The effect of pore size of the inhaler support upon the concentration of volatile drug emerging in the air stream from a nasal inhaler

Abstract

Abstract The effect that the pore size of the inhaler support has upon the concentration of methylamphetamine emerging in the airstream from a nasal inhaler has been investigated over a range of temperatures using a series of sintered glass plugs of differing porosity. The results showed that there was a reduction in the drug concentration with decrease in pore size of the plugs. An attempt was made to correlate these findings with the Kelvin equation. It was concluded that the degree of lowering of drug concentration was much greater than could be explained on the basis of this equation; and that this was due to the fact that the airstream was not saturated with the drug vapour. The degree of undersaturation appeared to be related to the porosity of the plugs.