Apparently Biomarin Pharmaceuticals' (NASDAQ:BMRN) investors got the memo a little late. They ignored yesterday's 900-point jump in the Dow and instead sent shares of the drugmaker soaring nearly 20% as I write.

Investors are clearly happy that the Rule Breakers pick has reached the holy grail of drug development -- positive earnings -- and it appears destined to stay there. Yesterday afternoon it announced $0.01 per share of net income -- its fourth quarter in a row in the black.

And what's not to like about revenue nearly tripling from the year-ago quarter? Part of that growth was thanks to the launch of Kuvan, one of its three drugs for treating orphan diseases. The other two drugs weren't slackers either. Revenue from sales of Aldurazyme, which it sells in conjunction with Genzyme (NASDAQ:GENZ), was up 82%, and Naglazyme was up 56% year over year. While the growth in sales of Naglazyme wasn't ideal -- it was down quarter over quarter -- sales can be lumpy, and Biomarin said it's getting more patients on the drugs, and that's the most important thing for the long-term growth.

Unfortunately the growth of patients using Kuvan hasn't picked up after the slowdown last quarter. The problem appears to be a concern about lack of long-term safety data for a drug that can be used in both children and adults. For instance, patients on message boards are apparently reminding each other of Merck's (NYSE:MRK) Vioxx, a drug which had been available for several years, and that's led to some resistance to start the drug. Biomarin is going to have to get over this hurdle -- probably with maintenance trial data -- in order to increase the growth rate of the adoption of Kuvan.

Biomarin has over $560 million in cash and short-term investments, which is a pretty nice nest egg for a company with positive earnings -- although it's still burning through some cash. Cash is king in this market, and Biomarin would be smart to license other orphan drugs from drugmakers like Alexion Pharmaceuticals (NASDAQ:ALXN), Regeneron Pharmaceuticals (NASDAQ:REGN), or Amicus Therapeutics (NASDAQ:FOLD) in order to better leverage its sales force. With the recent market turmoil, a couple of opportunities are looking good and the company is in discussions, according to comments in the conference call.

Whether Biomarin is cheap at this level remains to be seen. It's going to need to keep up this growth and add drugs from its internal pipeline or through smart acquisitions. That's a relatively tall order, but management has shown it can do it so far.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.