Technically it's an apothecary and not a pharmacy, the difference being that the first concentrates on producing custom blended compounds while the second primarily dispenses, but it's a bit of a tomatoe/toomato distinction for game purposes. You can print these out on sticker paper or use regular paper and then adhere them to a bottle or package using a glue stick. Both the color and black and white versions are at 300 dpi and sized for a 3" by 2" label. As always, click through for the full sized graphic.
Black and white version:
The upper half of the label is used to identify what the preparation or compound is and how it should be used. In the 1920's that included insecticides and cleaning compounds in addition to the more traditional pharmaceutical goods.