On September 26, 2017, DURECT entered into a patent purchase agreement whereby DURECT assigned to Indivior UK Limited, an affiliate of Indivior PLC, certain patents that may provide further intellectual property protection for Indivior's RBP‑7000. In consideration for such assignment, Indivior made an upfront non-refundable payment to DURECT of $12.5 million, and also agreed to make an additional $5 million payment to DURECT contingent upon FDA approval of RBP‑7000, as well as quarterly earn-out payments that are based on a single digit percentage of U.S. net sales for certain products covered by the assigned patent rights, including RBP‑7000. The patent rights include granted patents extending through at least 2026.

In December 2014, DURECT and Santen entered into an agreement (the Santen Agreement) granting Santen an exclusive worldwide license to develop and commercialize a sustained-release injectable ophthalmology product utilizing DURECT’s proprietary SABER® technology and other intellectual property. Santen will control and fund the development and commercialization program for this product. The parties will establish a joint management committee to oversee, review, and coordinate development activities.

In accordance with the Santen agreement, Santen paid DURECT an upfront fee of $2.0 million and agreed to make contingent cash payments to DURECT of up to $76.0 million upon the achievement of certain milestones—of which $13.0 million are development-based and $63.0 million are commercialization-based—including requirements for the achievement of certain product sales targets. Santen will pay for a certain portion of DURECT’s costs incurred in the development of the licensed product, and if the product is commercialized, DURECT will also receive a tiered single-digit to low-double-digit royalty on annual net product sales, determined on a country-by-country basis.

There are various termination provisions in this agreement.