NEW YORK, Nov 25 (Reuters Health) -- In rare cases, the antibiotic erythromycin can cause disturbances in the conduction system of the heart called heart arrhythmias, and a new study suggests that women are at greater risk than men of developing such drug-associated cardiac arrhythmias.
Of the 346 cases reported to the US Food and Drug Administration between 1970 and 1996, 58% occurred in women, report senior investigator Dr. Raymond L. Woosley and colleagues in the November 25th issue of The Journal of the American Medical Association.
In 49 life-threatening or fatal cases clearly linked to the use of intravenous erythromycin lactobionate, 67% were women and 33% were men -- even though equal numbers of men and women were prescribed the drug, according to the researchers from Georgetown University in Washington, DC.
In a separate study, the authors looked at the effects of erythromycin on the electrocardiogram (ECG) of male and female rabbits.
They found that intravenous erythromycin caused 12% of female rabbits to have a greater QT-prolongation, as seen on an ECG reading, compared with 7% of males. A prolonged QT interval increases the risk of torsades de points (TdP), a life-threatening heart arrhythmia.
"Therefore, we hypothesis that an increased sensitivity to erythromycin in women could facilitate, especially at slow heart rates, the induction of TdP ventricular arrhythmias," they conclude.
SOURCE: The Journal of the American Medical Association 1998;280:1774-1776.
