Dextromethorphan (3-methoxy-N-methylmorphinan), also known as "DXM" and "the poor man's PCP," is a synthetically produced drug that is available in more than 140 over-the-counter cough and cold preparations. Dextromethorphan (DXM) has overtaken codeine as the most widely used cough suppressant due to its availability, efficacy, and safety profile at directed doses. However, DXM is subject to...