Medicare's drug benefit has given a shot in the arm to pharmaceutical companies and insurers, whose revenue is climbing thanks to government subsidies for prescription medicine. What's happened so far: Drugmakers including GlaxoSmithKline and Pfizer reported higher-than-expected sales and profit in the second quarter, with some of the momentum coming from Medicare. Meanwhile, membership rolls of big insurers, including UnitedHealth Group and Humana, are mushrooming as Medicare beneficiaries sign up for drug plans. Drug companies -- which successfully thwarted price-control attempts -- are reaping the rewards of more seniors and disabled people getting access to their medications. British drugmaker GlaxoSmithKline's second-quarter net income grew 14 percent over the same quarter last year due in part to strong Medicare drug sales. Merck & Co., Schering Plough, Wyeth, Roche and Pfizer ... all exceeded analysts' expectations, reflecting sales boosts from the program. In the first three months of the benefit, brand-name drug prices rose 4 percent, according to a report from the AARP. WellPoint Inc., the nation's largest insurer, reported second-quarter profit gains of 34 percent. UnitedHealth ... posted quarterly profit gains of 26 percent. Humana reported earlier this week its second-quarter profit increased 9.9 percent and revenue jumped 52 percent over the same quarter last year, due in large part to a surge in Medicare membership. The insurer expects annual revenue to grow by 50 percent.