The U.S. Food and Drug Administration on Oct. 5 approved Ionis Pharmaceuticals’ drug for a potentially fatal genetic disorder, pitting the company against Alnylam Pharmaceuticals.

The two companies developed drugs for hereditary ATTR amyloidosis with polyneuropathy, in which abnormal protein buildup can be life threatening. Alnylam’s drug received an FDA nod in August.

Ionis, based in Carlsbad, has convenience on its side. Its drug Tegsedia — previously called Inotersen — requires an injection once per week at home, while Alnylam’s Onpattro requires an infusion over four to five hours at a clinic.

But analysts say Massachusetts-based Alnylam’s drug may have a better safety profile, disputed by Ionis.

In addition, the green light for Ionis and subsidiary Akcea Pharmaceuticals came with a black box warning.