Abstract
Background:
It is reported that the change in the number of water molecules in the
crystalline mineral salts which is used as pharmaceutical ingredients, can
cause variations in their physicochemical and pharmaceutical properties. The
number of water molecules of these pharmaceutical ingredients is subordinate to
Relative Humidity (RH) and temperature of the maintenance environments of the
medicines. The aim of the present study was to investigate variation in water
content of pharmaceutical solids including ferrous sulfate, barium sulfate and
magnesium chloride in different percentage of RH and temperature. Method:
For this purpose, the pharmaceutical solids (both inside and outside the
packaging) were subjected to various relative humidity at constant temperature
for a given period of time, then change in their water content was determined
with Thermo Gravimetry Analysis (TGA). To create a variety environments with
different RH in constant temperature, the saturated salt solutions were put in
a desiccator and the RH above mixtures of solids was determined with a
Hygroscope at 25°C. Results: According to the results obtained from TGA,
the water content of pharmaceutical solids studied in this research (ferrous
sulfate, barium sulfate and magnesium chloride) changed in different RH and
temperatures. Conclusion: It
is necessary to determine water uptake of Active
Pharmaceutical Ingredients (APIs) and excipients in each stage of pharmaceutical
development process. Furthermore, these results could be used to select an
appropriate packaging to avoid adverse effects caused by water absorption by
pharmaceutical solids. In cases where this is not possible, the allowable range
of relative humidity for each pharmaceutical solid should be noted on its
package.