A contentious relationship between drug manufacturers and the Drug Enforcement Agency may cause a continuing shortage of the attention deficit medication Adderall, which the FDA just added to its official drug shortages list, the New York Times reported.

As of 2007, about 9.5 percent, or 5.4 million, of school-aged children were diagnosed with Attention Deficit Hyper Disorder, according to the Centers for Disease Control and Prevention. Adderall prescriptions went  up 13.4 percent from 2009 to 2010, and more than 18 million prescriptions were written for the drug,  Reuters reported.

As demand for the drug grows, more and more patients have found the medication is out of stock at local pharmacies.

Experts say it's difficult to say where the reason for drug shortage lies. To manage controlled substances that can potentially be abused, the DEA sets manufacturing quotas for drug ingredients each year to control supplies like Adderall. But Adderall drug manufacturers, which include Shire Plc and Novartis, Teva and CorePharma LLC, say they cannot meet the growing demand for the product without looser limits from the DEA. The DEA questions whether there is actually a shortage of generic supplies, which are at an especially low supply, or whether the drug companies want to sell more of the expensive brand-name drugs.

Despite the growing demand, Special Agent Gary Boggs of the DEA's office of diversion control told the New York Times, "We believe there is plenty of supply."

Barbara Carreno, a DEA spokeswoman, told Reuters that hundreds of drugs that do not require a DEA quota, and those shortages are not caused by quota limits, but marketing ploys by drug makers.

"Any shortage of these products is therefore a result of decisions made by industry regarding manufacturing or distribution,"  Carreno told Reuters.

But a Teva spokesperson told Reuters, "Our production facilities are currently running at maximum capacity for Adderall utilizing all available API (the drug's active pharmaceutical ingredient). The catalyst for the problem is the quota system, not the business."

The addition of Adderall to the FDA drug shortage list comes on the heels of an executive order to ease drug shortages that Obama signed in October.

"The shortage of prescription drugs drives up costs, leaves consumers vulnerable to price gouging and threatens our health and safety," Obama said in a statement at the time. "This is a problem we can't wait to fix. That's why today, I am directing my administration to take steps to protect consumers from drug shortages, and I'm committed to working with Congress and industry to keep tackling this problem going forward."