Encysive Pharmaceuticals (NASDAQ:ENCY) announced today that it has received approval to start selling its pulmonary arterial hypertension drug, Thelin, in Australia. Although drug sales figures in Australia are dwarfed by North American sales, Australia is nonetheless one of the top 15 pharmaceutical markets in the world. For a small-cap company like Encysive, these fragmented markets still represent good opportunities for sales growth.

In the focus on U.S. and European markets, it is often forgotten that the rest of the world accounts for more than $130 billion of the $600 billion market for pharmaceutical drugs. Gaining approval to market drugs in these smaller-market countries can bring meaningful revenue to a drugmaker.

Encysive has had difficulty gaining regulatory approval for Thelin in the U.S., and it is possible that the drug will not get approved in this third go-round in June. Therefore, it is important that Encysive continues to bring Thelin to new markets throughout the rest of the world before it has to face possible competition from a rival drug by competitor Gilead Sciences (NASDAQ:GILD).

Even if Encysive fails to gain marketing approval for Thelin in the U.S., the drug's market potential is still strong in the rest of the world. For example, Encysive's biggest competitor, Actelion (with its PAH treatment, Tracleer) brought in $760 million in revenue last year. Fifty-four percent of those sales, or $410 million, occurred outside the U.S.

The first update on the sales figures for the launch of Thelin in the European Union will come out later this month when Encysive releases its fourth-quarter financial results. Since pricing negotiations haven't been finalized in many of the larger European markets, sales figures for this first quarter on the market will probably be in the single-digit millions of dollars. Getting Thelin approved in Australia and some of the other larger markets outside the U.S. and EU should go a long way toward improving these initial sales numbers.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool has a disclosure policy.