The influence of the moisture content of the fibrous support of a nasal inhaler upon the concentration of drug in the air stream

Abstract

The moisture contents of cellulose acetate and paper fibrous support materials used in nasal inhalers have been determined by infrared drying and extraction techniques. The mutual solubilities of water and methylamphetamine have been investigated at various temperatures, and the results indicated that the system exhibited both upper and lower consolute temperatures. The effect of molar composition of water on the total and partial vapour pressures of methylamphetamine-water mixtures have also been investigated. Positive deviations from Raoult's Law were observed for both total and partial pressures. The present results have been related to data obtained previously with an inhaler system to show that the moisture contents of the fibrous supports are partially responsible for the discrepancy between the derived and absolute vapour pressure values for methylamphetamine.