Measure of Irritation by Quantitative Determination of Extravasated Dye.

Abstract

Injection of an irritant into rat gastrocnemius muscles, followed in 15 minutes by intravenous injection of Evans blue dye, produced an accumulation of dye at the irritant site. The extravasated dye was removed by blending with Zephiran Cl., 12.8%, and subsequent extraction with isobutyl alcohol, and was measured spectrophotometrically. Statistical analysis of data obtained on a known irritant, formal-dehyde, proved the method is valid. Preservatives, vehicles, local anesthetics, vitamin products, and Ca compounds were tested to cover the range from non-irritating to highly irritating injectables. Modifications of the method were examined to permit its use to measure anti-inflammatory activity and topical irritation.