The Pharmaceutical Journal
Vol 268 No 7197 p633-640
11 May 2002

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Journal of the American Medicial Association (jama.ama-assn.org)
American Food and Drug Administration (www.fda.gov)
Medicines Control Agency (www.mca.gov.uk)

Limit use of new drugs until safety profile better known, researchers say

The safety of a new drug cannot be known until it has been on the market for many years, say American researchers. Therefore, patients given new drugs should be made aware of the limited experience of their use and doctors should avoid prescribing new drugs when older clinically efficacious agents are available.

Dr Karen Lasser, department of medicine, Cambridge Hospital, Massachusetts, and colleagues assessed how frequently serious adverse drug reactions (ADRs) are discovered after a new drug has been approved. They also examined how often such ADRs led to a drug being withdrawn from the market.

Between 1975 and 1999, a total of 548 new chemical entities were approved in the United States. Of these, 8.2 per cent acquired new "black box warnings" (additional to any that were given when the drug was approved). A black box warning alerts the prescriber to a serious risk with the drug.

A total of 16 drugs, or 2.9 per cent of those approved, were withdrawn from the market. The researchers estimate that new drugs had a 4 per cent probablity of being withdrawn over the 25-year period. Half of the withdrawals happened within two years of the drug's introduction.

The researchers say that reasons for ADRs only coming to light after a drug has been approved include premarketing trials involve too few patients to detect ADRs and limited follow-up periods.

"Some drugs represent a significant advance over existing drugs in the reduction of morbidity and mortality and warrant use despite limited experience. However, the drugs that do not represent a significant advance should be considered second-line drugs until their safety profile is better known," the researchers say. They suggest that the regulatory authorities should consider raising their threshold for approving new drugs when safe and effective therapies already exist or when the new drug treats a benign condition. In addition, the date of drug approval should be prominently displayed on drug labels, they say (JAMA 2002;287:2215).