Dextromethorphan Hydrobromide (10mg) + Menthol (3.75mg) + Terpin Hydrate (10mg) (Medical Monograph)

Overview

A fixed-dose combination antitussive (cough suppressant) and expectorant formulation. Dextromethorphan is a centrally-acting non-opioid antitussive. Menthol provides a local soothing and cooling effect on the throat mucosa. Terpin Hydrate acts as an expectorant, increasing bronchial secretions and reducing mucus viscosity. This combination is indicated for the symptomatic relief of dry, non-productive cough associated with conditions like the common cold, bronchitis, and upper respiratory tract infections.

Dextromethorphan acts centrally on the cough center in the medulla oblongata, raising the threshold for cough reflex. It is a sigma-1 receptor agonist and an uncompetitive NMDA receptor antagonist. Menthol acts locally on cold-sensitive TRPM8 receptors in the oropharyngeal mucosa, producing a cooling sensation that soothes throat irritation and provides a subjective feeling of easier breathing. Terpin Hydrate is an irritant expectorant; it stimulates gastric mucosa, leading to a reflex increase in respiratory tract secretions via the vagus nerve, thereby thinning bronchial mucus and facilitating its expulsion.