United Therapeutics is the latest pharma in the hot seat over its marketing practices, having received a US subpoena for documents relating to three of its blood pressure medicines.

The subpoena from the US The Department of Health and Human Services has requested documents on the firm's pulmonary arterial hypertension drugs Remodulin (treprostinil) Injection, Tyvaso (treprostinil) Inhalation Solution and Adcirca (tadalafil) Tablets, including marketing practices relating to these products.

The company gave no further details in its statement, only saying that it planned to co-operate with the investigation.

The drugmaker is the latest in a long line of pharmas being hauled over the coals because of dodgy marketing practices, with Amgen, Boehringer Ingelheim, J&J, and Lilly amongst those that have recently been investigated.

And the move comes at a somewhat rocky time for United. The firm suffered a massive setback when US regulators refused to approve the oral follow-up to Remodulin twice within six months, dashing any hopes of market entry any time soon.

On the other hand, shareholders were pleased with the firm's third-quarter sales performance, with revenues jumping 25% to $302.2 million.