Biomedical subjects

Jan Krzek

Publications and source records attributed to Jan Krzek.

12 recordsLinked to original sources

PubMed2006

Stability of atenolol, acebutolol and propranolol in acidic environment depending on its diversified polarity.

The main objective of this research was to investigate the relationship between the polarity of atenolol, acebutolol, and propranolol described by logP and kinetic and thermodynamic parameters characterizing their degradation process in acidic solution. Hydrolysis was carried out in hydrochloric acid at molal concentrations of 0.1 mol/L, 0.5 mol/L, and 1 mol/L for 2 hr at 40 degrees C, 60 degrees C, and 90 degrees C. Chromatographic-densitometric method was used for the determination of drugs under investigation. The identification of degradation products was carried out by using 1H NMR. The degradation processes that occurred in drugs under investigation are described with kinetic parameters (k, t0.1, and t0.5) and energy of activation (Ea). It has been found that the stability of drugs increases toward lipophilic propranolol in the assumed experimental model. The rate constants k decrease, contrary to t0.1, t0.5, and Ea, which vary comparably to logP, thus increasing from the most hydrophilic atenolol, through acebutolol, of lower polarity, to the most lipophilic propranolol. This study demonstrated that the stability of chosen beta-adrenergic blocking agents increases with their lipophilicity.

Acebutolol↗

PubMed2004

Direct separation, identification and quantification of epimers 22R and 22S of budesonide by capillary gas chromatography on a short analytical column with Rtx-5 stationary phase.

The conditions for separation, identification and quantitative determination of epimers 22R and 22S of budesonide by capillary gas chromatography (GC) with FID detection and two various sample injection methods, namely split-splitless and cool on-column, were established. In analysis helium as carrier gas and Rtx-5 capillary column of 7 m in length along with stationary phase Crossbond 5% diphenyl-95% dimethyl polysiloxane were used. The individual epimers were identified under specified conditions by using standard samples of different declared concentration of each epimer under investigation: (1) 51.2% of epimer 22R and 47.3% of epimer 22S, and (2) 95.1% of 22R and 4.4% of 22S, as well as Pulmicort, a preparation containing micronized budesonide as an active substance. It seems that good parameters of preliminary validation achieved by the proposed methods can confirm its suitability for quantitative analysis purpose. The retention times obtained for epimers 22R and 22S, depending on injection technique are about 7.7 and. 8.3 min for split and, approx. 10.3 and 10.9 min for cool on-column. The limits of detection and quantitation are 5.7 and 6.2 ng, for 22R respectively, and 4.3 and 4.8 ng for 22S. The linearity is maintained for concentrations ranging from 0.01 to 0.20 mg/ml. The quantitative analysis features of repeatability, high precision and accuracy confirmed by the obtained results and its statistical evaluation.

Budesonide↗

PubMed2004

Quality assessment for tramadol in pharmaceutical preparations with thin layer chromatography and densitometry.

Research studies have been carried out to develop a chromatographic and densitometric method suitable for identification and determination of tramadol and impurities. In addition, the stability of tramadol in solutions was investigated, including an effect of solution pH, temperature and incubation time. In the first instance the conditions for identification and quantitative determination of tramadol and impurities in pharmaceutical preparations were established. The separation was performed on silica gel-coated chromatographic plates (HPTLC) using two mobile phases: (I) chloroform-methanol-glacial acetic acid (9:2:0.1, v/v/v); (II) chloroform-toluene-ethanol (9:8:1, v/v/v). The UV densitometry was carried out at lambda = 270 nm. The developed method is of high sensitivity and low detection and determination limits ranging from 0.044 to 0.35 microg. For individual constituents the recovery ranges from 93.23 to 99.66%. The next step was to evaluate the stability of tramadol and determine a method of decomposition under various experimental conditions. It was found that tramadol decomposes in various ways in acidic and basic environments producing (1RS)-[2-(3-methoxyphenyl)cyclohex-2-enyl]-N,N-dimethylmethanamine (imp. B) and (1RS, 2RS)-2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol (imp. cis-T) or imp. cis-T, respectively.

Analgesics, Opioid↗

PubMed2003

The HPLC determination of propane-1,2,3-triyl trinitrite and impurities: (2RS)-3-hydroxypropane-1,2-diyl dinitrate and 2-hydroxypropane-1,3-diyl dinitrate in ointment.

A HPLC method for determination of propane-1,2,3-triyl trinitrate and impurities: (2RS)-3-hydroxypropane-1,2-diyl dinitrate and 2-hydroxypropane-1,3-diyl dinitrate ointment was developed. The conditions for good separation of constituents, while avoiding vehiculum interference were established. The results feature of high accuracy and good precision. For individual constituents R.S.D. is ranged from 0.7 to 9.9%, while recovery was 100.1% for propane-1,2,3-triyl trinitrate and 95.1-99.0% for impurities. It has been found that propane-1,2,3-triyl trinitrate used in medicine in the form of ointment contains such impurities which can be identified and quantified at relatively low concentrations of 70 ng ml(-1).

Chromatography, High Pressure Liquid↗

PubMed2002

Densitometric determination of diclofenac, 1-(2,6-dichlorophenyl)indolin-2-one and indolin-2-one in pharmaceutical preparations and model solutions.

A chromatographic-densitometric method for identification and quantitation of diclofenac and its impurities, i.e. 1-(2,6-dichlorophenyl)indolin-2-one and indolin-2-one in pharmaceutical preparations and model solutions was developed. The effect of pH, temperature and ultra violet (UV) radiation on diclofenac's concentration was investigated. Chromatographic separation was performed on TLC silica gel coated plates with the mobile phase: cyclohexane-chloroform-methanol (12:6:1, v/v/v). Densitometric detection was carried out in UV at lambda=248 nm. The conditions for good separation and the detection limit were established. The recovery for diclofenac was 99.20%, for 1-(2,6-dichlorophenyl)indolin-2-one--92.34% and for indolin-2-one--95.85%. The method was used for quality assessment of diclofenac in pharmaceutical preparations. Reliable results comparable to those determined by high performance liquid chromatography (HPLC) were obtained.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMedDate not supplied

Validation of a method for simultaneous determination of menthol and methyl salicylate in pharmaceuticals by capillary gas chromatography with cool on-column injection.

The conditions for the identification and quantitative determination of menthol and methyl salicylate in ointment Balsamum Mentholi Compositum on a hydrocarbon-ester base (vaseline-lanolin), have been established by using capillary gas chromatography with cool on-column injection and flame ionization detection (FID). The good separation of menthol (tR = 7.2 min), methyl salicylate (tR = 8.7 min) and thymol (tR = 12.3 min) and camphor (tR = 6.0 min), used as alternative internal standards, beside vehiculum constituents (peak of tR = 15.8 min) was obtained. The method features a high sensitivity - detection limit for menthol and methyl salicylate was 0.1 ng and 5.0 ng, respectively, high accuracy, precision and recovery for active substances: 100.0% +/- 2.2%, when camphor was used as an internal standard.

Chromatography, Gas↗

PubMedDate not supplied

Direct determination of Pb(II) and Cd(II) ions as impurities in some homeopathic drugs by using stripping voltammetry.

The conditions for identification and quantilication of Pb(II) and Cd(II) ions as impurities in homeopathic preparations by stripping voltammetry were established. The tests proved that the method was of high selectivity. The detection limits were 0.78 ng/mL and 1.56 ng/mL for Pb(II) and Cd(II) ions, respectively. The method was characterised by: repeatability of measurements, a wide range of linearity and satisfactory percent recovery. The Pb(II) and Cd(II) ions were detected in examined drugs as impurities at concentrations of 1.23 ? 9.5 ng/mL and 1.66 ? 3.7 ng/mL for Pb(II) and Cd(II), accordingly.

Cadmium↗

PubMedDate not supplied

Application of derivative spectrophotometry to simultaneous determination of indomethacin and 5-methoxy-2-methyl-3-indoleacetic acid in metindol injections.

Derivative spectrophotometry was employed to develop a rapid and accurate method for simultaneous determination of indomethacin and 5-methoxy-2-methyl-3-indoleacetic acid as its possible impurity in Metindol injections. At the selected wavelengths, 233.04 and 284.65 nm, no interference between the components determined was observed. Under the established experimental conditions, recoveries of the particular components were from 96.14 to 98.17%. Linearity was maintained over a broad range of concentrations, from 11.88 x 10(-3) to 35.64 x 10(-3) mg/mL for indomethacin and 0.4 to 1.2 mg/mL for 5-methoxy-2-methyl-3-indoleacetic acid. The limit of detection was found to be 6.0 x 10(-3) mg/mL for indomethacin and 0.04 x 10(-3) mg/mL for 5-methoxy-2-methyl-3-indoleacetic acid. The limits of quantitation were found to be 10.0 x 10(-3) mg/mL and 0.20 x 10(-3) mg/mL, respectively.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMedDate not supplied

Densitometric high performance thin-layer chromatography identification and quantitative analysis of psychotropic drugs.

A thin-layer chromatography (TLC)-densitometry method has been developed to identify and quantify haloperidol, amitriptyline, sulpiride, promazine, fluphenazine, doxepin, diazepam, trifluoperazine, clonazepam, and chlorpromazine in selected psychotropic drugs. Separation was performed on precoated silica gel 60 F254 TLC plates. Chromatograms were developed in various mobile phases, and 8 of 30 tested phases were selected based on spot location and developing time. The identification and quantification were carried out based on ultraviolet densitometric measurements at chosen wavelengths. In addition to retention coefficients, the absorption spectra recorded directly from chromatograms were also used in qualitative analysis. Under established experimental conditions, high sensitivity of the method was achieved. The limit of detection ranged from 0.009 to 0.260 microg, depending on the wavelength selected for measuring. A satisfactory recovery, ranging from 92.99 to 104.70%, was achieved for individual constituents.

Amitriptyline↗

PubMedDate not supplied

High-performance thin-layer chromatography with densitometry for the determination of ciprofloxacin and impurities in drugs.

A thin-layer chromatographic (TLC)-densitometric method has been developed for identification and quantification of ciprofloxacin (Rf = 0.61) and an ethylenediamine compound (Rf = 0.42), a desfluoro compound (Rf = 0.48), by-compound A (Rf = 0.53), and fluoroquinolonic acid (Rf = 0.68) as ciprofloxacin degradation products in pharmaceutical preparations. By using chloroform-methanol-25% ammonia (43 + 43 + 14, v/v/v) as the mobile phase and silica gel 60 F254 high-performance TLC plates as the stationary phase, it was possible to separate individual constituents that, when subjected to ultraviolet (UV) densitometric analysis at 330 nm for fluoroquinolonic acid and 277 nm for the other compounds, gave well developed peaks allowing easy qualitative and quantitative analyses. DMSO-methanol (1 + 1) was used to extract drug constituents. The method showed high sensitivity (limit of detection 10 to 44 ng), a wide linearity range (3 to 20 microg/mL), and good precision (2.32 to 6.46% relative standard deviation) and accuracy (percentage recoveries 98.62 to 101.52%) for individual constituents.

Chromatography, Thin Layer↗

PubMedDate not supplied

Identification and quantitation of polymyxin B, framycetin, and dexamethasone in an ointment by using thin-layer chromatography with densitometry.

A new thin-layer chromatographic-densitometric method has been developed for rapid identification and quantitative determination of polymyxin B, framycetin, and dexamethasone in a dental ointment. Silica gel 60 and F254 silica gel 60 plates were used for separating antibiotics and dexamethasone acetate, respectively. When determining framycetin and polymyxin B, chromatograms were developed by using 2 mobile phases, namely methanol and methanol-n-butanol-ammonia (25%)-chloroform (14 + 4 + 9 + 12, v/v/v/v/). The densitometric measurements were made at 550 nm after detection with 0.3% ninhydrin solution. Dexamethasone was determined by using the mobile phase cyclohexane-ethyl acetate (2 + 3, v/v) and ultraviolet densitometric recording at 245 nm. The results obtained for individual constituents with the chromatographic-densitometric method demonstrate similar accuracy, relative standard deviation values from 1.49 to 2.47%, and relative error values from 0.02 to 0.81% and are comparable to those obtained with the reference methods.

Chromatography, Thin Layer↗

PubMedDate not supplied

Reversed-phase high-performance liquid chromatography determination of selected phenolic acids in propolis concentrates in terms of standardization for drug manufacturing purposes.

A reversed-phase high-performance liquid chromatography method with gradient elution was developed for the determination of the caffeic, p-coumaric, and ferulic acids in propolis concentrates. Solid-phase extraction on an RP18 column was applied for preliminary purification, and chromatographic separation was performed on 100 RP18e Lichrospher column of particle size 5 microm. The mobile phase was obtained by mixing in appropriate ratios 0.03 mM NaH2PO4, acidified with H3PO4 up to pH = 3.0, with acetonitrile to obtain a gradient in the elution process. Spectrophotometric detection was conducted at 320 nm. Under the established conditions, the method featured high sensitivity, good precision, and comparability of results, as proven by method validation and statistical analysis of the obtained results. The limits of detection were 0.315, 0.325, and 0.695 microg/mL for caffeic, p-coumaric, and ferulic acids, respectively. The corresponding recovery values were 98.14, 101.05, and 99.42% and the linearity ranges from 1.31 to 99.18 microg/mL, 1.52 to 119.16 microg/mL, and 2.42 to 184.14 microg/mL. The precision of the method was expresed by relative standard deviation values that did not exceed 3%. It was also shown that the propolis concentrates under examination had similar antibacterial activity against Staphylococcus aureus ranging from 119.8 to 124.3 microg/mL, contrary to model mixtures that showed no antibacterial activity.

Anti-Bacterial Agents↗