The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
M. K. Rotich - One of the best experts on this subject based on the ideXlab platform.
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Modelling the thermal behaviour of carboxylic Acid derivatives with cylcodextrins in the solid-state
Journal of Thermal Analysis and Calorimetry, 2004Co-Authors: S. Agotonovic-kustrin, B. D. Glass, M. E. Brown, M. K. RotichAbstract:The application of classical QSAR and molecular modelling to the inclusion complexation of natural and modified cyclodextrins (CDs) with carboxylic Acid derivatives as guest molecules was examined. Information was available on the thermal behaviour, in the solid-state of benzoic Acid (BA), salicylic Acid (SA), and various substituted aminosalicylic Acids (3-aminosalicylic Acid, 3-ASA, 4-Aminosalicylic Acid, 4-ASA and 5-aminosalicylic Acid, 5-ASA), as well as on the thermal behaviour of 1:1 molar ratio physical and kneaded mixtures of these Acids with each of three different cyclodextrins, β-, (BCD) 2-hydroxypropyl-β-, (HPBCD) and γ-cyclodextrin (GCD). The thermal behaviour of the binary (1:1 stoichiometry) mixtures was modelled using stepwise multiple regression (SMR). Two models for the prediction of the percentage mass loss and enthalpy of dehydration of the physical mixtures were established with correlation coefficients ( r ) of 0.79 and 0.92, respectively. Decreased correlation in the thermal behaviour of kneaded mixtures indicated significant interaction and possible formation of inclusion complexes.
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Thermal studies on the sodium salts of aminosalicylic Acids
Journal of Thermal Analysis and Calorimetry, 2003Co-Authors: M. K. Rotich, M. E. Brown, B. D. GlassAbstract:The effect on the stability of the isomers of aminosalicylic Acid of formation of their sodium salts has been studied by use of differential scanning calorimetry and thermogravimetry, coupled with evolved gas analysis by Fourier transform infrared spectroscopy. X-ray powder diffraction and infrared spectroscopy provided complementary information. The DSC curves for the sodium salts of all of the isomers showed complex dehydration/decomposition endotherms. From the initial mass losses of the TG curves, the amounts of water per mole of salt were estimated as 0.5, 2.4 and 1.4 moles for the sodium salts of 3-aminosalicylic Acid, 4-Aminosalicylic Acid and 5-aminosalicylic Acid, respectively. TG-FTIR results for the sodium salt of 3-aminosalicylic Acid showed the evolution of carbon dioxide in three stages: below 150°C, between 200 and 300°C and continuous formation up to 500°C. This behaviour differs from that of 3-aminosalicylic Acid itself, which forms CO_2 between 225 and 290°C. For the sodium salt of 4-Aminosalicylic Acid, the formation of carbon dioxide starts from 250°C and is still being formed at about 650°C. 4-Aminosalicylic Acid decarboxylates above 150°C. 5-aminosalicylic Acid and its sodium salt showed no evolution of carbon dioxide below 600°C.
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Thermal studies on mixtures of aminosalicylic Acids with cyclodextrins
Journal of Thermal Analysis and Calorimetry, 2003Co-Authors: M. K. Rotich, Michael E. Brown, Beverley D. GlassAbstract:The thermal behaviour of the aminosalicylic Acids is compared with the behaviour of their 1:1 molar ratio physical and kneaded mixtures with each of three different cyclodextrins (b-, hydroxypropyl-b-, and g-cyclodextrin), using differential scanning calorimetry and thermogravimetry coupled with evolved gas analysis by Fourier transform infrared spectroscopy. X-ray powder diffraction and infrared spectroscopy provided complementary information. Comparison of the effects of the different cyclodextrins on the behaviour of the individual aminosalicylic Acid isomers shows that hydroxypropyl-b-cyclodextrin has the greatest interaction with 3-aminosalicylic Acid and 5-aminosalicylic Acid, followed by g-cyclodextrin, while b-cyclodextrin generally shows the least interaction. For 4-Aminosalicylic Acid, the effect of g-cyclodextrin seems to be more marked than for 3-aminosalicylic Acid and 5-aminosalicylic Acid.
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Thermal Studies on Some Substituted Aminobenzoic Acids
Journal of Thermal Analysis and Calorimetry, 2001Co-Authors: M. K. Rotich, Beverley D. Glass, Michael E. BrownAbstract:The thermal behaviour of various substituted aminobenzoic Acids(3-aminobenzoic Acid (3-ABA), 4-aminobenzoic Acid (4-ABA), 3-aminosalicylic Acid(3-ASA), 4-Aminosalicylic Acid (4-ASA), and 5-aminosalicylic Acid (5-ASA), as well as the‘parent’ benzoic Acid (BA) and salicylic Acid (SA) as reference substances, and possible decomposition products: 2-aminophenol (2-AP), 3-aminophenol (3-AP) and 4-aminophenol(4-AP) in the solid state has been examined.
M. Teresa Duarte - One of the best experts on this subject based on the ideXlab platform.
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Expanding the Pool of Multicomponent Crystal Forms of the Antibiotic 4-Aminosalicylic Acid: The Influence of Crystallization Conditions
Crystal Growth & Design, 2017Co-Authors: Vânia André, Dario Braga, Fabrizia Grepioni, Oleksii Shemchuk, M. Teresa DuarteAbstract:Finding new multicomponent crystal forms of commercially available pharmaceuticals is important, as they represent a straightforward way to drastically influence the solid-state properties of a drug. The antibiotic 4-Aminosalicylic Acid (ASA) is known to exist in several multicomponent crystal forms, and in this work we expand the world of ASA cocrystals and salts by reporting new crystalline forms comprising diazabicyclo[2.2.2]octane (DABCO), and caffeine. All species were characterized by X-ray single crystal, powder diffraction, and thermal behavior. This study contributes to the rationalization of preferred functional groups for the synthesis of 4-Aminosalicylic Acid new multicomponent crystal forms and highlights the relevance of the reaction conditions in the achievement of those forms.
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Mechanochemistry – A green synthetic methodology leading to metallodrugs, metallopharmaceuticals and bio-inspired metal-organic frameworks
Inorganica Chimica Acta, 2017Co-Authors: Sílvia Quaresma, Vânia André, Auguste Fernandes, M. Teresa DuarteAbstract:Abstract Mechanochemistry an environment-friendly synthetic technique has been successfully used in the search for new metallopharmaceuticals, metallodrugs and bio-inspired metal-organic frameworks. These materials recently became highly promising on the pharmaceutical and medical field due to their ability to function as drug carriers, allowing a controlled drug delivery and release in addition to potential applications in imaging and magnetic resonance imaging for diagnostic and therapy. Here we refer to some of our previous results on Ag and Ni with piracetam and 4-Aminosalicylic Acid complexes as well as on the bismuth salicylates metallodrugs. Our results on bioinspired gabapentin networks are also discussed. Furthermore we disclose herein novel metallopharmaceuticals with flufenamic Acid and a bio-inspired framework with muconic Acid. The synthesis and structural characterization of these materials is described and their thermal and on-shelf stability was assessed, showing that they are stable under the relevant temperature range for pharmaceutical applications.
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Polymorphic Ammonium Salts of the Antibiotic 4-Aminosalicylic Acid
Crystal Growth & Design, 2012Co-Authors: Vânia André, M. Teresa Duarte, Dario Braga, Fabrizia GrepioniAbstract:Reaction of the antibiotic 4-Aminosalicylic Acid with ammonia yields three polymorphic forms of the ammonium 4-aminosalicylate salt [NH4][C6H3NH2OH(COO)]. When the reaction is conducted in solution, the three polymorphs are obtained concomitantly, while liquid-assisted grinding and solid–gas reaction result in the formation of pure Form II. The three polymorphs are characterized by different patterns of hydrogen bonding interactions between the structurally rigid anions and the ammonium cations. Solid products were characterized by single-crystal and powder X-ray diffraction, variable temperature powder diffraction, calorimetric techniques (DSC and TGA), and hot-stage microscopy (HSM).
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Crystal Forms of the Antibiotic 4-Aminosalicylic Acid: Solvates and Molecular Salts with Dioxane, Morpholine, and Piperazine
Crystal Growth & Design, 2009Co-Authors: Vânia André, Dario Braga, Fabrizia Grepioni, M. Teresa DuarteAbstract:Reaction of the antibiotic 4-Aminosalicylic Acid with 6-membered ring compounds, such as dioxane, morpholine, and piperazine, yielded a solvate and three molecular salts. The new crystal forms were obtained using different crystallization techniques, such as grinding/kneading and solution techniques; interestingly, reaction with piperazine yields products with different stoichiometry, depending on the preparation conditions, i.e. solid-state or solution methods. All solid products were characterized by single-crystal X-ray diffraction; thermal stability was evaluated by variable temperature X-ray powder diffraction (VT-XRPD), calorimetric techniques (DSC and TGA), and hot-stage microscopy (HSM). Supramolecular interactions are discussed and compared with those in other similar crystal forms.
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Drug-containing coordination and hydrogen bonding networks obtained mechanochemically
CrystEngComm, 2009Co-Authors: Dario Braga, Vânia André, Fabrizia Grepioni, M. Teresa DuarteAbstract:In this communication we describe the solid-state preparation and structural characterization of the coordination and hydrogen bonding networks formed by the antibiotic 4-Aminosalicylic Acid and the nootropic drug piracetam with silver and nickel cations, respectively; the silver complex formed via solid-state reaction is anhydrous, while from solution its hydrated phase is obtained.
P. D. Patel - One of the best experts on this subject based on the ideXlab platform.
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Metal Complexation Studies, Characterization and Biological Activities of 1-(4-Carboxy-3-Hydroxy-N- Sec.Butyl Phenyl Amino Methyl) Benzotriazole
Asian Journal of Research in Chemistry, 2017Co-Authors: P. D. PatelAbstract:Aminomethylation of benzotriazole was carried out by treating benzotriazole with formaldehyde and N-sec.butyl 4-Aminosalicylic Acid. The resultant compound was designated as 1-(4-caroxy-3-hydroxy-N-sec.butyl phenyl amino methyl) benzotriazole (CSPB). The transition metal complexes of Cu 2+ , Co 2+ , Ni 2+ , Mn 2+ and Zn 2+ of CSPB have been prepared and characterized by elemental analysis, spectral studies, magnetic moment, molar conductivity and antimicrobial activity.
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Synthesis, Characterization and Biological Activities of 1-(4-Carboxy-3-Hydroxy-N- N-Butyl Phenyl Amino Methyl) Benzotriazole
International journal of scientific research, 2016Co-Authors: P. D. PatelAbstract:Aminomethylation of benzotriazole was carried out by treating benzotriazole with formaldehyde and N-n-butyl 4-Aminosalicylic Acid. The resultant compound was designated as 1-(4-caroxy-3-hydroxy-N-n-butyl phenyl amino methyl) benzotriazole (CBPB). The transition metal complexes of Cu 2+ , Co 2+ , Ni 2+ , Mn 2+ and Zn 2+ of CBPB have been prepared and characterized by elemental analysis, spectral studies, magnetic moment, molar conductivity and antimicrobial activity. Summary: The metal complexes of derivatives of benzotriazole were synthesized and characterized with various analytical techniques. The biological activities of those complexes were carried out and reported here.
Arun Singh - One of the best experts on this subject based on the ideXlab platform.
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SYNTHESIS, CHARACTERIZATION AND CHELATING PROPERTIES OF BENZIMIDAZOLE-SALICYLIC Acid COMBINED MOLECULE
Journal of Chemistry, 2020Co-Authors: Kamlesh V. Patel, Arun SinghAbstract:Aminomethylation (i.e. Mannich reaction) of benzimidazole was carried out by treating benzimidalzole with formaldehyde and 4-Aminosalicylic Acid. The resultant compound was designated as 1-(4-carboxy-3-hydroxyphenyl aminomethyl) benzimidazole (BI-SA). The transition metal complexes of Cu2
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Metal Complexation Studies of 1-(4-Carboxy-3-hydroxy-N-methyl phenyl- amino methyl) 2-methyl perimidine
Journal of Chemistry, 2020Co-Authors: Umang N. Patel, Arun SinghAbstract:Aminomethylation of 2-methyl perimidine was carried out by treating 2-methyl perimidine with formaldehyde and 4-Aminosalicylic Acid. The resultant compound was designed as 1-(4-caroxy-3-hydroxy-N-methyl phenylamino methyl)2-methyl perimidine. The transition metal complexes of Cu2
Abdul W. Basit - One of the best experts on this subject based on the ideXlab platform.
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Stereolithographic (SLA) 3D printing of oral modified-release dosage forms
International Journal of Pharmaceutics, 2016Co-Authors: Jie Wang, Alvaro Goyanes, Simon Gaisford, Abdul W. BasitAbstract:The aim of this work was to evaluate the suitability of stereolithography (SLA) to fabricate drug-loaded tablets with modified-release characteristics. The SLA printer creates solid objects by using a laser beam to photopolymerise monomers. In this work polyethylene glycol diacrylate (PEGDA) was used as a monomer and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide was used as a photo-initiator. 4-Aminosalicylic Acid (4-ASA) and paracetamol (acetaminophen) were selected as model drugs. Tablets were successfully printed and formulations with different properties were fabricated by adding polyethylene glycol 300 (PEG 300) to the printing solution. The loading of paracetamol and 4-ASA in the printed tablets was 5.69% and 5.40% respectively. In a realistic dynamic dissolution simulation of the gastrointestinal tract, drug release from the tablets was dependent on the composition of the formulations, but independent of dissolution pH. In conclusion SLA 3DP technology allows the manufacture of drug loaded tablets with specific extended-release profiles. In the future this technology could become a manufacturing technology for the elaboration of oral dosage forms, for industrial production or even for personalised dose.
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Colonic delivery of 4-Aminosalicylic Acid using amylose–ethylcellulose-coated hydroxypropylmethylcellulose capsules
Alimentary Pharmacology & Therapeutics, 2002Co-Authors: Catherine Tuleu, Abdul W. Basit, Wendy Waddington, Jm NewtonAbstract:BACKGROUND: 4-Aminosalicylic Acid has the potential for use in the treatment of diseases of the colon. AIM: To assess the feasibility of delivering 4-Aminosalicylic Acid directly to the colon using a hydroxypropylmethylcellulose capsule coated with a mixture of amylose, a polysaccharide metabolized by bacterial enzymes in the colon, and ethylcellulose. METHODS: Seven healthy male volunteers received, on three separate occasions, an uncoated or amylose-ethylcellulose-coated hydroxypropylmethylcellulose capsule containing 4-Aminosalicylic Acid Na (550 mg), or an intravenous injection of 4-Aminosalicylic Acid Na (135 mg). The capsules were radiolabelled with 99mTc to allow their positions in the gastrointestinal tract to be followed using a gamma camera. Plasma and urine samples were collected and assayed for 4-Aminosalicylic Acid and metabolite concentrations. RESULTS: The uncoated capsules broke down within 10 min in the stomach, allowing rapid and complete absorption of the drug. The coated capsules remained intact in the upper gastrointestinal tract, and had a median gastric emptying time of 61 min (interquartile range, 77 min) and a median colon arrival time of 363 min (interquartile range, 185 min). For the coated capsules, only the metabolite was detected in the plasma and/or urine after the capsules had reached the colon. CONCLUSIONS: The specific coating protected the drug until the capsule reached the colon, where 4-Aminosalicylic Acid was slowly released and absorbed. Thus, such a formulation has the potential for use in the treatment of inflammatory bowel disease.
