Earlier today drug developer Biogen Idec (NASDAQ:BIIB) announced second-quarter financial results and continued its streak of measured revenue and earnings growth.

Revenue in the quarter was up a healthy 17% year over year, as revenue from its multiple sclerosis franchise drugs, Avonex and Tysabri, continue to pick up due to the recent worldwide launch of Tysabri. Net income excluding some charges was up 22% versus the second quarter of 2006.

Based on the 13,000 patients that Biogen and partner Elan (NYSE:ELN) yesterday announced were taking Tysabri commercially, and an average annual wholesale sales price of $28,400 for the drug (as given by Elan), the drug's annualized sales run-rate is nearly $370 million (split between the two partners and not accounting for price differences in different locales).

This newly updated Tysabri patient count compares to the over 9,000 patients that were on the drug commercially in April and shows some good prescription growth in the past three months. This proves that Tysabri will be a good complement to Biogen's sales of Avonex even if it isn't approved as a first-line therapy for MS or as a treatment for other indications like Crohn's disease. Positive decisions like the British medical authorities' approval earlier this month to reimburse patients' use of the drug will also help drive more sales growth.

During the quarter Biogen repurchased 16% of its shares in a Dutch auction for $3 billion. Based partly on this reduced share count, Biogen upped its earnings forecast for the year to $1.75 to $1.87 a share, including potential stock options expenses but excluding amortization charges.

None of Biogen's top compounds except for Tysabri are in a high sales growth phase anymore. That's fine as long as the drugmaker can keep its costs in check and continue to improve its gross and operating margins. For the quarter R&D expenses did jump as a percentage of revenue, but cost of sales and SG&A spending remained in check and accounted for 37% of all revenues, just as they did in the second quarter of 2006.

Investors often shy away from the biopharma sector because of the precarious financial situations of many of its companies. Investors looking for solid top- and bottom-line growth could do worse than taking a look at Biogen.

Biogen Idec is a Stock Advisor recommendation. To see what other companies David and Tom Gardner have recommended to investors since 2002, click here for 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.