Shares of Astex Pharmaceuticals plummeted in the biggest single day drop since 2004 after an expert panel rejected the use of Dacogen as a treatment for acute myeloid leukemia because it has an unfavorable risk-benefit profile. Dacogen is licensed to Eisai and is already approved to treat myelodysplastic syndromes – a group of diseases in which the production of blood cells by bone marrow is disrupted. The U.S. Food and Drug Administration questioned the data on the drug and said a clinical trial for Dacogen did not meet the trial’s goal of improving overall survival.

Amgen failed to win the backing of a U.S. advisory panel for the use of its drug Xgeva to delay tumors spreading to bones in patients with advanced prostate cancer. The advisory panel voted 12-1 that the risks outweighed the benefits of the drug and questioned whether the ability of Xgeva to delay tumor growth in bones is enough to justify approval. Xgeva was previously approved in 2010 to prevent bone pain and fractures caused by bone metastases. Amgen has been seeking approval of the drug for use in men who aren’t responsive to hormone treatment and whose cancer has not yet spread to the bone. The U.S. Food and Drug Administration is scheduled to make a final decision on Xgeva by April 26 and is not required to follow the advisory panel’s recommendation, although it often does.

NeurogesX shares plunged the most in nearly three years after U.S. Food and Drug Administration raised questions about whether the company’s prescription-strength patch, Qutenza, proved substantial efficacy in treating pain related to nerve damage commonly associated with HIV. Nearly one-third of people with HIV/AIDS experience peripheral nerve damage caused by the virus or drugs used to treat the disease according the Center for Peripheral Neuropathy. NeurogesX hoped its patch would provide some relief for those afflicted with nerve damage. Though Qutenza is still up for review, with a decision due by March 7, the newly raised questions by the FDA sent the company’s shares reeling. They fell nearly 25 percent on the day of the announcement, to 88 cents and have fallen 83 percent over the past 12 months.

Merck notified doctors that its newly approved hepatitis C drug Victrelis interferes with and considerably lessens the effectiveness of some widely used AIDS drugs. “These drug interactions may be clinically significant for patients infected with both chronic hepatitis C virus and HIV by potentially reducing the effectiveness of these medications when co-administered,” Merck said in a letter to healthcare professionals. The drug interactions were seen in a study among healthy volunteers who took Victrelis and the HIV treatment Norvir in combination with one of three other anti-HIV pills. For its part the U.S. Food and Drug Administration has advised that any patient taking Victrelis not stop taking the drug without consulting their physician and also stated that Victrelis’ label would be updated with information about the drug interactions with other anti-HIV pills.

Apotex handed over $444 million to Sanofi and Bristol-Myers Squibb as repayment for prematurely launching its generic version of Plavix, Sanofi and Bristol-Myers Squibb’s blockbuster blood thinner medication. The payment puts an end to a 10 year patent dispute that dates back to 2002 when Sanofi sued Apotex for infringement of its Plavix patents. Though Sanofi had won a preliminary injunction against the Apotex by 2006, Apotex had already shipped its generics version to market. The cheaper generic version of Plavix quickly gained traction and ended up costing Sanofi and Bristol-Myers Squibb hundreds of millions in sales.

Four LEO Pharma salespeople filed a putative class action, accusing LEO of infringing on U.S. wage-and-hour laws by misclassifying their overtime as “exempt from overtime” even though their jobs included non-exempt activities. The pharmaceutical sales reps are being represented by Sanford Wittles & Heisler, the same law-firm that represented a group of Novartis reps that received $99 million to settle a similar wage-and-hour lawsuit.

Bruno Strigini, president of Europe/Canada at Merck believes pharmaceutical companies are owed nearly $16 billion ($10 billion pounds) for unpaid medicine bills in the Eurozone. Half of that amount, Strigini said, comes from Spain alone. While speaking at the Economist’s annual pharmaceuticals summit, Strigini acknowledged that the Spanish government was making an effort to pay back its debts to the pharma industry but he also suggested that the International Monetary Fund and the European Union would need to help in efforts to recover its debts.