Your state pharmacy law probably includes a provision for the pharmacist to leave temporarily, sometimes even for an entire lunch break, WITHOUT shutting down the whole pharmacy.
In Florida:
64B16-28.109
(1) The prescription department of any community pharmacy permittee shall be considered closed whenever the establishment is open and a pharmacist is not present and on duty. [next sentence omitted]
(2) The term “not present and on duty” shall not be construed to prevent a pharmacist from exiting the prescription department for the purpose of consulting or responding to inquiries or providing assistance to patients or customers, attending to personal hygiene needs, taking a meal break pursuant to Rule 64B16-27.1001, F.A.C., or performing any other function for which the pharmacist is responsible, provided that such activities are conducted in a manner consistent with the pharmacist’s responsibility to provide pharmacy services.