Benzydamine oral spray inhibiting parasympathetic function of tracheal smooth muscle

Benzydamine is a nonsteroidal anti-inflammatory agents agent with anti-inflammatory and local anesthesia properties that is available in the entire world as an oral spray for oral mucositis patients who are suffering from radiation effects. The effect of benzydamine on oral mucositis in vivo is well known; however, the effect of the drug on tracheal smooth muscle has rarely been explored. During administration of the benzydamine for oral symptoms, it might affect the trachea via oral intake or inhalation.

We examined the effectiveness of benzydamine on isolated rat tracheal smooth muscle. The following assessments of benzydamine were performed: effect on tracheal smooth muscle resting tension; effect on contraction caused by 10(-6)M methacholine as a parasympathetic mimetic; and effect of the drug on electrically induced tracheal smooth muscle contractions.

Addition of methacholine to the incubation medium caused the trachea to contract in a dose-dependent manner. Addition of benzydamine at doses of 10(-5)M or above elicited a significant relaxation response to 10(-6)M methacholine-induced contraction. Benzydamine could inhibit electrical field stimulation-induced spike contraction. It alone had a minimal effect on the basal tension of trachea as the concentration increased.

This study indicated that high concentrations of benzydamine might actually inhibit parasympathetic function of the trachea. Benzydamine might reduce asthma attacks in oral mucositis patients because it could inhibit parasympathetic function and reduce methacholine-induced contraction of tracheal smooth muscle.