into the colon, four hours after being placed in the rectum

So there are several trials of vaginal microbicides going on, but it looks like only one potential rectal product is even at a very early stage of trials.

It also doesn't help that understanding of HIV infection in the rectum is still not that well understood, and the rectum and colon are more fragile than the vagina, so there are increased safety issues (it's quite possible that using a vaginal microbicide might not work, and might be actively harmful!)

TMI: I was hoping to post this on (the UK's)Mother's Day...

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I would be quite concerned about the increased risk of thrush for the vaginal version :-(

Quite - it's tricky tying to keep the bacteria you do want while killing off the bacteria and viruses you don't, and it gets even more complicated in the gut.

The designers of BufferGel (and this could be the one that's in early trials, I am utterly out of the loop) want it to be tested as a rectal microbicide as well, and have since the beginning of their research (I did my graduate work in their lab). I don't think it's happening yet, though, because the clinical trials process is so nightmarish that they're testing it as a vaginal microbicide first. But it was something very much on their mind during the design process, and when they were doing the initial research they were specifically looking for a polymer that would not be absorbed in the rectum. But, as you mentioned, it's a much more difficult environment to work in and the open tube vs. pouch thing is, in particular, a killer. Particularly for those microbicides that are designed to work by forming a physical barrier instead of a hostile environment. I need to get read back up on the microbicide research. I hate being this far behind.

I understand that at least three of the vaginal ones are doing rectal safety tests, but this is to see if they cause harm rather than work.

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