Tablets comprising a biologically active substance and an excipient containing calcium carbonate

Tablet comprising at least one biologically active substance and an excipient, in which the excipient contains calcium carbonate and at least one additive selected from fatty acids, their salts, their esters, lipid materials, polysaccharides, polyvinylpyrrolidone and polyvinylpyrrolidone derivatives, acrylic compounds, mono-, di- or triglyceride esters, animal proteins, and mixtures of at least two of these. Method for producing these tablets. Use of calcium carbonate in tablets containing at least one biologically active substance, for the prolonged release of this substance.