September 21, 2007 (Amsterdam, the Netherlands) - Pioglitazone (Actos) manufacturer Takeda is trumpeting the results of two in-house studies presented here at the European Association for the Study of Diabetes (EASD) 2007 Meeting, with plump press packages and a media event. But the studies themselves, both poster presentations at the meeting--should not be "overinterpreted," one outside expert told heartwire.
The first study, by Teresa McCall and colleagues--with McCall and two of five coauthors being Takeda employees--found that the starting dose of 30-mg pioglitazone in the Takeda-sponsored GLAI study was better than the starting dose of 4-mg rosiglitazone (Avandia, GlaxoSmithKline) in terms of controlling glucose levels and improving lipid profiles during the three-month run-in phase of the trial.
The second study, by Dr Yaping Xu (Takeda Pharmaceuticals) and colleagues, was a retrospective analysis of the US healthcare plan database i3 Innovus. Xu et al report that risk of stroke and MI were reduced in subjects taking pioglitazone as compared with patients taking other, nonthiazolidinedione diabetes drugs.
Taken together, the findings "reinforce the consistency of pioglitazone data and underscore that Actos has different effects from the other thiazolidinedione, rosiglitazone, due to differences in molecular structure," a Takeda press release proclaims.
But commenting on the results to heartwire, Dr Giatgen A Spinas (Universitatsspital, Zurich, Switzerland) expressed misgivings about even discussing the results, saying they did not constitute "new" news and that studies of this nature cannot be used to inform the choice of drug in diabetes care.
Lipid, glucose effects of starting doses: pioglitazone vs rosiglitazone
McCall et al's analysis included 369 diabetic patients with dyslipidemia randomized to pioglitazone and 366 randomized to rosiglitazone. While the primary end point of the GLAI trial was change in triglycerides at six months, the present analysis looked only at three-month outcomes, during which time patients had not yet been uptitrated to the full dose. At this point, pioglitazone produced significantly better effects on triglycerides, HDL, non-HDL-cholesterol, and HbA1c levels than did rosiglitazone, the authors report, suggesting that "initial treatment" with the pioglitazone starting dose is more effective than the rosiglitazone starting dose.
Spinas, however, dismissed the analysis as data mining, emphasizing that the 4-mg dose of rosiglitazone was "not a good dose," since it is already well accepted that a 4-mg starting dose is not an effective dose. Most patients need to be uptitrated to the 8-mg dose to get the benefit of rosiglitazone, he said.
"You should compare pioglitazone 30 mg with rosiglitazone 8 mg, to be fair," he said. Of note, results for the second half of the GLAI trial, looking at the maintenance doses over an additional three months, were not included in the EASD poster. Looking only at the starting doses, "this is was what you would expect; this is not new," Spinas commented. "If you really use comparable doses of pioglitazone and rosiglitazone, the effect on glucose lowering is similar and the effect on lipids is more favorable for pioglitazone, but this is not new information. We knew already about the more favorable lipid effects from the GLAI trial."
Stroke, MI: Pioglitazone vs nonthiazolidinedione drugs
Xu et al's study looked only at patients taking pioglitazone or a nonthiazolidinedione drug, using pharmacy and medical claims in the i3 Innovus database. Among the more than 11 000 patients taking pioglitazone, the relative risks of stroke and MI were lower than that of the >55 000 patients taking other diabetes drugs, even after adjustment for age, gender, hypertension, hyperlipidemia, heart failure, edema, use of concurrent antidiabetic drugs, antiplatelet drugs, and lipid-lowering drugs.
We conclude that, in a clinical-practice setting, in patients with type 2 diabetes mellitus, therapies that include pioglitazone are associated with significant reductions in the risk for stroke or MI compared with nonthiazolidinedione therapies," the authors conclude.
But again, Spinas emphasized that Xu et al's results must be firmly kept in perspective. "This is just a retrospective look at data; it may give some hints but is not proof," he said. "This can only give some hints that maybe, maybe one drug is better. But really, one should not use retrospective studies to say this. This needs to be done in a setting where patients are enrolled in a randomized, controlled, prospective study designed for this purpose."
Prevention the best medicine
That said, Spinas echoed the prediction made by others in recent months that a large, randomized study comparing pioglitazone and rosiglitazone is unlikely. "To compare the two in terms of these kinds of cardiovascular end points, stroke and MI, would take years," he said. "And in a couple of years, these drugs will not seem as fancy as they do now."
Spinas also emphasized that all the current hullabaloo over the cardiovascular safety of the thiazolidinedione class of drugs flies in the face of the fact that, particularly for rosiglitazone, red flags were raised when the agents were first approved. "We knew from the outset that there might be problems with cardiovascular disease with these drugs. This was stated from the beginning, and doctors who knew about it were probably careful about this. So this is not such a big surprise."
He believes that all of the attention being paid to the glitazone drugs and to other up-and-coming agents is diverting attention from the main problem at hand: diabetes prevention. Indeed, for all the fuss in the media and even in the cardiology community over the rosiglitazone-pioglitazone controversy, these drugs took up minimal turf in the EASD program, a nod, perhaps, to the larger task at hand.
"Diabetes is increasing, so it's going to be a market for a long time, and companies are always watching out for possible indications," Spinas observed. "But I still think the best treatment for diabetes is prevention, and we should not be treating healthy people with harmful drugs. People like to take drugs and carry on with their unhealthy lifestyles, but this should not prevent governments and society from putting the emphasis on prevention very early. There are so many drugs on the market for diabetes, but the epidemic is still increasing, and the drugs aren't helping with that."
The complete contents of Heartwire, a professional news service of WebMD, can be found at www.theheart.org, a Web site for cardiovascular healthcare professionals. Related Links
External Links
More EASD news on MedscapeRosiglitazone and Pioglitazone: Thiazolidinedione Alert Center