Sales of medications were up 5.1% in 2009, to over $300 billion, from a 2008 growth rate of 1.8%, a market research firm reports.

The arrival of new drugs for cancer, thrombosis and other diseases were a main reason for the increase, according to IMS Health, Norwalk, Conn., which conducted the study. Meanwhile, the arrival of lower-cost generic drugs for epilepsy, migraine, and other disorders helped moderate the rise in costs, IHS said.

Top-selling medication categories in 2009 were antipsychotics, with sales of $14.6 billion, equal to the 2008 level; lipid regulators, with sales of over $13 billion, down 10% from 2008 levels; proton pump inhibitors, $13.6 billion, down 2% year over year; and antidepressants, growing 3% to $9.9 billion.

Generic products now represent 75% of all dispensed prescriptions in the U.S., up from 57% percent in 2004, IMS reported.