The solubility of form A metformin
hydrochloride (MET·HCl)
in water, methanol, ethanol, water + methanol, water + ethanol, water
+ acetone, and water + isopropanol at the temperatures ranging from
283.15 to 323.15 K was determined by gravimetric method. The experimental
results show that the solubility increases with the increase of temperature
and the initial water content of the binary solvents. The order of
solubility in the four aqueous solvent mixtures is water + methanol
> water + ethanol > water + isopropanol > water + acetone,
which is
mainly contributed by the hydrogen bond interactions. The modified
Apelblat model, CNIBS/R–K model, and Apelblat–Jouyban–Acree
model were used to correlate the solubility data. The results show
that the Apelblat model can correlate the solubility of four binary
solvents best, and all average relative deviations are less than 6%.