FDA to Review Arena's Diet Drug, Alkermes' Painkiller Addiction Med

The U.S. Food and Drug Administration is going to have a busy day. Two advisory panels will meet to discuss two different drugs on Thursday: Arena Pharmaceuticals' (ARNA) obesity treatment lorcaserin and Alkermes' (ALKS) Vivitrol Opioid for opioid addiction. A third drug -- AstraZeneca's(AZN) blood thinner Brilinta -- faces an approval decision, but that will be delayed.

Arena shares had a rough week, sinking over 46% since Monday after FDA reviewers on Tuesday released an initial analysis raising questions about lorcaserin's safety and effectiveness. Arena shares will be halted Thursday.

Arena's Diet Drug -- Yea or Nay?

In their analysis ahead of the meeting, FDA reviewers raised concerns about cancerous breast tumors, although this was only seen when lorcaserin was tested in rats, not humans. Also of concern were other side effects, such as heart-valve disease, psychiatric and memory problems. In addition to its safety, the drug's effectiveness was also questioned, as it failed to meet one of the agency's efficacy benchmarks for weight loss while meeting a second criteria for effectiveness only "by a slim margin."

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Several companies have attempted to create a safe diet drug over the years, but ever since the debacle 13 years ago of combination drug phen-fen, which was linked to heart-valve damage and a rare but deadly lung disease, the FDA has been extra cautious.

While Arena's rival Vivus (VVUS) has already faced the panel and got a "no" vote for its obesity treatment Qnexa, Arena's lorcaserin is seen as the safer of the three recent diet drugs. Orexigen (OREX) is the third. Proponents of lorcaserin say it hasn't demonstrated serious side effects. In fact, after two years of safety data, patients are free from any additional cardiovascular problems, and nearly half of the patients in a study achieved at least 5% weight loss after a year.

But complicating matters further for Arena was the panel's mixed vote on Wednesday regarding Abbott's (ABT) already approved weight-loss pill Meridia. The advisory panel urged tougher action against the controversial drug but split over whether to call for a ban. European regulators have already pulled Meridia from the market.

More Tests Needed for Alkermes Vivitrol Opioid?

Alkermes shares first fell when regulators released their analysis ahead of the panel meeting, but then recovered even as it seemed the panel might ask for another test before voting in favor of expanding the indication of alcoholism drug Vivitrol to treat opiate addiction. Trading in Alkermes shares has been halted Thursday morning.

Vivitrol helped prevent relapse in patients addicted to heroin and painkillers who were trying to stop using drugs in a Russian study, FDA reviewers said. Moreover, there were no major new safety issues. But they questioned whether the small, single study with perhaps a different target population than in the U.S. was sufficient to clear the drug for this use. The agency is scheduled to decide on the supplemental new drug application by Oct. 12.

As for AstraZeneca's ticagrelor, or Brilinta, the company announced the FDA has extended the time to complete its review of the experimental blood thinner by three months to Dec. 16. In July, FDA advisory committee members voted 7 to 1 to recommend the approval of Brilinta in patients with acute coronary syndrome, or blocked arteries.

Brilinta is seen as a potential blockbuster drug for AstraZeneca. The blood thinner market is currently dominated by Plavix from Sanofi-Aventis (SNY) and Bristol-Myers Squibb (BMY). Plavix has total sales of $9.8 billion globally. An international study conducted by AstraZeneca showed that patients taking Brilinta versus Plavix were less likely to experience various heart-related problems.

Oddly enough, however, U.S. patients studied were more likely to report heart problems while taking Brilinta. Brilinta might also eliminate the need for genetic testing. It's currently under regulatory review in the European Union, Canada, and Brazil.