Abstract: In accordance with this invention there is provided a granular product with an effervescent system which comprises acid-sensitive pharmaceutically active substances, such as, for example, betacarotene, cimetidine, ranitidine or cisapride, which is specially useful to prevent antacid action, having an acid-neutralizing capacity below about 5 meq, at a weight of about 1.6 to about 2.3 grams. The effervescent grains are made from carrier crystals of at least one solid, edible organic acid, preferably citric acid and/or tartaric acid, and are present as a granular product, separate from the pharmaceutically active substance, and are coated with at least one layer of a neutral substance which is soluble in water and/or alcohol and which is able to bring about a melting point depression of the acid grains at their surface, such as, for example, a water-soluble polymer, a polyalcohol, a carbohydrate and/or a hydrocolloid.