Drugs firms AstraZeneca and Sanofi are to exchange 210,000 compounds from their libraries to help boost their search for new small-molecule medicines.

The companies have selected the compounds based on differences from those in their own libraries and will share chemical structures and synthetic procedures to facilitate their use. Each company will receive sufficient quantities to enable high throughput screening for several years to determine whether they are active against specific biological targets.

There are no payments associated with the exchange and each company can investigate the compounds it receives without restrictions on disease areas.

Describing the agreement as “highly innovative,” Mene Pangasol, executive vice president of innovative medicines and early development at AstraZeneca, said the exchange was by far the largest it had achieved. He added that it would enable AstraZeneca to significantly increase the diversity of its compound library and accelerate its ability to identify new medicines.

Meanwhile, AstraZeneca has agreed to sell US rights for its Entocort gastroenterology treatment to Perrigo. US sales of Entocort, a treatment for patients with mild to moderate Crohn’s disease, were $89 million for the first nine months of 2015.

The US-based healthcare firm will pay AstraZeneca $380 million upon completion of the deal which is expected by the end of 2015, subject to the usual conditions.

AstraZeneca said the deal with Perrigo completes its global divestment of Entocort. In July this year, Tillotts Pharma agreed to buy global rights for Entocort outside the US.