Magazine article Drug Topics

Once a Day

Magazine article Drug Topics

Once a Day

Article excerpt

Dynabac (dirithromycin), a once-a-day semisynthetic macrolide antibiotic from Eli Lilly & Co., has been granted Food & Drug Administration approval.

In an interview with Drug Topics, Jack Harris, M.D., Clinical Research Physician, U.S. Medical Operations, Eli Lilly, said that dirithromycin, unlike other macrolides, does not interact with the cytochrome P450 system. Data indicate that classical macrolide drug interactions with agents such as theophylline and cyclosporine do not occur with dirithromycin.

Two clinical trials have looked specifically at the effect of dirithromycin on theophylline levels. No clinically significant change in metabolism of theophylline was noted when that drug was coadministered with dirithromycin in healthy volunteers or in patients taking theophylline for medical conditions.

According to the package insert, another drug interaction study in six healthy males showed that dirithromycin did not significantly alter the pharmacokinetic profile of terfenadine. Terfenadine carries a black box warning against its use in patients taking macrolide antibiotics.

While data indicate that dirithromycin has a different drug interaction profile than other macrolide antibiotics, Harris emphasized that "it's prudent always to be cautious."

When dispensing dirithromycin, pharmacists still need to look at concomitant medications. "I would feel better about dirithromycin than I would about other macrolides with respect to drug interactions," Harris said. "However, if the patient is on terfenadine or astemizole, I'd make a special note of that and talk with the patient or doctor about it, as kind of a safety net. …

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