The US Food and Drug Administration refused to accept an application for a drug for atrial fibrillation from Astellas Pharma US, playing havoc with the share price of the drug’s originator, Canadian company Cardiome.

Astellas Pharma and Cardiome said the FDA had refused the filing for the intravenous formulation of RSD1235 because of inconsistencies and omissions in the dossier, sending Cardiome’s Nasdaq-listed shares down nearly 20% yesterday to close at $9.03.

Cardiome and Astellas said they intend "to meet with the FDA as soon as possible to discuss the issues raised and to determine what remedies are required for the filing to be accepted." The Canadian firm insisted that the drug was still approvable, despite the delay.

Cardiome is also developing an oral formulation of RSD1235 in Phase II testing.

Meanwhile, Astellas Pharma says that it has ended an agreement with France's Laboratoires Servier regarding the anti-osteoporosis agent FK481 (strontium ranelate), which it licenses in Japan.

Phase II trials in Japan produced similar efficacy data to European studies, said the firm, but despite this, and partially as a result of reassessment of its product pipeline, Astellas has decided to withdraw from further development of the product.