The Effect of pH and Cocrystal Quercetin-Isonicotinamide on Quercetin Solubility and its Thermodynamic

This study aimed to improve the solubility of quercetin by solvent pH control method and crystal modification through co-crystal formation using isonicotinamide as its co-former. Solubility of quercetin was tested at nine pH levels using phosphate buffer solvents. Quercetin-isonicotinamide co-crystal was prepared by a solvent evaporation method. Co-crystal preparation was carried out using two different stoichiometric ratios of quercetin-isonicotinamide (1:1 and 1:3). The co-crystalline solubility test was performed in 50 mL citrate buffer (pH 5.0 ± 0.05) at a temperature of 37 ± 0.5C. The thermodynamic parameters of quercetin and co-crystal were analyzed to determine the mechanism of the quercetin solubility process. Increasing the pH of solvents has proven to increase the solubility of quercetin. The quercetin oxidation reaction starts at pH level of 7.4. The formation of quercetin-isonicotinamide co-crystal at ratio of 1:1 and 1:3 shows the increase of quercetin solubility by 1.36 and 1.27 times, respectively. The thermodynamic parameters of the quercetin and quercetinco-crystal, which include entropy, enthalpy, and free energy values, can be used to explain the solubility process of quercetin. Quercetin has increased solubility under alkaline pH conditions, but undergoes an oxidation reaction at pH 7.4 and easily oxidized at alkaline pH. Crystal modification of quercetin by the co-crystal formation method has proven to increase the solubility of quercetin so that it can be used for the development of quercetin as a candidate for effective, safe, and acceptable active pharmaceutical ingredient.

Poly(butylene succinate-co-butylene acetylenedicarboxylate): Copolyester with Novel Nucleation Behavior

Big spherulite structure and high crystallinity are the two main drawbacks of poly(butylene succinate) (PBS) and hinder its application. In this work, a new type of copolyester poly(butylene succinate-co-butylene acetylenedicarboxylate) (PBSAD) is synthesized. With the incorporation of acetylenedicarboxylate (AD) units into PBS chains, the crystallization temperature and crystallinity are depressed by excluding AD units to the amorphous region. In contrast, the primary nucleation capability is significantly strengthened, without changing the crystal modification or crystallization kinetics, leading to the recovery of total crystallization rate of PBSAD under the same supercooling condition. The existence of specific interaction among AD units is found to be crucial. Although it is too weak to contribute to the melt memory effect at elevated temperature, the interaction continuously strengthens as the temperature falls down, and the heterogeneous aggregation of AD units keeps growing. When the aggregating process reaches a certain extent, it will induce the formation of a significant amount of crystal nuclei. The unveiled nucleation mechanism helps to design PBS copolymer with good performance.

Selective recovery of Cr from electroplating nanosludge via crystal modification and dilute acid leaching

Amorphous nanosized particles in electroplating sludge are modified for selective extraction of heavy metals.

Review: Metode Peningkatan Kecepatan Disolusi Dikombinasi Dengan Penambahan Surfaktan

Dissolution and solubility rates are very important parameters in designing a pharmaceutical dosage form, especially for oral drug administration. Oral drugs that have low dissolution rates often require high doses loading to improve the absorption and effectiveness in order to achieve therapeutic concentration. The increasing of drug dose is a less safe alternative solution, therefore researchers have developed physics, chemistry, and other modification in order to increase dissolution rate. These methods such as salt formation, prodrug formation, particle size reduction (micro-crystallization), co-grinding, crystal modification, micellar solubilization and complex formation, solid dispersion and self emulsifying. This review paper will focus on different methods that will be compared with the present of surfactant in these methods. The present of surfactants was able to overcome the limitation of each methods with a mechanism for reducing surface tension, micellar formation, reducing contact angle and increasing of wetting behaviour. Therefore, the present of surfactant in modification of drug dosage form could be considered to increase dissolution rate in order to achieve therapeutic effect.

Novel Approaches for Efficient Delivery of Tyrosine Kinase Inhibitors

Epidermal growth factor receptors (EGFRs) have potential to be considered as therapeutic target for cancer treatment especially in cancer patients with overexpression of EGFR. Cetuximab as a first monoclonal antibody and Imatinib as the first small molecule tyrosine kinase inhibitor (SMTKI) were approved by FDA in 1998 and 2001. About 28 SMTKIs have been approved until 2015 and a large number of compound with kinase inhibitory activity are at the different phases of clinical trials. Although Kinase inhibitors target specific intracellular pathways, their tissue or cellular distribution are not specific. So treatment with these drugs causes serious dose dependent side effects. Targeted delivery of kinase inhibitors via dendrimers, polymeric nanoparticles, magnetic nanoparticles and lipid based delivery systems such as liposomes, solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) can lead to reduction of side effects and improving therapeutic efficacy of the drugs in the target organs. Furthermore formulation of these drugs is challenged by their physicochemical properties such as solubility and dissolution rate. The main approaches in order to increase dissolution rate, are particle size reduction, self-emulsification, cyclodextrin complexation, crystal modification and amorphous solid dispersion. Synergistic therapeutic effect, decreased side effects and drug resistant, reduced cost and increased patient compliance are the advantages associated with using combination therapy especially in the treatment of cancer. Combination of TKIs with chemotherapeutic agents or biopharmaceuticals such as monoclonal antibodies and oligonucleotides and also combination of two TKIs within one formulation is possible by new targeting delivery systems. This article reviews the recent advances in the design and development of delivery systems for TKIs.

Nanoengineering colloidal and polymeric celluloses for threshold scale inhibition: towards universal biomass-based crystal modification

The first family of threshold (ppm level) cellulose-based scale inhibitors and crystal modifiers has been developed through the chemical nanoengineering of cellulose fibrils, the building blocks of plant cell walls, overcoming the structural and chemical limitations of conventional nanocelluloses.