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Can Drug Clinical Trials Be Trusted?

Drug Safety, Drug Efficacy, and Clinical Trials: Your Frequently Asked Questions
By
WebMD Health News
Reviewed by Louise Chang, MD

April 15, 2008 -- Clinical trials are the gold standard for judging the benefits and risks of new drugs. But new revelations suggest this gold standard is sometimes adulterated.

Today's issue of The Journal of the American Medical Association suggests that a major sponsor of clinical trials, the drug company Merck, may have used misleading statistics to downplay the risks Vioxx might pose to people with Alzheimer's disease. Another article in The Journal of the American Medical Association suggests that clinical-trial and review articles about Vioxx often were written by company-hired ghostwriters and later signed by researchers who had little to do with the actual study or review.

Don't scapegoat Merck -- other pharmaceutical companies do the same thing, suggest Catherine D. DeAngelis, MD, MPH, and Phil B. Fontanarosa, MD, MBA. DeAngelis is editor-in-chief of The Journal of the American Medical Association; Fontanarosa is the executive deputy editor.

"Make no mistake -- the manipulation of study results, authors, editors, and reviewers is not the sole purview of one company," they write in a scathing editorial.

Can we still trust clinical trials? Are the drugs we're now taking safe? Here's WebMD's FAQ.

What do clinical trials test?

When a drug finally makes it through clinical trials and FDA approval, here's what we know about it:

  • The new drug, in combination with standard treatment, is more helpful than standard treatment alone.
  • If the trial tested one drug against another, the new drug is at least as good as the other.
  • Benefits of the new drug -- for narrowly defined groups of patients -- outweigh the drug's risks.

But there are a lot of important things clinical trials usually don't tell us:

  • Clinical trials don't tell whether a new drug works better than existing drugs -- unless the trial compared one drug to another.
  • Clinical trials don't show that a drug is risk-free.
  • Clinical trials usually don't show whether a drug is safe to take in combination with other drugs, vitamins, or supplements.
  • Clinical trials don't show whether a drug might have unexpected long-term side effects.
  • Clinical trials don't show how well a drug might work in people, such as pregnant or breastfeeding women, who weren't included in the study.

How are clinical trials supposed to work?

The clinical trial system is designed first to look at whether a drug is safe enough for further testing (phase I clinical trials), then to look at whether a drug seems both safe and effective (phase II clinical trials), and then to compare the drug to an inactive placebo or standard treatment to see whether the drug is both safe and at least minimally effective (phase III clinical trials).

After a drug is shown to be safe and effective in phase III clinical trials, the drugmaker may ask the FDA for approval. The new drug does not have to be more effective than existing drugs, just more effective than placebo in defined patient groups. FDA approval, if granted, sets the conditions under which the drug can be sold.

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