Clinical question
Is there any benefit to prescribing brand-name medications rather than generic brands?
Bottom line
According to the best available evidence, generic medications are bioequivalent and produce similar clinical outcomes to brand-name medications.
Evidence
Bioequivalence1
Regulators require 90% CIs for the maximum peak concentration and total drug exposure over time, or area under the curve (AUC), to be within the limits of 0.80 to 1.25.
-This means the absolute differences in bioequivalence must be no more than about 5% to 7%.
Between 1996 and 2007, 2070 single-dose bioequivalence studies showed the average differences in maximum peak concentration and AUC were 4.35% and 3.56%, respectively.
Overall, 98% of studies showed the AUCs of generic and innovator products differed by less than 10%.
Generic and brand-name levothyroxine have been shown to be bioequivalent.2
Clinical outcomes (brand-name vs generic medications)
A systematic review (38 trials) of cardiovascular medications3 found the following:
-Clinical equivalence was shown in 35 of 38 trials including all β-blocker, antiplatelet, statin, angiotensin-converting enzyme inhibitor, α-blocker, class 1 antiarrhythmic agent, and warfarin trials; and most diuretic (10 of 11) and calcium channel blocker (5 of 7) trials.
-Differences in single outcomes were found in 3 trials.
—Brand-name furosemide produced more diuresis in a 1985 trial.
—For calcium channel blockers, 2 trials found differences in the PR interval on electrocardiography but no associated changes in heart rate or other clinical outcomes.
A systematic review of warfarin4 found the following:
-Five trials (higher level evidence) found no statistically significant difference in international normalized ratio or dosage changes required.
-Six observational studies (lower level evidence) showed inconsistent results at higher risk of bias.
Context
Of 43 editorials on generic medication issues, 23 (53%) expressed negative views about generic substitution,3 while only 8% of trials found any difference in any outcome.3
If there were important clinical differences between generic and brand-name medications, companies would do studies to prove brand-name superiority and prevent losing millions of dollars from generic substitution.
-In fact, one company tried to suppress data demonstrating equivalence of its product to related generics.5
Implementation
Generic and brand-name medications produce similar clinical outcomes. Nonetheless, differences in shape, colour, taste, and name can lead to patient, and sometimes clinician, confusion. These differences have been associated with nonpersistent use of medications.6 Also, generic medications can contain different fillers, and rarely some patients might not tolerate the medication for that reason. To prevent confusion, it is essential that we let patients know they might, over time, receive medications that look or sound different but contain the exact same medication. If they have any concerns they should always check with their pharmacist, physician, or health care provider.
Notes
Tools for Practice articles in Canadian Family Physician (CFP) are adapted from articles published on the Alberta College of Family Physicians (ACFP) website, summarizing medical evidence with a focus on topical issues and practice-modifying information. The ACFP summaries and the series in CFP are coordinated by Dr G. Michael Allan, and the summaries are co-authored by at least 1 practising family physician and are peer reviewed. Feedback is welcome and can be sent to toolsforpractice{at}cfpc.ca. Archived articles are available on the ACFP website: www.acfp.ca.
Footnotes
The opinions expressed in Tools for Practice articles are those of the authors and do not necessarily mirror the perspective and policy of the Alberta College of Family Physicians.
- Copyright© the College of Family Physicians of Canada
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