A study of the ageing of the gel structure in a nonionic O/W cream by X-ray diffraction, differential scanning calorimetry and spin-lattice relaxation measurements

Abstract

Abstract:The time dependent changes of the lamellar gel structure in a nonionic O/W cream were studied. It appeared that the changes were connected with alterations in the hydrophilic layers of this lamellar gel structure. The structure of the hydrocarbon layers did not change. The alterations were induced by an increasing hydration of the surfactant molecules on cooling from the preparation temperature to room temperature. Ageing of the cream involves a decrease of the thickness of the hydrophilic layers and a change of the distribution of the surfactant molecules, resulting in, among other things, a decrease of the release rate of a hydrophilic drug. Ageing of the cream can be prevented by using the appropriate amount of starting materials or by the use of polymerizable surfactants. In the former case a cream, from which a drug is slowly released, is obtained. On the other hand, creams containing polymerized surfactants can release drugs at a relatively high rate.

Liquid Crystalline Phases in the Structuring of Food Products

“…A large variety of applications are found in the fields of pharmaceuticals, cosmetics, and detergents. Ointments and creams are frequently used as vehicles for drugs (1,2). In their most basic form these products consist of water, oil and surfactant.…”

Investigating the influence of excipient batch variation on the structure, consistency and physical stability of polysorbate 60–based topical vehicles

“…In a series of studies on the aged samples of the CSA -POE (20) glycerol monostearate (PGM 20 ) -water system [29][30][31], de Vringer and co-workers found a decrease in thickness of the lamellae indicated by X-ray diffraction data and a repulsion of water from the lamellae ascertained by the measurements of spin lattice relaxation rates of water. It was explained by changes in the distribution of surfactant molecules among lipophilic bilayers [32]. Immediately after preparation, the gel network of our CSA -polysorbate 60 -water systems can exist in two possible extreme situations with reference to the distribution of polysorbate 60 among the lipophilic bilayers: (i) 'inhomogeneous' (polysorbate 60 molecules are grouped to form clusters) and (ii) 'homogeneous' (polysorbate 60 molecules are distributed more randomly throughout the system).…”

“…Proposed lamellar structure of CSA-polysorbate 60-water ternary system. Redrawn from [32] with some modification to fit polysorbate 60 molecules component built up in our systems more quickly than the elastic component. On further ageing, there were no marked differences in tan δ.…”