The 4-1-1 on the difference between generic and brand-name drugs

As a Regional Medical Director I often get inquiries and questions about Partnership’s generic-medication-based formulary. Misconceptions and myths abound about generic drugs. I thought I might address a few here.

Are generics drugs allowed to differ by as much as 45% over branded drugs? 

No. This myth is commonly quoted by the pharmaceutical industry. The FDA recently evaluated 2,070 human studies conducted between 1996 and 2007 comparing absorption of brand name and generic drugs. The average difference in absorption between the two was 3.5% – in either direction. This variation in absorption is similar to the differences between batches of a branded drug compared to itself.1 The 45% figure, or numbers like it, represent the far edge of a 95% confidence interval in comparison trials. No generic drug is approved without meeting FDA standards for bioequivalence.

Are generic drugs substituted for brand drugs in the control of epilepsy likely to result in loss of control? Are generics of poorer quality?

No. A meta-analysis of seven RCTs comparing branded vs. generic antiseizure medications showed that the aggregate odds ratio of an uncontrolled seizure in patients on generic vs. branded seizure meds was 1.0 (95% confidence interval of 0.7 -1.4).2 In fact from 1990 to 1995 there were 12 recalls of Parke-Davis’ branded Dilantin – nearly 1 million oral doses and 30,000 injectable doses were recalled.3

Pharmaceutical companies responsible for the manufacturing of their branded drug often also enter the generic side of the market once patent protection is lost. The drugs are often identical in ingredients, size, shape, and even color. About 50% of generic drugs are produced by branded pharmaceutical companies.

Doesn’t switching to an equivalent generic drug risk treatment failure?

There is no evidence for this claim. Unfortunately, even under continued treatment, many conditions can relapse. Patients under treatment for depression, seizures, and gastric ulcers, for example, can relapse despite continuous stable treatment.4 When this occurs coincidentally after a switch to a generic formulation, the generic drug is often blamed.

What about critical drugs like cardiovascular drugs?

In 2008, Kesselheim published an analysis of 38 clinical trials comparing generic cardiovascular drugs to their brand-name counterparts. There was no evidence that branded heart drugs worked any better than their generic counterparts.5

Is there a difference in cost for Partnership HealthPlan between generic drugs and brand-name drugs?

Yes there is! The average monthly cost of a generic drug to PHC is about $16 and for a brand-name drug about $180. As I have often said, “You can either pay the pharmaceutical company or save the funding to be redistributed to your local health care communities.”

Marshall Kubota, MD

  1. Davit et al., Comparing generic and innovator drugs: a review of 12 years of bioequivalence data for the United States Food and Drug Administration. Ann Pharmacother. 2009;43(10):1583-97.
  2. Kesselheim, AS, et al.,  Seizure outcomes following use of generic vs. brand-name antiepileptic drugs:  A systematic review and meta-analysis. Drugs.2010 March 26; 70(5): 605-621.
  3. Wolfe SM.  Statement by Sidney M. Wolfe, MD, Concerning Warner-Lambert criminal conviction and poor manufacturing practices… includes Dilantin recalls, HRG publication #1380, Nov 29, 1995.
  4.  Byrne and Rothchild, Loss of antidepressant efficacy during maintenance therapy: possible mechanisms and treatments. J Clin Psychiatry. 1998;59(6); 279-88. Randomised study of antiepileptic drug withdrawl in patients in remission.  Medical Research Council Antiepileptic Drug withdrawal Study Group. Lancet. 1991;337(8751):1175-80. A percentage of people will re-experience gastric ulcers, despite an initial, positive response to and continued treatment with prescription strength antacids {cimetidine tablets, http://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?id=8131#nlm34067-9}.
  5. Kesselheim et al., Clinical equivalence of generic and brand-name drugs used in cardiovascular disease: a systematic review and meta-analysis. JAMA. 2008;300(21)2514-2526.

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