By Paige Twenter

A growing list of drugmakers are reporting back orders for Adderall and its generics in a shortage that's been slowly worsening since August.

The American Society of Health-System Pharmacists identified four immediate-release amphetamine mixed salts products, the Adderall generic, that are on back order as of Sept. 19. The latest addition brings the total list to 20 generics in short supply, with the other 16 being extended-release tablets manufactured by four drugmakers.

One of those companies, Teva Pharmaceuticals, makes up most of the nation's supply — and it also has the longest list of Adderall generic back orders.

Not all of Teva's Adderall products are on back order. The Israel-based company said a labor shortage on its packaging line earlier this year was the reason for the shortage and estimated late September and early October for resupply dates, according to the ASHP.

Two more updates:

1. CVS and Walgreens can't fill all Adderall prescriptions as diagnoses for attention-deficit/hyperactivity disorder have rapidly risen in recent years.

2. The issue is largely felt in retail pharmacies but might not affect health systems as much.

"We're watching the Adderall one closely. It's hitting different markets," said Jason Chou, PharmD, New Orleans-based Ochsner Health's vice president of pharmacy services. "One of the things that's complex about these is that a particular area or group, depending on where the kink in the line is for the supply chain issue, may see that earlier."

Because of this unequal distribution across industries, Dr. Chou said hospital pharmacy leaders shouldn't overreact or stockpile the generic.