A 46-yeаr-оld mаle pаtient is diagnоsed with uncоmplicated Acute Bacterial Rhinosinusitis (ABRS) after failing watchful waiting. He was treated for a dental infection with Amoxicillin 3 weeks ago, but otherwise has no medical history. He has NKDA and takes no other daily medication. Which of the following therapies is the most inappropriate to include in the management of this patient's condition?