Smiths Medical allegedly conspired with United Therapeutics to stifle a generic version of pulmonary arterial hypertension drug Remodulin, according to a lawsuit filed this week by Novartis (NYSE:NVS) unit Sandoz.

The  Smiths Group (LON:SMIN) subsidiary, which is slated for a spinout as a separately traded company next year, makes the infusion pumps and single-use cartridges for the PAH drug treprostinil, sold by United Therapeutics under the brand name Remodulin.

Smiths and United allegedly told pharmacies selling the generic treprostinil developed by Sandoz and RareGen that they’re barred from selling it for us with the Smiths cartridges – all of which that company agreed to sell to United or its proxies, according to the suit.

“Defendants’ anticompetitive conduct has allowed them to control access to treprostinil for subcutaneous injections and enabled them to maintain higher prices for that critical treatment. The anticompetitive restrictions imposed by defendants have no public benefit or medical justification – they merely protect United Therapeutics’ bottom line,” the lawsuit alleged, claiming that Remodulin brought in more than $1.87 billion in sales over the last three years – or more than 35% of United Therapeutics’ top line.

“Absent defendants’ anticompetitive conduct, that entire franchise would now be under attack by plaintiffs’ generic alternative, which is substantially cheaper than Remodulin,” according to the April 16 lawsuit, filed in the U.S. District Court for New Jersey.

Sandoz and RareGen want compensatory damages, treble damages, legal costs and pre- and post-judgment interest, according to the suit.