Pickering emulsions are systems without surfactants, stabilized by solid particles. These emulsions are experiencing a renewed interest, on the one hand, because it is preferable to limit the use of synthetic surfactants for toxicological and environmental reasons and, on the other hand, the need to make new formulations in order to control the drug release patterns by encapsulation or controlled release. Thus, we were interested in the formulation and evaluation of W/O Pickering emulsions stabilized by particles of magnesium oxide with paracetamol in the internal phase and griseofulvin in the external phase. The Bancroft rule served as a model for the formulation. The emulsification was carried out by progressively adding an aqueous phase dispersed in an oil-dispersing phase using a turbo rotor stator mixer. The stability of these emulsions was studied using several parameters (droplet size, pH, viscosity, conductivity ...) and the qualitative and quantitative analysis of the active ingredients by UV-visible spectrophotometry. The results obtained showed that the dye test and the conductivity measurement confirmed the W/O nature of these emulsions. Some parameters such as droplet size, pH and viscosity were strongly influenced by the amounts of magnesium oxide particles and the two active ingredients used. The qualitative and quantitative analysis of the active ingredients confirmed the presence of griseofulvin in the oil phase and paracetamol in the aqueous phase. Thus, we have succeeded in developing a stable W/O Pickering emulsion with magnesium oxide particles. In addition, we were able to incorporate paracetamol into the dispersed phase and griseofulvin into the How to cite this paper:

Pickering emulsions are systems without surfactants, stabilized by solid particles. These emulsions are experiencing a renewed interest, on the one hand, because it is preferable to limit the use of synthetic surfactants for toxicological and environmental reasons and, on the other hand, the need to make new formulations in order to control the drug release patterns by encapsulation or controlled release. Thus, we were interested in the formulation and evaluation of W / O Pickering emulsions stabilized by particles of magnesium oxide with tramadol hydrochloride in the internal phase. The Bancroft rule served as a model for the formulation. The emulsification was carried out by progressively adding an aqueous phase dispersed in an oil-dispersing phase using a turbo rotor stator mixer. The stability of these emulsions was studied using several parameters (droplet size, pH, viscosity, conductivity...) and the qualitative and quantitative analysis of the active ingredient by UV-visible spectrophotometry. The results obtained showed that the dye test and the conductivity measurement confirmed the W / O nature of these emulsions. Some parameters such as droplet size, pH and viscosity were strongly influenced by the amounts of Magnesium oxide particles and the active ingredient. The qualitative and quantitative analysis of the active ingredient confirmed the presence of tramadol in the internal aqueous phase. Thus, we have succeeded in developing a stable W / O Pickering emulsion with magnesium oxide particles. In addition, we were able to encapsulate tramadol in the dispersed aqueous phase.

Nanomedicine has been a booming industry with the development of nanovectors to encapsulate water-soluble or amphiphilic molecules for drug delivery. As the new therapeutic agents synthesized are increasingly lipophilic, the development of new nanoparticulate vectors allowing their transport and targeting is now a major challenge. These particles are lipid nanoparticles, a few hundred nanometers in diameter, stabilized by a layer of surfactants composed of castor oil and stealth agents. Solid lipid nanoparticles based on shea butter, stabilized by cremophor® ELP, encapsulating griseofulvin, were formulated by the temperature phase inversion method. The shea butter nanoparticles thus obtained were the subject of characterization relating to: determination of the morphology, size, polydispersity index, pH and zeta potential. The results confirm the stability of our preparations. The anti-inflammatory activity of shea butter being known, the tests were carried out on mice. The inflammation was induced by a solution of croton oil acetone. There is a very big improvement in anti-inflammatory activity. This is due to better penetration of the preparation through the different layers of the skin. Griseofulvin release studies have been carried out on our various preparations. Systems designed as reservoirs of active ingredients and intended for a priori controlled release obey kinetics of the order of one-half (½) corresponding to a proportionality between the quantity released and the square root of time. Shea butter in nanoparticulate forms has thus enabled us to considerably prolong the release of griseofulvin. Keywords: Nanoparticles; Shea Butter; Inflammation; Griseofulvin.

Multiple emulsions are of great therapeutic interest especially in the administration of medicines which can be inactivated by digestive enzymes; moreover the researches of formulation not being often easy, a control of the different phases physicochemical parameters would be of great interest in rapid formulations and at low cost. When formulating emulsions, the preliminary tests, also known as formulation tests, constitute a step which can be long and expensive because of the quantity of reagents that can be used. A rigorous methodology could thus be of great interest, which is at the aim of our study which consists of evaluating the physico-chemical parameters of different phases used to make thus multiple emulsions. In our study, physico-chemical parameters such as conductivity, pH, density, viscosity, and surface tension have been studied by direct measurement using equipment and also by means of suitable mounting. The results showed that the pH and the surface tension have an important role in the prediction of the stability of emulsions, these latter must be of the same order of magnitude. For all phases conductivity does not have too much interest apart from helping to determine the type of the emulsion.

There are two problems that hinder the use of double emulsions in pharmacies: large-scale equipment not available for one-step emulsification and obtaining a double emulsion and limited ingredients available to replace the tensionactive agents as primary emulsifier because these surfactants are toxic. To overcome these difficulties, a two-stage emulsification strategy has been developed, first generating a water-in-oil Pickering emulsion stabilized by magnesium oxide particles and then the double W/O/W emulsion, thereby reducing significantly the amount of voltage-active. Pickering emulsions are surfactant-free emulsions, stabilized by colloidal particles. These systems are experiencing renewed interest on the one hand, because it is preferable to limit the use of synthetic surfactants for ecological reasons, and on the other hand, because the functionalization of particles has undergone recent advances. It is possible to make very simple calibrated emulsions of controlled size, exploiting a phenomenon called "limited coalescence". The Bancroft rule served as a model for the formulation. The emulsification was carried out using a rotor stator mixer. The stability of these emulsions has been studied using several parameters (pH, conductivity, droplet size, dye test). The dye test and the conductivity measurement confirmed the W/O nature of the emulsion and W/O/W nature of the double emulsion. This study showed that we were able to develop a saturated double W/O/W emulsion.

This study investigates the formulation of surfactant-free Pickering emulsions that release a drug at a specific pH to improve its oral bioavailability. The stabilizing particles composed of magnesium carbonate particles. Pickering oil-in-water emulsions stabilized with magnesium carbonate particles and encapsulating a hydrophobic drug model (ibuprofen) were formulated using a high-energy process with rotor-stator turbo mixer (IKA® T25 digital ultra-Turrax). The experimental approach explored the impact of all formulation parameters, dispersed phase and amount of magnesium carbonate particles on the physicochemical properties of Pickering emulsions. The O/W Pickering emulsion was characterized by a methylene blue test, pH and conductivity measurements, and droplet size determination. In addition, Pickering emulsions stabilized by magnesium carbonate particles have the advantage of being destabilized in acidic medium leading to the release of the active principle via the droplets. The acidic medium release study (pH equal to 1.2) showed ibuprofen release as a function of initial droplet loading and saturation concentration. In the simulated intestinal medium at pH equal to 6.8, we found a better release of ibuprofen from emulsions that already had saturation in an acid medium. Thus, the interest of these Pickering emulsions lies on the fact that their non-toxicity and magnesium carbonate particles allow destabilization of the emulsions and release of the drug. These emulsions not only protect patients from the side effects of acid-based drugs, but also contribute to increase the bioavailability of these acidic drugs. Keywords: emulsion -Pickering-magnesium carbonate- ibuprofen-oral bioavailability

The purpose of this study was to develop a pH-thermosensitive oral chitosan-based hydrogels, able to release phenobarbital in the small intestine of the newborn. Phenobarbital is an active drug used in neonatal treatment of epilepsy. pHthermosensitive hydrogels will improve its bioavailability and therapeutic efficiency with less side effects. This study allowed us to understand the free energy variation at the interface between chitosan chains themselves and the surrounding available molecules with its interactions behavour. Indeed, inverted tube method was used to prepare hydrogels containing 2.45 and 2.55% of chitosan, eudragitE100 and phenobarbital at 37+/-1°C via sol-gel transition. The characterization of their morphology was done by using XL SIRION 200 FEG SEM. In addition, conductivity, refractive index and density's values were determinated. The phenobarbital release mechanism from hydrogels at different pH values, simulating the gastrointestinal tract of the newborn was also studed. UV / visible spectrophotometer SHIMADZU from the UV-2400PC series was used to determine the phenobarbital released amount as a function of time. The results showed that sol-gel transition time decreases when the chitosan concentration increases. In addition, it showed that the hydrogels structure was heterogeneous and the phenobarbital released amount were more important at pH simulating the small intestine at 2.45% of chitosan, final solution's pH6.85 and with the presence of eudragitE100. These results were confirmed by conductivity's values. The sols and hydrogels had a comparable refractive index and density's values. The Korsmeyer-Peppas model was used to fit the phenobarbital release profiles. In short, the hydrogels formulated lend themselves to a phenobarbital pulsatile release usable in the newborn. The phenobarbital release profiles fitting makes possible to predict the phenobarbital amounts, which will be released at the action sites according to the need.

This study investigates the formulation of surfactant-free Pickering emulsions that release a drug at a specific pH to improve its oral bioavailability. The stabilizing nanoparticles composed of hydroxyapatite were obtained by a process of nanoprecipitation. Pickering oil-in-water emulsions stabilized with hydroxyapatite nanoparticles and encapsulating a hydrophobic drug model (ibuprofen) were formulated using a high-energy process with rotor-stator turbo mixer (IKA® T25 digital ultra-Turrax). The experimental approach explored the impact of all formulation parameters, dispersed phase and amount of hydroxyapatite nanoparticles on the physicochemical properties of Pickering emulsions. The system was characterized by a methylene blue test, pH and conductivity measurements, and droplet size determination. In addition, Pickering emulsions stabilized by hydroxyapatite nanoparticles have the advantage of being destabilized in acidic medium leading to the release of the active principle via the droplets. The acidic medium release study (pH equal to 1.2) showed ibuprofen release as a function of initial droplet loading and saturation concentration. In the simulated intestinal medium at pH equal to 6.8, we found a better release of ibuprofen from emulsions that already had saturation in an acid medium. Thus, the interest of these Pickering emulsions lies on the fact that their non-toxicity and hydroxyapatite nanoparticles have advantage of being biocompatible because having the same mineral composition as bones and teeth. In addition, they allow destabilization of the emulsions and release of the drug. These emulsions not only protect patients from the side effects of acid-based drugs, but also contribute to increase the bioavailability of these acidic drugs.