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Biomedical subjects

A Radi

Publications and source records attributed to A Radi.

17 recordsLinked to original sources
PubMed2005

Differential pulse voltammetric determination of the dopaminergic agonist bromocriptine at glassy carbon electrode.

The electrochemical oxidation of bromocriptine at glassy carbon electrode has been carried out in Britton-Robinson (B-R) buffer solutions in the pH range 2.0-11.0 employing cyclic, linear sweep and differential pulse voltammetry (DPV). Bromocriptine showed one well-defined oxidation peak accompanied by a smaller one. The oxidation process was found irreversible. For analytical purposes, the well-resolved diffusion controlled voltammetric peak at pH 5 was critically investigated. The linear relationship between peak current height and bromocriptine concentration allowed the differential pulse voltammetric determination of the drug over a wide concentration range, from 0.04 to 5.00 microg ml(-1) with a detection limit of 0.01 microg ml(-1). A relative standard deviation of 1.44% at 0.1 microg ml(-1) level was obtained. The proposed DPV method was successfully applied for the individual tablet assay to verify the uniformity content of bromocriptine in commercial tablets.

Bromocriptine↗
PubMed2005

Spectroscopic and voltammetric studies of pefloxacin bound to calf thymus double-stranded DNA.

Spectral and electrochemical studies have been carried out on the interaction of pefloxacin with calf thymus double-stranded dsDNA. The voltammetric behavior of pefloxacin was investigated at glassy carbon, carbon paste and dsDNA-modified carbon paste electrodes using cyclic voltammetry. Pefloxacin was oxidized, yielding one irreversible oxidation peak. The modification of the carbon paste surface with dsDNA allowed an accumulation process to take place for pefloxacin such that higher sensitivity was achieved compared with the bare surface. The response was characterized with respect to ionic strength, accumulation time, pefloxacin concentration, and other variables. The stripping differential pulse voltammetric response showed a linear calibration curve in the range 1.0 x 10(-7)-1.0 x 10(-5) mol l(-1) with a detection limit of 5.0 x 10(-8) mol l(-1) at the dsDNA modified electrode. The method was applied to the direct determination of pefloxacin in diluted urine samples.

Animals↗
PubMed2004

Differential pulse voltammetric determination of carvedilol in tablets dosage form using glassy carbon electrode.

The electrochemical oxidation of antihypertensive drug carvedilol has been studied in pH range 2.0-11.0 at a glassy carbon electrode by cyclic and differential pulse voltammetry. Two oxidation processes were produced in different supporting electrolyte media. Both oxidation processes were irreversible and diffusion-controlled. The first oxidation process was chosen for the analysis of carvedilol. A very resolved voltammetric peak was obtained in Britton-Robinson buffer at pH 8.0 using differential pulse mode. The linear response was obtained in the range of 0.25-10.00 microg ml(-1). The limit of detection was found to be 0.10 microg ml(-1). The developed method was used for the determination of carvedilol in tablet dosage form.

Antihypertensive Agents↗
PubMed2004

Voltammetric behaviour of rabeprazole at a glassy carbon electrode and its determination in tablet dosage form.

The oxidative behaviour of rabeprazole was studied at a glassy carbon electrode in Britton-Robinson (BR) buffer solutions using cyclic, linear sweep and differential-pulse voltammetry. The oxidation process was shown to be irreversible over the pH range (6.0-11.0) and was diffusion-adsorption controlled. An analytical method was developed for the determination of rabeprazole in BR buffer solution at pH 8.0 as supporting electrolyte. The anodic peak current varied linearly with rabeprazole concentration in the range 1.0 x 10(-6) to 2.0 x 10(-5) M of rabeprazole with a limit of detection of 4.0 x 10(-7) M. Validation parameters, such as sensitivity, accuracy, precision and recovery, were evaluated. The proposed method was applied to the determination of rabeprazole in the tablet dosage form. The results were compared with those obtained by a published high-performance liquid chromatographic method. No difference was found statistically.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2003

Voltammetric study of glibenclamide at carbon paste and Sephadex-modified carbon paste electrodes.

The oxidative behaviour of the antidiabetic agent glibenclamide on a bare carbon paste electrode (CPE) and a Sephadex-modified carbon paste electrode (SMCPE) was explored by cyclic and differential pulse voltammetry (DPV). The analysis procedure consisted of an open circuit accumulation step in stirred sample solution of Britton-Robinson buffer (0.04 mol L(-1), pH 2.0). This was followed by medium exchange to a clean solution of Britton-Robinson buffer (0.04 mol L(-1), pH 5.0), and subsequently an anodic potential scan was effected to obtain the voltammetric peak. The glibenclamide oxidation peak current obtained by DPV was proportional to the concentration of the glibenclamide in the range of 1.0 x 10(-9) mol L(-1) to 5.0 x 10(-8) mol L(-1) for 180 s accumulation time, with a detection limit of 4.0 x 10(-10) mol L(-1). A method was developed for the determination of glibenclamide in formulation and spiked human serum. Moreover, the proposed procedure was used to estimate the serum concentrations after oral administration of a 5 mg tablet of glibenclamide to three diabetic subjects.

Calibration↗
PubMed2003

Square-wave adsorptive cathodic stripping voltammetry of pantoprazole.

Adsorption and reduction of pantoprazole were investigated by cyclic and square-wave voltammetry on a hanging mercury drop electrode in Britton-Robinson buffers at pH 2.0-11.0. The reduction process gave rise to a single peak within the entire pH range. Study of the variation of the reduction signal with solution variables such as pH and concentration of pantoprazole and instrumental variables such as accumulation time and potential, frequency, pulse height and pulse amplitude, has resulted in optimization of the reduction signal for analytical purposes. The voltammetric procedure was applied successfully to give a rapid and precise assay of pantoprazole in a tablet dosage form.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2003

Determination of cefonicid in human urine by adsorptive square-wave stripping voltammetry.

The adsorption behavior of cefonicid on the hanging mercury drop electrode (HMDE) has been examined using cyclic voltammetry and square-wave voltammetry techniques in Britton-Robinson (B-R) buffers in the pH range of 2.0-11.0. The effect of different parameters on the accumulation behavior of the adsorbed species has been evaluated. Sensitive measurements can be achieved after controlled adsorption on the surface of HMDE followed by square-wave voltammetry. Under optimal conditions, a detection limit of 4.0 x 10(-8) M and a linear calibration graph in the range 1.0 x 10(-7)-1.0 x 10(-6) M were obtained. Direct simple determination of cefonicid in urine was established with no manipulation of urine sample other than dilution and subsequent adsorptive stripping voltammetric determination. The detection limit of the method was 1.0 microg x ml(-1) of cefonicid in urine.

Adsorption↗
PubMed2003

Anodic voltammetric assay of lansoprazole and omeprazole on a carbon paste electrode.

The electrochemical oxidations of lansoprazole and omeprazole have been studied at a carbon paste electrode by cyclic and differential-pulse voltammetry in Britton-Robinson buffer solutions (0.04 M; pH 6.0-10.0). The drug produced a single oxidation step. By differential-pulse voltammetry, a linear response was obtained in B-R buffer pH 6.0 in a concentration range from 2.0 x 10(-7) to 5.0 x 10(-5) M for lansoprazole or omeprazole. The detection limits were 1.0 x 10(-8) and 2.5 x 10(-8) M for lansoprazole and omeprazole, respectively. The method was successfully applied for the analysis of omeprazole and lansoprazole in capsules. The results were comparable to those obtained by spectrophotometry.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2003

Determination of pantoprazole by adsorptive stripping voltammetry at carbon paste electrode.

A voltammetric method was described for the determination of pantoprazole by differential-pulse adsorptive stripping voltammetry at a carbon paste electrode. Accumulation of pantoprazole was found to be optimized in Britton-Robinson buffer (0.04 M, pH 4.0) solution following 5 min accumulation time at open circuit condition. Under optimized conditions, the current showed a linear dependence with concentration in the range 1.0 x 10(-7)-1.0 x 10(-5) M. The detection limit was 2.0 x 10(-8) M. The method was applied successfully for the analysis of pantoprazole in tablet dosage form. The results of accuracy and precision were comparable to those obtained by spectrophotometry.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2002

Assay of dipyridamole in human serum using cathodic adsorptive square-wave stripping voltammetry.

A rapid and sensitive square-wave voltammetric procedure was optimized for the determination of dipyridamole after its adsorption preconcentration onto a hanging mercury drop electrode. The peak current of the first of the two peaks developed for this drug in Britton-Robinson buffer at pH 8.0 has been considered for the present analytical study. An accumulation potential of -1.0 V versus Ag/AgCl/KCl(s), pulse amplitude a =100 mV, scan increment Delta E =10 mV, and frequency f =120 Hz were the optimal experimental parameters. Dipyridamole can be determined in the concentration range of 9.0 x 10(-9) to 5.0 x 10(-6) M using accumulation times of 30-300 s. A detection limit of 4.0 x 10(-11) M was achieved after a 300 s accumulation time. Applicability to serum samples was illustrated. The average recoveries for dipyridamole spiked to serum at 0.25-4.50 micro g ml(-1) were 96.0-102.0%, and the higher standard deviation was 2.9%. A detection limit of 0.06 micro g mL(-1) of serum was obtained.

Dipyridamole↗
PubMed2002

Electrochemical reduction of meloxicam at mercury electrode and its determination in tablets.

The electrochemical reduction of meloxicam has been studied at a mercury electrode using various electrochemical methods in aqueous solutions over a wide pH range. The reduction of the drug produced a single reduction step in acidic media, whereas in slightly acidic and neutral media two reduction steps were observed. In alkaline media meloxicam shows a single pH-independent reduction step. The irreversibility of the electrode process was verified by different criteria. At all pH values, reactant adsorption at mercury electrode was observed. The mechanism of reduction was discussed. Using differential-pulse voltammetry, the drug yielded a well-defined voltammetric response in Britton-Robinson buffer solution, pH 4.0 at -1.286 V (vs. Ag/AgCl). This process could be used to determine meloxicam concentration in the range 1.0 x 10(-8)-5.0 x 10(-6) M. The method was successfully applied for the analysis of meloxicam in the tablet dosage form.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Stripping voltammetric determination of indapamide in serum at castor oil-based carbon paste electrodes.

The diuretic drug indapamide has been characterized voltammetrically at carbon paste electrodes by means of cyclic and differential pulse voltammetry. An adsorptive stripping method at carbon paste electrode modified with castor oil for trace determination of indapamide was described. A study of the variation of the peak current with solution variables such as pH, ionic strength, concentration of indapamide, possible interference, and instrumental variables such as scan rate, pulse amplitude, preconcentration time, accumulation potential, paste composition has resulted in the optimization of the oxidation signal for analytical purposes. By anodic stripping differential pulse voltammetry, the calibration plot was linear in the range 5 x 10(-8) x 10(-7) M with a detection limit of 5 x 10(-9) M at carbon paste electrode modified with castor oil in pH 4.0. The preconcentration medium-exchange approach was utilized for selective determination of indapamide in spiked serum. A detection limit of 15 ng ml(-1) was obtained for dilute serum sample after 3 min accumulation and medium-exchange procedure.

Carbon↗
PubMed2001

Determination of Norfloxacin by square-wave adsorptive voltammetry on a glassy carbon electrode.

The adsorptive and electrochemical behavior of norfloxacin on a glassy carbon electrode were investigated by cyclic and square-wave voltammetry. Cyclic voltammetric studies indicated that the process was irreversible and fundamentally controlled by adsorption. To obtain a good sensitivity, the solution conditions and instrumental parameters were studied using square-wave voltammetry. In acetate buffer of pH 5.0, norfloxacin gave a sensitive adsorptive oxidative peak at 0.920 V (versus Ag-AgCl). Applicability to measurement of norfloxacin at submicromolar levels in urine samples was illustrated. The peak current was linear with the norfloxacin concentration in the range 5-50 microg ml(-1) urine. The detection limit was 1.1 microg ml(-1) urine.

Anti-Infective Agents↗
PubMed1992

[Reconstruction of the function and shape of the middle region of the face].

The anatomical structures and biomechanical features of the middle third of the face require various methods of osteosynthesis in case of fracture. Compression osteosynthesis is mainly confined to the lateral margin of the orbits, where the transverse section of the bone is made so as to resist the force applied to attach the osteosynthetic material. If thin bone blades are fractured, as is often observed in the middle level of the face, adapting osteosynthesis is a method operating without compression. It can be regarded as the method of choice for this type of fracture.

Bone Plates↗