Pharmacology of benzydamine.

Benzydamine is a topical anti-inflammatory drug which is widely available and used topically for the treatment of the mouth. It is also used as a gel for application to inflamed joints. It has physicochemical properties and pharmacological activities which differ markedly from those of the aspirin-line non-steroidal anti-inflammatory drugs. Benzydamine is a weak base unlike the aspirin-like drugs which are acids or metabolized to acids. A major contrast with the aspirin-like drugs is that benzydamine is a weak inhibitor of the synthesis of prostaglandins but it has several properties which may contribute to its anti-inflammatory activity. These properties include inhibition of the synthesis of the inflammatory cytokine, tumour necrosis factor-alpha (EC(50), 25 micromol/L). Inhibition of the oxidative burst of neutrophils occurs under some conditions at concentrations of 30 to 100 micromol/L, concentrations which may be produced within oral tissues after local application. A further activity of benzydamine is a general activity known as membrane stabilization which is demonstrated by several actions including inhibition of granule release from neutrophils at concentrations ranging from 3 to 30 micromol/L and stabilization of lysosomes. Lack of knowledge of the tissue concentrations of benzydamine limit the correlation between pharmacological activities in vitro and in vivo. The concentration of benzydamine in the mouthwash is 4 mmol/L but the concentrations in oral tissues have not been studied adequately. Limited data in the rat indicates that concentrations of benzydamine in oral tissues are approximately 100 micromol/L.