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Over-Prescribing of Anthrax Drugs

March 14, 2003

In response to the first US bioterrorist-associated anthrax attacks, it appears that many more antimicrobial drugs were prescribed than was warranted based upon confirmed or suspected Bacillus. anthracis exposure, according to results to be published in the April/May issue of Pharmacoepidemiology and Drug Safety, to be published online on 19th March 2003.

On October 4, 2001 the first case of inhalation anthrax due to the intentional delivery of Bacillus anthracis spores was reported in the US. The Centers for Disease Control and Prevention (CDC) ultimately recommended a sixty-day course of antimicrobials for about 10,000 people potentially exposed to anthrax. These antimicrobials were supplied by the CDC's National Pharmaceutical Stockpile Program.

Researchers at the US Food and Drug Administration (FDA) have studied national prescription trends in relation to the anthrax attacks and found generally that antimicrobial usage for some drugs was less in 2001 than in the preceding year. However in October 2001, usage for ciprofloxacin, one of the antimicrobials recommended for anthrax post-exposure, increased by more than 40% over utilization the previous October.

The team, lead by Dr. Douglas Shaffer, suggested that considerably more widespread prescribing of antimicrobials occurred than can be ascribed to CDC recommendations. For ciprofloxacin, approximately 160,000 more prescriptions were issued in October 2001 compared to October 2000 and there were 96,000 more prescriptions for doxycycline.

While certainty that the medicines were prescribed in response to the anthrax attacks can not be absolute because the intention of the prescribed drugs was not available in the study, the temporal relationship of the increase in ciprofloxacin and doxycycline prescriptions to the anthrax attacks strongly suggests a link.   It is thought that some of these prescriptions could have represented stockpiling by concerned Americans.

Problems associated with such potential widespread antimicrobial prescribing beyond the CDC's recommendations may include the propagation of antimicrobial resistance, an unwarranted risk of adverse effects, and sub-optimal care for individuals needing more extensive clinical evaluation. The CDC conducted an extensive evaluation of the individuals recommended to receive treatment in an effort to understand compliance, adverse events, and outcomes. No such epidemiological evaluation, surveillance, or follow-up may be assured for individuals prescribed antimicrobials beyond the scope of the CDC's campaign.

"While both the public and physicians' concern is warranted during such a period of uncertainty," says Dr. Shaffer, "sensible prescribing of antimicrobials must be considered based upon not only the potential benefits but the risks involved as well."

John Wiley & Sons