A Clinical Comparison of Two Preparations of Calciferol

Summary The effectiveness of calciferol in tablet form has been compared with that of calciferol in opaque oil‐filled capsules in four patients with vitamin D‐resistant rickets and three patients with hypoparathyroidism. The approximate potency of the tablets in terms of the capsules varied from 0·4 to 1·2, in keeping with the variation in the content of the tablets permitted by the British Pharmacopœia and the known liability of calciferol to chemical deterioration. Deficiencies in the preparation of calciferol used have probably been responsible for some reported instances of apparent increased sensitivity or resistance to treatment. It is concluded that the use of calciferol in tablet form should be discontinued.