And the list goes on. Combined with Norvir, the amount of Viracept in the blood is increased more than 15 times. For people starting PI therapy, numerous studies have determined that one protease inhibitor is usually enough to reduce viral load and keep it undetectable for a prolonged period of time. But the fact that low doses of Norvir can simplify a regimen may be reason enough to start therapy using two PIs. After all, a regimen that is easier to take is much more likely to be taken correctly.
Intensification is a relatively new concept in the struggle to deal with drug-resistant virus.
When HIV begins to show signs of drug resistance, such as an increasing viral load while taking a regimen containing a single PI and two nucleoside analogues, the usual approach is to switch to another regimen. Unfortunately, switching from a regimen containing one PI to another regimen containing yet another single PI is rarely successful in returning viral load to undetectable levels or in keeping it there. When HIV mutations start accumulating during PI therapy, what's really changing is the sensitivity of the virus to the drugs being used. With each additional mutation in HIV's structure, the virus's sensitivity to the drug or combination of drugs dwindles further. To keep viral load undetectable, you'll either need to go around the wall by finding new drugs or you can go over the wall by increasing the amount of drug in your bloodstream to keep HIV in check.