Final answer:
An auditor should report concerns to the independent audit committee of the board of directors.
Step-by-step explanation:
An auditor should report concerns to the independent audit committee of the board of directors when a private pharmaceutical company refuses to properly disclose a going concern issue in the notes. This is the appropriate course of action as it ensures that the concerns are brought to the attention of the company's governing body and can be addressed appropriately. It is important for auditors to fulfill their responsibility of reporting any potential issues or concerns to the relevant authorities.