Sodium alendronate used in bone treatment: A complex study on the thermal behavior of the bioactive compound and its binary mixtures with several excipients

The thermally induced interactions of sodium alendronate trihydrate in 1:1 mass ratio binary mixture with talc, silica, magnesium stearate, microcrystalline cellulose, starch, gelatin and mannitol were studied under non-isothermal conditions. The heat flow (HF) signal, obtained by converting the temperature differences (DTA) into power units, was used for detecting the thermally induced events. By all the seven excipients, no thermally induced interactions with alendronate were observed, but the thermal stability of the excipients is very different. The talc and silica, as expected, are very thermostable. By starch, gelatin, and microcrystalline cellulose, the HF signal corresponding to the thermo degradation is over 270 °C, the deamination step of alendronate. The magnesium stearate and mannitol substances are not recommended for solid formulation due to its low thermal stability.