Françoise Nielloud

Emulsions in Health Care Applications—An Overview

ABSTRACT Pharmaceutical applications of emulsions are reviewed with special emphasis on the main reasons these vehicles are used and on their limitations. The development of current applications and future directions are considered according to their delivery routes: these routes can be either parenteral, ocular, or oral, or even transdermal. We examine the raw materials generally used in the formulation of these emulsions, and we consider the main factors influencing the release and absorption of the drugs from these vehicles. We also treat the pharmaceutical applications of emulsified vehicles, particularly submicron emulsions, multiple emulsions, and microemulsions. We have also developed some interesting applications of these formulations such as self-emulsifying drug delivery systems, fat emulsions, and drug carrier systems.

Benzophenone-3: rapid prediction and evaluation using non-invasive methods of in vivo human penetration

The study described in this paper constitutes a practical assay system to evaluate in vivo drug penetration using two complementary non-invasive methods. An electrical capacitance test was first applied to the skin on the forearm to evaluate the hydration of the skin, and check the integrity of the stratum corneum. In the first step, the percentage absorption was measured using an occlusive and difference method; following benzophenone-3 application any residual formulation was washed off and the amount removed analyzed. In the second step, the tape stripping method-a useful procedure for selectively removing the skins outermost layer, the stratum corneum, and measuring the stratum corneum adsorption-was performed. Under these conditions the human skin permeation of this UV-filter over four hours was near to 35% of the applied dose with the occlusive method. The amount of topically applied benzophenone-3 found in the stratum corneum after 30 min exposure using the stripping procedure was evaluated at 4% to the applied dose.

Emulsion Formulations: Study of the Influence of Parameters with Experimental Designs

AbstractParameters of formulation of emulsions were performed by the aid of experimental designs. The aim of the work was to investigate five factors at two levels: temperature of manufacture, time of phase introduction, rate of homogenization, mode of cooling, and operators. The study of the flow behavior of the emulsions corresponds to the quantitive response. This work allowed us to show the dominating influence of the factor “mode of cooling”. The progressive cooling at room temperature gives a better stability than the brutal cooling with a water bath corresponding to a shorter homogenization. A further aim was to study the influence of an additional factor: the nature of the sulfactant with the best mode of cooling, progressive cooling. In that case, we can conclude that the main factor, the nature of the surfactant, influences the response.

Stability of UV Filters in Different Vehicles: Solvents and Emulsions

AbstractIn this paper, we analyzed the stability of several ultraviolet (UV) filters exposed to simulated solar light. Evaluation of the photostability of UV-A/UV-B filters has an important impact on the efficiency of sunscreen preparations. The purpose of this study is first to relate some of the solvent shifts that can interact with UV filters; secondly, it is to formulate sunscreen emulsions (oil in water and water in oil) in order to evaluate the photostability of sunscreens in the mixture, and therefore their efficiency in solar protection, because photostability and protection are closely linked together.

Optimization with Experimental Design of Nonionic, Anionic, and Amphoteric Surfactants in a Mixed System

AbstractIn a mixture experiment the response depends only on the relative proportions of material present in the mixture. In this study, we consider shampoo formulations with three different classes of surface-active agents: amphoteric, nonionic, and anionic mild sufactants. A major purpose of this study is to help the formulator with a strategy using a three-component simplex-centroid design. This methodology offers the maximum return in terms of information about the interplay of multiple factors while requiring the minimum investment.

Effect of the Addition of Oxybenzone or Octyl-Methoxycinnamate on Particle Size of Submicron Emulsions

The formulation of sunscreen products requires understanding of the solubilization of these products in different vehicles to obtain aesthetic preparations and to evaluate long-term stability. For this study, two different ultraviolet (UV) filters were selected: oxybenzone (powder) and octyl-methoxycinnamate (liquid). First, the solubility of these UV filters was tested using a three-component simplex-centroid design strategy. The mixtures were prepared with three oily phases used in this field of cosmetics: liquid paraffin, isopropyl myristate, and coconut oil. A phase diagram method was used to carry out a systematic study of submicron oil-in-water emulsions. Phase diagrams were produced by diluting fixed binary mixtures with water. The surfactant consisted of polyoxyethylene-20-sorbitan monostearate/sorbitan monostearate (50/50, w/w). The oily phase contained equal quantities of each oil studied. From this water/surfactant/oil ternary system, we selected two reference emulsions with receptively 75/5/20 and 68/7/25 proportions. Photon correlation spectroscopy (PCS) was used to investigate the influence of these two UV filters at several concentrations on droplet size and distribution of the oil droplets in the material. All emulsions were stored and checked every month for 6 months.

Influence du protocole opératoire sur les caractéristiques d'une émulsion L/H réalisée avec des surfactifs polymériques non ioniques

The mode of operation has an effect on the properties of emulsions. We have studied the influence of the method of preparation (temperature, stirring rate, time of phase introduction and method of cooling) on the rheological properties of an oil in water emulsion. The importance of factors is classified with the help of two‐level full and fractional factorial designs. The most significant factor is the mode of cooling, a progressive cooling produces an increase of viscosity and the influence of the other studied factors is insignificant. Sudden cooling entails a lowering of the viscosity and a diminution of the stability, and shows the influence of the rate of mixing and the temperature of manufacture.

Consideration on the Formulation of Benzoyl Peroxide at Ambient Temperature: Choice of Non-Polar Solvent and Preparation of Submicron Emulsion Gels

ABSTRACT The aim of this study performed at ambient temperature was first to determine the solubility of benzoyl peroxide in various solvents with a large range of polarity. All these solvents can be used in the dermatological field. Then, using the most suitable solvent, a new drug vehicle submicron oil-in-water emulsion was formulated. Correlation between dielectric constant (ε) and drug solubility in various solvents and different binary mixtures was verified. An original ternary diagram with surfactant–co-surfactant/oil/water was performed at low temperature to determine the regions of submicron emulsions. A dramatic change in the magnitude of benzoyl peroxide solubility occurred above a dielectric constant value of about 20. The solubility of this drug can be enhanced by the replacement of polar solvent by a vehicle of lower dielectric constant. A stable submicron emulsion gel was made with cremophor EL, glycerol, caprilic–capric triglycerides, and water in the proportion of 20–20/35/25, respectively; 1.5% benzoyl peroxide was also added. This submicron emulsion vehicle consisted of oil droplets, with a mean diameter of approximately 100–150 nm, dispersed in a continuous water phase. These studies confirm the potential of benzoyl peroxide incorporation into submicron emulsion gel and the stability of this formulation.

PHASE BEHAVIOR AND INTERFACIAL PROPERTIES OF SYSTEMS OF NON-IONIC SURFACTANTS AND SALICYLATE COMPONENTS

Abstract The present study reports the phase diagrams of two salicylate components in the presence of non-ionic surfactants, water and mineral oil. The phase diagrams show that 1% Methyl Salicylate enhances the fine emulsion formation, unlike 3% MS and 1% and 3%Sodium Salicylate which reduce the total emulsion phase region. The data obtained through interfacial tension measurements are used to confirm these phase behaviors.