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

2021 ◽  
pp. 4657-4661
Author(s):  
Budipratiwi Wisudyaningsih ◽  
Solihatus Sallama ◽  
Siswandono Siswandono ◽  
Dwi Setyawan
Keyword(s):  
Thermodynamic Parameters ◽  
Oxidation Reaction ◽  
Control Method ◽  
Active Pharmaceutical Ingredient ◽  
Ph Control ◽  
Crystal Modification ◽  
Crystal Formation ◽  
Alkaline Ph ◽  
Citrate Buffer ◽  
Ph Level

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.

Amine-Citrate Buffers for pH Control in Starch Gel Electrophoresis

1972 ◽  
Vol 29 (8) ◽  
pp. 1169-1172 ◽  
Author(s):  
J. W. Clayton ◽  
D. N. Tretiak
Keyword(s):  
Gel Electrophoresis ◽  
Ph Control ◽  
Starch Gel Electrophoresis ◽  
Good Resolution ◽  
Citrate Buffer ◽  
Starch Gel ◽  
Ph Range ◽  
Amine Buffers

Amine-citrate buffer systems for pH control in starch gel electrophoresis gave good resolution of some dehydrogenase isozymes. The pK's of three new amine buffers, N-(3-aminopropyl)-morpholine, pK2 25 C, 6.12; N-(3-aminopropyl)-diethanolamine, pK2 25 C, 6.90; and 1,3-bis(dimethylamino)-2-propanol, pK2 25 C, 7.55, were determined at 5 C intervals in the range 10–40 C. These compounds, together with N, N-bis(2-hydroxyethyl)iminotris(hydroxymethyl)methane (bis-Tris) and tris-(hydroxymethyl)-methylamine(Tris), provide a series of amine buffers with pK's at 0.5 unit intervals in the pH range 6.1–8.1.

Review on Pharmaceutical Co-Crystals and Design Strategies

2021 ◽  
pp. 175-180
Author(s):  
A.V.S. Ksheera Bhavani ◽  
A. Lakshmi Usha ◽  
Kayala Ashritha ◽  
Radha Rani E.
Keyword(s):  
Aqueous Solubility ◽  
Active Pharmaceutical Ingredient ◽  
Crystal Formation ◽  
Stoichiometric Ratio ◽  
Design Strategies ◽  
Great Opportunity ◽  
Drug Products ◽  
Drug Substances ◽  
Component Systems ◽  
Physical And Chemical

Poor aqueous solubility and low oral bioavailability of an active pharmaceutical ingredient are the major constraints during the development of new product. Various approaches have been used for enhancement of solubility of poorly aqueous soluble drugs, but success of these approaches depends on physical and chemical nature of the molecules being developed. Co-crystallization of drug substances offers a great opportunity for the development of new drug products with superior physicochemical such as melting point, tabletability, solubility, stability, bioavailability and permeability, while preserving the pharmacological properties of the active pharmaceutical ingredient. Co-crystals are multi component systems in which two components, an active pharmaceutical ingredient and a coformer are present in stoichiometric ratio and bonded together with non-covalent interactions in the crystal lattice. This review article presents a systematic overview of pharmaceutical co-crystals, differences between co-crystals with salts, solvates and hydrates are summarized along with the advantages of co-crystals with examples. The theoretical parameters underlying the selection of coformers and screening of co-crystals have been summarized and different methods of co-crystal formation and evaluation have been explained.

scholarly journals Electrochemical Detection of Free-Chlorine in Water Samples Facilitated by In-Situ pH Control Using Interdigitated Microelectrodes

2020 ◽  
Author(s):  
Alan O'Riordan ◽  
Benjamin O'sullivan ◽  
Pierre Lovera ◽  
Ian Seymour ◽  
James Rohan
Keyword(s):  
Water Samples ◽  
Hypochlorous Acid ◽  
Control Method ◽  
Tap Water ◽  
Distribution Networks ◽  
Ph Control ◽  
Free Chlorine ◽  
Residual Chlorine ◽  
Solution Ph

Residual free-chlorine concentration in water supplies is a key metric studied to ensure disinfection. High residual chlorine concentrations lead to unpleasant odours and tastes, while low concentrations may lead to inadequate disinfection. The concentration is most commonly monitored using colorimetric techniques which require additional reagents. Electrochemical analysis offers the possibility for in-line analysis without the need for additional reagents. Electrochemical-based detection of chlorine is influenced by the solution pH, which defines the particular chlorine ionic species present in solution. As such, controlling the pH is essential to enable electrochemical based detection of residual chlorine in water. To this end, we explore the application of solid state interdigitated electrodes to tailor the in-situ pH of a solution while simultaneously detecting free-chlorine. Finite element simulations and subsequent electrochemical characterization, using gold interdigitated microelectrode arrays, were employed to explore the feasibility of an in-situ pH control approach. In practice, the approach converted residual chlorine from an initial mixture of two species (hypochlorous acid and hypochlorite ion), to one species (hypochlorous acid). Chlorine detection was shown in water samples using this exploratory method, resulting in a two-fold increase in signal response, compared to measurements without pH control. Finally, tap water samples were measured using the in-situ pH control method and the results showed excellent correlation (within experimental error) with a commercial instrument, demonstrating the efficacy of the developed technique. This work establishes the possibility of deploying an electrochemical based reagent-free, in-line chlorine sensor required for water distribution networks.

Kinetic and thermodynamic parameters in biodiesel oxidation reaction in the presence of coffee leaves and sage extracts

2018 ◽  
Vol 28 ◽  
pp. 60-64 ◽  
Author(s):  
Ana Paula Hilário Gregório ◽  
Érica Signori Romagnoli ◽  
Dionísio Borsato ◽  
Diego Galvan ◽  
Kelly Roberta Spacino
Keyword(s):  
Thermodynamic Parameters ◽  
Oxidation Reaction ◽  
Kinetic And Thermodynamic Parameters

Electrochemical Detection of Free-Chlorine in Water Samples Facilitated by In-Situ pH Control Using Interdigitated Microelectrodes

2020 ◽  
Author(s):  
Alan O'Riordan ◽  
Benjamin O'sullivan ◽  
Pierre Lovera ◽  
Ian Seymour ◽  
James Rohan
Keyword(s):  
Water Samples ◽  
Hypochlorous Acid ◽  
Control Method ◽  
Tap Water ◽  
Distribution Networks ◽  
Ph Control ◽  
Free Chlorine ◽  
Residual Chlorine ◽  
Solution Ph

Residual free-chlorine concentration in water supplies is a key metric studied to ensure disinfection. High residual chlorine concentrations lead to unpleasant odours and tastes, while low concentrations may lead to inadequate disinfection. The concentration is most commonly monitored using colorimetric techniques which require additional reagents. Electrochemical analysis offers the possibility for in-line analysis without the need for additional reagents. Electrochemical-based detection of chlorine is influenced by the solution pH, which defines the particular chlorine ionic species present in solution. As such, controlling the pH is essential to enable electrochemical based detection of residual chlorine in water. To this end, we explore the application of solid state interdigitated electrodes to tailor the in-situ pH of a solution while simultaneously detecting free-chlorine. Finite element simulations and subsequent electrochemical characterization, using gold interdigitated microelectrode arrays, were employed to explore the feasibility of an in-situ pH control approach. In practice, the approach converted residual chlorine from an initial mixture of two species (hypochlorous acid and hypochlorite ion), to one species (hypochlorous acid). Chlorine detection was shown in water samples using this exploratory method, resulting in a two-fold increase in signal response, compared to measurements without pH control. Finally, tap water samples were measured using the in-situ pH control method and the results showed excellent correlation (within experimental error) with a commercial instrument, demonstrating the efficacy of the developed technique. This work establishes the possibility of deploying an electrochemical based reagent-free, in-line chlorine sensor required for water distribution networks.

scholarly journals Safe use of Dexamethasone in pediatrics: design and evaluation of a novel stable oral suspension

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Ana Santoveña-Estévez ◽  
Diego Dorta-Vera ◽  
Iris González-García ◽  
Javier Suárez-González ◽  
Nuria Teigell-Pérez ◽  
...  
Keyword(s):  
Quality Criteria ◽  
Standard Operating Procedure ◽  
Active Pharmaceutical Ingredient ◽  
Dosage Forms ◽  
Oral Dosage ◽  
Citrate Buffer ◽  
Physical Chemical ◽  
Oral Formulations ◽  
Minimum Number ◽  
And Control

Abstract Background Dexamethasone is used in pediatrics mainly for treatment of croup and bronchopulmonary dysplasia. Commercially available pediatric oral formulations include inadequate excipients for this population. When there are only commercially available oral dosage forms for adults, a formulation is prepared to reduce the dose by manipulation of authorized tablets or injectable dosage forms. This practice most of times is made without the quality and control that process requires. The aim of this study is to propose a formulation secure and suitable for pediatrics by the use of a Standard Operating Procedure that ensures its quality. Methods Design of two formulations was performed with lowest number and amount of excipients suitable for pediatrics, avoiding use of dexamethasone salts and preservatives. An accurate and precise analytical method and a methodology for analyzing uniformity of doses were developed. Physical, chemical and microbiological stability was tested. Results Stability of Dexamethasone was improved by acidification with citric/citrate buffer. Proposed suspension complies with quality criteria required for an oral non-sterile formulation using Dexamethasone as active pharmaceutical ingredient, and the minimum number and quantity of excipients suitable for pediatrics. Conclusions This formulation is physical, chemical and microbiologically stable during 15 days storage at 5 and 25°C.

scholarly journals Fluconazole-tartaric acid co-crystal formation and its mechanical properties

2021 ◽  
pp. 116-122
Author(s):  
Fikri Alatas ◽  
Nia Suwartiningsih ◽  
Hestiary Ratih ◽  
Titta Hartyana Sutarna
Keyword(s):  
Mechanical Properties ◽  
Tartaric Acid ◽  
Crystal Morphology ◽  
Active Pharmaceutical Ingredient ◽  
Raw Material ◽  
Molar Ratio ◽  
Crystal Formation ◽  
Polarization Microscopy ◽  
Scanning Calorimetry ◽  
Pxrd Pattern

Introduction: The formation of co-crystal is widely studied to obtain more favourable physicochemical properties than the pure active pharmaceutical ingredient (API). The co-crystal formation between an anti-fungal drug, fluconazole (FLU), and tartaric acid (TAR) has been investigated and its impact on mechanical properties has also been studied. Methods: The co-crystal of FLU-TAR (1:1) molar ratio was prepared by ultrasound-assisted solution co-crystallization (USSC) method with ethanol as the solvent. Polarization microscopy was used to observe the crystal morphology. Meanwhile, powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) methods were used to characterise the co-crystal formation. The mechanical properties of the co-crystal, such as flowability and tablet-ability, were compared with pure FLU. Results: Photomicroscopes revealed the unique crystal morphology of the USSC product was different from the two starting components. The typical PXRD pattern was shown by the USSC product, which indicated the formation of FLU-TAR co-crystal. In addition, the DSC thermogram revealed 169.2°C as the melting point of the FLU-TAR co-crystal, which is between the melting points of FLU and TAR. It indicates that FLU-TAR co-crystal has better flowability and tablet-ability than pure FLU. Conclusion: FLU-TAR co-crystal is one of the alternative solid forms for a raw material in pharmaceutical tablet preparation because it has better mechanical properties than pure fluconazole.

Epidemiology

2016 ◽  
Author(s):  
Nicola Dalbeth
Keyword(s):  
Uric Acid ◽  
Gouty Arthritis ◽  
Ph Control ◽  
Tissue Response ◽  
Crystal Nucleation ◽  
Crystal Formation ◽  
Fluid Temperature ◽  
Acute Gouty Arthritis ◽  
Adaptive Immune Cells ◽  
Msu Crystals

The aetiopathogenesis of gout is initiated by urate overproduction and uric acid under-excretion, leading to hyperuricaemia. Foods such as seafood, red meat, beer, and sugar-sweetened beverages contribute to overproduction. Under-excretion is mediated by renal and gut uric acid transporters such as SLC2A9, ABCG2, and URAT1. In hyperurcaemia, there is formation of monosodium urate (MSU) crystals in joints, with acute gouty arthritis mediated by the innate immune system occurring in response to these crystals. Factors such as urate concentration, proteins present in synovial fluid, temperature, and pH control crystal nucleation and growth. Activation of the inflammasome by MSU crystals and production of interleukin-1ß‎ is central to acute gouty arthritis. Advanced gout occurs when there is persistent gouty arthritis and tophus with the tophus being an organized immune tissue response to MSU crystals that involves both innate and adaptive immune cells. Progression through the gout checkpoints (hyperuricaemia, MSU crystal formation, and immune response) is governed by inherited genetic variants, lifetime environmental exposures, and their interaction.

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