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B Gachályi

Publications and source records attributed to B Gachályi.

At least 19 recordsLinked to original sources
PubMed1998

High-performance liquid chromatographic method with coulometric detection for the determination of buspirone in human plasma by means of a column-switching technique.

A reversed-phase high-performance liquid chromatographic method with electrochemical detection has been developed for the determination of buspirone from human plasma. The separation was carried out by using a Supelcosil ABZ+ plus C18 reversed-phase column and 0.05 M potassium dihydrogenphosphate (pH 6.5)-acetonitrile (7:3, v/v) as the mobile phase. The compounds were detected by coulometry. Buspirone and the internal standard were extracted from the human plasma using Bond-Elut C18 solid-phase extraction cartridges. Following removal of the the highly lipophilic plasma components we applied a column-switching technique which reduced the duration of HPLC measurement from 60 min to 15 min. The limit of quantitation was found to be 100 pg/ml plasma.

Buspirone↗
PubMed1998

Validated liquid chromatographic method for the determination of N-3-(2,2,5,5-tetramethyl-3-pirrolin-3-carboxamidopropylphthalimide hydrochloride), a novel antiarrhythmic agent in human plasma.

A simple high-performance liquid chromatographic method with ultraviolet absorbance detection has been developed to determine the concentration of N-3-(2,2,5,5-tetramethyl-3-pirrolin-3-carboxamidopropylphthalim ide hydrochloride; A-2545), a new antiarrhythmic agent from human plasma. Separation of the investigated compound and internal standard was achieved on a Nucleosil 7 C18 column with a 0.01-M potassium dihydrogenphosphate buffer (pH 2.5)-methanol (60:40, v/v) mobile phase. The detection was performed at 220 nm. During the determinations, buspirone served as the internal standard. The compounds were isolated from plasma on a Bakerbond C18 solid-phase extraction cartridge and the mean absolute recovery was 92.9%. The limit of quantitation was found to be 10 ng/ml. The bioanalytical method was validated with respect to linearity, within- and between-day accuracy and precision, system suitability and stability. All validated parameters were found to be within the internationally required limits. The developed analytical method for A-2545 was found to be suitable for application in pharmacokinetic studies and for human drug monitoring.

Anti-Arrhythmia Agents↗
PubMed1998

[Role of food interaction pharmacokinetic studies in drug development. Food interaction studies of theophylline and nifedipine retard and buspirone tablets].

Due to several mechanism, meals may modify the pharmacokinetics of drug products, thereby eliciting to clinically significant food interaction. Food interactions with the drug substance and with the drug formulation should be distinguished. Food interaction of different drug products containing the same active ingredient can be various depending on the pharmaceutical formulation technology. Particularly, in the case of modified release products, the food/formulation interaction can play an important role in the development of food interaction. Well known example, that bioavailability of theophylline can be influenced in different way (either increased, decreased or unchanged) by concomitant intake of food in the case of different sustained release products. The role and methods of food interaction studies in the different kinds of drug development (new chemical entity, modified release products, generics) are reviewed. Prediction of food effect response on the basis of the physicochemical and pharmacokinetic characteristics of the drug molecule or formulations is discussed. The results of three food interaction studies carried out the products of EGIS Pharmaceuticals Ltd. are also reviewed. The pharmacokinetic parameters of theophyllin 400 mg retard tablet were practically the same in both fasting condition and administration after consumption of a high fat containing standard breakfast. The ingestion of a high fat containing breakfast, increased the AUC of nifedipine from 259.0 +/- 101.2 ng h/ml to 326.7 +/- 122.5 ng h/ml and Cmax from 34.5 +/- 15.9 ng/ml to 74.3 +/- 23.9 ng/ml in case of nifedipine 20 mg retard tablet, in agreement with the data of literature. The statistical evaluation indicated significant differences between the pharmacokinetic parameters in the case of two administrations (before and after meal). The effect of a high fat containing breakfast for a generic version of buspiron 10 mg tablet and the bioequivalence after food consumption were studied in a single-dose, three-way (test and reference products administered after consumption of standard breakfast, as well as test product in fasting condition), cross-over, food effect bioequivalence study. According to the results, the test product--which, in a former study proved to be bioequivalent with the reference product in fasting state--is bioequivalent with the reference product under feeding conditions and the food intake influenced the pharmacokinetics of the test tablets.

Buspirone↗
PubMed1997

Liquid chromatographic method for the determination of ticlopidine in human plasma.

A simple high-performance liquid chromatographic method for determination of ticlopidine in human plasma using ultra violet detection was developed. The separation of the investigated compound and internal standard was achieved on a C18 BD column with a 0.01 M potassium dihydrogen phosphate buffer (pH 4)-acetonitrile-methanol (20:40:40, v/v) mobile phase. The detection was performed at 215 nm. The compounds were isolated from plasma by Bond Elut C18 solid-phase extraction, the mean absolute recovery was 84.9%. The limit of quantitation was 10 ng ml(-1), the limit of detection was 5 ng ml(-1). The bioanalytical method was validated with respect to linearity, within- and between-day accuracy and precision. system suitability and stability. All validated parameters were found to be within the internationally required limits. The developed analytical method for ticlopidine was found to be suitable for application in pharmacokinetic studies and human drug monitoring.

Chromatography, High Pressure Liquid↗
PubMed1997

[Validity of a liquid chromatographic (HPLC) method for the determination of ticlopidine in human plasma].

A simple high-performance liquid chromatographic method for determination of ticlopidine in human plasma using UV detection was developed. The separation of the investigated compound and internal standard was achieved on "BST Rutin" 10, C18 BD column with a 0.01 M, (pH 4) potassium dihydrogen phosphate bufferacetonitrile-methanol (20:40:40 v/v) mobile phase. The detection was performed at 215 nm. The compounds were isolated from plasma by Bond Elut C18 solid-phase extraction, the mean absolute recovery was 84.9%. The limit of quantitation was 10 ng/ml, the limit of detection was 5 ng/ml. The assay has been validated with respect to accuracy, precision and system suitability. All validated parameters were found to be within the necessary limits. The developed analytical method for ticlopidine was found to be suitable for application in pharmacokinetic studies and human drug monitoring.

Chromatography, High Pressure Liquid↗
PubMed1996

Determination of alpha-methyldopa in human plasma by validated high-performance liquid chromatography with fluorescence detection.

A sensitive reversed-phase gradient elution high-performance liquid chromatographic method with fluorescence detection has been developed for the determination of alpha-methyldopa (AMD) in human plasma. Separation of the investigated compound and the 3,4-dihydroxyphenylalanine (DOPA) internal standard was achieved on a Nucleosil 7 C18 column with a 5 mM heptanesulphonic acid sodium salt containing 0.05 M potassium dihydrogenphosphate (pH 3.2)-acetonitrile mobile phase. The composition of the mobile phase was changed according to a linear gradient time program. Detection was performed at 270 nm fluorimetric excitation and 320 nm emission. The compounds were isolated from plasma by Bond-Elut C18 solid-phase extraction. The limit of quantitation was found to be 10 ng/ml plasma. The assay was validated with respect to accuracy, precision and system suitability. All validated parameters were found to be within the 20% required limits. On the basis of the sensitivity, linearity and validation parameters the developed analytical method was found to be suitable for application in a bioequivalency study.

Chromatography, High Pressure Liquid↗
PubMed1995

The effect of combined pre-treatment on the metabolism of antipyrine in the rat.

Determination of the effect of the known enzyme-inducers phenobarbital-Na and spironolactone on the activity of the MFO was carried out. Male Wistar rats were treated either with 40 mg/kg phenobarbital-Na or 40 mg/kg spironolactone, and also in combination with 100 mg/kg of the MFO was inhibitor alpha-methyldopa. The activity of the MFO was assessed by changes in antipyrine half-life. Our results show that given alone both phenobarbital-Na and spironolactone are potent inducers of the MFO. Co-treatment with the enzyme-inhibitor alpha-methyldopa, however, led to different results in two cases: It slightly diminished the enzyme inducing effect of phenobarbital-Na, while the effect of spironolactone has completely ceased. These findings may suggest that phenobarbital-Na and spironolactone are acting on different cytochrome isoenzymes.

Animals↗
PubMed1994

Polymorphic paracetamol conjugation: phenotyping in a Hungarian population.

The authors studied the distribution of the paracetamol conjugation in a Hungarian population (53 adult Caucasian persons). The data indicated that the excretion of paracetamol glucuronide and sulphate were not normally distributed. Bimodality were apparent in both conjugation pathways: 15.1% of subjects was relatively extensive glucuronidators, and the 24.5% of subjects was extensive sulphatators. Monitoring the ratios of various urinary paracetamol conjugates/paracetamol may be useful as a tool for determining the glucuronide and sulphate conjugation capacity in humans.

Acetaminophen↗
PubMed1993

TxA2-PGI2-PGF2 alfa responses in the kidney to blood pressure reduction induced by vasodilator/vasorelaxing agents with different action in patients with essential hypertension.

In blood pressure (BP) reduction induced by gallopamil, hydralazine and prazosin in patients with essential hypertension a common trend was found in renal prostanoid production which included increased TxB2 excretion and/or augmented TxB2/6-keto-PGF1alfa ratio and, with the exception of response to prazosin, enhanced PGF2alfa excretion. Role of direct biochemical actions by the drugs in these responses was excluded by in vitro experiments with kidney slices from rats. The clinical and in vitro experimental findings suggested a mediator role of sympathetic activation but not that of the increased renin release in the urinary eicosanoid responses. Significant correlation was observed between the changes in reabsorbed amounts of sodium and excreted amounts of TxB2 and PGF2alfa. The results suggest that the reactivity of pressure type prostanoids in the kidney could be considered as part of a more complex renal counteraction to BP decrease.

Adolescent↗
PubMed1991

Human paraoxonase polymorphism: Hungarian population studies in children and adults.

The paraoxonase phenotype distribution pattern was studied in a Hungarian population of 102 children and 100 adults. All the subjects were of Caucasian origin and are not related. The adult population showed the trimodality in phenotype distribution similar to other European population data. The gene frequencies obtained were statistically not significantly different either. There was no correlation between the activity of serum paraoxonase and activity of cholinesterase, sex, age and body weight. The phenotype distribution was trimodal in the children's population too. There was a significant difference in gene frequency, however, compared to data from adult population.

Adolescent↗
PubMed1990

[Determination of paracetamol in urine by liquid chromatography].

Since the biotransformation of paracetamol (Acetaminophen) is practically confined to conjugation, the quantitative determination of paracetamol excretion may provide important information on phase II of the drug metabolism. We elaborated a simple and rapid liquid chromatographic method for the assessment of paracetamol and its conjugated metabolites in the urine to be available for routine use in the clinicopharmacological laboratory. The persons involved in the trial were administrated 500 mg of paracetamol to be taken on an empty stomach in the morning. Subsequently, their urine was collected for 8 hours. The so-called free paracetamol of unchanged form excreted into the urine was measured from this 0 to 8 hours' urine fraction, then, after treating it with beta-glucuronidase/arysulphatase enzyme, the total amount of paracetamol released from the conjugate, as well as that of the existing free paracetamol, the so-called total paracetamol were determined. The urine extracts containing paracetamol obtained by ethylacetate, at pH 10, and dried under nitrogen stream were analysed by HPLC on an ODS column in an eluent of methanol and water mixture (3:7, v/v) in the presence of 3-acetaminophenol internal standard. The flow rate was 1 ml/min, the detection wavelength was 254 nm.

Acetaminophen↗
PubMed1990

Pantothenic acid, acute ethanol consumption and sulphadimidine acetylation.

The effect of pantothenic acid and acute ethanol loading on the genetically determined N-acetyltransferase activity has been studied using sulphadimidine as a test substance. The administration of 1100 mg pantothenic acid daily (600 mg orally, 500 mg iv) for seven days did not significantly alter sulphadimidine kinetics in the primarily elderly 21 subjects we investigated. Acute ethanol loading (0.73 g/kg pure alcohol at start and 0.11 g/kg pure alcohol hourly for 8 hours afterwards, stock solution: 20% v/v ethanol in fruit juice) did not change sulphadimidine acetylation in 10 healthy male volunteers. It is concluded that despite theoretical assumptions exogenous factors like pantothenic acid and ethanol do not significantly influence the cytosolic N-acetyltransferase activity. Consequently they do not interfere with the acetylator phenotyping procedure.

Acetylation↗
PubMed1989

Simple high-performance liquid chromatographic method for the determination of tolbutamide and its metabolites in human plasma and urine using photodiode-array detection.

A high-performance liquid chromatographic method has been developed for the determination of tolbutamide and its metabolites in human plasma and urine. The compounds examined were extracted with diethyl ether from the acidified biological fluid. Chlorpropamide was used as internal standard, and 235 nm was chosen as the wavelength for diode-array detection. A study of the relationship between the capacity factor and the mobile phase composition and pH showed that acetonitrile-2-propanol-0.1% orthophosphoric acid (17: 17: 66, v/v) was the best eluent on a C8 reversed-phase column. The method is precise, sensitive and suitable for pharmacological investigations.

Chromatography, High Pressure Liquid↗