Stability of almagate and pharmaceutical formulations prepared from it.

The stability under accelerated conditions of almagate (Al2Mg6(OH)14(CO3)2 X 4 H2O, Almax) a new crystalline synthetic hydrated aluminium-magnesium hydroxycarbonate antacid, and pharmaceutical formulations prepared from it, were compared with other pharmaceutical formulations prepared from aluminium hydroxide gel or co-gels of aluminium-magnesium hydroxide. The antacid properties of almagate, Almax tablets and suspension, did not change during eight months storage at 60 degrees C whereas preparations of aluminium hydroxide gel and aluminium-magnesium hydroxide co-gel suffered considerable losses in acid neutralization capacity. Neither the X-ray diffraction nor the IR absorption spectrum of almagate changed during storage for 8 months at 60 degrees C. Thus almagate and pharmaceutical formulations prepared from it are thermally stable and will maintain their antacid properties for long periods of time unlike products prepared from aluminium hydroxide gels or aluminium-magnesium hydroxide co-gels.