Effect of Cyclodextrin Complexation on the Aqueous Solubility and Solubility/Dose Ratio of Praziquantel

Praziquantel (PZQ), the primary drug of choice in the treatment of schistosomiasis, is a highly lipophilic drug that possesses high permeability and low aqueous solubility and is, therefore, classified as a Class II drug according to the Biopharmaceutics Classification System (BCS). In this work, β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) were used in order to determine whether increasing the aqueous solubility of a drug by complexation with CDs, a BCS-Class II compound like PZQ could behave as BCS-Class I (highly soluble/highly permeable) drug. Phase solubility and the kneading and lyophilization techniques were used for inclusion complex preparation; solubility was determined by UV spectroscopy. The ability of the water soluble polymer polyvinylpyrolidone (PVP) to increase the complexation and solubilization efficiency of β-CD and HP-β-CD for PZQ was examined. Results showed significant improvement of PZQ solubility in the presence of both cyclodextrins but no additional effect in the presence of PVP. The solubility/dose ratios values of PZQ-cyclodextrin complexes calculated considering the low (150 mg) and the high dose (600 mg) of PZQ, used in practice, indicate that PZQ complexation with CDs may result in drug dosage forms that would behave as a BCS-Class I depending on the administered dose

Ecological Indicators of Ecosystem Recovery : Microbial Communities as Ecological Indicators of Ecosystem Recovery Following Chemical Pollution

National audience‘Ecosystem recovery’ is a concept that emerged from the need to preserve our environment against increasing contamination from human activity. However, ecological indicators of ecosystem recovery remain scarce, and it is still difficult to assess recovery of ecological processes at relevant spatial and temporal scales. Microbial communities hold key relevance as indicators of ecosystem recovery as they are ubiquitous among diverse ecosystems, respond rapidly to environmental changes, and support many ecosystem functions and services through taxonomic and functional biodiversity. This chapter summarizes the state-of-the-art in knowledge on the processes driving the structural and functional recovery of phototroph and heterotroph microorganisms following chemical pollution. It covers several successful case studies providing proof of principle for the relevance of using microorganisms in recovery studies in various ecosystems such as soil, freshwater and seawater. Questions remain for microbial ecotoxicologists to fully understand and predict how structural and functional recovery observed at microbial scale can reflect the recovery of an ecosystem. Moreover, new standards and norms taking into account recent advances in microbial ecotoxicology are now necessary in order to inform legislators and policymakers on the importance of considering microorganisms in environmental risk assessment, including ecological recovery monitoring

Functionalized Calcium Carbonate as a Novel Pharmaceutical Excipient for the Preparation of Orally Dispersible Tablets

PURPOSE: To overcome the limitation of insufficient hardness during the production of rapidly disintegrating orally dispersible tablets (ODTs). Furthermore, we investigated the properties and usefulness of functionalized calcium carbonate (FCC) as a new pharmaceutical excipient for the production of ODTs. METHODS: A highly sensitive tensiometer-based method was developed to measure kinetics of weight loss during tablet disintegration. With this method we were able to determine the residence time of tablets placed on a basket immersed into a test medium. The shapes of tensiometer plots allowed us to categorize substances into four different types of disintegration. RESULTS: At the same volume and hardness, the tablet formulations with FCC showed a significantly higher porosity (over 60%) than all other formulations. Residence time depended mainly on the tablet composition rather than on porosity. When combined with disintegrants, FCC formulations exhibited favorable disintegration properties, comparable to those of the marketed drug risperidone oro (disintegration time ca. 10 s). CONCLUSIONS: Oral dosage forms - based on the new pharmaceutical excipient FCC - can be designed to have a short disintegration time combined with good mechanical strength. Due to these properties, FCC can be used for the preparation of ODTs

Temperature-responsive properties and drug solubilization capacity of amphiphilic copolymers based on N-vinylpyrrolidone and vinyl propyl ether

A series of amphiphilic copolymers were synthesized by free-radical copolymerization of N-vinylpyrrolidone (NVP) with vinyl propyl ether (VPE), and the structure of the copolymers was characterized by elemental analysis and gel permeation chromatography. The reactivity of VPE in copolymerization was found to be significantly lower than the reactivity of NVP, which resulted in a decrease of copolymers’ yields and molecular weights with higher content of VPE in the feed mixture. An investigation of the behavior of the copolymers in aqueous solutions at different temperatures by dynamic light scattering revealed the presence of lower critical solution temperature, which depending on the content of VPE ranged within 23−38 °C. Aqueous solutions of these copolymers were studied by fluorescent spectroscopy with pyrene as a polarity probe to reveal the formation of hydrophobic domains. The copolymers were found to be useful for enhancing the solubility of riboflavin in water

Taxonomy of coherency detection and coherency‐based methods for generators grouping and power system partitioning

In a bulk power system, generators can be divided into groups based on the variation of their swing curves after disturbance occurrence. In this regard, generators that have the same variations are placed in the same group and are called ‘coherent’. Identifying coherent generators is an important step in creating a reduced model of bulk power systems for dynamic wide-area analysis. The aim of this study is to provide a comprehensive and up-to-date bibliographic review of the literature related to coherency detection and power system partitioning after disturbance occurrence. In this study, coherency detection methods are classified into model-based and measurement-based categories. Furthermore, existing methods for power system partitioning based on coherency concept are also reviewed and categorised using two different criteria. Finally, the future trend toward coherency and coherent areas detection is discussed.</p

Fast-disintegrating sublingual tablets: Effect of epinephrine load on tablet characteristics

The aim of this study was to evaluate the effect of increasing epinephrine load on the characteristics of fast-disintegrating sublingual tablets for the potential emergency treatment of anaphylaxis. Four tablet formulations, A, B, C, and D, containing 0%, 6%, 12%, and 24% of epinephrine bitartrate, respectively, and microcrystalline cellulose:low-substituted hydroxypropyl cellulose (9∶1), were prepared by direct compression, at a range of compression forces. Tablet weight variation, content uniformity, hardness, disintegration time, wetting time, and friability were measured for each formulation at each compression force. All 4 tablet formulations at each compression force were within the United States Pharmacopeia (USP) limits for weight variation and content uniformity. A linear increase in compression force resulted in an exponential increase in hardness for all formulations, a linear increase in disintegration and wetting times of A, and an exponential increase in disintegration and wetting times of B, C, and D. At a mean±SD hardness of ≥2.3±0.2 kg, all tablet formulations passed the USP friability test. At a mean±SD hardness of ≤3.1±0.2 kg, all tablet formulations resulted in disintegration and wetting times of <10 seconds and <30 seconds, respectively. Tablets with drug loads from 0% to 24% epinephrine can be formulated with hardness, disintegration times, and wetting times suitable for sublingual administration