Shortages of drugs for attention deficit hyperactivity disorder have sent patients and their families on a hunt for pharmacies with drugs in stock.

Some families are paying more for pricey alternatives, or cutting back usage to stretch supplies. "It's a huge inconvenience," says Erin Fox, manager of the drug-information service at the University of Utah Hospital & Clinics. "Parents and patients are running around and calling pharmacies to see who has their product." Recent shortages of Adderall XR and its generic equivalents, also known as amphetamine mixed salts, as well as of methylphenidate, a generic version of the brand-name drug Ritalin, have been reported in Pennsylvania, Maryland, Minnesota, Washington state and elsewhere.

The shortages affect drugs that generated a combined 24.2 million prescriptions in 2010, according to data provided by IMS Health.

Matt Cabrey, spokesman for Shire PLC, the maker of Adderall and generic versions, said rising demand for the drugs due to increased diagnoses of ADHD, which in turn may be fueled by greater awareness of the disorder, can make it difficult to forecast ingredient needs. But the current shortage, Mr. Cabrey said, is due to a delay last year at the U.S. Drug Enforcement Administration in releasing extra supplies of the drug's active ingredients. He said increased supplies are expected this month.

Because of the potential for abuse, the DEA regulates the active ingredients of some ADHD drugs as controlled substances. DEA spokesman Lawrence Payne said the agency has approved enough supply to allow for uninterrupted distribution of the drugs and it's up to manufacturers to allocate the ingredients among their various products.