Question
Will an increase in weight reduce my drug levels?
13 August 2007. Related: All topics, Living with HIV long-term, Side effects, Starting treatment.
I am currently on first line treatment. I strted treatment 10 months ago and I’m doing well.
My CD4 count is 725 and my viral load is now below 50 copies/mL.
However, my weight went up from 64kg to 74kg.
Will my ARV drug level reduce in my blood as my weight increases?
Is there a risk of drug levels falling below the level I need for my treatment?
I go to the gym 3 times a week.
Answer
No, this change in your weight will not reduce your drug levels or stop your drugs from working.
Only two HIV drugs need to have doses changed by weight.
These are d4T (stavudine) and ddI (didanosine), when a lower dose is used if you weigh less than 60kgs. As you weighed more than this when you started treatment, even if you are using these drugs, no dose change is needed.
All other drugs seem to work just as well for a very wide range of weights.
Last months IAS conference in Sydney included a study from the US suggesting that very overweight individuals (obese, BMI over 25) had a lower chance of getting undetectable viral load, and that this may have been related to drug absorption, but most studies show no impact at lower body weight.
It is very common to put on weight during the first six months of treatment. This is a healthy reaction to your body having more energy from reducing viral load.
It is not clear from your email whether you are happy with the weight gain (ie you are returning to a normal health weight for your height), whether is is a result of increased muscle from going to the gym (muscel weighs more than fat), or whether it might be from increased body fat (lipodystrophy) which can be a side effect of some combinations.
I’d give different information on each of these aspects, but would also need to know a few more details including which combination of HIV drugs that you are taking.
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