Merck & Co has signed a deal to develop Cardiome Pharma Corp’s investigational heart drug vernakalant which could net the Canada–based drugmaker $600 million.

Under the terms of the agreement, Merck is getting exclusive global rights to oral vernakalant for the maintenance of normal heart rhythm in patients with atrial fibrillation. In addition, its Swiss affiliate Merck Sharp & Dohme gets the rights outside the USA, Canada and Mexico to the intravenous formulation of the drug for rapid conversion of acute atrial fibrillation to normal heart rhythm.

Cashwise, Merck is making a $60 million upfront payment to Cardiome and the Vancouver-based firm is eligible to receive up to $200 million based on achievement of certain milestones. This includes $35 million for initiation of a planned Phase III programme for oral vernakalant and submission for regulatory approval in Europe of IV form, plus another $100 million tied into approvals in subsequent indications of both forms of the drug.

Cardiome will also receive tiered royalties and up to $340 million in milestone payments “based on achievement of significant sales thresholds”, Merck noted. The former company also has retained an option to co-promote oral vernakalant through a hospital-based sales force in the USA and Merck will be responsible for all future costs associated with the development, manufacturing and commercialisation of drug. It has also granted Cardiome an interest-bearing credit facility of up to $100 million.

Luciano Rossetti head of atherosclerosis and cardiovascular programmes at Merck Research Laboratories, said the agreement underscores the firm’s commitment to developing new cardiovascular drugs. "Vernakalant is an important addition to our broad portfolio of products and candidates that target multiple aspects of heart disease," he added.

Cardiome's co-development partner in North America, Astellas Pharma, submitted a New Drug Application with the US Food and Drug Administration for the iv formulation of vernakalant, under the brandname Kynapid in December 2006. The agency’s Cardiovascular and Renal Drugs Advisory Committee recommended approval a year later but in August 2008, the FDA issued an approvable action letter requesting additional information.

A Phase IIb clinical trial in patients at risk of recurrent atrial fibrillation has shown that at the 500mg dose, oral vernakalant significantly reduced the rate of relapse compared to placebo.