It happened Wednesday at the store on 36th south and Riverdale road around 9:30 p.m.
Surveillance video shows two of the men jumping over the counter while a third acts as a lookout.
Police say the two men assaulted the pharmacist and then forced open a locked cabinet to take pills.
The video then shows the men forcing the clerk to open the register.
After they got the cash, they took off.
Police say the men were violent, brazen and methodical leading them to believe they've done this before.
If you have any information about this crime, call police.