US-based Xenoport has accused UK-based pharmaceutical major GlaxoSmithKline (GSK) of a breach of contract and is threatening to end the pact relating to restless legs syndrome medication Horizant.
Xenoport claimed that GSK is not doing enough to market the drug, breaching the terms of the agreement signed in November 2010 that deemed GSK responsible for post-marketing requirements and commitments of Horizant. The company also claimed that GSK must also seek a New Drug Application for the therapy for post-herpetic neuralgia and other indications.
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Extended-release tablets of the drug received US approval in April 2011 for use by adults suffering from moderate to severe restless legs syndrome, and Xenoport alleges that GSK has materially breached its contractual obligation since this approval. As per the terms of the original agreement, Xenoport is eligible to receive $312.5m, of which $120m has already been received, with an additional $290m due related to the achievement of sales milestones.
Xenoport is free to terminate the agreement 90 days after the receipt of written notice providing GSK does not resolve the contractual breach. GSK is yet to respond to Xenoport’s allegations.
