Abstract: Essentially sodium-free effervescent solid pharmaceutical compositions The present invention relates to an effervescent solid pharmaceutical composition, which is essentially free of sodium content, comprising: a therapeutically effective amount of an active pharmaceutical ingredient; one or more pharmaceutically acceptable alkaline earth metal carbonates or hydrogencarbonates in an amount from 1 to 31% by weight of the composition; and one or more pharmaceutically acceptable acids, pharmaceutically acceptable acid salts, or alternatively, a mixture thereof, in an amount from 2 to 62% by weight of the composition; together with one or more pharmaceutically acceptable excipients or carriers; wherein, the total content of the ion sodium in the effervescent solid pharmaceutical composition is equal to or lower than 1 mmol. It also relates to processes for its preparation and its use in therapy.