The main objective of this study was to optimize the stability of @entity47938 / @entity58109 emulsions in terms of percentage of internal phase volume, emulsifier type and concentration, and amount of external phase (water). Creams (o/w emulsions) were prepared by phase inversion and physical properties as particle size of the internal phase, apparent viscosity, and sedimentation volume evaluated. Stability was performed at room temperature, 40 degrees C, 50 degrees C, and under stress conditions. High hydrophilic lipophilic balance (HLB) nonionic surfactants as @entity9266 , @entity9266 , Myrj 52, @entity30131 , and low HLB @entity33756 were used as emulsifying agents. The percentage of internal phase components ( @entity47938 and @entity58109 ), percentage of emulsifying agents, and percentage of aqueous external phase were varied, and stability was investigated. As the level of emulsifier agent ( @entity9266 and @entity33756 ) increased from 3% to 15%, and the percent of the internal phase remained constant at 30%, the particle size of the internal phase decreased and the cream became more stable. Formulations of the same composition, but prepared using Myrj 53 and @entity9266 as emulsifiers, showed a larger particle size than formulations prepared using @entity9266 and @entity30131 . As the level of the internal phase volume increased and consequently the amount of water decreased, emulsion viscosity increased. The best formulation containing 30% internal phase (50% @entity47938 , 35% @entity58109 ), 15% emulsifying agents ( @entity9266 / @entity33756 ratio of 3:1), and 70% water was selected, and effects of process temperature and cooling rate on emulsion stability investigated. This formulation was further investigated in terms of stability of a 1% @entity701 addition by varying the percentage (30%, 35%, 40%, and 45%) of internal phase and percentage of water (70%, 65%, 60%, and 55%). The best formulation contained 45% internal phase (22.5 g @entity47938 , 15.75 g @entity58109 , 15% emulsifying agent, which is equivalent to 5 g @entity9266 and 1.7 g @entity33756 ), and 55% w/w water, was manufactured under different manufacturing processes. Emulsions prepared by homogenization at the beginning of the process of emulsification were stable with small internal phase particle diameter. This study demonstrates that at every @entity47938 / @entity58109 ratio there is a phase volume/emulsifier HLB ratio, which results in optimum stability.

Relationship between internal phase volume and emulsion stability: the @entity47938 / XXXX system.

@entity33756 :: ('MESH:C009298', 'Chemical') :: ['span 60'] @entity58109 :: ('MESH:C009316', 'Chemical') :: ['stearyl alcohol'] @entity701 :: ('MESH:D006854', 'Chemical') :: ['hydrocortisone'] @entity9266 :: ('MESH:D011136', 'Chemical') :: ['tween 80', 'tween 20'] @entity30131 :: ('MESH:C515901', 'Chemical') :: ['Brij 35'] @entity47938 :: ('MESH:C005031', 'Chemical') :: ['cetyl alcohol']
@entity58109 :: (MESH:C009316,Chemical) :: ['stearyl alcohol']
