Eli Lilly & Co.'s (LLY) and Daiichi Sankyo Co.'s (4568.TO) new anti-clotting drug, Effient, will cost about 18% more than the current gold standard, Plavix, the companies disclosed Wednesday.

Lilly and Sankyo are betting they can justify the price premium to insurers and patients by touting Effient's ability to prevent more heart attacks than Plavix in a large clinical trial. It might be a tough sell, however, because the same study showed Effient increased the risk of bleeding versus Plavix.

Effient will cost about $5.45 per tablet when it hits pharmacy shelves, which Lilly and Daiichi expect will happen by mid-August, executives from the companies told Dow Jones Newswires on Wednesday. In comparison, Plavix, which is co-marketed by Sanofi-Aventis (SNY) and Bristol-Myers Squibb Co. (BMY), costs about $4.60 per tablet. Retail prices for both drugs may be vary from the wholesale price.

"We have robust data that tells us that Effient is going to be very cost-effective," said Javan Collins, vice president of Lilly's U.S. cardiovascular business.

On Monday, Leerink Swann analyst Seamus Fernandez predicted Effient would be priced at a 30% premium to Plavix. But he said Wednesday that the 18% premium wouldn't affect his sales forecasts at this time. The price might help Lilly and Daiichi get good health insurance coverage for Effient and hospital utilization, in an effort to boost initial use, he said.

Effient was approved last week by the U.S. Food and Drug Administration, about a year after Lilly and Daiichi had initially hoped for the green light. Wall Street enthusiasm for the drug has waned due to the delay and the FDA's insistence that Effient's prescribing label carry a prominent warning about the bleeding risk, though some analysts still think peak annual sales could exceed $1 billion. Plavix global sales were about $8.6 billion in 2008.

A Bristol-Myers spokeswoman declined to comment on the planned pricing for Effient. Bristol has previously played down the competitive risk of Effient, noting its bleeding risk and a narrower range of approved uses than Plavix.

Indianapolis-based Lilly and Japan's Daiichi will be co-promoting Effient in the U.S., with sales representatives from both companies discussing the drug with hospitals, cardiologists and primary-care doctors. Some, but not all, of Daiichi's 1,850 U.S. reps will be promoting Effient, said Lorenz Muller, Daiichi's executive director of the U.S. thrombosis business. Lilly declined to say how many sales reps would promote Effient.

Lilly will book U.S. revenues for Effient, but the companies are splitting costs and Daiichi will derive alliance revenue from the arrangement, the executives said. Effient is already on sale in Europe.

The companies are also beginning talks with health insurers in the hope of obtaining favorable coverage for the drug, with relatively low out-of-pocket costs for insured members. The process of securing positions on so-called "formularies" - or preferred drug lists - could take months, however. Low-income and other qualifying patients can receive financial assistance from the companies.

The companies hope to impress insurers and payers with the clinical data on Effient. The large trial was designed specifically to test whether Effient was superior to Plavix; such a head-to-head challenge isn't done for all experimental drugs, Lilly's Collins noted. And the companies think they can convince payers and doctors that the bleeding risk is manageable, with identifiable groups of patients who should avoid the drug or be watched carefully because of heightened risk.

"Our goal is to get payers to reimburse Effient in a similar form and fashion to how they reimburse for Plavix, for the for right patient type," said Daiichi's Muller.

But the pricing differential will change in a few years when Plavix is set to lose U.S. patent protection, clearing the way for cheaper generic copies. Drug-benefit plans will be tempted to steer their members to generic Plavix, but Lilly and Daiichi still think Effient will be a compelling option because of its proven efficacy and other characteristics.

Lilly and Daiichi are actively talking to wholesale distributors and retail pharmacies - including CVS Caremark Corp. (CVS) and Walgreen Co. (WAG) - to ensure the drug is adequately stocked when it first goes on sale.

The companies have no immediate plans for direct-to-consumer advertising for Effient.

Lilly shares rose 47 cents to $33.38 Wednesday.

-Peter Loftus, Dow Jones Newswires; 215-656-8289; peter.loftus@dowjones.com