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Biomedical subjects

P Solich

Publications and source records attributed to P Solich.

At least 19 recordsLinked to original sources
PubMed2007

Fluorescence optosensing implemented with sequential injection analysis: a novel strategy for the determination of labetalol.

The coupling of sequential injection analysis and optosensing has been developed for the first time. It has been applied to the determination of labetalol in both pharmaceuticals and urine samples, with the analytical signal (native fluorescence) being monitored directly on sensing zone microbeads. The solid support used was the nonionic silica gel C18, using 20% methanol-water (v:v) as a carrier. By using a 1.5-ml sample volume, we achieved a detection limit of 3.3 ng ml-1. This sensitivity allowed the determination of the compound in urine samples. A recovery study was carried out at the labetalol levels usually found in urine after pharmaceuticals administration, and recovery percentages close to 100% were obtained. The relative standard deviation was 3.4% for 100 ng ml-1 labetalol. No pretreatment was needed for urine samples, only an appropriate dilution, therefore minimizing the time required per sample analysis. In addition, the determination of the analyte was also carried out in one pharmaceutical, with a satisfactory result being obtained.

Flow Injection Analysis↗
PubMed2006

HPLC determination of chlorhexidine gluconate and p-chloroaniline in topical ointment.

A novel fast isocratic reversed-phase HPLC method for simultaneous determination of chlorhexidine and its degradation product p-chloroaniline was developed. Zorbax SB Phenyl column (75 mm x 4.6 mm, 3.5 microm) was used for the separation. Mobile phase composed of acetonitrile and buffer solution of 0.08 M sodium phosphate monobasic containing 5 ml of triethylamine (0.5%) and adjust with 85% phosphoric acid to pH 3.0 in ratio 35:65 (v/v) pumped isocratically at flow rate 0.6 ml min(-1) was used. UV detection was performed at 239 nm, the total analysis time was about 10 min. The method is suitable for practical routine analysis of topical ointment in the quality control laboratory.

Acetonitriles↗
PubMed2006

Estimation of ochratoxin A in portuguese population: new data on the occurrence in human urine by high performance liquid chromatography with fluorescence detection.

With increasing knowledge of the persistence of OTA in the food chain, exposure to this mycotoxin is a potential human health hazard to humans, and evaluating its presence in populations has become highly important. A sensitive and accurate analytical method for the determination of ochratoxin A in urine was validated, since is less invasive than blood monitoring. It involves extraction with 5% NaHCO3, immunoaffinity column (IAC) for clean-up and high performance liquid chromatography with fluorescence detection (HPLC-FD). The limit of quantification was 0.02 ng/mL of urine (1.3 ng/mL of the extract injected) and recovery of ochratoxin A from urine samples spiked at the three fortification levels, were higher than 90% with RSD lower than 9%. The identification of OTA was confirmed by methyl ester derivatization and then HPLC analysis. Based in ours first results we can assume that OTA conjugation with glucuronic acid in human urine occurs. In the present study, we follow up OTA levels in 60 urine samples of inhabitants from Coimbra city, Portugal, in order to evaluate population contamination, and the presence of OTA was found in 42 samples, at concentrations above the LOQ, ranged between 0.021 and 0.105 ng/mL.

Adult↗
PubMed2006

HPLC determination of calcium pantothenate and two preservatives in topical cream.

A RP-HPLC method for simultaneous determination of calcium pantothenate and two preservatives methylparaben and propylparaben present in topical cream was developed. Different analytical columns with various stationary phases were tested. During method development, Supelco Discovery C18 column (125 mmx4.0 mm, 5 microm) and Zorbax SB-CN column (150 mmx4.6 mm, 5 microm) were tested. Both were not convenient for analytical separation because of the co-elution of calcium pantothenate with dead volume, and problems with the peak-shape of all components. Good separation was achieved using Zorbax TSM (250 mmx4.6 mm, 5 microm) and Hypersil ODS column (250 mmx4.6 mm, 5 microm), the latter was finally used for the analysis. The analysis time was 12 min, at flow rate 0.7 ml min-1. Chromatography was performed using binary mobile phase composed of methanol and phosphoric acid, pH 2.5, 65:35 (v/v). UV detection was accomplished at 214 nm. The method was validated according to ICH guideline recommendations. The method is suitable for practical routine analysis of commercially produced topical pharmaceutical preparations.

Administration, Topical↗
PubMed2005

Validation of an analytical methodology for determination of oxytetracycline and tetracycline residues in honey by HPLC with fluorescence detection.

An analytical method for the determination of OTC and TC residues in honey was developed. Sample treatment involves an extraction in EDTA-McIlvaine buffer, followed by a solid-phase cleanup step. With regard to the cleanup procedure, different SPE cartridges were evaluated and the results presented. The method was validated according to the guidelines laid down by the 2002/657/EC European Decision parameters: decision limit (Cc alpha) and detection capability (CC beta) were 20 and 21 microg/Kg and 49 and 50 microg/Kg for OTC and TC, respectively, and recoveries of OTC and TC from spiked samples, at three fortification levels, were higher than 87% for both compounds. The analytical method was applied to 57 honey samples.

Chromatography, High Pressure Liquid↗
PubMed2005

Automated system for release studies of salicylic acid based on a SIA method.

The aim of this work was to describe a fully automated system for the in vitro release testing of semisolid dosage forms based on SIA technique. The system was tested for monitoring release profiles of different ointments containing 3% of salicylic acid (Belosalic, Diprosalic, Triamcinolone S). The native fluorescence of salicylic acid was used for fluorimetric detection. Phosphate buffer pH 7.4 was the receptor medium; samples were taken at 10 min intervals during 6 h of the release test; and each test was followed by calibration with five standard solutions. The linear calibration range was 0.05-10 microg ml(-1) (r = 0.9996, six standards); the maximal SIA sample throughput for this system was 120 h(-1), sample volume being 50 microl and flow rate 50 microl s(-1). The detection limit for salicylic acid was 0.01 microg ml(-1).

Chemistry, Pharmaceutical↗
PubMed2005

Development and validation of HPLC method for determination of indomethacin and its two degradation products in topical gel.

Indomethacin forms by decomposition two degradation products: 4-chlorobenzoic acid and 5-methoxy-2-methylindoleacetic acid. They have to be monitored together with an active substance both during manufacturing process and storage of pharmaceuticals. European Pharmacopoeia (Ph. Eur. 4) describes titration method for determination of indomethacin, which is not very convenient in this case for practical use. Therefore, high performance liquid chromatography is the method-of-choice enabling determination of active substance and its degradation products during one-step procedure simultaneously and automatically. We have developed a fast, simple and fully automated analytical method for determination of indomethacin and its two impurities in pharmaceutical preparation using HPLC with UV detection. Various stationary phases were tested, especially new types of Zorbax columns made by Agilent. While the conventional C18 stationary phases were not convenient enough to achieve quick and reliable separation, Zorbax-Phenyl analytical column (75 mm x 4.6 mm, 3.5 microm) enables separation of indomethacin and its two degradation products during 7.5 min. Chromatography was performed using isocratic elution with binary mobile phase composed of acetonitrile and 0.2% phosphoric acid (50:50, v/v) at flow rate 0.6 ml/min. Even faster separation of standards was obtained with analytical column Zorbax SB-CN (150 mm x 4.6 mm, 5 microm). The separation was effected with mobile phase of the same composition, only the flow rate was increased to 1.2 ml/min. The analytical run was shortened to 5 min. Both methods use detection wavelength 237 nm and both can use either ketoprofen or flurbiprofen as internal standard for quantitation. The first method was finally chosen for validation because of the occurrence of placebo interferences in the case of using Zorbax SB-CN. System suitability parameters and validation parameters including method precision, accuracy, linearity, selectivity and robustness were set up. Afterwards, the method was successfully applied for the practical determination of indomethacin and its degradation products in a topical gel and for compound degradation control during stability studies.

Administration, Topical↗
PubMed2005

[Effect of manganese (II), cobalt (II), and nickel (II) ions on the growth and production of coumarins in the suspension culture of Angelica archangelica L].

The plant cell reacts to an increased concentration of metals in the environment by various mechanisms. They include an increase in the formation of heat-shock proteins, metallothioneins, phytochelatins, amino acids (cysteine, histidine), organic acids (citric, malic), or secondary metabolites. The latter mechanism is being investigated for its possible use in explant cultures for the stimulation of secondary metabolism, which is the source of substances of pharmaceutical importance. The study tested manganese (II) (0, 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, and 50 mM in the medium), cobalt (II), and nickel (II) ions (0, 0.1, 0.5, 1, 5, 10, 50, 100, 200, and 500 microM in the medium) as potential elicitors of coumarin production. At the same time, toxicity of these metals for the culture was examined by evaluating their effect on growth (characterized by fresh and dry weight of biomass at the end of a two-week cultivation). Cultures were cultivated in the dark and in the light. It has been found that the growth of cultures is not influenced by manganese in concentrations ranging from 0 to 2 mM, then it slightly decreases, at a concentration of 50 mM it is lower by 20 % when cultivated in the dark and by 30 % when cultivated in the light in comparison with the control. Cobalt in concentrations of 0 to 50 microM does not significantly influence the growth of the culture, higher concentrations decrease the biomass yields, more markedly when cultivated in the light (at 500 microM Co by 60 %, in the dark only by 30 % in comparison with the controls). Nickel in concentrations of 0.1 to 200 microM does not influence growth, and in a concentration of 500 microM decreases it by approximately 30 % in comparison with the control both in the light and dark. Production of coumarins was not stimulated by any metal in comparison with the control cultures, only the removal of manganese from the medium in the culture cultivated in the dark increased production by about 15 % versus the control.

Angelica archangelica↗
PubMed2004

Simultaneous HPLC determination of ketoprofen and its degradation products in the presence of preservatives in pharmaceuticals.

A novel and quick high-performance liquid chromatography (HPLC) method with UV spectrophotometric detection was developed and validated for the determination of five compounds in topical gel. The described method is suitable for simultaneous determination of active component ketoprofen, two preservatives methylparaben and propylparaben and two degradation products of ketoprofen--3-acetylbenzophenone and 2-(3-carboxyphenyl) propionic acid--in a topical cream after long-term stability tests using ethylparaben as an internal standard. The chromatographic separation was performed on a 5microm Supelco Discovery C18 column (125mm x 4mm i.d., Sigma-Aldrich); the optimal mobile phase for separation of ketoprofen, methylparaben, propylparaben, degradation products 3-acetylbenzophenone and 2-(3-carboxyphenyl) propionic acid and ethylparaben as internal standard consists of a mixture of acetonitril, water and phosphate buffer pH 3.5 (40:58:2, v/v/v). At a flow rate of 1.0ml min(-1) and detection at 233nm, the total time of analysis was less than 10min. The method was applied for routine analysis (batch analysis and stability tests) of these compounds in topical pharmaceutical product.

Chromatography, High Pressure Liquid↗
PubMed2004

Sensitive fluorimetric method based on sequential injection analysis technique used for dissolution studies and quality control of prazosin hydrochloride in tablets.

This report introduces a fully automated flow system for drug-dissolution studies based on the coupling of the sequential injection analysis (SIA) technique with a conventional dissolution apparatus. The methodology described was used for monitoring of dissolution profiles of prazosin hydrochloride (PRH) in pharmaceutical formulation. The very sensitive fluorimetric detection of PRH was performed at lambda(ex)=244 nm (lambda(em)>or=389 nm). Under the optimal conditions, the calibration curve was linear over the range 0.02-2.43 mg x l(-1) of PRH with R.S.D. 1.89, 1.23, and 1.80% (n=10) when determining 0.02, 1.22, and 2.43 mg x l(-1) of PRH in standard solutions, respectively. Equation of the calibration curve was calculated giving the following values: F=4.108 c-3.9 (n=6), r=0.9996. Detection limit was calculated 0.007 mg x l(-1) of PRH. The dissolution test of Deprazolin tablets was programmed for 60 min, with a continuous sampling rate of 70 h(-1) under conditions required by USP 26. Results obtained by SIA technique compared well with HPLC standard method.

Chromatography, High Pressure Liquid↗
PubMed2004

[Oxidative determination of rutin in tablets using flow injection analysis and chemiluminescence].

A simple, rapid and fully automated flow injection method (FIA) with chemiluminescence detection after oxidation with KMnO4 in acid medium at room temperature has been developed for the determination of routine in pharmaceutical formulation. Hexamethaphosphate sodium was utilized as enhancer of chemiluminescence. The calibration curve was linear in the range 0.01-0.26 mmol.l-1 with detection limit 0.005 mmol.l-1, RSD 0.46% (n = 10) and a sample throughput of 75.h-1 using a 200 microliters sample volume. The method was used for the determination of routine in mass-produced dosage form: Rutin 250 tablets á 50 mg, (firm Nature's Bounty, USA). The FIA method was statistically compared with the official German Pharmacopoeia method and showed comparable accuracy, but with the advantages of simplicity, speed and amounts of reagents consumed.

Flow Injection Analysis↗
PubMed2003

Simultaneous determination of methylparaben, propylparaben, hydrocortisone acetate and its degradation products in a topical cream by RP-HPLC.

A novel reversed-phase high-performance liquid chromatographic method with UV spectrophotometric detection was developed and validated for the determination of compounds in topical cream. The method describes determination of active component hydrocortisone acetate (HCA), its degradation products hydrocortisone (HC) and cortisone acetate (occurring in formulation after long-term stability tests) and two preservatives presented in the cream-methylparaben and propylparaben, using dexamethasone as an internal standard. The chromatographic separation was performed on a 5 microm SUPELCO Discovery C18 125 x 4-mm ID column. The optimised mobile phase for separation of all the compounds consists of methanol, acetonitrile and water (15:27:58, v/v/v), with the analysis time less than 13 min. The method was applicable for routine analysis (assays and stability tests) of active compound HCA, preservatives and degradation products in pharmaceutical product--topical cream Hydrocortizone cream 1%.

Administration, Topical↗
PubMed2003

Determination of methylparaben, propylparaben, triamcinolone acetonide and its degradation product in a topical cream by RP-HPLC.

A novel reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the determination of active component triamcinolone acetonide, its degradation product triamcinolone (occurring in formulation after long-term stability tests) and two preservatives presented in the cream-methylparaben and propylparaben, using hydrocortisone as an internal standard. The chromatographic separation was performed on a Supelco Discovery C18 column; the mobile phase for separation of all compounds consists of a mixture of acetonitrile and water (40:60 v/v). The analysis time was less than 9 min, at a flow rate of 0.6 mL min(-1) and detection at 240 nm. The method was found to be applicable for routine analysis (stability tests, homogeneity) in the pharmaceutical product topical cream Triamcinolon cream 0.1%.

Administration, Topical↗
PubMed2001

Simultaneous determination of quercetin, kaempferol and (E)-cinnamic acid in vegetative organs of Schisandra chinensis Baill. by HPLC.

A reversed-phase high-performance liquid chromatographic (RP-HPLC) separation method with UV spectrophotometric detection has been developed for the determination of major components in leaves and caulomas of Schisandra chinensis Baill. The flavonols (quercetin and kaempferol) and (E)-cinnamic acid were analysed after extraction with alcohol from the dry plant material. Identification was based on retention times and UV spectra by comparison with commercial standards. Quercetin, kaempferol and (E)-cinnamic acid were separated within 12 min using acetonitrile-aqueous 0.05% ortho-phosphoric acid (40:60 v/v) mobile phase. The method has been successfully applied for the quantitative analysis of all three major components in several samples from different harvests using propylparaben as the internal standard.

Chromatography, High Pressure Liquid↗
PubMed2001

Application of automated flow injection analysis to drug liberations studies with the Franz diffusion cell.

The flow-injection method with sensitive fluorimetric detection is used to monitor the liberation profiles of a topical dermatological formulation containing the model compound salicylic acid. The connection of a standard Franz diffusion cell with the automated flow-injection system enables an acquisition of multi-point liberation data in a form of series of fluorescence peaks in a short time. Examples of liberation profiles for a topical dermatological formulation containing salicylic acid are shown.

Autoanalysis↗
PubMed2000

Automated flow-injection spectrophotometric determination of catecholamines (epinephrine and isoproterenol) in pharmaceutical formulations based on ferrous complex formation.

A novel automated flow-injection spectrophotometric method for the determination of catecholamines (epinephrine and isoproterenol) has been developed based on the formation of their coloured complexes with Fe(II) in aminoacetic-carbonate buffer pH 8.3 and measuring of the absorbance peaks at the lambda(max) of 530 nm. A fully automated FIA system controlled by home-made software (FIA-MOD) was used for optimising the chemical and manifold parameters and running of routine measurements. The calibration graph was linear in the range of 5-200 mg l(-1) for epinephrine with an RSD of 0.24% (n = 5; c = 150 mg l(-1)) and 10-300 mg(-1) for isoproterenol with an RSD of 0.13% (n = 5; c = 200 mg l(-1)). Measurement throughput was 120 h(-1) ensuring a sample throughput of 40 h(-1) analysed in triplicate. Common excipients for tablets and injections were found not interfering. The proposed method was applied for the assay of various commercial pharmaceutical formulations containing epinephrine and isoproterenol and for the content uniformity test for the isoproterenol tablets. The assay results with RSD 2-4% (n = 3) were comparable with those obtained with the official USP XXIII methods (mean difference 1.9%).

Artifacts↗
PubMed2000

20-Hydroxyecdysone release from biodegradable devices: the effect of size and shape.

20-Hydroxyecdysone (20-OH) is a natural compound with many demonstrated effects on the physiological functions of vertebrates, particularly increased protein synthesis. Our study sought a suitable dosage form with continuous release of the drug lasting several weeks for implantation into agricultural animals. Biodegradable microparticles and implants of poly(L-lactic) and poly(DL-lactic) acids were prepared. Oligomers of these materials were synthesized, and a method of melting the binary mixture of the oligomer and 20-OH was employed. The particles were prepared simply by grinding the solidified block of the melt and sieving. Implants were prepared by extruding the melt into silicone tubes, removing the solidified content, and cutting into cylinders of 2 mm diameter and various lengths. A new method of preparation of hollow cylinders by aspirating air into silicone tubes filled with the melt was developed. The experiments demonstrated stability of 20-OH during heat treatment. Release of the active ingredient was tested in static in vitro conditions, analogous to those at the site of implantation, and prolonged drug release was obtained with both types of implant. The hollow implants gave release rates nearest to ideal zero-order kinetics and would appear most appropriate for testing in vivo.

Absorbable Implants↗