A study published in the Journal of the American Medical Association claims that “contrary to the perception of some patients and physicians, there is no evidence that brand-name drugs are clinically superior to their generic counterparts”.

Aaron Kesselheim of Brigham and Women's Hospital and Harvard Medical School, Boston, and colleagues assessed the clinical differences resulting from the use of generics or brand-name drugs used to treat cardiovascular disease, and conducted a meta-analysis on studies on this subject published from 1984 to August 2008.

The researchers identified 47 articles, covering nine different subclasses of cardiovascular drugs, of which 38 were randomised controlled trials (RCTs). Clinical equivalence was noted in seven of seven RCTs of beta-blockers, ten of 11 RCTs of diuretics, five of seven for calcium-channel blockers, three of three of antiplatelet agents, two of two for statins, one of one RCT of ACE inhibitors, and one of one RCT of alpha-blockers.

Among narrow therapeutic index drugs (NTI), drugs whose effective doses and toxic doses “are separated by a small difference in plasma concentration”, the authors noted that clinical equivalence was reported in one of one RCT of class 1 anti-arrhythmic agents and five of five RCTs of warfarin.

Interestingly, of the 43 editorials and commentaries were identified as meeting study criteria, 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 NTI drugs, 12 (67%) expressed a negative view while only four (22%) supported substitution.

The authors said that one explanation for this discordance between the data and editorial opinion “is that commentaries may be more likely to highlight physicians' concerns based on anecdotal experience or other nonclinical trial settings”. Another explanation is that the conclusions “may be skewed by financial relationships of editorialists with brand-name pharmaceutical companies, which are not always disclosed”. Approximately half of the trials in the sample and nearly all of the editorials and commentaries, did not identify sources of funding, the researchers write.

The study goes on to claim that “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”. The researchers add that the findings support the notion of formulary designs aimed at stimulating appropriate generic drug use and say that “to limit unfounded distrust of generic medications, popular media and scientific journals could choose to be more selective about publishing perspective pieces based on anecdotal evidence of diminished clinical efficacy or greater risk of adverse effects with generic medications”.

'Without innovative drugs, there is no generics industry
The article prompted a swift response from the Pharmaceutical Research and Manufacturers of America’s senior vice president Ken Johnson. He noted that the USA already has one of the highest rates of generic drug use in developed countries, (seven out of every 10 prescriptions in America are now filled with a generic drug) and “without today’s innovative brand-name drugs to legally copy, there would be no generic drug industry”.

Mr Johnson added that “the contention that brand-name medicines drive up the cost of health care is fatally flawed”, citing data from the Centers for Medicare and Medicaid Services which shows that drug price growth was 1.4% in 2007. “Price trends for brand-name medicines are influenced by many factors, including the significant investment required to research and develop – and gain regulatory approval – of an innovative drug”, he noted.

Mr Johnson concluded by saying that it takes ten-15 years to develop a new medicine through to approval and “only two of every 10 drugs that reach the market ever earn back enough money to match or exceed the average R&D cost of getting them to the marketplace”.