Provided are effervescent granules of gamma-hydroxybutyric acid (GHB). In an embodiment a granule comprises a solid core on which GHB or one of its pharmaceutically acceptable salts is supported, the granule further comprising, by weight based on the total weight of the granule: - 15-25% of solid core, - 50-60% of GHB - 5-15% of a gas generating compound selected from the group of carbonates and bicarbonates - 2-18% of an aluminometasilicate derivative as a diluent - 3-10% of shellac as a binder - 3-6% of a coating membrane. Further provided is a pharmaceutical composition comprising a mixture of granules with different release profiles. GHB may be used in the treatment of narcolepsy and alcohol withdrawal.
