CILIOTOXICITY OF INTRANASAL FORMULATIONS - MENTHOL ENANTIOMERS

It is shown, using in vitro measurements of beat frequency of rat trac heal cilia, that (+)-(1S, 2R, 5S)-menthol and (-)-(1R, 2S, 5R)-menthol have equipotent ciliotoxicities despite the fact that inhalation of m enthol vapours from the crystals of the pure enantiomers show clearly that the (-)-(1R, 2S, 5R)-menthol produces a more potent cooling sensa tion. Differential scanning calorimetry demonstrates the formation of a racemic compound when equimolar amounts of the two enantiomers are a dmixed.