NCIt definition : A powder composed of active and/or inert ingredient(s), and a mixture of acids and
sodium bicarbonate, which release carbon dioxide when dissolved in water.;
Alternative definition : EDQM-HC: Solid single-dose or multidose preparation consisting of one or more powders
generally containing acid substances and carbonates or hydrogen carbonates that react
rapidly in the presence of water to release carbon dioxide. Effervescent powders are
intended to be dissolved or dispersed in water before administration.;