FDA requests heart rhythm study for Abbott HIV drug

WASHINGTON Abbott Laboratories’ HIV drug Norvir may cause a type of heart rhythm disturbance called PR prolongation in patients with cardiac disease, according to new physician labeling for the drug requested by the Food and Drug Administration.

The FDA had requested that Abbott conduct a heart rhythm study using the drug, known generically as ritonavir. The FDA had also requested that other manufacturers of HIV drugs conduct similar studies.

Heart block results from blockage of electrical signals traveling between the heart’s upper and lower chambers. Third-degree heart blockage, the most serious kind, requires implantation of a pacemaker.

“Postmarketing cases of second- or third-degree block have been reported in patients,” the new label reads. “Norvir should be used with caution in patients with underlying structural heart disease, preexisting conduction system abnormalities, ischemic heart disease, [and] cardiomyopathies, as these patients may be at increased risk for developing cardiac conduction abnormalities.”