New Cipro, Same Side Effects

by Francesca Lunzer Kritz

Next month's scheduled debut of a once-a-day version of Cipro -- the Bayer antibiotic that became subject to hoarding after it was prescribed to prevent and treat anthrax inhalation last year -- could make it easier for patients to complete a course of therapy and thereby not contribute to growing antibiotic resistance.

But with patients in clinical trials reporting identical side effects, including headache and nausea, for both the once-daily and twice-daily forms of the drug, it remains to be seen whether the more-convenient dosing will be enough to keep people using any version. Complaints of side effects have often been cited as a reason for poor compliance among patients, including workers at the Brentwood postal facility in Northeast Washington.

The new version, Cipro XR (extended release), contains 500 milligrams of ciprofloxacin, twice as much as each pill in the twice-daily formulation. Last week, the Food and Drug Administration gave approval to Bayer to market Cipro XR for the treatment of uncomplicated urinary tract infections (UTIs), which affect millions of Americans each year. While Bayer may publicize only this use, doctors can prescribe the new version for any condition they think appropriate.

For UTIs, at least, the new drug has proved at least as effective as standard Cipro. Clinical trials showed a 2 percent higher cure rate for patients who took Cipro XR rather than two of the standard pills. Standard formulation Cipro is also used to fight salmonella poisoning and gastrointestinal infections.

More than 2,000 Brentwood workers were put on a 60-day Cipro regimen (two 500 mg tablets of the standard variety per day) after the deaths of two colleagues last year from anthrax spores discovered in the facility. Of 245 workers interviewed by epidemiologists from the Centers for Disease Control, only 98 said they completed the therapy, according to a study in the October issue of the journal Emerging Infectious Diseases. Side effects and anxiety were blamed by 102 others for their taking the drug intermittently and 45 who stopped it completely.

A letter sent to the General Accounting Office from Sen. Max Baucus (D-Mont.) last week offered a reminder that Cipro's side effects may exceed the merely uncomfortable. Baucus asked for a long-term investigation of Cipro's effects, citing a staffer who, within days of taking Cipro to protect against anthrax exposure, developed a condition that affects his tendons, making it difficult for him to walk. The condition is a rare but previously noted side effect of Cipro therapy.

Even if patients find it easier to stay on the once-a-day version, there could be other problems, says Ligia Pic-Aluas, an epidemiologist and infectious disease specialist at the Washington Hospital Center. Until it is used widely, physicians can't be sure that an extended-release version of a drug will provide the identical benefit for all conditions as doses given at separate times. And, says the doctor, since the XR form of any drug remains in the body longer -- in this case, for 24 hours -- it's difficult for physicians to quickly change antibiotics should the extended version prove ineffective.

A Bayer spokesman says Cipro XR will likely be priced higher than conventional Cipro, for which drugstore.com charges about $3.50 per tablet. The price difference could increase a year from now when Bayer's patent for conventional Cipro expires and generic competitors stake their claim.