New Accelerating Stability Testing Protocol for O/W Emulsions Stabilized by Nonionic Surfactants Including Storage Temperature Determination
57, Abdul Hakeem El-Refahy Street, Apartment 23, Nasr City, Cairo, Egypt.
57, Abdul Hakeem El-Refahy Street, Apartment 23, Nasr City, Cairo, Egypt. E-mail: [email protected]
Betnovate®, Daktacort®, Daktarin®, Hemoclar®, Kenacomb® and Lotriderm® are O/W creams stabilized by nonionic surfactant/s and distributed in the Egyptian market without stability problems. In this work, the above creams were used as stability reference standard creams to extrapolate numeral values for the proposed parameters of the new accelerated stability testing protocol. The temperature–conductivity relations that represent all the above tested creams have strong direct linear relationships. Determination coefficient R2 values of these relations were ≥0.909 and their yield values represented as temperatures were ≥21º. The stability-indicating phase inversion temperatures of these creams were more than 80º. These common characteristic results represent the basis parameters of the new accelerating stability testing protocol as well as for the determination of the optimum storage temperature of the emulsion under examination. The applicability and validity of this protocol is confirmed by comparing the parameters results obtained from newly formulated O/W 2% miconazole nitrate cream to that obtained from the and also by subjecting all the tested O/W creams including the newly formulated one to accelerating stability testing studies according to the recent approved Issues of ICH Guidelines Q1A (R2). These accelerating stability studies include the measurements of the homogeneity, average weight and leakage test, drug content, pH, viscosity and microbiological analysis of the emulsion. Matching of the compared results and the approval of the stability testing studies confirms the applicability and validity of the new protocol. The new protocol determines the optimum storage temperature condition required for each cream under examination through the determination of the yield value represented as temperature of its temperature–conductivity relation.