Crystallization of excipients in tablets.

Whisker-like crystals appeared on the surface of tablets that contained lactose or mannitol, a hygroscopic material such as docusate sodium, magnesium chloride, or potassium acetate, and other ingredients stored in an atmosphere of high relative humidity. The crystals were observed under a scanning electron microscope and were measured using differential scanning calorimetry and TLC. The crystals contained lactose or mannitol.