Danish drugmaker Lundbeck is betting that shark antibodies may offer a new way of getting drugs into the brain to fight Alzheimer's and other diseases, after successful early research with privately owned U.S. biotech firm Ossianix.

The two companies said on Thursday that Lundbeck had made an undisclosed payment to Ossianix, which has labs in Britain, following experiments in mice showing the effective transfer of potential drugs across the blood-brain barrier.

Getting modern large-molecule medicines across the barrier that protects the brain is a major challenge for drug developers.

Sharks, as the most evolutionarily ancient animal species to have an immune system similar to humans, may offer a solution.

Ossianix has found a way to attach therapeutic proteins to shark-derived antibodies, allowing treatments to be shuttled across the barrier into the brain where they bind to a drug target.

The technology is still years away from producing a marketed medicine but Lundbeck research head Kim Andersen said it had "significant potential" to benefit patients by delivering antibody-based medicines and other complex drugs into the brain.