STERLING WINTHROP BEGINS SHIPPING OMNISCAN (GADODIAMIDE) IMAGING AGENT JAN. 12 FOLLOWING APPROVAL JAN. 8; PRICING IS ON PAR WITH BRISTOL'S PROHANCE

Sterling Winthrop began shipping Omniscan (gadodiamide) on Jan. 12 following FDA's Jan. 8 approval of the nonionic magnetic resonance imaging agent. Omniscan is approved for "intravenous administration with magnetic resonance imaging in adult patients to provide contrast enhancement in those central nervous system lesions with abnormal vascularity or those thought to cause abnormalities in the blood brain barrier," labeling states. "Omniscan injection has been shown to facilitate visualization of central nervous system lesions including but not limited to tumors." FDA review of the imaging agent took 27 months. Sterling filed the Omniscan new drug application on Oct. 12, 1990. Omniscan was favorably reviewed by FDA's medical imaging drugs advisory committee in November 1991 ("The Gray Sheet" Nov. 11, 1991, p. 14). Omniscan was approved with labeling similar to that of Bristol-Myers Squibb's ProHance (gadoteradol), which was also reviewed at the November advisory committee meeting. ProHance was approved Nov. 16, 1992. "The most frequent adverse reactions observed in patients during Omniscan clinical trials were nausea, headache and dizziness with an incidence of 3% or less. The majority of these adverse reactions were of mild to moderate intensity," Omniscan labeling states. By comparison, ProHance labeling cites mild to moderate nausea and taste perversion as the most common side effects, with an incidence of 1.4%. Both products have identical warnings and precautions, including a warning against the possibility of potentiation of sickle erythrocyte alignment and a precaution against use in patients with impaired renal function. Omniscan labeling alone notes that "asymptomatic transitory changes in serum iron have been observed" but that "the clinical significance is unknown." Omniscan and ProHance are both recommended for doses of .1 mmol/kg or .2 ml/kg. ProHance labeling, however, directs that "in the presence of negative or equivocal scans...at the clinician's discretion a second dose of .2 mmol/kg (.4 ml/kg) can be administered up to 30 minutes after the first dose." When ProHance was approved, Bristol declared that it would offer "the widest range of dosing options" among MRI agents. As one of its Phase IV commitments for Omniscan, Sterling has agreed "to collect data for the .3 mmol/kg dose level to supplement the NDA," FDA's approval letter notes. During a December meeting with securities analysts, Sterling said that a high-dose supplemental NDA would be filed "soon" ("The Gray Sheet" Dec. 21, 1992, p. 8). Three other postmarketing commitments are outlined in the approval letter. Sterling has agreed "to expand postmarketing studies to include patients with renal or hepatobiliary disease; uncontrolled seizure disorders...; hemolytic anemias including sickle cell anemia; and active serious and/or life-threatening diseases unrelated to a CNS lesion," FDA said. Sterling will also collect pediatric data to supplement the NDA and submit efficacy and safety analyses by demographic factors such as sex, age and race. Sterling is pricing Omniscan on a par with ProHance and with Berlex' ionic gadolinium agent Magnevist (gadopentetate). The price to wholesalers for 10-vial boxes of Omniscan will be $580 for 10 ml vials, $850 ml for 15 ml vials and $1,050 for 20 ml vials, Sterling said. The company noted that the price is "very similar" to the market price for the agents. Sterling pointed out that "ionic agents dissociate into particles and may slightly modify the body's chemistry. Gadodiamide, however, remains a single entity in solution." The company concluded that Omniscan "may be physiologically easier for patients to handle." In a June letter to industry, FDA warned against unsupported comparisons between ionic and nonionic imaging agents in promotions and expressed willingness to discuss appropriate claims. Sterling met with FDA in August in response to that letter ("The Gray Sheet" Aug. 17, 1992, p. 15). Sterling is promoting its Carpuject with Interlink cannula delivery system for Omniscan as a "safer system for saline flushing" following Omniscan administration. "The new Interlink system represents a significant effort to minimize needle sticks during I.V. administration and disposal of contrast media," Sterling declared. The company developed Interlink through an alliance with Baxter. According to Sterling, 6 mil. MRI scans were performed in 1991, a 300% increase from 1987. The company estimated that about 2 mil. people received contrast agents as part of their scans. Sterling's Sanofi Winthrop Pharmaceuticals subsidiary already markets the Omnipaque (iohexol) x-ray contrast agent, which the company expects to top $500 mil. in sales for 1992. Sterling licenses Omniscan from Nycomed. The firm also obtained a license from Berlex in August as part of a settlement of a suit filed by Berlex/Schering AG claiming infringement of the Magnevist patent. In exchange for the license, Sterling granted Berlex comarketing rights to unnamed earlier stage MRI agents.