CHICAGO — Adding pioglitazone to a niacin regimen boosted the rise in serum levels of HDL cholesterol in a controlled study of 72 patients with metabolic syndrome.
Although the finding needs to be replicated in a larger number of patients, it suggests that patients without diabetes but with metabolic syndrome and a low serum level of HDL cholesterol might benefit from combined treatment with pioglitazone and niacin, Dr. Richard L. Dunbar said while presenting a poster at the annual meeting of the American College of Cardiology.
This approach would nicely jibe with an emerging approach for treating patients with prediabetes with a thiazolidinedione, the drug class that includes pioglitazone (Actos), said Dr. Dunbar, a cardiologist at the University of Pennsylvania, Philadelphia. Adding a drug like pioglitazone may also blunt the tendency of niacin to trigger insulin resistance, which means that the combination can have multiple benefits, he said in an interview.
The study was funded in part by Kos Pharmaceuticals, which was subsequently acquired by Abbott. Abbott markets an extended-release formulation of niacin (Niaspan). Dr. Dunbar and his associates have no other financial relationship with Kos or Abbott.
The study enrolled patients with metabolic syndrome, including a low serum level of HDL cholesterol, but without diabetes. Their average HDL level at baseline was 37 mg/dL. Their average age was about 52 years, and about 75% were men.
All patients were titrated over 4 weeks to a 2-g/day dosage of extended-release niacin. They were then randomized, with 34 patients treated for 6 weeks with 30 mg/day pioglitazone, followed by 6 weeks on 45 mg/day. Thirty-eight patients were randomized to placebo instead of pioglitazone.
At the end of the niacin run-in, when all patients were only taking the maximum dosage of niacin, serum HDL cholesterol levels rose by an average of about 20% over baseline. After 6 weeks of treatment with 30 mg/day pioglitazone, the average HDL cholesterol level was 36% over baseline, compared with an average of about 20% over baseline in the placebo patients, a statistically significant difference.
After an additional 6 weeks of treatment with 45 mg/day pioglitazone, the average HDL cholesterol level was 24% over baseline, compared with an average of 11% over baseline in the niacin-alone group.
Women had greater increases in HDL cholesterol than men, and also received a greater boost from adding pioglitazone (see table).
As expected, treatment with pioglitazone had no discernible effect on levels of other serum lipids. Niacin treatment led to about a 10% drop in serum levels of LDL cholesterol, and about a 30% drop in triglyceride levels.
Also as expected, treatment with niacin alone worsened energy metabolism, leading to an average 8% rise in serum glucose, and an average 47% rise in serum insulin. In contrast, patients who took pioglitazone plus niacin had an average 1% rise in serum glucose and an average 12% drop in serum insulin levels. The differences in these measures between the two treatment arms were statistically significant.
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