Spectrophotometric determination of tizanidine and orphenadrine via ion pair complex formation using eosin Y

A simple, sensitive and rapid spectrophotometric method was developed and validated for the determination of two skeletal muscle relaxants namely, tizanidine hydrochloride (I) and orphenadrine citrate (II) in pharmaceutical formulations. The proposed method is based on the formation of a binary complex between the studied drugs and eosin Y in aqueous buffered medium (pH 3.5). Under the optimum conditions, the binary complex showed absorption maxima at 545 nm for tizanidine and 542 nm for orphenadrine. The calibration plots were rectilinear over concentration range of 0.5-8 μg/mL and 1-12 μg/mL with limits of detection of 0.1 μg/mL and 0.3 μg/mL for tizanidine and orphenadrine respectively. The different experimental parameters affecting the development and stability of the complex were studied and optimized. The method was successfully applied for determination of the studied drugs in their dosage forms; and to the content uniformity test of tizanidine in tablets

Synthesis and characterization of 1,4,8,11-tetraazacyclotetradecane carrying poly(p-chloromethyl styrene-ethylene glycol dimethacrylate) microbeads and its metal ion-chelated forms

Poly (p-chloromethyl styrene-ethylene glycol dimethacrylate) polymeric microbeads, poly (p-CM S-EGDMA), with an average size of 186 mum were synthesized by the suspension polymerization of p-CMS conducted in an aqueous medium. To increase the rigidity of the polymeric microbeads, EGDMA monomer was added to polymerization medium in the 25% for the cross-linking. 1,4,8,11-Tetraazacyclotetradecane ligand was reacted with polymer active groups that was p-CMS under a nitrogen atmosphere for 18 h at 65degreesC. The maximum cyclam attachment was found 2.24 mmol/g polymer using an elemental analyser. Fourier transform infrared (FT-IR) spectrophotometer, thermogravimetric analyser (TGA) and differential scanning calorimeter (DSC) were used to characterize the plain, ligand modified microbeads and metal ion-chelated microbeads. TGA and DSC characterization of modified microbeads showed that stability of cyclam was increased attaching onto the polymer and metal ion-chelated form of the cyclam-modified polymer were more stable at high temperature for different applications. (C) 2002 Elsevier Science B.V. All rights reserved

Selectivity of cyclam modified poly (p-chloromethyl styrene-ethyleneglycol dimethacrylate) microbeads for Cu(II), Ni(II), Co(II) and Zn(II)

Poly (p-chloromethyl styrene-ethyleneglycol dimethacrylate) polymeric microbeads, poly(p-CMS-EGDMA), with an average size of 186 mu m were synthesized by the suspension polymerization of p-chloromethyl styrene conducted in an aqueous medium. 1,4,8,11-Tetraazacyclotetradecane (cyclam) was reacted with polymer active group under the nitrogen atmosphere for 18 h at 65 degrees C. Fourier transform infrared spectrometer (FT-IR) and elemental analyzer were used to characterize the plain and cyclam modified microbeads. The affinity of the cyclam modified poly(p-CMS-EGDMA) microbeads for some metal ions was examined. The adsorption/desorption behaviour of the modified microbeads from aqueous solution containing different amount of metal ions (0.05-20 mM) at different pH values (2.0-7.0) was studied. The uptake of metal ions onto the modified poly(p-CMS-EGDMA) microbeads from solution containing a single metal ions were found to be 232.1, 119.2, 132.1, and 116.8 mg g(-1). polymer for Cu(II), Zn(II), Ni(II), and Co(II), respectively. More than 95% of the adsorbed metal ions were desorbed for 48 h in desorption medium containing 3 M HNO3. Poly(p-CMS-EGDMA) co-polymeric microbeads containing cyclam ligand were found to be suitable for repeated use without noticeable loss of adsorption capacity. The selectivity of metal ions was found in the order of Cu(II) >> Ni(II) > Zn(II) > Co(II). The recovery of different metal ions in the competitive medium is really high for Cu(II), Co(II), Ni(II), and Zn(II) besides the other metal ions namely Cr(III), Pb(II), Cd(II), and Mn(II) at pH 5.0 and also pH 2.0. (C) 2005 Elsevier B.V. All rights reserved

Investigation of surface properties of biodegradable albumin microspheres via phagocytosis phenomena

The phagocytosis of biodegradable albumin (Alb) microspheres by peripheral blood cells (neutrophils and monocytes) and mouse macrophage cells (peritoneal and lung macrophages) as a carrier matrix in drug targeting applications was investigated. Glutaraldehyde crosslinking was used to produce albumin microspheres with different sizes. Plain (nonmodified) microspheres with diameters of 1, 2, and 4 pm were cultured with cells and their uptake was determined as 8, 5, and 1 particles/cell, respectively. Albumin microspheres (2 pin diameter) were also modified with various opsonization and passivation agents, such as fibronectin (Fn), amicasine, and poly(ethylene glycol) (PEG). Plain, Alb-PEG, Alb-Fn, and Alb-amicasine microspheres were phagocytized by monocytes and neutrophils and the number of particles taken up by each cell significantly increased for Alb-Fn microspheres with respect to the plain microspheres. No significant phagocytosis was observed for Alb-PEG microspheres. The number of particles taken up by each cell was less than the plain and amikacin modified albumin microspheres. Almost zero uptake was obtained for the phagocytosis of Alb-PEG microspheres with lung and peritoneal macrophages. For phagocytosis of plain and other modified particles by the macrophages, although the number of particles taken up by each cell increased with respect to those with neutrophils and monocytes, similar tendencies were also obtained

1,4,8,11-tetraazacyclotetradecane bound to poly(p-chloromethylstyrene-ethylene glycol dimethacrylate) microbeads for selective gold uptake

Poly(p-chloromethylstyrene-ethylene glycol dimethacrylate) (poly(p-CMS-EGDMA)) polymeric microbeads, with an average size of 186 mum were synthesized by the suspension polymerization of p-CMS in an aqueous medium. To increase the rigidity of the polymeric microbeads EGDMA monomer was added to polymerization medium at 25% for cross-linking. 1,4, 8,11-Tetraazacyclotetradecane (cyclam) was reacted with p-CMS under nitrogen atmosphere for 18 h at 65 degreesC. Fourier transform infrared (Fr-IR) spectrophotometry, thermogravimetric analysis (TGA) and elemental analysis were used to characterize the plain and ligand-attached microbeads structures. The affinity of the cyclam-attached poly(p-CMS-EGDMA) microbeads for gold ions were used to test the adsorption/desorption behavior from aqueous media containing different concentrations of gold (0.05-10 mM) at different pH values (2.5-5.0). The uptake of gold ions onto the poly(p-CMS-EGDMA) microbeads from solution was 6.18 mmol g(-1). More than 95% of the adsorbed gold ion was desorbed over 48 h in a desorption medium containing 0.8 M thiourea in 3 M HCl. Poly(p-CMS-EGDMA) co-polymeric microbeads containing the cyclam ligand were found to be suitable for repeated use without noticeable loss of adsorption capacity. The selective adsorption of gold onto the microbeads at pH 3.0 was very high compared to Cu(II), Ni(II), Co(II) and Zn(II). (C) 2002 Elsevier Science B.V. All rights reserved

Immobilization of catalase in poly(isopropylacrylamide-co-hydroxyethylmethacrylate) thermally reversible hydrogels

WOS: 000082364300021Catalase was entrapped in thermally reversible poly (isopropylacrylamide-co-hydroxyethyl-methacrylate) (pNIPAM/HEMA) copolymer hydrogels. The thermoresponsive hydrogels, in cylindIl-rical geometry, were prepared in an aqueous buffer by redox polymerization. It was observed that upon entrapment, the activity retention of catalase was decreased between 47 and 14%, and that increasing the catalase loading of hydrogel adversely affected the activity. The kinetic behaviour of the entrapped enzyme was investigated in a batch reactor. The apparent kinetic constant of the entrapped enzyme was determined by the application of lMichaeiis-Menten model and indicated that the overall reaction rate was controlled by the substrate diffusion rate through the hydrogel matrix. Due to the thermoresponsive character of the hydrogel matrix, the maximum activity was achieved at 25 degrees C with the immobilized enzyme. The K-m value for immobilized catalase (28.6mM) was higher than that of free enzyme (16.5mM). Optimum pH was the same for both free and immobilized enzyme. Operational, thermal and storage stabilities of the enzyme were found to increase with immobilization. (C) 1999 Society of Chemical Industry

Conjugates of Poly(N-isopropyl acrylamide-co-acrylic acid) with alanine monopeptide, dipeptide, and tripeptide

A random copolymer of N-isopropyl acrylamide (NIPAAm) and acrylic acid (AAc) with an AAc content of 3.1 +/- 0.19 mmol of carboxylic acid groups per gram of the copolymer and with a number-average molecular weight of 1400 was synthesized by free-radical polymerization with 2,2'-azoisobutyronitrile in dimethylformamide. Then, monopeptide, dipeptide, and tripeptide (i.e., alanine) conjugates of this copolymer were prepared with their carboxyl-end-protected (with methyl ester hydrochloride) form of alanine, with a water-soluble carbodiimide. Of the carboxylic acids, 93, 69, and 57% were conjugated (loaded) with alanine at the monopeptide, dipeptide, and tripeptide conjugation steps, respectively. The chemical structures of the copolymer and conjugates were analyzed by Fourier transform infrared and H-1-NMR, which revealed the conjugate formation. Amino acid conjugation caused significant decreases in the lower critical solution temperatures (LCST) of the copolymer, especially at pH 7.4. The LCST values of the dipeptide and tripeptide conjugates of poly(NIPAAm-co-AAc) at both pH 4.0 and 7.4 shifted to significantly higher temperatures. (C) 2003 Wiley Periodicals, Inc

Primary non-hodgkin lymphoma of breast in a patient with rectal carcinoma and magnetic resonance spectroscopic examination

A 62-year-old woman being treated for stage IIIC rectal. adenocarcinoma was diagnosed with primary non-Hodgkin lymphoma of the breast after a 4-year follow-up. This case illustrates the importance of close and Long-term follow-up as well as of differential diagnostic procedures for second primary malignancies after the initial diagnosis and treatment of a solid tumor. (c) 2004 Elsevier Ltd. All rights reserved