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Adverse reactions after approval in 10% of drugs. (FDA Standards Questioned).

Serious adverse drug reactions were noted after marketing in more than 10% of 548 drugs approved between 1975 and 1999, according to Dr. Karen E. Lasser of Harvard Medical School, Boston, and her associates.

These drugs eventually acquired at least one black box warning for serious adverse drug reactions (ADRs) or were withdrawn from the market for safety reasons that were not recognized at the time of Food and Drug Administration approval, the investigators said.

The investigation included all prescription drugs considered to be new molecular entities during the 25-year period. A manual search of the 26 annual volumes of the Physicians' Desk Reference from 1975 to 2000 was done to determine the proportion of new drugs that acquired new black box warnings or that were withdrawn from the market.

The findings led the investigators to recommend that new drugs that do not represent a significant advance over existing therapies be considered second-line treatments until their safety is better known.

Also, the investigators advised the FDA to raise the threshold for approving new drugs when safe, effective therapies al ready exist and when a new drug treats a benign condition. New drugs that significandy reduce morbidity and mortality may warrant use despite limited experience with these drugs and the potential for ADRs in the postmarketing period (JAMA 287[17]:2215-20, 2002).

In an accompanying editorial, Dr. Robert J. Temple and Dr. Martin H. Himmel of the FDA in Rockville, Md., questioned the validity of the statistical methods used in the study (JAMA 287[17]: 2273-75, 2002).

Further, the study failed to analyze shifts that show drug benefits over time, according to a statement from the Pharmaceutical Research and Manufacturers of America. Statins, for instance, are examples of drugs whose additional benefits were recognized only after marketing.

The study investigators concluded that nearly 20 million patients in the United States took at least one of the five drugs that were withdrawn from the market in a 1-year period between 1997 and 1998. Three of the five drugs had been on the market for less than 2 years.

Seven drugs that were approved in 1993 and were subsequently withdrawn possibly contributed to 1,002 deaths.

Factors associated with serious ADRs included:

* Limitations in study populations and testing duration before drug approval.

* Aggressive marketing before the full range of ADRs was known.

* Delayed or inadequate postmarketing reports of ADRs.

* Insufficient postmarketing studies.

* FDA approval despite the identification of serious ADRs in premarketing trials.

* Inconsistencies and asynchronies among Physicians' Desk Reference safety warnings across same-class drugs.

Dr. Temple and Dr. Himmel said this approach overestimates the delay between marketing a new drug and labeling changes.

They observed that the Physicians' Desk Reference cannot change between editions, but labeling does change, and this is not accounted for in the study. The PDR-focused analysis also does not consider changes communicated to physicians by "Dear Health Care Professional" letters or warnings that appear in promotional materials prior to changes in the PDR.

The rate of serious injury associated with postmarketing adverse drug reactions is relatively low, the authors stated, and in some cases even drugs that have been on the market a long time are found to have unexpected toxic effects.
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Author:Mahoney, Diana
Publication:OB GYN News
Date:Jul 15, 2002
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