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Biomedical subjects

S Marton

Publications and source records attributed to S Marton.

At least 19 recordsLinked to original sources
PubMed2006

Application of sucrose fatty acid esters in transdermal therapeutic systems.

Transdermal therapeutic systems (TTSs) were studied applying different sucrose fatty acid esters (SEs) as drug delivery agents. Matrix and membrane controlled TTSs were prepared and compared. Membrane was made from a methacrylic polymer (Eudragit NE) of pH independent permeability which can achieve diffusion controlled drug liberation. Model drug was a water soluble beta-blocker, metoprolol, which has short biological half-life, so applying it in a TTS, the duration of its action could be prolonged. Sucrose fatty acid esters of different fatty acid chain lengths and consequently different hydrophilic-lipophilic balance (HLB) values were studied considering their effect on the metoprolol release from TTSs. Different mathematical models were applied for the evaluation of the release process. The results of the in vitro studies indicated that SEs of shorter fatty acid chain length and higher HLB value increased the amount of released drug about 10 times. SEs could be promising agents in transdermal therapeutic systems to control the drug release and cutaneous absorption.

Administration, Cutaneous↗
PubMed2003

Lack of effect of prophylactic N-acetylcysteine on postoperative organ dysfunction following major abdominal tumour surgery: a randomized, placebo-controlled, double-blinded clinical trial.

Sepsis and respiratory dysfunction leading to multiple system organ failure remains the leading cause of postoperative morbidity and mortality following major surgical procedures. It has been suggested the oxygen free radicals might play a pivotal role in this process. The aim of this study was to investigate whether short-term infusion of N-acetylcysteine (N-acetylcysteine), a potent antioxidant, administered before and during extensive abdominal surgery, could ameliorate the progression of early postoperative organ dysfunction and improve oxygenation. Out of the 93 patients, 47 received N-acetylcysteine and 46 were given placebo in a randomized, controlled, double-blinded fashion. Patients received N-acetylcysteine (150 mg.kg-1 bolus followed by a continuous infusion of 12 mg.kg-1.h-1) or the same volume of placebo (5% dextrose) during surgery. Treatment effect on organ function was assessed by organ dysfunction scores according to physiological parameters of six main organ systems: respiratory, cardiovascular, renal, hepatic, haematological and central nervous system. The scores were obtained on admission, then daily during the first three postoperative days. For statistical analysis Mann-Whitney U and Chi-squared tests were used. There was no significant difference between the two groups in any of the six organ dysfunction parameters, length of intensive care stay, days of mechanical ventilation and mortality. Our results do not support the routine use of N-acetylcysteine as a prophylactic measure during surgery, and reinforce previous evidence which challenges the indication of N-acetylcysteine in the critically ill.

Abdominal Neoplasms↗
PubMed2001

Influence of chlorhexidine species on the liquid crystalline structure of vehicle.

The aim of this study was to investigate the influence of three chlorhexidine species, chlorhexidine base and its salts (diacetate and digluconate), on the physico-chemical features of liquid crystalline systems and on drug transport through lipophilic membranes. Nonionic surfactant, Synperonic A7 (PEG(7)-C(13--15)) was selected for the preparation of the liquid crystalline systems. Mixtures of different ratios of Synperonic A7 and water were prepared. The liquid crystalline systems were characterized using polarizing microscopy, small-angle neutron scattering and transmission electron microscopy. Membrane transport was also examined. The addition of chlorhexidine species to the liquid crystalline system modified the structure of the liquid crystalline system. As a result of liquid crystal--drug interaction, the solubility of chlorhexidine base and its diffusion through lipophilic membranes increased in comparison with those of the chlorhexidine salts.

Chemical Phenomena↗
PubMed2001

Study of the theophylline content of single coated particles by gas chromatography/mass spectrometry.

The aim of the present study was to determine by gas chromatography/mass spectrometry (GC/MS) the content uniformity of single theophylline microcapsules of different particle size ranges. Microencapsulation was carried out in a laboratory fluidized bed system using Eudragit L30D aqueous dispersion. Scanning electron microscopy was applied for the characterization of the surface morphology of the prepared theophylline microcapsules of two different particle size ranges. The theophylline content of single particles was determined by GC/MS analysis. It was found that the particle size of microcapsules greatly influenced their theophylline content. The GC/MS analysis was successully applied to indicate the changes in the content uniformity and thus the interparticular costing distribution of single theophylline microcapsules in the presence of several excipients.

Calibration↗
PubMed2001

[Preformulation study of atenolol-containing solutions.. I. The pH dependence of thermostability].

The stability of atenolol solutions was evaluated under accelerated isothermal degradation conditions at 90 degrees C. A specific and sensitive HPLC method was adapted to study the pH dependence of the stability. The maximum stability of atenolol was achieved at pH 4 with a k value of 1.1 x 10(-3) h-1. The degradation of atenolol followed first-order kinetics at above mentioned conditions.

Atenolol↗
PubMed2000

The effect of liquid crystalline structure on chlorhexidine diacetate release.

The aim of this study was to examine different liquid crystalline preparations containing chlorhexidine diacetate and to find connection between their structure and the kinetic of drug release. Nonionic surfactant, Synperonic A7 (PEG(7)-C(13-15)) was selected for the preparation of the examined liquid crystalline systems. Mixtures of different ratios of Synperonic A7 and water were produced. By increasing the water content of the systems, lamellar and hexagonal liquid crystal structures were observed. For the analysis of the prepared liquid crystalline systems polarising microscopy, rheology study, differential scanning calorimetry and dynamic swelling tests were carried out. The chlorhexidine diacetate release was examined by Franz-type vertical diffusion cell apparatus. The chlorhexidine diacetate release from hexagonal liquid crystalline preparations was characterised by zero-order release kinetics, while the drug release from lamellar liquid crystalline systems was described by anomalous (non-Fickian) transport. The results indicate that the drug release kinetic is strongly dependent on the liquid crystalline structure.

Anti-Infective Agents, Local↗
PubMed2000

The effect of temperature and polymer concentration on dynamic surface tension and wetting ability of hydroxypropylmethylcellulose solutions.

The purpose of the present study was to evaluate quantitatively the changes of dynamic surface tension and contact angle of hydroxypropylmethylcellulose (HPMC) aqueous solutions as a function of temperature and polymer concentration of the examined solutions. HPMC aqueous solutions of different concentrations (1%, 2%, 3%, 4% w/w) were prepared without plasticizer and with 1% w/w Lutrol F127. Dynamic surface tension of the prepared solutions was determined by the Du Nouy ring method of the KSV Sigma 70 computer-controlled and programmable tensiometer. The dynamic contact angle of Avicel PH-101 tablets was measured against HPMC solutions of various concentrations by the plate method of the KSV Sigma 70 tensiometer. The obtained results indicate that dynamic surface tension measurement can be applied for the accurate determination of the thermal gelation temperature of the prepared HPMC solutions. With increasing concentration of HPMC, dynamic contact angle values of solutions also increased, thus decreasing the spreading behavior on the surface of Avicel tablets.

Anticholesteremic Agents↗
PubMed2000

Effect of the wettability characteristics of polyethylene glycol derivatives on the drug release of wax matrices.

The purpose of the present work was to study the relationship between the physicochemical characteristics of different polyethylene glycol aqueous solutions and the kinetics of potassium chloride release from wax matrix samples containing polyethylene glycol derivatives. Potassium chloride was embedded into thermosoftening matrix material to produce a sustained-release dosage form. Potassium chloride release was measured by the rotating paddle method of USP 23 and the dissolution process was characterized by a modified Nernst equation. Physicochemical characteristics--surface tension, dynamic contact angle, viscosity--of the polyethylene glycol aqueous solutions were also determined. The results indicate that the adhesion tension of surfactant containing aqueous solutions has a decisive impact on the prediction of the potassium chloride release rate from wax matrices.

Adhesiveness↗
PubMed1999

Examination of the polymorphism of piroxicam in connection with the preparation of a new "soft-patch" type pharmaceutical dosage form.

The influence of different solvents (propylene glycol, glycerol, ethanol), as well as different technological procedures (melting, rapid and slow cooling), on the formation of polymorphous piroxicam modifications was examined in the course of the elaboration of a "soft-patch" type of semisolid pharmaceutical dosage form. The thermodynamical behavior, some physicochemical properties (such as melting point, dissolution rate), and infrared (IR) spectrum of the formed (needle and cubic) crystal modifications were studied, and the possibilities of their formation and their avoidance were examined.

Administration, Cutaneous↗
PubMed1998

Effect of the formulation parameters on the characteristics of pellets.

Pelletization is increasingly applied currently for the preparation of solid oral controlled-release dosage forms. The production of the particles, which are regular in shape and size, can be achieved with the application of the proper polymer auxiliary materials and new pharmaceutical technological methods (extrusion, spheronization). Regularity in shape and size, attained by the optimization of several production parameters, can promote the coating procedure. Under optimal conditions, particles were prepared for coating in a high-shear mixer, which is used to produce uniform particles. The effect of the rotating speed of the applied chopper and the amount of microcrystalline cellulose in the composition on the physical characteristics of the pellets was modeled by a second-order polynomial equation fitted to the data gathered by a face-centered central composite statistical design.

Administration, Oral↗
PubMed1996

[Role of mass transfer processes in drug formulation].

Authors call attention on the possibilities that drug release from solid preparations can be influenced by solubility and dissolution rate according to the clinical requirements regarding the duration of action. The therapeutic time interval may be modulated influencing the rate of absorption by controlling dissolution rate and changing the transport through the membranes. The results obtained from dissolution, absorption and efficacy studies of the evaluated active substances (magnesium oxide, metoprolol, nitrofurantoin) demonstrate the significance of mass transfer processes in the drug formulation.

Dosage Forms↗
PubMed1996

Preformulation studies of atenolol in oral liquid dosage form. I. Effect of pH and temperature.

The stability of atenolol solutions was evaluated under accelerated isothermal degradation conditions at 90 degrees C. A specific and sensitive HPLC method was adopted to study the pH dependence of the stability. The maximum stability of atenolol was achieved at pH 4. The degradation of atenolol followed first-order kinetics at 90 degrees C, pH 4 with k value of 1.1.10(-3) hour-1.

Administration, Oral↗
PubMed1990

[Preformulation study of controlled release nitrofurantoin preparations. 2].

In their previous publications the authors rendered account of preparation and stability test of products containing controlled release nitrofurantoin in circumstances of preparing and storing. Following previous publications in vitro active principle release of developed product has been investigated by rotating basket method and by applying Sartorius Dissolution tester. Absorptions of active principle and coated pharmacon have been determined by means of Sartorius Membrane transport tester. On basis of results it can be ascertained that compressed and capsuled products coated with Eudragit L 100-55 has proved to be the most suitable concerning release of active principle as well as in vitro absorption. Taking into account probability values of absorption, active principle release and absorption of product have been properly controlled and so optimal bioavailability of the preparation can be expected.

Absorption↗