Swiss drugmaker Novartis AG's unit Sandoz Inc. said it launched the first generic version of United Therapeutics Corp.'s blood pressure drug Remodulin in the U.S.

Remodulin, also called treprostinil, is used to treat pulmonary arterial hypertension, or PAH, a type of high blood pressure that affects the arteries in the lungs and the right side of the heart. The disease mainly affects women.

Sandoz said the copycat launched with 180 days of marketing exclusivity, which is part of the U.S. Food and Drug Administration's effort to encourage generic competition.

The exclusivity is granted to the first generic drug applicant to submit a substantially complete generic application that includes a challenge to the brand-name drug's patents.

According to Sandoz, about 52,000 patients have been diagnosed with the disease in the U.S., with rates expected to rise due to increased survival and diagnosis.

Sandoz said it will partner with RareGen LLC to commercialize treprostinil injection in the U.S. Silver Spring, Md.-based United Therapeutics reported global sales of $599 million from treprostinil in 2018.

In 2018, United Therapeutics bought SteadyMed Ltd. after the San Ramon, Calif.-based company won a ruling invalidating one of United's patents related to Remodulin.