TOPICAL ANTIRHEUMATIC AGENTS AS HYDROXYL RADICAL SCAVENGERS

Camphor, capsaicin, ketoprofen, lavender oil, cineole, beta-pinene and methyl nicotinate which are used in topical formulations for the relief of pain associated with rheumatic and musculo-skeletal disorders were assessed for hydroxyl radical scavenging properties. The compounds tested were irradiated with simulated sunlight in a model aqueous system containing dequalinium chloride and hydrogen peroxide. The rate of degradation of the dequalinium chloride by the photogenerated hydroxyl radicals was measured and found to follow second-order kinetics. Ketoprofen, a clinically used antirheumatic agent, gave the optimal results. The hydroxyl radical scavenging properties of the other compounds are discussed in terms of their chemical structure and possible reactivity.