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The scientific article focuses on the role of azulene and its derivatives in the therapy of dermatological diseases, presenting the latest laboratory and clinical research as well as prospects for further studies. In a synthetic literature review, various databases such as PubMed, Scopus, Web of Science, and the Database of Polish Scientific Journals were queried to select relevant articles concerning azulene. The conclusions drawn from the thematic analysis of the studies emphasize the multifaceted pharmacological actions of azulene and its derivatives including their anti-inflammatory properties, potential anticancer effects, photoprotective abilities, alleviation of itching, management of atopic dermatitis, and treatment of erectile dysfunction. However, there are certain limitations associated with the application of unmodified azulene on the skin, particularly related to photodecomposition and the generation of reactive oxygen species under UV radiation. These effects, in turn, necessitate further research on the safety of azulene and azulene-derived substances, especially regarding their long-term use and potential application in phototherapy. The authors of this work emphasize the necessity of conducting further preclinical and clinical studies to fully understand the mechanisms of action. Incorporating azulene and its derivatives into the therapy of dermatological disorders may represent an innovative approach, thereby opening new treatment avenues for patients. [ABSTRACT FROM AUTHOR]

A simple and accurate reverse phase HPLC method has been developed and validated for quantification of varenicline in bulk drug and pharmaceutical dosage forms. Herein, an isocratic LC analysis was carried out on a Chromolith Performance RP18e column with methanol-buffer solution pH 3.5 (a buffer solution containing sodium benzoate (0.5 mmol/l) adjusted to pH 3.5 with trifluoroacetic acid (20 mmol/l) (55:45, V/V)) at a flow rate of 1.2 ml/min. The detection wavelength was set at 320 nm. The calibration curve was linear (r = 0.9999) in the studied range of concentration (0.2-10 μg/ml). The selectivity and sensitivity of the elaborated method were satisfactory, and the limits of detection and quantification was less than 20% of the specification level. Moreover, the inter- and intra-day precisions was found to be less than 3% (RSD), while the recovery values expressing inter- and intra-day accuracy was varied from 99.73 to 101.23. The varenicline solution was stable over a period of 3 days on storage under refrigeration. The utility of the developed method was examined by analysing the tablets containing VAR. As a result, the method was found to be selective, sensitive, precise and accurate.

A simple and accurate reverse phase HPLC method has been developed and validated for quantification of varenicline in bulk drug and pharmaceutical dosage forms. Herein, an isocratic LC analysis was carried out on a Chromolith Performance RP18e column with methanol-buffer solution pH 3.5 (a buffer solution containing sodium benzoate (0.5 mmol/l) adjusted to pH 3.5 with trifluoroacetic acid (20 mmol/l) (55:45, V/V)) at a flow rate of 1.2 ml/min. The detection wavelength was set at 320 nm. The calibration curve was linear (r = 0.9999) in the studied range of concentration (0.2-10 μg/ml). The selectivity and sensitivity of the elaborated method were satisfactory, and the limits of detection and quantification was less than 20% of the specification level. Moreover, the inter- and intra-day precisions was found to be less than 3% (RSD), while the recovery values expressing inter- and intra-day accuracy was varied from 99.73 to 101.23. The varenicline solution was stable over a period of 3 days on storage under refrigeration. The utility of the developed method was examined by analysing the tablets containing VAR. As a result, the method was found to be selective, sensitive, precise and accurate. [ABSTRACT FROM AUTHOR]

A simple procedure to perform for the determination of amoxicillin is presented, based on reaction with 1-[(quinolin-6-ylcarbamoyl)oxy]pyrrolidine-2,5-dione (AccQ-Fluor) in borate buffer medium at pH of 7.4. The resulting amoxicillin+AccQ-Fluor derivative was determined by reversed-phase chromatography with combined fluorescence (λex=245 nm/λem=368 nm) and UV detection (λ=245 nm) for control. The calibration graph was linear (r=0.9992 ) over the range 5.0-30 µg/mL. The method was applied to the determination of amoxicillin in pharmaceutical formulations with acceptable precision and accuracy. [ABSTRACT FROM AUTHOR]

A simple and sensitive procedure for the determination of gentamicin is presented, based on reaction with o-phthaldialdehyde (OPA) in combination with N-acetylcysteine (NAC) in a basic medium. The use of N-acetylcysteine instead of liquid mercaptans for the formation of isoindole derivatives is a good solution for avoiding the unpleasant odour of thiol compounds. Determination of the resulting fluorescent derivatives was carried out by reversed-phase chromatography at λex=328 nm and λem=423. Stability of OPA/NAC/gentamicin-conjugate was improved by the addition of hydroxypropyl-β-cyclodextrin. The calibration graph was linear (r = 0.9997) over the range 0.4-12.8 μg mL-1. The precision (RSD%) of the method varied from 1.5 to 8.5. The method was satisfactorily applied to the determination of gentamicin in pharmaceutical preparations with a mean recovery of 100.02% for injections and 88.94% for drops. [ABSTRACT FROM AUTHOR]

A novel hybrid hydroxyapatite (HAP) matrix, covalently coated with rarely applied, hardly degradable keratin and effectively modified by gentamicin immobilized in mixed‐type mode (via interactions of diverse strength), was created. This hybrid showed a remarkably high drug immobilization yield and the most sustainable antibiotic release among all tested composites. It was also able to inhibit bacterial growth, both in surrounding liquid and on matrix surface, much longer (for at least 121 days of experiment) than analogous gelatin‐modified and nonmodified matrices. Gentamicin‐keratin‐coated‐HAP granules were nontoxic to human osteoblasts and enabled their proliferation with a rate similar as noncoated HAP. Presence of keratin on HAP granules seemed to slightly enhance the osteoblast proliferation. The results indicate that newly created HAP hybrid with covalently immobilized keratin and gentamicin—nontoxic and osteoblast‐friendly—is a promising biomaterial of significantly prolonged antibacterial activity. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [ABSTRACT FROM AUTHOR]

The article describes a capillary zone electrophoresis for the simultaneous separation of 14 antiarrhythmic drugs belonging to various classes. The effects of buffer pH, temperature and applied voltage on the migration of the drugs are discussed. The proposed method demonstrated satisfactory precision and accuracy when used for the determination of both drugs in their commercial forms. Detection and quantitation limits are also mentioned.

A method using capillary zone electrophoresis was developed for the simultaneous separation of 14 antiarrhythmic drugs belonging to various classes. The drugs are separated on a fused-silica capillary, 90 cm x 75 microm (72 cm effective length), with phosphate and acetate buffers as background electrolytes and UV detection at 217 nm. The effects of buffer pH, temperature, and applied voltage on the migration of the drugs were studied. The pH was found to be the most significant factor determining effective separation. The antiarrhythmic compounds are completely separated within a relatively short time (< 7 min) by using 70 mM phosphate buffer at pH 7.91, an applied voltage of 28 kV, and a temperature of 32 degrees C. Mexiletine (MEX) and flecainide (FLE) were quantified under conditions of the optimum separation. The calibration graphs were constructed over the concentration range of 4.0-14.0 microg/mL for both drugs with good correlation (r > or = 0.9999). Detection and quantitation limits were found to be 0.5 and 1.5 microg/mL for FLE and 0.7 and 2.1 microg/mL for MEX, respectively. The proposed method was used for the determination of both drugs in their commercial forms with satisfactory precision (relative standard deviations of 0.36-1.21% for FLE and 0.78-1.66% for MEX) and accuracy (relative standard errors of 0.13-1.17% for FLE and 0.35-1.18% for MEX).

Nifedipine (Nif) is widely used in treating cardiovascular disorders (especially hypertension) and for inhibiting preterm labor. A fully validated selective high-performance liquid chromatographic method with diode array detection, using solid-phase extraction, was developed for the determination of Nif in human serum. To assess specificity, Nif and its degradation products were separated on a Purospher RP-18 (5 microm, 125 x 4 mm) column plus a LiChrospher 100 RP-18 (5 microm, 4 x 4 mm) precolumn with a mobile phase of methanol-10 mM aqueous trifluoroacetic acid, pH 7.3 (57 + 43, v/v); chromatographic separation was followed by UV detection at 238 nm. For toxicological analysis, Nif in the presence of other calcium-channel antagonist drugs was identified under optimum chromatographic conditions. The calibration graph was constructed over the concentration range of 12.5-400 ng/mL in serum with good correlation (r = 0.9956). This method was not subject to interference by other plasma components and was successfully applied to the assay of Nif in spiked human serum and in serum of women in preterm labor after sublingual administration of 30 mg Nif per day divided into 3 equal doses. The mean recovery based on the ratio of the slopes of serum and mobile phase standard curves was 96.5%. The detection and quantification limits of the drug in spiked human serum were found to be 6 and 17.5 ng/mL, respectively. Validation of the method demonstrated good intraday and interday precision, which ranged from 2.18 to 6.67% and from 6.52 to 11.93%, respectively.

A first order derivative UV-spectrophotometric method for the determination of diltiazem hydrochloride and mexiletine hydrochloride has been developed and validated. In the assay, the first- and second-order measurements with the use of the "peak-zero" and "peak-peak" techniques were applied. The linear correlation (r < 0.9999) between the amplitude of the peak and the concentration of the examined drugs in the range of 3.0-8.0 microg mL(-1) for diltiazem and 50-100 microg mL(-1) for mexiletine was obtained. The proposed method was successfully applied for accurate (mean recovery about 100%), precise (RSD about 1%) and selective determination of the studied drug in the pure and dosage forms.

Polyvinyl chloride matrix membrane ion-selective electrodes for the determination of methiaden hydrochloride based on the ion-pair of methiaden cation with tetraphenylborate anion were prepared using bis(2-ethylhexyl)sebacate, (electrode A), 2-nitrophenyl octyl ether (electrode B). 2-nitrophenyl dodecyl ether (electrode C) and 1-isopropyl-4-nitrobenzene (electrode D) as the membrane solvents. The electrodes exhibit near-Nernstian response in different concentration ranges, depending on the used membrane solvents. The basic analytical parameters of these electrodes were evaluated. The potentiometric titration method was used to determine methiaden hydrochloride with good precision and accuracy.