Processing-induced-transformations (PITs) during direct compression: impact of compression speeds on phase transition of caffeine

International audienceFor pharmaceutical industry, understanding solid-phase transition of the active pharmaceutical ingredient (API) induced by the manufacturing process is a key issue. Caffeine was chosen as a model API since it exhibits a polymorphic transformation during tableting. This study investigated the impact of the compression speed on the phase transition of anhydrous Form I (CFI) into Form II. Tablets were made from pure CFI and binary mixtures of CFI/microcrystalline cellulose, with an electric press well instrumented at three different compression speeds (50, 500 and 4500 mm min−1). For each velocity of the mobile punch studied, tablets made from three compression pressures (50, 100 and 200 MPa) were analyzed. The determination of the CFI transition degree was performed using a Differential Scanning Calorimetry (DSC). The CFI transition degree was monitored during three months in order to obtain the transformation profile of the API in tablets and in uncompressed powder. The modeling of the profile with a stretched exponential kinetic law (Johnson–Mehl–Avrami model) was used for the identification of the transition mechanism. The direct compression process triggered the polymorphic transformation in tablet when a sufficient compression pressure is applied. The velocity of the punch did neither impact the transition degree just after compression nor the transformation profile. The transition mechanism remained driven by nucleation for several operating conditions. Consequently, the punch velocity is not a decisive process parameter for avoiding such phase transition in tableting. As already observed, the compression pressure did not influence the transition whatever the compression speed and the velocity

Étude expérimentale et modélisation de la cohésion d’un lit de particules

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Model-based optimization of parameters for degradation reaction of an organophosphorus pesticide, Paraoxon, using CeO2 nanoparticles in water media .

International audienc

Mechanism of nanocapsules formation by the emulsion–diffusion process

International audienceA detailed investigation into the mechanisms of nanocapsule formation by means of the two stages “emulsion–diffusion” process is reported. Such widely used process is still poorly understood. An emulsion of oil, polymer and ethyl acetate is fabricated as a first step; dilution with pure water allows ethyl acetate to diffuse out from the droplets, leaving a suspension of nanocapsules at the end. It has been shown that the size of nanocapsules was related to the chemical composition of the organic phase and the size of primary emulsion through a simple geometrical relationship. As a consequence, most of the properties of the nanocapsules were decided at the emulsification step. The influence of several formulation and processing parameters of the primary emulsion was studied accordingly. The thin polymer membrane of nanocapsules was observed by means of cryo-fracture electron microscopy. Finally two experiments were designed for a mechanistic investigation of the diffusion step. A step-by-step diffusion of the organic solvent takes place by successive partition equilibria of ethyl acetate between the droplets and aqueous phase. A time-resolved experiment shows the fast diffusion (less than 20 ms) related to the small droplet size of the emulsion

Experimental study of tensile strength of pharmaceutical tablets: effect of the diluent nature and compression pressure

International audienceIn the pharmaceutical field, tablets are the most common dosage form for oral administration in the world. Among different manufacturing processes, direct compression is widely used because of its economics interest and it is a process which avoids the steps of wet granulation and drying processes. Tablets are composed of at least two ingredients: an active pharmaceutical ingredient (API) which is mixed with a diluent. The nature of the powders and the processing conditions are crucial for the properties of the blend and, consequently, strongly influence the mechanical characteristics of tablets. Moreover, tablets have to present a suitable mechanical strength to avoid crumbling or breaking when handling, while ensuring an appropriate disintegration after administration. Accordingly, this mechanical property is an essential parameter to consider. Experimental results showed that proportion of the diluent, fragmentary (DCPA) or plastic (MCC), had a large influence on the tensile strength evolution with API content as well as the compression load applied during tableting process. From these results a model was developed in order to predict the tensile strength of binary tablets by knowing the compression pressure. The validity of this model was demonstrated for the two studied systems and a comparison was made with two existing models

In vitro skin decontamination of the organophosphorus pesticide Paraoxon with nanometric cerium oxide CeO 2

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Effectiveness of grafting modes of methoxycinnamate sunscreen onto silica particles

International audienc

Inorganic ions in the skin: Allies or enemies?

International audienceSkin constitutes a barrier protecting the organism against physical and chemical factors. Therefore, it isconstantly exposed to the xenobiotics, including inorganic ions that are ubiquitous in the environment. Some ofthem play important roles in homeostasis and regulatory functions of the body, also in the skin, while others canbe considered dangerous. Many authors have shown that inorganic ions could penetrate inside the skin andpossibly induce local effects. In this review, we give an account of the current knowledge on the effects of skinexposure to inorganic ions. Beneficial effects on skin conditions related to the use of thermal spring waters arediscussed together with the application of aluminium in underarm hygiene products and silver salts in treatmentof difficult wounds. Finally, the potential consequences of dermal exposure to topical sensitizers and harmfulheavy ions including radionuclides are discussed

The Nanoceria: a new strategy for skin decontamination of Organophosphorus compound.

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