Benzydamine
4 sources
Mechanism of action
Despite being categorized as a non-steroidal anti-inflammatory drug (NSAID), benzydamine demonstrates various mechanisms of action that differ from those of traditional aspirin-like NSAIDs. In particular, benzydamine predominantly acts by inhibiting the synthesis of pro inflammatory cytokines like tumour necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) without largely affecting other pro inflammatory cytokines (ie. such as IL-6 and IL-8) or anti-inflammatory cytokines (ie. like IL-10 or IL-1 receptor antagonist). Moreover, benzydamine is largely a weak inhibitor of prostaglandin synthesis as it has been shown to effectively inhibit cyclooxygenase (COX) and lipoxygenase enzyme activity only at concentrations of 1mM or greater. Considering most contemporary usages of benzydamine are topical applications that are generally not well absorbed through the skin and/or non-specialized mucosae, benzydamine does not often achieve the kind of absorption or blood concentrations necessary to cause any extraneous distant systemic effects or COX inhibition, allowing it to localize its action. Additionally, it is also hypothesized that benzydamine is capable of inhibiting the oxidative burst of neutrophils and membrane stabilization. These actions are exhibited by the substance’s ability to inhibit the release of granules from neutrophils and to stabilize lysosomes. Furthermore, benzydamine is capable of a local anaesthetic effect that may be related to its capability for inhibiting the release of inflammatory mediators like substance P and calcitonin gene related peptide from sensory nerve endings. Since substance P is capable of causing the release of histamine from mast cells, benzydamine’s prevention of substance P release further contributes to an anti-inflammatory effect. Benzydamine also demonstrates a non-specific antibacterial activity against various bacterial strains that are resistant to broad-spectrum antibiotics such as ampicillin, chloramphenicol, and tetracycline at concentrations of about 3 mmol/L. Combinatorial use of benzydamine and other antibiotics like tetracycline and chloramphenicol are also synergistic against antibiotic resistant strains of *Staphylococcus aureus* and *Pseudomonas aeruginosa*.
Pharmacodynamics
Benzydamine is a non-steroidal anti-inflammatory drug (NSAID) designed to elicit local anesthetic and analgesic effects mainly for the mouth and throat. It specifically acts on the local mechanisms of inflammation such as pain, oedema, or granuloma. Typically applied topically, the drug demonstrates anti-inflammatory activity reducing oedema as well as exudate and granuloma formation. Moreover, benzydamine exhibits analgesic properties and local anaesthetic activity if pain is caused by an inflammatory condition. Benzydamine can be absorbed into the oral mucosa and intact skin. Once absorbed in the local area of pain or inflammation, benzydamine binds selectively to local inflamed tissues, usually allowing it to act with few adverse systemic effects. On average a period of 2 to 4 hours is necessary for the substance to reach peak plasma concentration. Benzydamine can be synthesized with the reaction of the N-benzyl derivative from methyl anthranilate with nitrous acid to give N-nitoso derivative. This is next reduced by sodium thiosulfate to give transient hydrazine. This hydrazine can then undergo spontaneous internal hydrazide formation. Treating this resultant enolate with 3-chloro-1-dimethylamkino propane ultimately yields benzydamine.
Pharmacokinetics
Half-life
Approximately 13 h after oral administration, with a terminal half life of about 7.7 h.
Absorption
Oral doses of benzydamine are well absorbed and plasma drug concentrations reach a peak fairly rapidly and then decline with a half-life of approximately 13 hours. When applied topically, although the local drug concentrations are relatively large, the systemic absorption of topically applied benzydamine is relatively low compared to oral doses. This low topical absorption contributes to a decreased potential for any systemic drug side-effects when benzydamine is administered in this way.
The relatively high lipid solubility of the weak base benzydamine is thought to be associated with considerable passive resorption within the renal tubule, which suggests that only approximately 5% of benzydamine is excreted unchanged in the urine. At the same time however, other studies have suggested that considerably larger amounts (50-65%) of the drug is excreted unchanged in urine. While several inactive oxidized metabolites of benzydamine are excreted in urine, the benzydamine N-oxide metabolite can remain in plasma and demonstrate a half-life that is longer than the parent benzydamine compound. Nevertheless, it is generally believed that excretion occurs mainly through urine and is mostly in the form of inactive metabolites or conjugation products.
The volume of distribution of benzydamine is 10 L.
Benzydamine demonstrateas a systemic clearance of 170 ml/min.
Metabolism
Benzydamine is primarily metabolized by oxidation, dealkylation, and conjugation into hydroxy, dealkylated, and N-oxide metabolites. In general, however, when used at the recommended doses the levels at which benzydamine is absorbed or exposed into the body are usually not sufficient to produce systemic pharmacological effects [L
Protein binding
Benzydamine exhibits < 20% plasma protein binding after oral administration.
Fact-sheets from PsychonautWiki. Harm-reduction reference only — not medical advice.