August 6, 2009

Drug Interaction Confirmed Between Lopid and Kaletra

Kaletra (lopinavir/ritonavir) can significantly lower blood levels of the triglyceride-reducing drug Lopid (gemfibrozil), according to a study published online August 3 in the Journal of Acquired Immune Deficiency Syndromes.

Modern HIV drugs have proved quite potent in reducing HIV reproduction, but many of them can send blood fats—including cholesterol and triglycerides—out of whack. This is mostly true of protease inhibitors (PIs). Though different PIs have varying effects on triglycerides, most PIs are frequently prescribed with low-dose Norvir (ritonavir), one of the worst culprits. When cholesterol and triglycerides get too high, the risks take off for heart disease, fatty liver and pancreatitis as well.

Triglycerides should ideally be less than 150 mg/dL, and anything above 200 is considered high. PI therapy, along with other factors such as age, diet and exercise, can sometimes send levels skyrocketing. To lower triglycerides in those people, providers often turn to a class of drugs called fibrates.

Previous studies have suggested that Lopid might interact negatively with HIV drugs. To test this theory, Kristin Busse, PharmD, from the Pharmacy Department at the National Institutes of Health Clinical Center in Bethesda, Maryland, and her colleagues conducted a study in 15 HIV-negative volunteers. On day one of the study, Busse’s team tested the volunteers’ blood levels after they took 600 mg of Lopid. The volunteers then took Kaletra every day for two weeks. After 14 days, the study participants took another dose of Lopid, while the Kaletra was still in their systems.

Busse and her colleagues found that Kaletra reduced Lopid levels by more than 40 percent. They could not, however, identify exactly how Kaletra was lowering Lopid blood levels, nor were they able to determine if the lopinavir or ritonavir in Kaletra was to blame.

Because the exact mechanism by which Kaletra alters Lopid blood levels is unknown, Busse’s team do not make specific recommendations for managing this interaction. Simply increasing the Lopid dose may not be safe or appropriate. Exchanging Kaletra for another Norvir-boosted PI may not work if the primary problem is the ritonavir. Switching to another fibrate—such as Tricor (fenofibrate)—may also not be the best course of action, as it is possible that they might also interact with Kaletra.

Ultimately, the authors are encouraging further study to better understand the reason behind the interaction; they also want to alert providers about the problem.

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