Ciprofloxacin ER "showed efficacy that was clearly at least as good as ciprofloxacin IR twice daily," investigator Dr. Bret Berner told Reuters Health.

Dr. Berner, of Depomed Inc., Menlo Park, California, and colleagues note in the October issue of Antimicrobial Agents and Chemotherapy that by reducing the release rate of ciprofloxacin, the ER formulation may reduce gastrointestinal side effects and improve patient compliance.

To investigate, the researchers studied 272 women with uncomplicated urinary infection who were randomized to the ER formulation 500 mg daily for three days. A further 257 women received 250 mg of the IR formulation twice daily for three days.

Clinical cure rates at up to 11 days after treatment were 85.7% in the ER group and 86.1% in the IR group. Biological and clinical cure rates outcomes at up to 6 weeks after treatment were similar for both groups and comparable to the earlier findings.

Both treatments were well tolerated but the frequency of nausea in the ER group (0.6%) was significantly lower than that in the IR patients (2.2%). This was also true of diarrhea (0.2% versus 1.2%).

The researchers conclude that the ER formulation is not inferior to the IR variety and leads to significantly fewer adverse gastrointestinal effects.

"Ciprofloxacin ER has such a low incidence of nausea and diarrhea that is the only marketed fluoroquinolone where the label treats these as uncommon adverse events," Dr. Berner said.

Antimicrob Agents Chemother 2005;49:4137-4143

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