EXTON, Pa. (AP) — ViroPharma Inc. shares climbed Monday after the drug developer said its 2013 revenue may grow beyond analysts' expectations.

The Exton, Pa., company expects revenue to range from $450 million to $475 million in the new year. It made the announcement a day ahead of an appearance by CEO Vincent Milano at the annual J.P. Morgan health care conference in San Francisco.

Analysts surveyed by FactSet expect, on average, revenue of $466.1 million this year.

ViroPharma also expects $390 million to $400 million in North American sales from Cinryze, which is used to prevent and treat attacks of hereditary angioedema, a rare genetic disorder that can cause dangerous swelling of the throat or larynx.

ViroPharma focuses on serious diseases with few, if any, available therapies. It also makes the seizure drug Buccolam and antibiotic Vancocin.

ViroPharma shares rose $1.01 cents, or 4.3 percent, to $24.77 in afternoon trading. The stock has ranged from $19.02 to $33.17 in the past 52 weeks.