Abstract: The residence time in the human stomach of pharmaceutical, gastric controlled release, solid units can be increased significantly if the units have a density that is much higher than normal. A preferred oral dosage form according to the invention comprises a capsule or other dosage form having a dimension above 2 mm and that contains one or more of the said units. The density of each unit is preferably at least 2.5 and usually at least 2.7 g/ml and can conveniently be achieved by including at least 50% by weight of a weighting agent such as barium sulphate.