Which of the following drugs is categorized as an antitussive?

Dextromethorphan is categorized as an antitussive, which means it is specifically designed to suppress cough. This class of medication works by affecting the signals in the brain that trigger the cough reflex, providing relief for individuals experiencing persistent coughing that doesn't have a productive purpose, such as those caused by colds or other respiratory conditions.

In contrast, guaifenesin is an expectorant, which helps to loosen mucus in the airways, making it easier to cough it up; fluticasone is a corticosteroid used primarily to reduce inflammation in the respiratory tract and manage conditions like asthma or allergies; and codeine, while an antitussive at lower doses, is primarily an opioid used for pain relief, and its use as a cough suppressant is secondary and associated with potential for abuse and side effects. Thus, dextromethorphan is uniquely positioned as a straightforward and effective antitussive for managing coughs.