Yesterday, drug developer BioMarin (NASDAQ:BMRN) announced its first-quarter financial results. Sales growth was fantastic, with enzyme replacement therapy Naglazyme more than doubling compared to the year-ago period. BioMarin's other drug, Aldurazyme, is marketed by Genzyme (NASDAQ:GENZ), and sales growth of this product was a very healthy 26%. Overall revenue was up 65%, though the firm's net loss remained steady at $10 million for the quarter due to increased clinical trial expenses and SG&A spending.

As a result of Naglazyme sales of $18 million for the quarter, which trended higher than expected, BioMarin improved its financial guidance for the year of a GAAP net loss to only be in the $20 million range.

BioMarin experienced one setback with its drug development programs earlier in the quarter. Its potential treatment for various cardiovascular conditions, 6R-BH4, failed in a phase 2 trial testing its effects on reducing hypertension. While the drug failed to show an improvement compared to placebo in the primary endpoint, BioMarin announced slightly more positive results from a post hoc subgroup analysis yesterday.

With the caveat that subgroup analyses that are not pre-specified are fraught with all sorts of dangers and often indicative of a pharma struggling to find an excuse to continue with a drug compound, BioMarin's retrospective look at the study noticed that patients with worse hypertension who took the drug did fare better than placebo patients. Therefore, another study examining 6R-BH4 in this indication is warranted.

As for the rest of BioMarin's pipeline, it still expects a New Drug Application for Kuvan in the second quarter with possible FDA approval by the end of the year, and for marketing partner Merck Serono to file a European Union marketing application in the third quarter.

Even though BioMarin is not yet profitable, its management team has proven capable in all areas of drug development, from the clinical stage to commercialization. While there will always be setbacks like what occurred with 6R-BH4, shares of BioMarin are worth a look for longer-term investors.

Looking for more Foolish drug stock coverage? Check out the Fool's market-beating Rule Breakers newsletter. You can check out all our recommendations as well as get access to our message boards and exclusive content with a 30-day free trial.

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