Contrary to the perception of some patients and physicians, there is little evidence that brand-name drugs are clinically superior to their generic counterparts for treating cardiovascular diseases, according to an article in the Dec. 3 issue of the Journal of the American Medical Association.

“The primary drivers of elevated drug costs are brand-name drugs, which are sold at high prices during a period of patent protection and market exclusivity after approval by the FDA,” the authors wrote.

Some patients and physicians have expressed concern that generic drugs may not be equivalent in their effectiveness. “Brand-name manufacturers have suggested that generic drugs may be less effective and safe than their brand-name counterparts. Anecdotes have appeared in the lay press raising doubts about the efficacy and safety of certain generic drugs,” the authors noted.

Aaron S. Kesselheim, MD, of Brigham and Women's Hospital, and colleagues conducted a meta-analysis on studies published from 1984 to 2008 that could shed light on the efficacy of generic drug interchangeability. To determine the expert opinion on the subject of generic substitution, they also reviewed the content of editorials published during this time.

The researchers identified 47 articles for detailed analysis, covering nine different subclasses of cardiovascular drugs, of which 38 were randomized controlled trials (RCTs). Researchers found clinical equivalence in:

• 7 of 7 RCTs of beta-blockers
• 10 of 11 RCTs of diuretics
• 5 of 7 RCTs of calcium-channel blockers
• 3 of 3 RCTs of antiplatelet agents
• 2 of 2 RCTs of statins
• 1 of 1 RCT of angiotensin-converting enzyme (ACE) inhibitors, and
• 1 of 1 RCT of alpha-blockers.

Among narrow therapeutic index drugs—drugs whose effective doses and toxic doses are separated by a small difference in plasma concentration—researchers reported clinical equivalence in

• 1 of 1 RCT of class 1 anti-arrhythmic agents, and
• 5 of 5 RCTs of warfarin.

The majority of editorial opinions ran counter to published trial results. Of 43 editorials and commentaries, 23 expressed a negative view of the interchangeability of generic drugs compared with 12 that encouraged substitution. The remaining eight did not reach a conclusion on interchangeability.

Among editorials addressing narrow therapeutic index drugs specifically, 12 expressed a negative view while only four supported generic drug substitution.

The authors suggested that skewed commentary might be the result of financial relationships of editorialists with brand-name pharmaceutical companies that are not always disclosed. They reported that nearly half of the trials and editorials in their sample did not identify sources of funding.