In the news ... 2007

New Drug Interaction Discovered
Between Kaletra and Crestor

April 13, 2007

A poster presentation at the 14th Conference on Retroviruses and Opportunistic Infections in February 2007 reported on an unexpected drug interaction between the widely used protease inhibitor Kaletra (lopinavir/ritonavir) and the lipid-lowering drug Crestor (rosuvastatin). Crestor is part of a widely used class of drugs, called statins, that reduce cholesterol and is thought to lower the risk of heart disease. Many of these drugs interact with anti-HIV drugs, notably PIs and non-nucleoside reverse transcriptase inhibitors (NNRTI).

It was thought that Crestor was unlikely to have this kind of interaction, and would be a viable option for the growing number of people living with HIV who have high cholesterol. Researchers at the University of Colorado found a significant increase of Crestor levels (between 2- and almost 5-fold) when it’s taken with the boosted PI, Kaletra. Increases of this scale are potentially hazardous, and reducing the dose of Crestor might lessen its affect on cholesterol. Although the reason for this interaction is not understood, using Crestor in people taking any boosted PI should be done with great caution.

There are remaining options for people with HIV trying to lower their cholesterol levels. Changes in diet and exercise habits can be somewhat beneficial. While concerns still exist about their drug interactions, Pravachol (pravastatin) and Lipitor (atorvastatin) can be given with a boosted PI, with some dose adjustment. People on a drug regimen that includes an NNRTI likely need to take a somewhat higher dose of either Pravachol or Lipitor. NNRTIs have been shown to reduce the levels of these drugs.

While the news of this unexpected drug interaction is sobering, it highlights the need for more drug interaction studies. What happens in a laboratory, or makes sense scientifically doesn’t always turn out to be true in humans. As people live longer with HIV, the list of other medicines taken along with anti-HIV drugs grows longer, and the need for drug interaction studies becomes greater.