Is there in vivo synergy between amprenavir (agenerase) and abacavir (ziagen)? If so can you tell me how much the levels of the drugs are changed? Feel free to use terms like Cmax, AUC and Cmin. Thanks.

I quickly checked my resources on drug/drug interactions and could not find any suggestion that amprenavir changes the drug levels of abacavir, or vice versa. (if anyone has any newer data, pipe up). That is what we are often calling in vivo synergy, although it probably should just be called favorable drug interactions. Many docs are using ritonavir to enhance the drug levels of amprenavir, as well as to cut down on the pill burden. Using 100 mg ritonavir with 750 mg amprenavir gives a much higher cmin, an modestly elevated AUC, and cuts down from 8 to 6 pills bid. Clinical efficacy studies are still in progress

There is in vitro synergy between the two drugs, meaning that the inhibitory effect on the virus of the two drugs in the test tube is higher than what would be expected from just adding their effect. To what degree this matters in people is open to debate. Hope this helps