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The chromatographic behavior of the phenolic drugs niclosamide, hexachlorophene, ibuprofen, pentazocine, ethamivan, bithionol, salicylanilide, caffeic acid, p -coumaric acid, 4-aminosalicylic acid, ferulic acid, and methyldopa has been investigated on RP8F 254s and RP18F 254s TLC plates with methanol-water mixtures in different volume proportions as mobile phases. Linear relationships were obtained between the R M values of the drugs and the volume fraction of methanol in the mobile phase. Retention values, R M , were extrapolated to zero methanol content and the lipophilicity values R MW(RP8) and R MW(RP18) obtained were compared both with measured partition coefficients (log P exp ) and with partition coefficients (AlogPs, IAlogP, AB/logP, COSMOFFrag, miLogP, KOWWIN, and xlogP) calculated using seven different software products. Comparison of the calculated partition coefficients revealed IAlogP, KOWWIN, miLogP, and
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(where is the average of all the theoretical partition coefficients) usually correlate best with chromatographic lipophilicity R MW . The results indicate that chromatographic lipophilicity R MW can be used as a measure of the lipophilicity of the phenolic drugs investigated.
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Our earlier thin-layer chromatographic and polarimetric investigations enabled discovery of the spontaneous in-vitro oscillatory chiral inversion of the profen drugs S -(+)-ibuprofen, S -(+)-naproxen, and S -(+) and R -(−)-flurbiprofen, etc., and then of the α-amino acids l -phenylalanine, l -alanine, and l -tyrosine. In those investigations, thin-layer chromatography convincingly demonstrated its potential as a flexible and handy tool in the service of physical organic chemistry in general and investigation of organic reaction mechanisms in particular. Later — largely on the basis of thin-layer chromatographic evidence — we proposed a reaction-diffusion model that may provide the core of a mechanistic understanding of the spontaneous oscillatory in-vitro chiral inversion of profens and α-amino acids. In this study, we present thin-layer chromatographic and polarimetric evidence of the analogous process of the oscillatory chiral in-vitro inversion of S -(+)-ketoprofen, which is meant to expand an already existing database, mostly originating from our laboratory and documenting the universal nature of this process with α-substituted chiral propionic acid derivatives (in the first instance, profen drugs and α-amino acids).

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The chromatographic separation of fenbufen, ibuprofen, ketoprofen, diclofenac sodium, mefenamic acid, and tiaprofenic acid has been investigated. Normal-phase chromatography on silica gel by the ascending and horizontal techniques, and reversed-phase chromatography on octadecyl-bonded silica gel (RP-18) in horizontal chambers, were performed with suitable mobile phases. The substances were identified by UV illumination at λ = 254 nm and by use of dyeing reagents. Reversed phase chromatography with phosphate buffer, pH 5.73–10% CTMA-Br in methanol, 3.5 + 6.5 ( v/v ), as mobile phase enabled better separation of the six drugs than normal-phase mode. A simple videodensitometric TLC method on silica gel RP-18 was developed and validated for quantitative determination of fenbufen in tablets. The limits of detection and quantification were determined by videodensitometry at λ = 254 nm. A calibration plot was constructed in the range 2.0–12.0 μg/5-μL spot and was linear with a good correlation coefficient (0.9926). RSD for quantitation of fenbufen were from 2.44 to 3.10%. The method was applied satisfactorily to pharmaceutical preparations.

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Summary

Transfer of four rapid thin-layer chromatography (TLC) screening methods used to detect substandard and counterfeit pharmaceutical products to quantitative high-performance TLC (HPTLC)-densitometry methods is demonstrated. These methods for acetaminophen, acetylsalicylic acid, ibuprofen, and chlorpheniramine maleate are contained in a Compendium of methods developed by Kenyon and Layloff for use in countries with limited resources. The new quantitative methods use Merck HPTLC silica gel 60 F254 glass plates, automated standard and sample application, and automated densitometry for detection, identification, and quantification. Standard and sample solution preparation and application procedures for obtaining calibration curves and bracketed samples are described. The HPTLC plates give better efficiency, selectivity, and resolution than TLC, and the new methods overcome the deficiencies in technology related to manual application and visual zone comparison that do not allow the Compendium TLC procedures to support regulatory compliance actions. These transferred methods can be fully validated according to International Conference on Harmonization (ICH) guidelines or by interlaboratory studies if their applications require. The approach described can be used to transfer the remaining Compendium methods as well as the GPHF [Global (formerly German) Pharma Health Fund E.V.] Minilab kit TLC screening methods.

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Four ecotypes of pomegranate fruits growing in the Salento area were characterized for their content in terms of total phenols, sugars, organic acids, anthocyanins, antioxidant and anti-inflammatory activity. The results showed that in the fruit juice the amount of phenols ranged between 0.8–1.7 g l−1; the content in terms of simple sugars was about 140 g l−1, while the amount of citric and malic acids ranged between 1.4–13.3 and 0.8–7.7 g l−1, respectively. Seven anthocyanin pigments were found; these were analysed quantitatively and qualitatively by HPLC-DAD-MS and identified as delphinidin 3,5-diglucoside, cyanidin 3,5-diglucoside, pelargonidin 3,5-diglucoside, delphinidin 3-glucoside, cyanidin 3-glucoside, pelargonidin 3-glucoside and cyanidin 3-arabinoside. The antioxidant activity, determined as DPPH scavenger and TEAC, ranged between 17.2 and 39.1% and between 9 and 19 μmol Trolox per ml of juice, respectively. All the pomegranate juices showed an anti-inflammatory activity (measured by COX inhibitory assay) which was compared with two commercial anti-inflammatory drugs (Ibuprofen and Nimesulide).

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Thin-layer chromatography has been used to investigate possible chemical interactions of vitamins A and D with frequently used therapeutics (estrogens and progestins, corticosteroids, HMG CoA reductase inhibitors, vitamins, and nonsteroidal anti-inflammatory drugs). We also compared our results with biochemical interactions found in the literature. Concentrations of vitamins and drugs applied to the plate were adjusted to mimic the doses usually prescribed in therapy. TLC was performed on 10 cm × 20 cm TLC plates precoated with silica gel 60 F 254 . The first step was to determine R F values for each vitamin and drug using three different mobile phases — cyclohexane-ether, 50 + 50 ( v/v ), cyclohexane—ether, 85 + 15 ( v/v ), and ethyl acetate. Solutions of vitamins A and D were applied to the plates as 8 mm bands and the investigated drugs were applied as spots. Chromatography was performed in ascending mode. After calculation of R F values we used a combination of stationary and mobile phase for which overlapping of the vitamin band and drug spot occurred during chromatogram development. The strength of interaction was measured as a surface below or above the distorted part of the sample band, visible under short wavelength UV light ( λ = 254 nm) or after exposing the plates to iodine vapor. The chromatograms were documented by use of a Camag Reprostar 3 System.We established the occurrence of chemical interactions between vitamin A and estradiol propionate, tocopherol acetate, ibuprofen, and ketoprofen, and between vitamin D and hydrocortisone, medrox-yprogesterone acetate, norethisterone acetate, aspirin, ketoprofen, and acetaminophen. A clear relationship between chemical and biochemical interactions could not be established.

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T Jha 1996 Development of indomethacin and ibuprofen loaded polymethylmethacrylate microparticles Pharm Sci 2 209 213

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Orvosi Hetilap
Authors: Viktor József Horváth, Gy. Ádám Tabák, Gergely Szabó, Zsuzsanna Putz, Csaba Géza Koós, and Péter Lakatos

placebo-controlled, ex vivo, serial placebo-controlled serial crossover study. Eur. J. Clin. Pharmacol., 2013, 69 (3), 365–371. Curtis, J. P., Wang, Y., Portnay, E. L., et al.: Aspirin, ibuprofen, and mortality after

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studies. PLoS Med. 2011; 8: e1001098. 16 European Medicines Agency. Updated advice on use of high-dose ibuprofen. EMA/325007/2015. Available from: https://www.ema.europa.eu/en/documents/press-release/updated-advice-use-high-dose-ibuprofen

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We have previously described unexpected two-dimensionality in the thin-layer chromatographic separation of pairs of enantiomers of chiral 2-arylpropionic acids (2-APA) by one-dimensional development on a chiral stationary phase prepared by impregnating silica gel layers with l -arginine. The two-dimensionality of this separation was because in planar chromatography all analytes undergo two-dimensional effective diffusion and thus — theoretically at least — can migrate in two mutually perpendicular directions, i.e. in the direction of the mobile phase flow and in a direction perpendicular to this. Demonstration (and quantification) of this striking behavior was possible by use of densitometric detection. Migration of analytes in a direction perpendicular to that of the mobile-phase certainly is not commonplace in thin-layer chromatography and, as far as we are aware, the example described in our previous paper was the first of its kind reported. It was apparently induced by the chirality of the analytes and the stationary phase.In the work discussed in this paper we demonstrated another example of deviation from the vertical of the migration tracks of the same analytes, optically pure S -(+)-ibuprofen and S -(+)-naproxen, when chromatographed on unmodified commercial precoated silica gel plates. Keeping in mind that (i) such deviations can occur only with a chiral analyte developed in an asymmetric chromatographic system, and that (ii) silicon dioxide (chemically identical with chromatographic silica gel) can crystallize as quartz (i.e. as rock crystal) in two asymmetric — left-handed and right-handed — forms, we assumed the working hypothesis that chromatographic silica gel layers can also seem to have an asymmetric microcrystalline structure responsible for deviation from the vertical of the migration tracks of chiral analytes. To verify our hypothesis we acquired circular dichroism (CD) spectra and UV absorption spectra of samples of the silica gel used for coating commercial TLC plates. The results obtained from these measurements provide convincing evidence of the correctness of our hypothesis and it seems most likely that the commercial silica gel layers are characterized by the crystalline asymmetry of the silicon dioxide particles.

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