Biomedical subjects

D Bonazzi

Publications and source records attributed to D Bonazzi.

At least 19 recordsLinked to original sources

PubMed1998

Determination of imidazole antimycotics in creams by supercritical fluid extraction and derivative UV spectroscopy.

A supercritical fluid extraction (SFE) method was developed for the isolation of imidazole antimycotic drugs (miconazole, econazole, clotrimazole and bifonazole) from cream preparations. The SFE process involved static (1 min) and dynamic (4 min) extraction steps using pure and 10% methanol modified carbon dioxide. The SFE step was then followed by derivative UV spectrophotometric analysis. The method proved to be suitable for quality control assays of the examined antimycotics in commercial cream formulations.

Antifungal Agents↗

PubMed1997

Analysis of ACE inhibitors in pharmaceutical dosage forms by derivative UV spectroscopy and liquid chromatography (HPLC).

Derivative UV spectroscopy and high performance liquid chromatography (HPLC) were applied to the determination of angiotensin-converting enzyme (ACE) inhibitors in their pharmaceutical dosage forms. For spectrophotometric determinations, the more appropriate derivative order was selected for each drug: ramipril (third-order), benazepril (second-order), enalapril maleate (second-order), lisinopril (first- and second-order) and quinapril (first-order). Reverse phase HPLC procedures (ODS column) were developed able to provide a single, symmetric peak for each drug; mixtures A-B, where A is 20 mM sodium heptansulphonate (pH 2.5) and B is acetonitrile-THF (95:5 v/v), proved to be suitable mobile phases to obtain selective separations of the cited ACE inhibitors. At ambient temperature, a low pH value (2.5) was found to be critical to avoid peak splitting and band broadening.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1997

HPLC-fluorescence determination of chlorocresol and chloroxylenol in pharmaceuticals.

The use of 2-chloro-6,7-dimethoxy-3-quinolinecarboxaldehyde as a fluorogenic labelling reagent in pre-column derivatization for the HPLC separation of chlorophenols has been investigated. The compound reacts (50 min at 110 degrees C) with 2- and 4-chlorophenols to give fluorescent ethers that can be separated by reversed-phase HPLC and detected at lambda exc = 360 nm, lambda em = 500 nm. The experimental conditions for derivatization and chromatographic separation are discussed. Applications for the determination of chlorocresol (4-chloro-3-cresol) and chloroxylenol (4-chloro-3,5-xylenol) in pharmaceutical formulations (creams, ointments) are described.

Calibration↗

PubMed1996

A comparative evaluation of three detectors in the HPLC analysis of sodium fusidate.

A reversed phase liquid chromatographic (HPLC) method is proposed for the determination of sodium fusidate, a steroid antibiotic, in a commercial ointment using three different detectors: a) fluorescence detector, after a preliminary derivatization with 2-bromoacetyl-6-methoxynaphthalene (Br-AMN), b) UV detection and c) evaporative light scattering detector (ELSD). Fluorescent derivatization was applied directly to the diluted sample, without any purification, whilst UV and ELSD detectors involved a preliminary liquid-liquid extraction procedure to obtain accurate analysis data.

Anti-Bacterial Agents↗

PubMed1995

HPLC analysis of liquorice triterpenoids--applications to the quality control of pharmaceuticals.

A reversed-phase HPLC method is proposed for the separation of five liquorice triterpenoids, 18 beta glycyrrhetic acid (beta GA), 18 alpha glycyrrhetic acid (alpha GA), 24-hydroxy-18 beta-glycyrrhetic acid (24-OH-beta GA), alpha and beta liquiritic acid (alpha and beta LA), with potentially different biological activities. The method has been developed by studying the influence of the type of stationary phase, pH, amine modifier and organic modifier on the resolution of the five compounds. The optimized chromatographic conditions were then successfully applied to the analysis of alpha- and beta-GA in pharmaceutical preparations (toothpaste and creams) on a reversed-phase Phenomenex Ultracarb 5 ODS (30) column (150 x 4.6 mm i.d.), using as the mobile phase acetonitrile-THF-0.010 M dioctylammonium phosphate buffer (pH 6.5) (25:20:55, v/v/v) at a flow-rate of 0.8 ml min-1. SPE methods with diolic and C18 sorbents were developed to isolate and concentrate the analytes and to enhance the sensitivity for the determination of alpha-GA as an impurity in the beta-GA preparations. The method was found to be reliable and suitable for the quality control of beta-GA preparations.

Anti-Infective Agents↗

PubMed1995

Analysis of pharmaceutical creams: a useful approach based on solid-phase extraction (SPE) and UV spectrophotometry.

Solid-phase extraction (SPE) using C-18, diol and ion-exchange sorbents followed by UV spectrophotometric (conventional and derivative mode) assay was applied to the analysis of basic, acidic and neutral drugs commercially available in creams. A representative set of drugs (promethazine, chlorhexidine, benzydamine, ketoprofen, ibuprofen, fentiazac, piroxicam, fluorouracil, crotamiton and hydrocortisone acetate) was selected, and for each drug the appropriate SPE conditions (adsorption, washing and elution) were investigated to obtain a practical and reliable sample clean-up. It was shown that the developed SPE procedures were capable of removing interfering cream components (excipients including preservatives) allowing accurate spectrophotometric analyses to be performed. In some applications, derivative spectrophotometry was advantageous over the conventional absorption mode with respect to higher selectivity and versatility.

Pharmaceutical Preparations↗

PubMed1994

HPLC determination of glutathione and L-cysteine in pharmaceuticals after derivatization with ethacrynic acid.

Ethacrynic acid and its methyl ester are proposed as useful pre-chromatographic derivatization reagents for the HPLC analysis (UV detection) of reduced glutathione (GSH) and L-cysteine. The optimum experimental conditions for the thiol derivatization, the removal of the excess reagent by liquid-liquid or solid-phase extraction and the reversed-phase chromatographic separations of the thiol adducts were investigated. The method was applied to the HPLC determination of GSH and L-cysteine in commercial formulations and proved to be suitable for the HPLC determination of oxidized glutathione (GSSG) after reduction to GSH using dithiothreitol (DTT).

Calibration↗

PubMed1994

Analysis of Trimethoprim--sulfonamide drug combinations in dosage forms by UV spectroscopy and liquid chromatography (HPLC).

Derivative and difference spectrophotometric methods are described for the direct simultaneous analysis of combinations of Trimethoprim with sulfonamide drugs (sulfadiazine, sulfamethoxazole, sulfamethoxypyridazine) in commercial dosage forms. The more advantageous approach (derivative and difference mode) is suggested for each binary mixture. The assay results are compared with those obtained by a new chromatographic (HPLC) method, involving a C-18 column and a mobile phase (pH 6.5) containing 1.8 diaminooctane as amine modifier and sodium heptansulfonate as ion pairing agent.

Capsules↗

PubMed1991

Analysis of flucytosine dosage forms by derivative UV spectroscopy and liquid chromatography.

A simple second-order derivative spectrophotometric method was developed for the selective determination of flucytosine (an antimycotic drug) in the presence of 5-fluorouracil (a cytotoxic agent), its synthetic precursor and degradation product. Traces of 5-fluorouracil in flucytosine were also determined by derivative UV spectroscopy; flucytosine was removed by a selective solid-phase extraction (SPE) procedure using a strong cation-exchange sorbent. The spectrophotometric methods were applied successfully to the quality control of commercial dosage forms of flucytosine and the results were compared with those obtained by a HPLC procedure (cyano column) developed as a reference method.

Chromatography, High Pressure Liquid↗

PubMed1990

Determination of minoxidil in pharmaceutical formulations by difference spectrophotometry and liquid chromatography (HPLC).

A simple difference spectrophotometric method has been developed for the selective and rapid determination of minoxidil in pharmaceutical formulations. The method is based on the characteristic modifications of the minoxidil UV spectrum induced by pH changes; a difference spectrum can be obtained and the absorbance A282.8 or the absorbance difference delta A = (A282.8-A259.2) can be used for the selective drug quantitation. As an alternative, a derivative second-order spectrophotometric method was also developed. The spectrophotometric methods were applied to the quality control of commercial minoxidil dosage forms and the results were comparable with those obtained by a reference HPLC procedure.

Chromatography, High Pressure Liquid↗

PubMed1989

Determination of ethacrynic acid in pharmaceutical formulations by difference ultraviolet spectrophotometry after derivatisation with N-acetylcysteine.

A selective difference spectrophotometric procedure is described for the assay of ethacrynic acid (a diuretic drug) in pharmaceutical dosage forms. The method is based on the reaction of the drug with N-acetylcysteine at pH 7.4 and ambient temperature, affording thiol adducts having different spectral properties, and involves the measurement of the absorbance of the reaction mixture relative to an equimolar solution of unreacted ethacrynic acid. The absorbance at 270 nm (A(270)) and the absorbance difference, delta A=A(270-A(244), obtained from the difference spectrum, were found to be linearly correlated with the drug concentration. The proposed spectrophotometric procedure was applied successfully to the determination of ethacrynic acid in pharmaceutical formulations using a reversed-phase high-performance liquid chromatographic procedure as a reference method.

Acetylcysteine↗

PubMed1988

[Nonsteroidal anti-inflammatory agents. 19. Synthesis and activity of stereomeric phenylacetic homologues].

The authors synthesized the title compounds as analogues of previously prepared potential antiphlogistic agents. Starting from appropriate carbonyl compound and alpha-metallated phenylacetic acid the diastereomeric racemate pairs were obtained; they were separated, attributed to erythro/threo-configuration by NMR and finally resolved. The potassium salts of the enantiomers were tested for analgesic and antiinflammatory activity, as well as for acute toxicity. Their action in the carrageenan test has been found to be stereoselective, but relatively poor or of briefly lastening.

Analgesics↗

PubMed1985