SQUIBB's ISOVUE (IOPAMIDOL) SHOWS FEWER SERIOUS NEUROTOXIC REACTIONS

SQUIBB's ISOVUE (IOPAMIDOL) SHOWS FEWER SERIOUS NEUROTOXIC REACTIONS when compared to both ionic and nonionic imaging agents, Squibb Cardiovascular Clinical Research VP John Alexander, MD, declared in presenting results of the firm's clinical studies to FDA's Radiopharmaceutical Drugs Advisory Cmte. as its May 10 meeting. Alexander said that in studies comparing 147 patients on Isovue with 135 patients on Winthrop's nonionic imaging agent Amipaque (metrizamide) no serious neurotoxic reactions were reported for Isovue as compared to a 10% rate in the metrizamide group. Further studies conducted since the Isovue NDA was submitted involving over 400 patients have found similar results, Alexander said.

Alexander also pointed to a lower incidence of adverse reactions, particularly serious ones, in the trials comparing Isovue with ionic agents. He noted that, in general, "adverse reactions after iopamidol are qualitatively similar, but much less frequent" over a variety of different arteriographic procedures than with the ionic agents. However, he noted that there was "a striking difference in the neurotoxic effects. These are rare after iopamidol. Iopamidol produces significantly less pain and warmth during arteriography, especially arteriography of the external carotid peripheral arterial vessels."

FDA's reviewing officer Hsien Ju told the Advisory Cmte. that he had "no problems nor any quarrels with the efficacy as well as safety of this drug." However, he said that in his opinion more data would have to be submitted to the agency before the labeling for pediatric use and for ventriculography could be finalized. The NDA for Isovue, licensed by Squibb from the Italian firm Bracco, has been pending at FDA since March 1983. The NDA includes indications for the agent for both intrathecal and intravascular uses.

The cmte. also considered a class labeling petition for expanding the use of three Technetium Tc 99m diagnostic radiopharmaceuticals for the evaluation of LeVeen (peritoneo-venous) shunt patency. The cmte. recommended that all three agents -- Technetium Tc 99m macroaggregated albumin, albumin microspheres and sulfur colloid -- be approved for this expanded use, and that no special labeling requirements be applied to the sulfur colloid.