The Pharmacy Scene...

Can anyone make out what the psychiatrist wrote for a prescription and why the Pharmacist reacted weird? I couldn't tell if it was from the prescription or to give the audience a feel that she might actually be crazy or "the mechanic" wrote the prescription so the Pharmicist had like a possessed moment, etc. I know it was suppose to be an antidepressant but the way he acted was as if it was something way more f'd up...