An important reminder of the concerns of once per day lopinavir/ritonavir treatment came from a report of a patient who developed resistance to lopinavir/ritonavir. Such a report would not be noteworthy for most drugs but in this case it is only the fourth report of someone without previous protease inhibitor treatment prior to starting lopinavir/ritonavir developing resistance to this drug. In three of the four reports the person was taking this drug alone, and in the fourth it was said that the person missed many doses. Consequently, single drug treatment with lopinavir/ritonavir should be done with great caution until more research is performed. In fact, other studies are underway to further test this treatment strategy.
Other Important Studies with Lopinavir / Ritonavir
There were two other important studies related to more traditional use of lopinavir/ritonavir. One was follow-up of subjects enrolled in a pivotal study that established that lopinavir/ritonavir can be given as a once daily protease inhibitor. The drug was originally approved as three capsules twice per day until this study demonstrated that those who had never been on antiretroviral therapy did as well with six capsules once daily as they did with the standard twice daily dose. A major limitation to this study was that the six capsules once per day were associated with substantial more gastrointestinal side effect, particularly diarrhea than twice-daily dosing. Another presentation reported data using a new tablet form of lopinavir/ritonavir. In this case the equivalent dose given with capsules would be taken as only two tablets twice per day or four once per day. The study showed that the levels of drug in the blood were equivalent using the tablets as with the capsules. It is hoped that in addition to being less pills it will also cause less gastrointestinal symptoms, such as diarrhea. The latter remains to be seen in future clinical trials.
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