Prescription drug spending is expected to have grown 5.2 percent in 2009, a 2 percent rise from 2008, to $246.3 billion, and growth in the use of prescription drugs per person was driven by an increase in the use of antivirals related to the H1N1 virus, according to a report in Health Affairs.

Another factor was higher price growth for brand-name drugs, as the Consumer Price Index for prescription drugs has increased from 2.5 percent in 2008 to a projected 3.4 percent rate in 2009. By 2011, drug spending growth is expected to accelerate to 5.6 percent. In 2012 and 2013, there will be a pause as big-selling meds lose patent protection and lower-cost generics become available. As a result, price growth is expected to fall from 3 percent in 2011 to 1.9 percent in 2012. And growth in spending should reach 4.7 percent in 2012 and 5.4 percent in 2013.

Prescription drug spending growth is anticipated to accelerate through 2019, reaching 7.7 percent that year. Increases in drug prices are expected to account for about half of this growth. Also, expected increases in the number of new drug approvals, as well as an increase in the share of expensive specialty drugs, are projected to result in accelerating growth.