NCIt definition : Vaporized active and/or inert ingredient(s) intended for administration by inhalation.;
Alternative definition : CDISC: A special class of inhalations consisting of a drug or combination of drugs,
that by virtue of their high vapor pressure, can be carried by an air current into
the nasal passage where they exert their effect; the container from which the inhalant
generally is administered is known as an inhaler. (NCI);