| Dissertation note |
Multiple emulsion is a triphasic system in which the two miscible phases are separated from each other by an inner immiscible phase. In w/o/w multiple emulsion the two queous phases are separated by oily layer. Formulation and stabilization of multiple emulsions from natural oil is the difficult task due to the complex nature of the oil and poor interaction with emulsifiers. Hippophae rhamnoide L. oil, a natural oil, obtained from barries of plant belong to family Elaeagniaceae naturally found in northern areas of Pakistan is effective for healing of skin wounds, Eczema and Psoriasis. In the present study two multiple emulsions were prepared multiple emulsion base 'B' (containing Magnesium sulfate as marker substance) and multiple emulsion formulation 'F' Containing zinc sulfate as (active ingredient). Both preparations contained Hipophae rhamnoides L. oil. Both multiple emulsions were prepared using Two-step method and its stability was evaluated by observing changes in organoleptic parameters, pH, globule size, electrical conductivity and viscosity in samples kept at 4Co ,25Co, 40Co ,40Co+75% RH at various time intervals (Ohr.24hrs,48hrs,72hrs,lstweek, 2ndweek,3rd week, 4th week) for period of 28 days. Data was analyzed using ANOV A-Two ways and LSD design to see variations in parameters at time and temperature levels in each formulation kept at different storage conditions and unpaired student T-test to compare results of stability parameters of Formulation B with Formulation F . Both the multiple emulsions B' and 'F' showed phase inversion at 4°C after 24hrs of storage were excluded from further evaluation. Change in color was observed in all the samples except sample at 2SoC. Sample of multiple emulsion base 'B' kept at 40Co + 7S% RH showed liquefaction after 72 hours. Multiple emulsion formulation 'F' at 40Co and 40Co + 7S% RH showed a significant change in liquefaction and phase separation. The average globule size of multiple emulsion base 'B' (TZurn) is larger than the multiple emulsion formulation 'F' which decreased more significantly in the samples of multiple emulsion base 'B' than samples of'F'. Similarly the pH of the multiple emulsion 'B' (S.l) is more than 'F' (4.2) but in both multiple emulsions kept at different temperatures increased significantly. The increase in electrical conductivity and decrease in viscosity of both multiple emulsions 'B' and 'F' was rather more at 40°C and 40°C+ 7S%RH temperatures while this change was comparatively more in multiple emulsion 'F'. So multiple emulsion 'B' and 'F' at 25°C were stable with respect to organoleptic parameters (except liquefaction), centrifugation, globule size, pH, electrical conductivity and viscosity change than at other temperatures (40°C and 40°C + 7S% RH). Multiple emulsion 'F' is rather more stable at 25°C than 'B' as no liquefaction occurred during the whole stability period in 'F'. For multiple emulsions from Hippophae rhamnoide L. oil refrigeration and high temperature storage condition is fatal for the stability and for relatively high shelf life formulation must be stored at room temperature. Multiple emulsion has advantages over simple emulsion as the droplets may act as reservoir for entrapping the drug molecules to release them slowly to the outer continuous phase so the advantages of multiple emulsion are i) the protection of material entrapped in the internal phase ii) more than one incompatible components can be formulated in a single preparation. None of the multiple emulsions for dermal applications has yet been available in Pakistani market so keeping in view the advantages of multiple emulsion and the Hippophae rhamnoides L. oil prospective researchers hereby suggested to manufacture such a stable formulation which can effectively be marketed in this region.
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