You want further proof that there are large amounts of money to be made in the pharmaceutical sector, even for indications like pulmonary arterial hypertension (PAH) that afflict only a few hundred thousand people worldwide? On Monday, specialty pharmaceutical company Actelion announced its intention to acquire biopharmaceutical firm CoTherix (NASDAQ:CTRX) for $420 million in cash.

Actelion and CoTherix both market drugs to treat PAH, a painful and debilitating condition caused by the constriction of the blood vessels of the lungs. PAH makes it very tiring and hard to perform even normal daily activities.

CoTherix's PAH drug, Ventavis, was approved in the U.S. in late 2004, and sales of the drug have been ramping up at a nice rate. Its 2006 sales are expected to land between $65 million and $70 million, with 2007 sales expected to grow another 50% to approximately $100 million.

Aside from an in-licensed drug candidate in phase 2 trials, and label-expansion trials with Ventavis, CoTherix doesn't have a drug pipeline to speak of. This acquisition is all about Actelion's ability to slim down marketing costs for Ventavis, while growing sales for the drug more quickly, now that it will be promoted by Actelion's much larger sales force.

Actelion's PAH drug, Tracleer, is dosed orally, while Ventavis is an inhalation therapy, indicated for a less serious form of the disease than Tracleer. Having both drugs promoted by the same sales force should result in little cannibalization of either drug's sales, yet reduce some of the redundancies in SG&A costs associated with two separate sales infrastructures for drugs treated by the same physicians.

By most standards, this is a simple acquisition, reducing the high level of per-unit costs required in having a sales force that only promotes a single drug. It's a win for both Actelion and CoTherix shareholders; the deal will increase Actelion's profitability, and CoTherix shareholders will receive a nice 21% premium for their shares compared to the stock's closing price on Friday.

Keep track of the latest pharmaceutical developments with a free 30-day trial to Motley Fool Rule Breakers.

Fool contributor Brian Lawler does not own shares of any company mentioned in this article.