With the ink only just dry on its signature for some pretty major alliances, GlaxoSmithKline this morning said it has signed two new deals that will see it boost its pipelines in the field of neuropathy, restless legs syndrome and major depressive disorder.

The first, with US firm XenoPort, is for the co-development and marketing of a gabapentin prodrug code-named XP13512, which is currently in the final stages of clinical testing for RLS and in Phase II for neuropathic pain. Gabapentin is the generic name for Pfizer’s Neurontin – once a $2 billion dollar epilepsy medicine before losing patent protection – and GSK says the prodrug formulation increases its availability for absorption through the gut wall.

And XenoPort will likely have a smile all over its face with some hefty sums on the table: an upfront cash payment of £40 million, milestones of up to £34 million on filing the regulatory application for RLS, up to £111 million for other potential milestones, and up to £153 million in sales milestones once launched for both RLS and neuropathic pain. The US biotech also stands to receive double-tiered royalties on US sales, unless it chooses to co-promote the product with GSK, when it will receive a share of net profits.

XenoPort will lead development for RLS, but GSK – which acquires the rights to the compound in all markets around the world with the exception of some Asian countries where Astellas is the licensee - will take the helm for all other indications.

Filing for major depression slated for this quarter

Meanwhile, the UK giant also this morning revealed a link up with US company Fabre-Kramer for the antidepressant gepirone ER, a selective serotonin agonist that will be filed for US Food and Drug Administration review in major depressive disorder before the end of the quarter.

Financial details of the alliance have not been revealed other than to say Fabre-Kramer will be entitled to an upfront cash payment, plus milestone fees on regulatory submission, approval and launch, as well as double-digit royalties on global sales.

In return, GSK gets its hands on the exclusive worldwide rights to gepirone ER, as well as any follow-on products for what it clearly sees is a potentially lucrative market. Subject to approval, gepirone ER would become a first in class medicine for treating major depressive disorder, which GSK says is an illness for which there is still a great unmet need, despite the availability of treatments. Data from studies already conducted have shown gepirone ER treats depression with less risk of the sexual side effects that plague other compounds and result in reduced compliance to medication.

Most recently, GlaxoSmithKline and Ranbaxy Laboratories signed a new R&D alliance which could be worth over $100 million to the Indian drugmaker. It also snapped up US firm Praecis Pharmaceuticals before Christmas, and penned deals with Genmab and Illumina as it looks to stock up its pipeline with late-stage compounds.