Question

If I adhere 100% will resistance happen over time anyway?

27 April 2011. Related: Adherence, All topics, CD4 and viral load, Changing treatment, HIV transmission, Resistance, Side effects, Starting treatment.

Hi, before I ask my question, can I just congratulate you for this wonderful resource which has been of great help to me since my diagnosis.

I have recently achieved an undetectable viral load after a year on therapy. My numbers are – VL less than 40 and CD4 663 with a CD4% of 33%. In the past year I had to switch treatments due to side effects (efavirenz and darunavir based regimens). I am currently taking Reyataz+Truvada+Norvir. I am generally happy with my treatment except for very high bilirubin. I am ~ 100% adherent.

My doctor advises me that with every year of successful viral suppression, the chances of resistance continue to drop; is this true?

On a more general note, I want to know, how long can one go on a regimen with good adherence and viral load suppression? Some people suggest that one can carry on theoretically indefinitely and realistically for decades without the need to change regimen. On the other hand, some suggest the inspite of viral load suppression and good adherence, resistance will eventually develop (but it happens at a slow rate).

I understand that everyone is different but can you shed some light on this question – how long can one go on with good adherence and VL suppression on a single regimen? Are there any studies that give us more insight into the mechanisim of resistance in such situations?

Apologies for being longwinded but I believe this is an important question and there doesn’t seem to be much information around.

Thanking in anticipation. Comments from other readers would be welcome!

Answer

Answer: Charlotte Walker

Thank you for your question.

If you do not start with a resistant strain and you adhere to your medication then you should not develop resistance regardless of how long you are on the same treatment. For a more detailed response please follow this link to a very similar question.

Your doctor is correct in stating that for every year you have viral suppression then resistance is less likely to occur.

Some people have been on the same regimen for over 10 years without any problems. If you find a combination that is right for you then you can stay on it for many years.

There are lots of studies on our website about adherence and virological failure. If you go to advanced search, select research reports and search ‘adherence and resistance’ they should come up. I thought this was a particularly good article about it.

I am sorry to hear you are having so many problems with your bilirubin levels. If you are getting on ok with atazanavir (Reyataz) there are some things you can try without having to switch medication if you would prefer?

One of the problems with protease inhibitors such as atazanavir, which are boosted with ritonavir (Norvir) is that the levels of drug in the body can vary depending on the individual. Ritonavir boosts atazanavir levels to around 10 times higher and makes them more consistent.

It is possible that the atazanavir levels are getting too high in your body. You need to ask your doctor about a Therapeutic Drug Monitoring (TDM) test. This is a test which measures the level of drugs in your blood. For more informaiton on TDM please follow this link.

If your drug levels are too high you may find that the doctor either reduces the amount of atazanavir and ritonavir you take or stops the ritonavir and slightly increases the atazanavir (e.g. from 300 to 400mg per day). It is fine to change the levels of these drugs if your viral load is undetectable. If you still have a detectable viral load your doctor may be less keen to try different dosages of atazanavir.

If you are taking Truvada which contains tenofovir and FTC, then you will need to change this if you stop the ritonavir. This is because tenofovir reduces the levels of atazanavir if it is taken without ritonavir. Alternative treatments include Kivexa and Combivir. For more information on these drugs please follow these links to Kivexa and Combivir.

For more information it migh help to read the relevant page in our side effect guidebook by following this link.