Category: Formulation and Quality
Purpose: Creams are heterogenous semi-solid preparations, where oil in water (O/W) or water in oil (W/O) is dispersed and stabilized using a suitable emulsifier. O/W creams are most commonly used topical formulation for various dermatological disorders. Moisture sensitive drugs like mechlorethamine, acyclovir, itraconazole and ketoconazole are liable to degradation in water phase. Hence, there is need for developing formulation using alternate aqueous component in cream preparation. Polyethylene glycol (PEG) are product of condensed ethylene oxide and hydrophilic in nature. PEG types are generally used as penetration enhancers and solubilizers in cream preparations. The objective of present study is to develop and optimize Oil in PEG creams suitable for incorporating hydrophobic and moisture sensitive drugs.
Methods: Oil in PEG creams were prepared by varying different grades of PEGs in combination with propylene glycol as aqueous phase. The Oil-in-PEG cream F1 through F16 (Table) was prepared by adding oil phase containing Tefose 63 (emulsifier) to aqueous phase at 70 °C by employing high shear homogenization technique. The prepared creams were subjected to accelerated stability studies, where the creams were exposed to 3 cycles of freeze thaw. The texture analyzer was used to determine work of adhesion, firmness, elasticity, strength and toughness of stable cream.
Results: Accelerated stability studies demonstrated formulations comprising PEG 2000 and 3350 (F5, F6, F7, F8, F9, F10, F11 and F12) were stable, whereas there was phase separation of creams comprising PEG1450 and PEG4500 (F1, F2, F3, F4, F13, F14, F15 and F16). Formulations F13, F14, F15 and F16 prepared with PEG 4500: PEG 400 were brittle and solid in nature. This study demonstrates PEG2000 and 3350 would be ideal for preparation of oil in PEG cream. Texture analysis of the creams (i.e. F5, F6, F7, F8, F9, F10, F11 and F12) which passed the stability studies were performed and the results for work of adhesion, firmness and elasticity are presented in Figure.
Conclusion: Oil in PEG creams were successfully prepared by the conventional method (High-Shear Homogenization). The formulation which consists of PEG 2000 (F5 – F8) and PEG 3350 (F9 – F12) were stable and texture analysis studies depicted cream possess ideal topical formulations characteristics. Moisture sensitive and hydrophobic drugs could be incorporated in the Oil in PEG emulsions. Oil in PEG creams have several advantages over oil in water creams, in terms of loading of hydrophobic drugs and moisture sensitive drugs, and for longer duration of action due to less metamorphosis or no metamorphosis of drugs.