Irish drugmaker Elan has agreed to sell the European rights to Prialt (ziconotide), its non-opioid severe chronic pain agent, to Japan’s Eisai, but will retain product rights in the USA.

Under the terms of the deal, Elan could receive up to $100 million in cash: $50 million on the closing of the transaction, which is expected by the end of this quarter; $10 million on the earlier of two years from closing or launches in key European markets; and an extra $40 million on the achievement of sales-related milestones in the region.

Commenting on the move, Kelly Martin, Elan’s President and Chief Executive Officer, said, "Prialt is a highly innovative, approved, intrathecal analgesic for patients suffering from severe chronic pain. Patient need in this area remains significant given that there have not been any meaningful therapeutic advances in this area for more than two decades. We are delighted that this transaction will enable Eisai to offer this new therapy to patients throughout Europe.”

Although Prialt is an important product to Elan, having been very much a lifeline to the firm when its troubles surrounding its multiple sclerosis drug Tysabri (natalizumab) kicked off, investors have always pinned their hopes on the latter drug as the main driver for future growth. But Tysabri was taken off the shelves last year after its use was linked to a rare brain infection, progressive multifocal leukoencephalopathy, which caused the deaths of a small number of patients.

However, since that time, Elan and its US partner Biogen Idec have gone to extraordinary lengths to uncover the true safety profile of Tysabri and, in October last year, it was given a clean bill of health when the companies found no further evidence of PML - either amongst multiple sclerosis patients, or in trials of the drug for rheumatoid arthritis or Crohn's disease.

The companies are still keeping their fingers crossed that the drug will make it back to market, after re-filing for approval both in the USA and Europe in autumn last year. A decision on approvability is expected from the FDA by the end of March after a priority review.