Question
Switching between TDF and TAF for PEP.
3 December 2021. Related: All topics, Changing treatment, PEP/PEPSE, Side effects.
My doctor has prescribed TDF/Emtricitabine/Dolutegravir for PEP and also mentioned another alternative where I can replace TDF with TAF.
I’ve taken the TDF drugs for 14 days, but after seeing a study which says that there is a risk of renal impairment from TDF (300 mg) regimen even when taken for a month, I’ve been thinking of switching to TAF alternative.
I want to know if switching to TAF for 14 days is a safer alternative and if there are any risks associated with it? I’ve read that TAF increases the LDL cholesterol but will it cause any significant impact if taken for 14 days ?
Answer
Hi, how are you doing?
There are no guidelines in the UK, or suggested by WHO that TAF should be used as PEP. TDF has been associated with renal failure although this is rare, often the side effects reverse once having stopped the medication.
Are you aware if you already have problems with your kidneys? TDF is not recommended in people with an eGFR below 80, eGFR being a measure of how your kidneys function.
TAF does have a lower risk of causing side effects that TDF but as it is not a recommended medication for PEP, you will need to discuss this with your prescribing doctor. The effect of TAF on LDL is still being studied. As it is often taken in combination it is difficult to directly link changes in LDL to the switch of TAF and TDF. It has also been suggested that maybe TDF reduces LDL and switching to TAF loses this positive side effect.
If you have any more questions please feel free to get in touch,
Josh.
Hi Rohan, a 4th generation test (like the one you took) is accurate from day 42. As you tested at day 60, your result is conclusive. You are HIV negative. The symptoms you are experiencing are not caused by HIV.
Hi ,
I had protected vaginal intercourse with csw in Singapore. But didn’t check the condom was intact. Started pep tdf/FTC rilpivrine 21 hours after act.took 30 doses didn’t miss any,
Tested negative on day 31 with p24 rapid test finger prick
Did a eclia ag/ab test and hiv-1 RNA PCR viral load test on day 60 that is 30 days after last pep dose
Now it’s almost 90 days but I think I am still having symptoms. Can you please tell me how accurate are the test I took at day 60
Hi Roger, thank you for your comment. I would just like to add that time is a likely factor for side effects, however this too has not been adequately studied between the two. Duration of medication is still ongoing research for the time expected to observe side effects.
I’d suggest that one of the key points is that the small increases in the risk of kidney and cholesterol abnormalities are generally seen in people taking these drugs on an ongoing basis, as part of their HIV treatment. On a 28 day course of PEP, the impact is likely to be non-existent or minimal.