Biogen Idec and Elan’s MS drug Tysabri realized a 15% increase in US revenues during the third quarter (compared with Q3 2009), a gain at least partially due to larger sales forces and increased patient assistance programs, according to Biogen Idec executives.

Additional sales reps were hired this year, and pre-existing sales forces were “strengthened” with additional training and communication tools, said Francesco Granata, EVP, global commercial operations, in an earnings call Tuesday morning. A spokesperson for the company declined to quantify the sales force increase, or provide an approximate number of total reps working on the brand.

In addition to professional marketing initiatives, Biogen Idec and Elan also launched new patient resources, including an unbranded wellness site located at MSActiveWellness.com. Launched in September, MSActiveWellness.com offers a free fitness DVD, and other tools for managing MS, according to Kate Weiss, a Biogen Idec spokesperson. In January, the company launched MyMSYoga.com, which features a yoga program (and free DVD) created especially for MS patients by yoga instructor Baron Baptiste and Dr. Elliot Frohman. The companies also launched a web-based research program (MyMSHealth.com) in June, which “collects and reports standardized patient-reported-outcomes” based on user surveys, according to the site.

Compliance rates for patients on Tysabri were stable during 2010, said Paul Clancy, Biogen Idec’s chief financial officer, on the earnings call, adding that some 23,000 new patients had been prescribed the drug, which also picked up an indication for Crohn’s disease in January. To underscore the importance of compliance, the company launched a new MS nursing initiative, said Granata on the call. Participation in patient assistance programs also increased during the third quarter, said Granata.

Revenues for Tysabri, which returned to the market in 2006 after being pulled in 2005 due to safety concerns, were $151 million in the US for the third quarter, and $307 million worldwide, according to financial data released on Tuesday. Biogen Idec is the MS “commercial lead” for Tysabri in the US, and Elan markets the drug for Crohn’s in the US, according to Weiss.