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At least 37 records · Page 2Linked to original sources
PubMed2003

Pediatric drug formulations of sodium benzoate: I. Coated granules with a hydrophilic binder.

High doses of sodium benzoate are applied in the treatment of some rare metabolic disorders. In most cases children are affected who often refuse the oral uptake of sodium benzoate as a powder or in solution due to its bad taste. Therefore, small-sized, saliva-resistant microcapsules have been developed containing high doses of the drug substance. Granules were produced by roller compacting of sodium benzoate powder without any additives, by solvent-free cold extrusion and hot-melt extrusion adding poly(ethylene glycol)s of different grades. The granules with a diameter of less than 1 mm were film-coated by an ethanolic solution of Eudragit E 100. The microcapsules from hot-melt extrusion containing 25% Macrogol 4000 were most stable during the coating process and showed the highest yields. Sodium benzoate is completely released from the microcapsules within 9 min into 0.1 N HCl and 0.01 N HCl whereas dissolution into buffer pH 6.8 is different in the initial phase and completed after 14 min. The bad taste of sodium benzoate is not recognized in the buccal space for at least 5 min. The microcapsules are stable during storage for at least 6 months.

Capsules↗
PubMed2003

Advanced ash management technologies for CFBC ash.

The combustion of high-sulphur coal demands the reduction of sulphur emissions. The sorbent most often used in sulphur capture technology is calcium-based. Ashes from technologies such as circulating fluidized bed combustion (CFBC), therefore, contain high calcium levels. The use and disposal of these ashes poses challenges, because of highly exothermic reactions with water, high-pH leachates, and excessive expansion of solidified materials. This paper looks at the potential of two post-combustion ash treatment processes, CERCHAR hydration and AWDS disposal, in solving these challenges. A high-sulphur coal-derived CFBC ash is examined, after CERCHAR hydration treatment, in conjunction with a conventionally hydrated ash, in a range of chemical, geotechnical and utilization scenarios. The ashes are used to make no-cement and roller-compacted concrete as well as Ash Water Dense Suspensions (AWDS). The solidified mortar paste from no-cement concrete is subjected to an extensive geochemical examination to determine how solidification progresses and strength develops, from a chemical point of view.

Air Pollution↗
PubMed1999

Optimization of crushing strength and disintegration time of a high-dose plant extract tablet by neural networks.

Optimization of crushing strength and disintegration time of a high-dose plant extract tablet was reached after extensive experimentation. Effects of the processing parameters, like compression force and tooling, and also of the excipients were found to be significant. Best results for both disintegration time and crushing strength were obtained with a plant extract that was granulated by roller compaction before compression. To gain more information about the different effects, artificial neural networks (ANNs) and a conventional multivariate method (partial least squares [PLS]) were used for data analysis. The topologies of the neural networks of the feed-forward type were optimized manually and by pruning methods. All methods were tested for contemplated parameters, crushing strength, and disintegration time. In general, ANNs were found to be more successful in characterizing the effects that influence crushing strength and disintegration time than the conventional multivariate methods.

Chemistry, Pharmaceutical↗
PubMed2005

The effects of physical parameters on laser-induced breakdown spectroscopy analysis of intact tablets.

With the advent of the Food and Drug Administration initiatives to investigate and encourage the use of process analytical technologies, laser-induced breakdown spectroscopy (LIBS) is considered an excellent analytical tool to understand the processability of solid dosage form. In this article, the feasibility of the LIBS system for quantitation of active drug within a solid dosage form, as well as the effects of various physical parameters on its signal, is investigated. A model drug containing chlorine and sulfur was used. The examination of the specificity and reproducibility of the measurements led to the use of chlorine and carbon as the internal standard. An overall relative SD of 1.1% for the signal was found. For quantitation purposes, calibration curves using compound-X in formulated tablets were generated. It was found that curves generated from roller-compaction tablets generally gave higher LIBS signal than those generated using direct-compressed (DC) process. To investigate these differences, effect of LIBS signals from several physical properties of the tablets were examined. It was found that unmilled compound-X used in the manufacture of the tablets gave a LIBS signal 30% lower than when milled compound-X was used. However, by using multiple crushing-recompression DC process of the milled compound-X, the LIBS results were comparable with those found from both processed tablets using milled compound-X. Other physical parameters, such as wide ranges of granule size and tablet hardness found in the typical manufacturing process, had limited effect on the LIBS signal. From these results, it was noted that for accurate quantitation, it is necessary to use the same physical properties of compound-X and the same manufacturing process in the calibration standards as the actual samples.

Chromatography, High Pressure Liquid↗
PubMed1998

Effect of the granulation process on nitrofurantoin granule characteristics.

We studied four granulation methods on the same quantitative and qualitative formula: wet massing by forced agglomeration (Lödige) and free agglomeration (Glatt); and dry massing by slugging and roller compaction technique. Three different particle sizes of nitrofurantoin (bioinequivalent drug) were used. The nitrofurantoin particle size has a very low influence on the physical characteristics of the granules. The granulating process influenced the binding of the particles. Granules processed using the wet granulating method were harder than those made by dry process. Lödige granules were more bonded than Glatt granules. Granules prepared by dry massing presented broken particles. The surface area and the porosity of Glatt granules were the most important parameters. Dissolution studies must be effected to make a correlation between the physical results and the dissolution rates. It is necessary to effect a new validation and a comparison of the results when a new granulating apparatus is used.

Anti-Infective Agents, Urinary↗
PubMed1992

Development of totally implantable electromechanical artificial heart systems: Baylor ventricular assist system.

An implantable electromechanical ventricular assist system (VAS) intended for permanent use has been developed. It consists of a conically shaped pumping chamber, a polyolefin (Hexsyn) rubber diaphragm attached to a conically shaped pusher-plate, and a compact roller-screw actuator. Design stroke volume is 63 ml. The device weighs 620 g, and has a total volume of 348 ml. The pump can provide 8 L/min flow against 120 mm Hg afterload with a preload of 10 mm Hg. The inner surfaces are biolized by dry gelatin coating, with inflow and outflow ports accommodating tissue valves. Three subacute in vivo validation studies have been conducted in calves up to two weeks. The entire system functioned satisfactorily in both the fill/empty and the fixed-rate modes. There was no thromboembolic complication without anticoagulation. The pump showed reasonable anatomical fit inside the left thorax. This VAS is compact, efficient, quiet, and easy to control.

Animals↗
PubMed2003

A compaction process to enhance dissolution of poorly water-soluble drugs using hydroxypropyl methylcellulose.

The purpose of this study was to develop a technique to enhance the dissolution rate of poorly water-soluble drugs with hydroxypropyl methylcellulose (HPMC) without the use of solvent or heat addition. Three poorly water-soluble drugs, naproxen, nifedipine, and carbamazepine, were studied with low-viscosity HPMC USP Type 2208 (K3LV), HPMC USP Type 2910 (E3LV and E5LV), and methylcellulose. Polymer and drug were dry-blended, compressed into slugs on a tablet press or into ribbons on a roller compactor, and then milled into a granular powder. Dissolution testing of the milled powder was performed on USP Apparatus II, 100 rpm, 900 ml deionized water, 37 degrees C. Drug distribution vs. particle size was also studied. The compaction processes enhanced drug dissolution relative to drug alone and also relative to corresponding loosely mixed physical mixtures. The roller compaction and slugging methods produced comparable dissolution enhancement. The mechanism for dissolution enhancement is believed to be a microenvironment HPMC surfactant effect facilitated by keeping the HPMC and drug particles in close proximity during drug dissolution. The compaction methods in this study may provide a lower cost, quicker, readily scalable alternative for formulating poorly water-soluble drugs.

Carbamazepine↗
PubMed1981

Densification of powders by concavo-convex roller compactor.

By means of a concavo-convex roller compactor, several pharmaceutical powders were compressed into sheets or flakes, which then were reduced in size by an oscillating granulator to form compacted granules. Several properties (bulk density, drop density, repose angle, and flow rate) of the powders and compacted granules were determined and compared. The primary effect of the roller compactor was to increase the bulk density without a significant change in flowability. Two materials compacted at five pressures demonstrated that the bulk and drop density are linearly related to the logarithm of compaction pressure.

Powders↗
PubMed1992

A compact centrifugal pump for cardiopulmonary bypass.

A majority of the cardiopulmonary bypass (CPB) systems still utilize bulky roller pumps. A direct-drive small centrifugal pump intended for second-generation CPB pump has been developed. The pump has a 50 mm diameter impeller and provides a 6 L/min flow at 3,000 rpm against 300 mm Hg. A flexible drive shaft allows us to separate the pump head from the console resulting in easier manipulation. An in vitro study showed that the pump generated less hemolysis (index of hemolysis = 0.0011, comparable to the value for Bio-medicus BP-80). To improve blood flow around the shaft-seal region and to reduce thrombus formation around the shaft, six holes were drilled through the impeller. In biventricular bypass experiments using calves, our pump demonstrated excellent antithrombogenicity and durability for 48 h. And the compact and atraumatic centrifugal pump system showed excellent performance and easy manipulation under actual CPB conditions in animal.

Animals↗
PubMed1993

Left and right pump output control in one-piece electromechanical total artificial heart.

Left master alternate (LMA) ejection control based on the left pump fill method was implemented for a one-piece electromechanical total artificial heart (TAH). The TAH consists of left and right pusher-plate-type blood pumps sandwiching a compact electromechanical actuator comprising a direct current (DC) brushless motor and a planetary roller screw. The motor rotation is controlled on the basis of the roller-screw position as detected by a Hall effect sensor and a commutation pulse counting method. Since the pusher-plate shaft and roller screw are decoupled during filling, both pumps fill passively with the right and left atrial pressure. To obtain response to the right atrial pressure change in the LMA mode, the left fill trigger level as detected by a Hall effect position sensor is adjusted to operate the pump at a higher rate and to drive the right pump at 85-90% of the full stroke level. The in vitro evaluation demonstrated that this method can respond to right atrial pressure changes provided that the right pump is operated at less than the full stroke level. When the preload is high and the right pump goes into full stroke operation, the left eject level can be decreased to run the pump at a higher rate and to transfer more blood from the right to the left. In the in vivo evaluation, which lasted 1 week in a 95 kg calf, the left and right atrial pressures were kept within physiological ranges.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

A unique, efficient, implantable, electromechanical, total artificial heart.

A completely implantable, one piece electromechanical total artificial heart (TAH) intended for permanent human use was developed. It consisted of left and right conically shaped pusher-plate blood pumps sandwiching a thin centerpiece with a compact, efficient electromechanical actuator. The actuator consisted of a direct current brushless motor; a planetary roller screw fit the space between the two conically shaped pusher-plates. The rotational motion of the motor was converted to the rectilinear motion of the rollerscrew to displace the left and right pusher-plates in the left master alternate mode. The diameter of the assembled TAH was 97 mm, with a central thickness of 82 mm. The overall weight was 620 g, with a displaced volume of 510 ml. The pump provided flows of 3-8 L/min with a preload of 1-15 mmHg against an afterload of 100 mmHg. The net efficiency ranged from 15% to 18%. This model showed good fit in the pericardial space of heart transplant recipients (body weight, 77 kg).

Cardiac Output↗
PubMed1995

Deformation of the Stokes B2 rotary tablet press: quantitation and influence on tablet compaction.

Deformations that affect the vertical punch displacement of a Stokes B2 rotary tablet press were characterized with a cathetometer. The press deformation was found to be elastic for both the upper and lower compression roller assemblies. However, the upper and lower compression roller assemblies have different Hookian spring constants: 8.58 x 10(4) and 5.18 x 10(4) kN/m for the upper and lower assemblies, respectively. Using two-way analysis of variance, the Hookian spring constants were shown to be independent of compaction phases and lower punch penetration setting. To study the influence of press deformation on tablet compaction, the Hookian spring constants were factored into the caculation of the incremental work of compaction for dibasic calcium phosphate dihydrate and microcrystalline cellulose. As the peak compression pressure increases, the force-displacement work done on the tablet during the loading phase decreases relative to calculations that neglect press deformation. This decrease in force-displacement work was attributed to elastic press deformation, which absorbs energy during the loading phase and then releases this energy later in the compaction cycle, altering the punch-displacement profile. The rate at which the press stores and releases elastic energy depends in part upon the viscoelastic properties of the tablet. Based upon these results, the coupling between press elasticity and a tablet's viscoelastic properties should be accounted for when analyzing tablet compaction or trying to simulate the punch-displacement profile of a tablet press that deforms during compaction.

Chemistry, Pharmaceutical↗
PubMed1994

Scrapie amyloid (prion) protein has the conformational characteristics of an aggregated molten globule folding intermediate.

The scrapie amyloid (prion) protein (PrP27-30) is a host-derived component of the infectious scrapie agent; the potential to replicate, propagate, and form amyloid is a result of the posttranslational event or conformational abnormality. In low concentrations of guanidine hydrochloride (Gdn.HCl), PrP27-30 dissociates into a compact equilibrium intermediate with a substantial portion of secondary structure, partially denatured tertiary structure, and tryptophan residues in an apolar environment [Safar, J., Roller, P. P., Gajdusek, D. C., & Gibbs, C. J., Jr. (1993) J. Biol. Chem. 27, 20276-20284]. Here we describe the characteristics of this metastable form as monitored by 8-anilino-1-naphthalenesulfonate (ANS) fluorescence spectroscopy and circular dichroism (CD) spectroscopy, and we propose a mechanism for scrapie amyloid association. The Gdn.HCl-induced equilibrium intermediate of PrP27-30 had multiple high-affinity hydrophobic binding sites for ANS, some close to the Trp residues. The amide CD spectrum of an acid-induced intermediate (A-form), in equilibrium at pH < 2.0, was similar to the Gdn.HCl-induced intermediate and suggested the presence of a significant portion of an alpha-helical or beta-turn secondary structure. In contrast, the PrP27-30 associated into aggregates in an all beta-sheet conformation with less ordered and more exposed hydrophobic side chains. The noncooperative unfolding of the Gdn.HCl-induced intermediate at high temperature was irreversible and correlated with the loss of infectivity. The results demonstrate that PrP27-30 associates through a compact, metastable hydrophobic intermediate with an nonnative, nondenatured secondary structure and a tertiary structure close to the unfolded form.(ABSTRACT TRUNCATED AT 250 WORDS)

Anilino Naphthalenesulfonates↗
PubMed1983

Initial in vitro evaluation of a pediatric vortex-mixing membrane lung.

A new design for a pediatric membrane lung is described in this paper. The lung consists of eight blood compartments, each having six U-shaped blood channels, with microporous PTFE membranes supported on rigid plates in such a way that the membranes form furrowed blood channels. Two rolling diaphragm pumps are attached to the open ends of the U-shaped blood channels; these pumps are operated in antiphase. Mean flow is provided by a roller pump placed at the inlet end of the membrane lung. Pulsatile blood flow within the blood channels produces successive vortex formation and ejection, leading to good blood mixing and high efficiency in gas transport. The design of the rolling diaphragm piston pumps ensures that the blood prime volume is low (280 ml), and the grouping of the pumps at one end of the oxygenator allows the driving mechanism to be simple and compact. The relatively wide blood channels (minimum width 0.5 mm) and vortex mixing make priming the membrane lung particularly easy. The membrane area is 0.39 m2. Preliminary performance testing of the pediatric membrane lung was undertaken by pumping blood around a circuit containing a roller pump, the membrane lung, and a bubble oxygenator (to adjust the blood gases at the inlet to the membrane lung). In five such experiments it was shown that the membrane lung transferred 80 ml O2/min and 120 ml CO2/min at a blood flow rate of 1.5 L/min.

Adult↗
PubMed1992

Development of a totally implantable electromechanical total artificial heart: Baylor TAH.

A totally implantable, one-piece, electrome-chanical total artificial heart (TAH) intended for permanent human use has been developed. It consists of left and right pusher-plate pumps (63 cc design stroke volume) sandwiching a thin center piece with a compact electromechanical actuator. The pusher-plates are shaped conically to accommodate an actuator in the space between them. The actuator consists of an efficient and durable planetary roller screw and direct current brushless motor. The left master alternate pumping mode was implemented utilizing the left pump pusher-plate position signal. The blood-contacting surface was coated with a dry gelatin to yield long-term clot-free performance. Trileaflet tissue valves of 27 and 23 mm are used in the inflow and outflow ports. The diameter and thickness of the TAH are 97 and 82 mm. the overall volume is 510 cc, and the weight is 620 g. Anatomic fit was confirmed in 26 heart transplant recipients (body weight 78 kg and surface area 2 m2) without compressing adjacent organs. The pump performance study revealed that the TAH can yield outputs of 3-8 L/min against the 100 mm Hg afterload with 1-10 mm Hg filling pressure. The input power to the motor ranged from 7 to 12 W, with an efficiency of 18% to 14%. A one-week in vivo calf study demonstrated adequate performance of the TAH, particularly the regulation of atrial pressures. Good anatomic fit and good biocompatibility were also demonstrated.

Animals↗
PubMed1988

[A new mobile respiration and monitoring system for transporting critically ill patients].

This article introduces a compact versatile system that can be used when transporting high-risk patients. The equipment can be coupled to a standard hospital bed. An instrument carrier device mounted on rollers which is independent of the medical equipment manufacturer can take up every kind of storage-battery driven apparatus required for monitoring, infusion therapy and continuous drug supply, as well as an artificial respiration unit with sufficient O2 for more than 20 hours of artificial respiration. The entire setup occupies a minimum of space.

Beds↗
PubMed1994

Clinical evaluation of a new type of centrifugal pump.

The major problems with existing centrifugal pumps are leakage, mechanical trauma, and thrombus formation. In consideration of these problems, a new compact centrifugal pump system was developed. The purpose of this study was to evaluate the new centrifugal pump system clinically. Ten patients underwent open heart surgery with a centrifugal pump or a roller pump. During surgery, hemodynamic and hematological data were obtained. A pulsatile assist device in the pump circuit was used in patients with severe heart disease. There was neither operative death nor hospital mortality, and there was no difference with regard to hemodynamic data between the two groups. The centrifugal pump groups, however, had significantly lower hemolysis, especially during prolonged cardiopulmonary bypass. This centrifugal pump could also create sufficient pulsatile flow with a pulsatile assist device. Postoperative macroscopic and microscopic findings demonstrated the smooth surface of the pump without thrombus formation. This centrifugal pump system might be useful for prolonged cardiopulmonary bypass.

Adolescent↗
PubMed1973

Microcapsule artificial kidney: treatment of patients with acute drug intoxication.

The microcapsule artificial kidney was used in the treatment of three patients with acute drug intoxication. The apparatus contains 300 g. of microencapsulated activated charcoal with a total membrane area available for diffusion of more than 2m.(2) The membrane thickness is only 500 A. These properties make possible a compact artificial kidney whose efficiency for the removal of uremic metabolites and drugs is much higher than standard hemodialysis apparatus. The microcapsules are made blood-compatible by coating with human albumin. A roller pump was used to propel the blood through the microcapsule artificial kidney at a flow rate of 300 ml./min. for two to three hours. The clearance values for glutethimide, methyprylon and methaqualone were much higher than those achieved by standard hemodialysis. Hemoperfusion quickly lowered the drug level in the blood with resulting clinical improvement.

Adult↗