AstraZeneca is linking up with Nektar Therapeutics to develop the latter’s treatments for constipation.

Under the terms of the deal, the Anglo-Swedish drugmaker is making an upfront payment of $125 million to get access to NKTR-118, a late-stage investigational treatment for opioid-induced constipation, and the early-stage NKTR-119 programme, which involves developing products for the treatment of pain without constipation side effects.

Nektar could also receive up to $235 million upon the achievement of certain regulatory milestones by NKTR-118, as well as additional tiered sales milestone payments of up to $375 million “if the product achieves considerable levels of commercial success”.

For NKTR-119, the California-based firm could receive development and sales milestones, plus “significant double-digit royalty payments”. Specifically, for each of the first two initial products based on NKTR-119, Nektar is eligible to receive up to $75 million in development and up to $310 million in sales milestones.

AstraZeneca added that it expects completion of the design of the Phase III programme for NKTR-118 in the near term, and anticipates filing the drug with regulators in 2013. It will also be responsible for global manufacturing and marketing for both programmes.

Chief executive David Brennan said that NKTR-118, which combines Nektar's advanced small molecule polymer conjugate technology platform with naloxol, a derivative of the opioid-antagonist, naloxone, “is an important late-stage programme that has the potential to address a real need for patients”. He added that the deal “provides us the opportunity to apply our deep knowledge and expertise in neuroscience, oncology and gastrointestinal areas” and is “a good example of using externalisation to enrich the company’s late-stage pipeline.”