Countless drugs are manufactured as generic equivalents to brand name counterparts. Generic drugs must be bioequivalent to the brand name drug, meaning that they contain the same active ingredient at the same dose, in the same dosage form, with the same route of administration. The rate and extent of availability of the drugs must also be identical. Brand name drugs and their generic equivalents are interchangeable, and have demonstrated the same therapeutic effectiveness in clinical trials. Generic drugs, however, may not contain identical inactive ingredients or have identical formulations, packaging, or appearance.

The United States Food and Drug Administration (FDA) allows generic drugs to be manufactured once the patent on the original brand name drug expires. The generic drug may have a patented formulation, but the active ingredient is no longer protected by patent. Manufacturers of generic drugs must only submit an Abbreviated New Drug Application to the FDA for approval and are not required to complete the lengthy and costly animal and clinical trials of the active ingredient.

Generic drugs are valuable in today’s health care system, mostly because they are often sold at a 30 to 80% savings compared to brand name drugs. Consumers save nearly $10 billion annually by buying generic drugs instead of brand name drugs.

Still, many patients and health care practitioners believe that brand name drugs are clinically superior to generic drugs. A new review published in the Journal of the American Medical Association in December 2008 maintains that this opinion is unfounded. The authors summarized nearly 25 years of randomized clinical trials comparing brand name and generic cardiovascular medications. They also separately addressed editorials concerning generic substitution for brand name drugs.

Among all the drugs examined by the authors, no evidence indicated that brand name drugs were clinically superior to generic equivalents. Clinical equivalence was reported for all classes of cardiovascular drugs studied. Interestingly, though, of the 43 editorials written on generic substitution, more than half (53%) of the authors had a negative view of generic drug use.

A similar investigation of bioequivalence examined psychoactive drugs, but concluded that generic drugs may not, in fact, have the same clinical efficacy and tolerability as brand name drugs. All of the psychoactive drugs reviewed were approved as bioequivalent and recommended as appropriate replacements for brand name counterparts when studied in healthy subjects in clinical trials. However, in clinical practice, significant differences were uncovered. Notably, several medications used to control seizures were not as effective as their brand name equivalents and previously seizure-free patients experienced a recurrence of seizures while taking generic medications. The authors of this review concluded that testing of generic drugs should include analysis of clinical use and tolerability in addition to assessment in healthy subjects.

Generic drugs are important today, primarily for cost-saving reasons. The FDA does require that all generic drugs are as safe and effective as their brand name counterparts and nearly 50% of generic drugs are actually produced by the brand name manufacturer. No one should be deterred from using generic equivalents, but rigorous testing should be employed to ensure that all formulations of generic drugs are tolerable and effective in clinical practice.

References

G Borgheini (2003). The bioequivalence and therapeutic efficacy of generic versus brand-name psychoative drugs Clinical Therapeutics, 25 (6), 1578-1592 DOI: 10.1016/S0149-2918(03)80157-1

A. S. Kesselheim, A. S. Misono, J. L. Lee, M. R. Stedman, M. A. Brookhart, N. K. Choudhry, W. H. Shrank (2008). Clinical Equivalence of Generic and Brand-Name Drugs Used in Cardiovascular Disease: A Systematic Review and Meta-analysis JAMA: The Journal of the American Medical Association, 300 (21), 2514-2526 DOI: 10.1001/jama.2008.758

P Meredith (2003). Bioequivalence and other unresolved issues in generic drug substitution Clinical Therapeutics, 25 (11), 2875-2890 DOI: 10.1016/S0149-2918(03)80340-5

Welage LS, Kirking DM, Ascione FJ, Gaither CA. Understanding the scientific issues embedded in the generic drug approval process. J Am Pharm Assoc (Wash). Nov-Dec 2001;41(6):856-867.

U.S. Food and Drug Administration Office of Generic Drugs.