UK changes PEP meds: raltegravir replaces PIs

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The UK has dropped the use of protease inhibitors (PIs) in combinations for Post Exposure Prophylaxis (PEP). This refers to when an HIV negative person uses HIV drugs for one month immediately after a risk for HIV – usually a missed or broken condom.

The switch to raltegravir as the third active drug in PEP should make it much easier to tolerate. A combination with fewer side effects has the potential to increase the number of people who come forward to use PEP.

It could also increase the number of people who complete the monthly course of PEP as drop out rates are generally high.

Raltegravir is more rapidly absorbed, compared to PIs, and this may improve the chance that PEP is effective at stopping potential HIV infections.

Prescribing guidelines are also being updated to say the PEP is no longer indicated if the HIV positive partner has an undetectable viral load.

This recommendation reflects the dramatic impact HIV treatment has on reducing the risk of transmission. Results from the PARTNER study reported no linked transmissions between sero-different partners after more than 44,500 times when sex occurred without using condoms.

See this report from CROI for more details of this important study:

For further information on PEP guidelines are on the BHIVA website:

Although some clinics have already switched to the new combination a few centres may continue with existing stocks (using Kaletra). This should only be for a short period.


  1. Steve

    A good initiative. The switch to raltegravir will help to overcome fewer side effects of PEP.

  2. Simon Collins

    Thanks Steve – I agree.

    The other reason PEP is under-used though is that many people will don’t know about it – or that the practical issues of getting PEP promptly are still difficult. Unless you live close to an experienced and friendly service the prospect of sitting in A&E at 4 am is not inviting.

    The easiest was to overcome this would be for PEP started packs to be easily available. The only study I remember that showed PEP was effective was in gay men who had these starter packs. This was years ago, I think in Mexico or Brasil.

    Given the high safety data from using tenofovir/FTC (Truvada) in PrEP studies, the starter pack of the new PEP combination, even for a few days, would be ideal. Raltegravir is especially exciting as PEP because of it’s rapid absorption and activity.

    I am also always concerned with the emphasis on a 72 hour window. Nearly all other community produced information still don’t get this, including the newly diagnosed booklet that has just come out from NAM/THT. Many people think 72 hours is much too late, so the impression it is still okay has completely the wrong emphasis.

    Historically, the 72 hour window was only included in the UK so as not to exclude people who were having a traumatised response. This is uses PEP for psychological support at a difficult time rather than a belief that there will be much medical activity. Most other guidelines keep a 48 hour window based on likely activity.

    With PEP, the earlier the better means that this should preferably be within a few hours. Starter packs could make the chance of efficacy much higher because there is immediate access.

    The packs would provide good ARV cover until someone can get to an HIV or GUM clinic when they are open during the week.


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