Can You Take PrEP With Fibre?

For many gay men, a daily regime of PrEP and fibre supplements like Metamucil(tm) has kept us ready for sex without worry.

There has been a long-standing question about whether taking your Truvada, or generic PrEP tablets, at the same time may lead to decreased drug absorption. Reduced absorption could mean a drop in its protection against HIV infection.
The concern was, if the tablet is caught in the middle of the fibre clump, the medicine may not dissolve and be absorbed.

Until this month, it has never been explored with a formal study.

Please welcome to the stage the fantastic science explorer Kyle Anthony who has created an experiment to tackle this question.

Long story short, Kyle replicated the stomach conditions in the lab. He ran two experiments where he dissolved generic PrEP tablets in a water solution compared to a solution of water and a standard dose of fibre tablets.

After mixing for 90 minutes, the average time food sits in the stomach, he tested the liquid for levels of the two drugs in PrEP - Tenofovir and Emtricitabine.

His study showed the drug levels were the same for water and water plus fibre conditions.

To be sure his study was accurate, he did the same test with a drug known to have absorption problems with fibre, Digoxin. This test version did show a drop in the drug levels.

This gives a level of reassurance that the experimental conditions did appear to replicate the conditions of the stomach short of having to do in human studies.

So what does this mean? To quote Kyle:

“Taking PrEP and fibre together probably doesn’t affect the absorption of PrEP into the bloodstream because the presence of fibre does not affect the PrEP’s solubility.”

He does add a level of caution to this:

” If it were me, I’d probably avoid taking fibre and any medication at the same time since we don’t know if a fibre interaction exists for most meds. But it’s likely not an issue if you currently take PrEP and fibre together.”

For me, the take-home message is if you have been taking PrEP with fibre, it’s unlikely fibre has altered PrEP’s protection.

I would add, as has Kyle, that: If you are taking a drug that is vital to staying alive, I recommend separating the fibre and the tablet by at least 4 hours.

I tell my patients, “Take your tablet in the morning and your fibre at night, or vice versa.”

With PrEP, when taken daily, it doesn’t matter what time you take it, so there is scope to separate taking your fibre and PrEP.

Huge kudos to Kyle for this excellent explorative experiment. It’s these grassroots efforts that can lead to exciting discoveries. I highly recommend following his tweets! @KylePlankton

Stay safe, team!

Dr George Forgan-Smith

TL:DR? Taking Fiber and PrEP together is unlikely to cause a drop in absorption however until a formal human study has been done, we can’t know for sure.