Dear Dr. Little, About 1 month ago, you wrote in one of your replies that you have no confidence in bid viracept and you prefer the tid dosing. Could you please share your reasoning as I have never heard this mentioned before?Sincerely,Luke

The best way to ensure ongoing complete viral suppression is to ensure that antiretroviral drug levels are high enough at all times during the day to inhibit or prevent viral replication. The key question is therefore, how high is high enough? Well, it is probably different for different drugs. In my opinion, the use of viracept in a twice a day regimen does not provide the best possible level of drug within the blood stream at all times to prevent viral replication. This does not mean that this type of regimen will not work in some people, only that there is less margin for error (ie missed doses) with this kind of approach. Most providers are now using ritonavir-boosted protease regimens which allow a much more comfortable margin of error with many different twice a day Protease inhibitor-based regimens.

The concept of ritonavir boosting is simply using ritonavir (in low dose) to bump up the level of the other protease inhibitor (given in more standard dose levels) so that it can be taken twice a day. With this approach, the drug levels of the second protease inhibitor (ie. not ritonavir) are generally significantly higher and are sustained at high enough levels between dosing intervals that antiviral activity is still more than sufficient to ensure ongoing suppression of viral replication - even if a dose is missed.