some technical problem: I choose the proper answer and it says incorrect and gives the same answer ari  

ditto

Noted and updated. Thanks! - Editors

same comment as Ari Lauden

I have observed severe delirious and even catatonic reactions in elderly patients with bronchitis given dextromethorphan and a macrolide (except with azithromycin that does not inhibit CYP3A4). Macrolides decrease DXM metabolism and produces a PCP-like reaction. No matter what, the ER GPs do not seem to get this!

CDT