University of Massachusetts Amherst police have charged a student worker with stealing a controlled substance, Adderall, from the pharmacy at University Health Services.

"This is very unusual, certainly in our memory, this is not something that has happened at all," says UMass Director of News and Information, Ed Blaguszewski.

Police say, 19 year old David Bach, may have substituted the Attention Deficit Disorder drug Adderall, with regular old fashioned ibuprofen.

"It doesn't give you any trust for the person caring for you," says UMass junior, Shannon McCarthy.

"It's purpose is to relax you and help you focus," McCarthy says.

And that explains why the drug is so popular on the college campus black market.

"It's probably 10 bucks a pill and around finals time, around 15 maybe 20," says McCarthy.

UMass police are still investigating what the alleged drug swap was used for, but it brings up security concerns for Health Services.

"That definitely makes me more concerned about where I'm getting my prescriptions from. I got another prescription today for allergies and and it kinda makes me worried about whether or not I need to have that checked," McCarthy says.

CBS 3 Springfield has learned Bach is a sophomore biochemistry and molecular biology major. That could explain how he got the job. But what no one can seem to explain is how he got access to the drugs.

"You need to check the students that are working there. Just because they are interested or in that major, it doesn't mean it qualifies them," McCarthy says.

UMass officials say this incident has them looking into getting security cameras for the pharmacy.

If you think your prescription may be wrong, patients are urged to call University Health Services at (413) 577-5041 or bring the medication or its empty container to the health center's Walk-In Care department at 150 Infirmary Way between 9AM-5PM.

CBS 3 Springfield did catch up with Bach at his UMass dorm and he told us this is the first time he's ever been in trouble.