Which is more toxic (abacavir or tenofovir)in regards to the lipids, mitochondria, and to lipoatrophy besides the hypersensivity reaction side effect of the abacavir? I know there were some studies comparing tenofovir and azt which had tenofovir a less toxic drug. Thank you for your answer/info.

The evidence for switching from Zerit to Ziagen and regaining fat is derived from 3 randomised controlled studies plus several large cohorts. It is the highest quality 'level of evidence' we have. Data with switching to viread are more sketchy and anecdotal although a large comparative trial of ziagen vs. viread switch will complete late this year. Both agents do not appear toxic to mitochondria in test tube studies. Abacavir has not been associated with fat loss in 2 prospective stidies (called FIRST and ABCDE) over >1 year of therapy. Viread has not been associate with fat loss over 3 years in a large prospective study so we expect it to facilitate fat recovery. Viread also seems to lead to cholesterol and triglyceride improvements which are not so evident with abacavir. Abacavir has an allergic reaction which ocurs in 5 % of recipients whereas viread is generally a well tolerated drug.Both can be given QD. So the choice lies in greater evidence for ziagen vs. a slightly better tolerated drug for the first 6 weeks in viread.

Regards

Graeme Moyle