Evaluation of accelerated stability test conditions for medicated chewing gums.

The overall stability of medicated chewing gums is investigated under different storage conditions. Active substances with
different chemical stabilities in solid state are chosen as model drugs. The dosage form is a three layer tablet obtained by direct
compression. The gum core contains the active ingredient while the external layers are formulated to prevent gum adhesion to
the punches of the tableting machine. Two accelerated test conditions (40°C/75%RH and 30°C/65% RH) are performed for six
months. Furthermore, a long-term stability test is conducted to verify the predictability of the results obtained from the stress
tests. Some drugs are stable in all the conditions tested, while for less stable drugs, the stress conditions of 40°C/75%RH are
not always predictable of chewing gum stability, instead, intermediate conditions, 30°C/65%RH, are more suitable for this
purpose. In fact, the results of drug content found after 6 months at intermediate stress conditions and 12 months at room conditions are generally comparable