Thursday, August 18, 2011

Generic drug trials: more transparency needed

The New York Times reported a couple of days ago that "Federal regulators and the generic drug industry are putting the final touches on an agreement that would help speed the approval of generic drugs in this country and increase inspections at foreign plants that export generic drugs and drug ingredients to the United States." The generic drug manufactures will pay an annual fee of 299$ million dollars, so that the FDA will be able to hire more reviewers and speed up approval of applications for marketing of generic drugs. The question is: what do we know about the generic drugs marketed today?

Van der Meesch et al. (2011) published in PLoS One a methodological systematic review about Bioequivalence trials which compared generic to brand-name drugs published between 2005 and 2008. They searched Medline for appropriate papers, as well as journals which regularly publish bioequivalence trials. Out of 134 papers that reported bioequivalence trials between brand-name drug and generic drug, 55 didn't include the reference drug name and were excluded. The final sample consisted of 79 papers which dealt with assessment of the bioequivalence of generic and brand-name drugs.

What do the FDA and the EuropeanMedicine Agency (EMA) demand from a generic drug?
The FDA wants to know three things:

Cmax - maximum plasma drug concentration
Tmax - time required to achieve a maximal concentration
AUC - total area under the plasma drug concentration-time curve

The 90% confidence intervals for the ratios (test:reference) have to be between 80% and 125%. The EMA wants to know only the Cmax and the AUC.

Experiments of bioequivalence are usually randomized crossover trials. They are conducted on healthy volunteers by administrating one dose of the drug. Seventy-three (92%) of the trials were indeed single-dose trials (6 (8%) were multiple-dose) and 89% of the single-dose trials reported bioequivalence. About a third didn't report CIs for all the FDA criteria, and 20% didn't report the required EMA criteria. Only 41% of the papers reported funding, 25% had private funding.

As always, the study has limitations: it included only papers from the years 2005-2008 and relied on FDA guidelines from 2003 and EMA guidelines from 2001 (updated 2008). It's also possible that they researchers' search in Pubmed didn't retrieved all the relevant papers.

In conclusion, there is a serious lack of available data about generic drugs. The authors point out that while 1,661 generic drugs were approved by the FDA during the study period, there weren't any data available about trials assessing generic drugs on the FDA and/or EMA sites. The authors also hypothesize that such a small percent (10%) of failed bioequivalence trials seem unlikely and suggested a possibility of publication bias.

van der Meersch, A., Dechartres, A., & Ravaud, P. (2011). Quality of Reporting of Bioequivalence Trials Comparing
Generic to Brand Name Drugs: A Methodological
Systematic Review PLoS One : 10.1371/journal.pone.0023611


  1. Speeding up the process is a good thing yet strict checks must be put in place. Even if the cost of medicine get lower because of it is exported, what is most important is it effectiveness.

    As stated in the conclusion, "there is a serious lack of available data about generic drugs..." Scientific research is based on data and trials.

    Hopefully, the 3 things that the FDA are looking for will be sufficient to address this issue.

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  3. I liked the way you describe generic drugs as "copy cat". But even if generic medicines are just a copy of branded drugs, sometimes they are producing equal therapeutic effects to human body
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  4. Generic drugs are actually the alternatives of branded medicines. In terms of salt, composition and quality, they are exactly similar. The only difference is their brand name. These generic variations of branded medicines have been innovated with a motive to cut individuals pharmacy bills as well as to lessen the increasing cost of pharmacies.

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