Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0085631 (agitation)
 12,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Self-emulsifying drug delivery systems (SEDDSs) represent a possible alternative to traditional oral formulations of lipophilic compounds. In the present study, a lipophilic compound, WIN 54954, was formulated in a medium chain triglyceride oil/nonionic surfactant mixture which exhibited self-emulsification under conditions of gentle agitation in an aqueous medium. The efficiency of emulsification was studied using a laser diffraction sizer to determine particle size distributions of the resultant emulsions. An optimized formulation which consisted of 25% (w/w) surfactant, 40% (w/w) oil, and 35% (w/w) WIN 54954 emulsified rapidly with gentle agitation in 0.1 N HCl (37 degrees C), producing dispersions with mean droplet diameters of less than 3 microns. The self-emulsifying preparation was compared to a polyethylene glycol 600 (PEG 600) solution formulation by administering each as prefilled soft gelatin capsules to fasted beagle dogs in a parallel crossover study. Pharmacokinetic parameters were determined and the absolute bioavailability of the drug was calculated by comparison to an i.v. injection. The SEDDS improved the reproducibility of the plasma profile in terms of the maximum plasma concentration (Cmax) and the time to reach the maximum concentration (tmax). There was no significant difference in the absolute bioavailability of WIN 54954 from either the SEDDS or the PEG formulations.
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PMID:Self-emulsifying drug delivery systems: formulation and biopharmaceutic evaluation of an investigational lipophilic compound. 158 15

The stability of oversaturated solutions of the highly lipophilic molecule deltamethrin under the conditions of continuous agitation and oxygenation by air bubble flow in a toxicologic test on fish embryos was studied. In polyethylene, glass, and Teflon containers, the 24-hr adsorption rate of 1 mg/l solutions was over 80%. Improvement by Sharon and Solomon's PEG-glass pretreatment did not exceed a small percentage. After agarose precoating, the adsorption rate in the glass or polyethylene containers was reduced to about 20%. The stabilizing effect of precoating agarose containers diminished with the concentration of the solution.
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PMID:Stabilization of oversaturated aqueous solutions of deltamethrin, a highly lipophilic molecule. 769 34

Poly (ethylene glycol) (PEG) conjugation masks the protein's surface and increases the molecular size of the polypeptide, thus preventing the approach of antibodies or antigen processing cells and reducing the degradation by proteolytic enzymes. Proteins are readily denatured by numerous stresses arising in solution (e.g., heating, agitation, freezing and pH changes) or by chemical reactions (e.g., hydrolysis and deamidation), many of which are mediated by water. Lyophilization is most commonly used to prepare dehydrated proteins, which, theoretically, should have the desired long-term stability at ambient temperatures. Through Raman spectroscopy, differential scanning calorimetry (DSC) associated with the determination of water content by Karl Fisher titration, it was observed that after the modification of BSA-PEG in a ratio of 1:0.25 showed lower degree of structural alterations and consequently lower variation on the physical-chemical characteristics when it was compared to BSA-PEG (1:0.5). Moreover, the BSA-PEG (1:0.25) optimizes the conditions during the lyophilization process and storage of the protein.
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PMID:Effect of lyophilization on the structure and phase changes of PEGylated-bovine serum albumin. 1618 7

Biodegradable thermosensitive poly (DL-lactide-co-glycolide-b-ethylene glycol-b-DL-lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymers with DL-lactide/glycolide molar ratio ranging from 6/1 to 15/1 were synthesized from monomers of DL-lactide, glycolide and polyethylene glycol and were evaluated for sustained release of bee venom peptide in vitro. The resulting copolymers are soluble in water to form free flowing fluid at room temperature but become hydrogels at body temperature. The gelation temperature of the copolymer solutions can be influenced by the concentration and DL-lactide/glycolide molar ratio of the copolymers. The release of bee venom peptide from the copolymer-based hydrogel and hydrogel degradation in the phosphate buffer (pH 7.4) was studied at 37 degrees C under agitation. Bee venom peptide was released from the copolymer-based hydrogels over 40 days in vitro and the variation of DL-lactide/glycolide molar ratio in the PLGA block of the copolymer did not significantly affect the release rate of bee venom peptide (P > 0.05). The hydrogels undergo slower degradation and then faster degradation rate during the whole release stage. Accordingly, the mechanism of bee venom peptide was Fickian diffusion during initial stage and then may be a combination of diffusion and degradation. The synthesized copolymers have the advantage of gelation temperature over the ReGel system. These results indicate that the PLGA-PEG-PLGA copolymer-based hydrogel could be a promising platform for sustained delivery of bee venom peptide.
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PMID:Sustained release of bee venom peptide from biodegradable thermosensitive PLGA-PEG-PLGA triblock copolymer-based hydrogels in vitro. 1659 59

In this study, immobilized Pseudomonas aeruginosa PU21 beads were used as an adsorbent for lead(II). Different weight percentages of chitosan were added to polyethylene glycol (PEG, 0.5 wt.% in aqueous solution) and alginate (18 wt.% in aqueous solution), and then blended or cross-linked using different concentrations of epichlorohydrin (ECH) to prepare beads of different sizes and increased mechanical strength. Before blending or cross-linking, different weight percentages of P. aeruginosa PU21 were added to increase lead(II) adsorption. Subsequently the optimized bead composition (concentration of ECH, percentages of chitosan and P. aeruginosa PU21) and the optimum adsorption conditions (agitation rate and pH in the aqueous solution) were ascertained. Finally, the optimized beads adsorbing lead(II) were regenerated by 0.1M aqueous HCl solutions and the most effective desorption agitation rate was ascertained. The results indicate that the reuse of immobilized P. aeruginosa PU21 beads was feasible. In addition, the equilibrium adsorption, kinetics, changes in the thermodynamic properties of adsorption of lead(II) on optimized beads were also investigated.
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PMID:Adsorption and recovery of lead(II) from aqueous solutions by immobilized Pseudomonas Aeruginosa PU21 beads. 1681 63

The aim of this study was to prepare biodegradable sustained release magnetite microspheres sized between 1 to 2 microm. The microspheres with or without magnetic materials were prepared by a W/O/W double emulsion solvent evaporation technique using poly(lactide-co-glycolide) (PLGA) as the biodegradable matrix forming polymer. Effects of manufacturing and formulation variables on particle size were investigated with non-magnetic microspheres. Microsphere size could be controlled by modification of homogenization speed, PLGA concentration in the oil phase, oil phase volume, solvent composition, and polyvinyl alcohol (PVA) concentration in the outer water phase. Most influential were the agitation velocity and all parameters that influence the kinematic viscosity of oil and outer water phase, specifically the type and concentration of the oil phase. The magnetic component yielding homogeneous magnetic microspheres consisted of magnetite nanoparticles of 8 nm diameter stabilized with a polyethylene glycole/polyacrylic acid (PEG/PAA) coating and a saturation magnetization of 47.8 emu/g. Non-magnetic and magnetic microspheres had very similar size, morphology, and size distribution, as shown by scanning electron microscopy. The optimized conditions yielded microspheres with 13.7 weight% of magnetite and an average diameter of 1.37 microm. Such biodegradable magnetic microspheres seem appropriate for vascular administration followed by magnetic drug targeting.
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PMID:Process and formulation variables in the preparation of injectable and biodegradable magnetic microspheres. 1740 8

The objectives of this study were to investigate the potential interactions between the model protein drug (bee venom peptide, BVP) and thermosensitive poly(dl-lactide-co-glycolide-b-ethyleneglycol-b-dl-lactide-co-glycolide) (PLGA-PEG-PLGA) copolymers and to examine the drug-copolymer interactions on the in vitro drug release and hydrogel degradation. The PLGA-PEG-PLGA copolymers were synthesized by ring-opening copolymerization of dl-lactide and glycolide with PEG as an initiator. Drug-copolymer co-precipitate blends were prepared and analyzed by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) to characterize the specific interactions between drug and copolymer. For the better understanding the drug-copolymer interactions on drug release, insulin was selected for comparison. The release of the two protein drugs from the copolymer-based hydrogels and hydrogel degradation was studied at 37 degrees C under agitation. The results of FTIR and XRD indicated that the hydrogen bonding interactions existed between the NH group of BVP and CO group of the copolymers. The insulin and BVP released from the copolymer hydrogel over 15 and 40 days, respectively. The BVP-copolymer interactions retarded the BVP release rate and degradation of hydrogel, but did not significantly affect the biological activity of BVP. These results indicate that the drug-copolymer interactions need to be considered when attempting to use PLGA-PEG-PLGA hydrogels as sustained delivery carriers of protein or peptide drugs.
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PMID:Effect of bee venom peptide-copolymer interactions on thermosensitive hydrogel delivery systems. 1762 39

A simple and efficient method for concentration of enteroviruses from water sample was established based on the membrane adsorption-elution method combined with eluant concentration. By means of real-time RT-PCR, microporous filters with various nominal pores and materials were compared; the membrane elution method was modified; the effect of PEG on virus recovery was studied; the optimal method was determined at last. In view of the virus recovery and cost, cellulose mixed-ester microporous filter with nominal pore size of 0.22 microm was superior to other filters. Magnetism agitation was used for membrane elution and the optimal final mass concentration of PEG was 130 g/L in eluant concentration step. The recovery of virus was studied in every step in various seeding viruses. The method was tested in surface water, secondary effluent and sewage seeded with viruses. The results showed that the modified method was reliable and suitable for separation and concentration of enteroviruses from various water samples.
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PMID:[Study on membrane adsorption-elution method for concentration of enteroviruses from environmental waters]. 1789 67

Thermosensitive PLGA-PEG-PLGA triblock copolymers with the DL-lactide/glycolide molar ratio ranging from 6/1 to 15/1 were synthesized by bulk copolymerization of DL-lactide, glycolide and PEG1500. The resulting copolymers are soluble in water to form a freely flowing fluid at room temperature but become hydrogels at body temperature. The release of IL-2 from the copolymer-based hydrogel in the phosphate buffer (pH 7.2) was studied at 37 degrees C under agitation. IL-2 was released from the copolymer-based hydrogels over 20 days in vitro and the release rate decreased with increasing copolymer concentration. The change of DL-lactide/glycolide molar ratio in the PLGA block of the copolymer had little effect on the IL-2 release. The released IL-2 remained 57-90% of its original activity during the release period. To evaluate the anti-tumor effect of the IL-2 loaded copolymer, solutions were injected subcutaneously to H22 tumor-bearing mice. IL-2 loaded copolymer hydrogel for in vivo use showed good anti-tumor effect. These results indicate that the thermosensitive PLGA-PEG-PLGA triblock copolymers could be a promising platform for sustained delivery of IL-2.
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PMID:Injectable thermosensitive PLGA-PEG-PLGA triblock copolymers-based hydrogels as carriers for interleukin-2. 1827 Dec 99

Gastroretentive drug delivery systems (GRDDS) of Ranitidine hydrochloride (RHC) has been designed based on the osmotic technology, with the floating and swelling features in order to prolong the gastric retention time. The developed system consisted of osmotic core (containing drug, osmotic agent and hydrophilic polymers), coated with semipermeable membrane (SPM) which is then further coated with compression coating of gelling agent (HPMC K4M) containing gas generating agent (citric acid). All the developed formulations were evaluated for floating lag time, duration of floating, drug content and in-vitro drug release profile. Formulation variables like levels of hydrophilic polymer (0-18.26%w/w), type of plasticizer (PEG-400, Dibutyl phthalate), coat thickness of SPM (60-100 microm), were found to affect the drug release from the developed formulations. Drug release was directly proportional to hydrophilic nature of plasticizer but inversely proportional to the levels of hydrophilic polymer and coat thickness of SPM. Drug release from developed formulations was independent of level of gas generating agent in compression coat, pH and agitation intensities of release media but dependent on osmotic pressure of the release media. All the developed formulation showed floating lag time of less than 2 min (desired) and were floated for more than 12 hr. Floating lag time was inversely related to level of citric acid in compression coat and directly related to the density of the developed formulations. The manufacturing procedure was found to be reproducible and formulations were stable after 3 months accelerated stability study. Prediction of steady state levels showed the plasma concentrations of RHC to be within desired range.
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PMID:Gastroretentive drug delivery system of Ranitidine hydrochloride based on osmotic technology: development and evaluation. 1885 5


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