Anaheim-based Questcor Pharmaceuticals Inc.’s shares fell today after it reported a lower rate of paid prescriptions for the main use of its sole drug.

Questcor’s shares closed down about 3% after falling as much as 5% earlier today.

The drug maker had a market value of about $2.7 billion at market’s close.

Questcor, which had $142.6 million in revenue through the first nine months of 2011, said that there were 615 to 625 paid prescriptions for its Acthar drug to treat multiple sclerosis in the the first two months of the current quarter. It saw 886 for the entire prior quarter. Prescriptions often pick up in the final month of a quarter.

Acthar, an injectable drug, is also used for treating infantile spasms, a rare form of epilepsy, and nephrotic syndrome, a kidney disorder.

Questcor said nephrotic syndrome paid prescriptions came in at 83 to 87 during the Oct. 1-Nov. 30 time frame, up from 60 in the third quarter.