Benzydamine oral spray inhibiting parasympathetic function of tracheal smooth muscle

Abstract

Objectives: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

Keywords: Anti-Inflammatory Agents, Non-Steroidal; Benzydamine; In Vitro Study; Smooth Muscle; Trachea.

Fig. 1

Tension changes in rat trachea after application of various benzydamine concentrations. Benzydamine alone had a minimal effect on the basal tension of trachea as the concentration increased. Original basal tension was 0.3 g.

Fig. 2

Original recording of the effects of benzydamine on 10^-6M methacholine-induced contraction of rat trachea.

Fig. 3

Effects of benzydamine on 10^-6M methacholine-induced contraction (contraction area calculated at 100% with no addition of benzydamine) of rat trachea. The difference in tension between 10^-8M benzydamine and 10^-5M benzydamine or 10^-4M benzydamine was statistically significant (P<0.05). Results were mean±standard deviation (n=6).

Fig. 4

Original recording of effects of benzydamine on electrically induced tracheal smooth muscle contractions was noted. Higher doses of benzydamine also decreased the spike contraction induced by electrical field stimulation.

Fig. 5

Effects of benzydamine on electrically induced tracheal smooth muscle contractions (contraction area calculated at 100% with no addition of benzydamine). The peak tension of the tracheal strip evoked by electrical field stimulation during the addition of 10^-4M benzydamine was significantly less than that at the addition of 10^-8M benzydamine (P<0.001). Results were mean±standard deviation (n=6).