Photochemical Degradation of Glaphenine Solution

Abstract

The aim of this work was to study the effect of light on glaphenine stability in solutions. Glaphenine solutions in various solvents, including alcohols, acidic alcohols, water and acidic aqueous media, were exposed to both artificial light source and solar radiation. The photodegradation was followed using different techniques including UV-visible spectrophotometry, spectrofluorometry, mass spectrometry, HPLC and TLC. Studying the effect of solvents on the stability showed that glaphenine is completely stable towards light in water and in acidic media. In neutral alcohols, the rate of photodecomposition was found to increase in the order methanol < ethanol < pentanol < butanol < propanol, which may be explained by solvent-solute interaction and viscous properties of the solvent. Two photodegraded products were separated and identified as a-glycerylanthranilate and 7-chloroquinoline. Drug molecules having particular structures may undergo photodegradation when irradiated with light. This necessitates the testing for photodecomposition in the preformulation stage to safeguard against such deterioration. Factors affecting photodecomposition differ between solid and liquid forms. Consequently, photodecomposed species need to be identified when possible, in solid and solution states. Glaphenine, a-glyceryl N-(7-chloro4-quinolyl) anthranilate, is an analgesic that has been used for the relief of all types of pain. Recently, its use has been limited by the high incidence of anaphylactic reactions. Glaphenine comprises anthranilic and quinoline nuclei, which show instability towards UV or visible radiation in solution (Fujishiro 1960; Stermitz et a1 1970). Glaphenine powder is stable against heat and moisture but undergoes photodegradation when exposed to UV-visible or solar radiation. The decomposition products are similar regardless of the method of radiation used. Two main photodecomposed products were identified as N(7-chloro-4-quinolyl) anthranilic acid and methyl N-(7-chloro-4-quinolyl) anthranilate; intramolecular abstraction leads to the formation of these photodegraded products (Badwan et a1 1992). It is of prime interest to compare the degradation products produced from solid state and those obtained Correspondence: A. A. Badwan, The Jordanian Pharmaceutical Manufacturing Co., PO Box 94, NAOR 11710, Jordan.