Where do PrEP and HIV meet in the body?

Dear Bob,
Do researchers know enough about the lifecycle of HIV as it enters the body and how this pertains to Truvada in the bloodstream? For example, in its lifecycle, will HIV always encounter the Truvada in the bloodstream before it can start an infection? Or can HIV start an infection in other cells without ever encountering Truvada in the bloodstream?
Looking for PrEP
Dear Looking,
Good question – the drugs used for PrEP have to meet HIV in order to block the spread of infection in the body.  Fortunately, PrEP drugs get around well in the body well.
The drugs in Truvada PrEP are absorbed in the intestine and are circulated by the blood stream.  We find the PrEP drugs in the blood, in vaginal tissues and fluids, in semen, in hair, and in the intestines, including the rectum.  Concentrations of drug in the rectum are especially high, partly because tenofovir disoproxil fumarate is only partially absorbed in the small intestine.  The drugs get into a variety of different cells in the body, including macrophages and lymphocytes which are the primary targets for HIV infection.
If the person has been taking PrEP before HIV exposure, the chances are high that HIV will meet a cell that has already been occupied with PrEP drugs.  One of the reasons that PrEP works so well when used daily before viral exposure, is that there is time for the cells in the body to absorb and process the drug so that HIV is stopped in its tracks when it comes along.


Posted on

April 15, 2015

1 Comment

  1. Luis

    Hi, good afternoon, I was curious if you have gastric bypass surgery will truvada still be absorbed enough to be effective? Thank you


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