Stability Of Citrate Research Articles

Forced Degradation and Stability Indicating Studies for Clomifene Citrate Tablet

Pharmaceutical medications must be stable to preserve their efficacy and safety over the period of their shelf lives. Studies on force degradation are crucial for identifying probable degradation pathways and identifying extreme stresses that may lead to the breakdown of the pharmaceutical product. This report offers a thorough analysis of the force degradation tests performed on Clomifene citrate tablets. Evaluation of the effects of several stress factors, including temperature, humidity, light, and mechanical forces, on the stability of clomifene citrate is the main goal. To replicate actual storage and handling situations, the study used stress testing criteria specified by the International Conference on Harmonization (ICH). According to the study, temperature and humidity have the biggest roles in the degradation of Clomifene citrate tablets. In this article the FDS was performed by using a stainless-steel column (250 mm x 4.6 mm) packed with Butylsilane C4 (5µm) L26, detector 233nm, mobile phase; mobile Phase was prepared by mixing 550 volumes of methanol, 450 volumes of water and 3 volumes of triethylamine. Then adjust the pH to 2.5 with phosphoric acid. Flow rate; 1 mL/mint. The quantification and hyphenation of the instrumental analysis were successfully accomplished using the developed method.

Композитные магнитовосприимчивые фотокатали-заторы на основе оксидов Fe3O4/SiO2/TiO2

In the present study the composite materials based on the Fe3O4/SiO2/TiO2 oxides, synthe-sized by the sol-gel method, were investigated. At the first stage, magnetite nanoparticles were precipitated by sodium hydroxide from a mixture of aqueous solutions of iron(II) and iron(III) sulfates under continuous ultrasonic treatment, after which they were washed with distilled water and dried under vacuum. At the second stage, the resulting magnetite particles were coated with silicon oxide according to the Stober method by dispersing them under the ultrasonic treatment in a solution of tetraethoxysilane in n-propanol, followed by hydrolysis of tetraethoxysilane in the presence of aqueous ammonia, washing and drying the obtained materials under vacuum. At the third stage, photocatalytically active particles based on titanium oxide were introduced into the composite by the solvent replacement procedure via dispersing the samples in an aqueous solution of peroxotitanic acid and adding n-propanol, stirring vigorously, followed by activation based on boiling in the water/ethanol (1:1) mixture, washing and drying under vacuum. The properties of samples influenced by the citrate stabilization and separation of magnetite particles at the stage of their synthesis into “light” and “heavy” magnetic fractions, as well as calcination of samples at 450 °C, were studied. The photocatalytic properties of the synthesized samples were studied during photodegradation of methyl orange, as well as their magnetic extraction from the suspension. The physicochemical characterization of the samples was performed using a high-resolution scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray powder diffraction, thermal analysis (TG–DSC), combined with mass spectrometry of gaseous thermolysis products. It has been found that the composites based on the mixed titanium-silicon oxide have a higher photocatalytic activity than the composites based on the pure titanium dioxide obtained via a similar procedure. The resulting photocatalysts can be used to purify water from dyes, followed by their extraction using a magnet.

Nanoelectrochemistry Reveals Selective Interactions of Perfluoroalkyl Substances (PFASs) with Silver Nanoparticles

AbstractNanoelectrochemistry allows for the investigation of the interaction of per‐ and polyfluoroalkyl substances (PFASs) with silver nanoparticles (AgNPs) and the elucidation of the binding behaviour of PFASs to nanoscale surfaces with high sensitivity. Mechanistic studies supported by single particle collision electrochemistry (SPCE), spectroscopic and density functional theory (DFT) calculations indicate the capability of polyfluorooctane sulfonic acid (PFOS), a representative PFAS, to selectively bind and induce aggregation of AgNPs. Single‐particle measurements provide identification of the “discrete” AgNPs agglomeration (e.g. 2–3 NPs) formed through the inter‐particles F−F interactions and the selective replacement of the citrate stabilizer by the sulfonate of the PFOS. Such interactions are characteristic only for long chain PFAS (‐SO3−) providing a means to selectively identify these substances down to ppt levels. Measuring and understanding the interactions of PFAS at nanoscale surfaces are crucial for designing ultrasensitive methods for detection and for modelling and predicting their interaction in the environment.

Nanoelectrochemistry Reveals Selective Interactions of Perfluoroalkyl Substances (PFASs) with Silver Nanoparticles.

Nanoelectrochemistry allows for the investigation of the interaction of per- and polyfluoroalkyl substances (PFASs) with silver nanoparticles (AgNPs) and the elucidation of the binding behaviour of PFASs to nanoscale surfaces with high sensitivity. Mechanistic studies supported by single particle collision electrochemistry (SPCE), spectroscopic and density functional theory (DFT) calculations indicate the capability of polyfluorooctane sulfonic acid (PFOS), a representative PFAS, to selectively bind and induce aggregation of AgNPs. Single-particle measurements provide identification of the "discrete" AgNPs agglomeration (e.g. 2-3 NPs) formed through the inter-particles F-F interactions and the selective replacement of the citrate stabilizer by the sulfonate of the PFOS. Such interactions are characteristic only for long chain PFAS (-SO3 - ) providing a means to selectively identify these substances down to ppt levels. Measuring and understanding the interactions of PFAS at nanoscale surfaces are crucial for designing ultrasensitive methods for detection and for modelling and predicting their interaction in the environment.

Direct determination of ethanol in alcoholic beverages based on its anti-aggregation of melamine-silver nanoparticle assembly

We report a new method for determination of ethanol based on anti-aggregation of silver nanoparticles (AgNPs) in the presence of melamine. In the system, ethanol and melamine act as protecting and aggregating agents, respectively. Melamine can induce citrate-stabilized AgNPs to aggregate, leading to a color change from yellow to green. However, if the AgNPs are pre-incubated in ethanol, ethanol readily surrounds the particles by forming hydrogen bonds with the citrate stabilizer. An external nanoshell of ethanol hinders particle aggregation caused by melamine. Minor aggregation of AgNPs was observed, the solution color maintained its yellow-orange color. Higher ethanol concentrations result in a lower degree of particle aggregation. The colorimetric response of AgNPs was monitored using a UV–vis spectrophotometer at 390 nm. The current method could determine ethanol concentrations over a wide dynamic range of 5–80% (v/v), with a detection limit of 3.1% (v/v) (3SD of blank/slope). This method was applied for direct quantification of ethanol in alcoholic drinks without sample pretreatment and the results are well correlated with those of gas chromatography. Our method is convenient and cost effective, making it auspicious for ethanol monitoring in alcoholic drink manufacture and control.

Sensitive Ion-Chromatographic Determination of Citric Acid in Urine

Urine citrate analysis is relevant in the screening and monitoring of patients with calcium nephrolithiasis. A sensitive, fast, easy, and low-maintenance ion chromatographic (IC) method with conductivity detection for the analysis of urine citrate is developed and validated. Its application on true samples is also reported. Sample urine is diluted with a water solution containing internal standard (IS) before the chromatographic assay. The isocratic chromatographic run time is twenty-five minutes, using sodium hydroxide aqueous solution as the mobile phase. The method is fully validated as a quantitative method to objectively demonstrate its applicability for the intended use. The analytical response is linear in the 0.08–10.4 mmol/L concentration range. Precision and accuracy studies carried out on spiked urine and internal quality control samples reveal an imprecision CV% lower than 11% and an accuracy between 85 and 103%. The stability of citrate in urine samples is also evaluated. An easy, rapid, and low-maintenance, cost-effective IC method for urinary citrate determination is developed and validated. Internal standardization improves reliability and precision. The method has been currently used in our laboratory over recent years to analyze more than 1000 samples per year.

Fast and sensitive detection of Procainamide: Combined SERS and DFT modeling studies

In this study, a surface-enhanced Raman scattering (SERS) spectroscopic approach was developed for a trace-level detection of procainamide in an aqueous medium. Silver-based nanoparticles as active substrates were synthesized using the reduction technique in presence of a citrate stabilizer and were characterized with UV–Vis, FT-IR, and FE-SEM techniques. The SERS spectra of procainamide were collected at a wide concentration range. The vibrational bands and frequency shifts associated with the enhanced Raman signals were identified, analyzed, and assigned to respective active modes. First-principle calculations were performed to elaborate on potential substrate-drug interaction possibilities and energies at the molecular level. The intensity enhancements observed for selected SERS peaks, namely at 1246 cm−1, 1370 cm−1, 1613 cm−1 and 1661 cm−1, were further utilized for the development of a consistent and fast quantification of procainamide. The developed approach displayed an excellent sensitivity and good reproducibility. The detection limit for procainamide was successfully attained at the level of one-tenth of nanomolar concentrations corresponding to a coefficient of regression (R2) of 0.9998. The obtained results revealed that this method is promising for drug and medical applications.

Melting and phase diagram of Au-Cu alloy at nanoscale

The Au-Cu nanoalloys (NPs) were produced by NaBH4 co-reduction from the mixture precursor solution of component Au and Cu, under the protection of sodium citrate stabilizer. The Au-Cu NPs encapsulated in SiO2, Au5Cu5@SiO2 NPs, were then synthesized by the Stöber method based on the obtained Au-Cu NPs. The microstructure and particle sizes were characterized by TEM observation. The phase transition temperature of Au-Cu@SiO2 was determined by DSC measurement. The surface tension, surface segregation and surface energy of Au-Cu NPs as a function of particle size and temperature were calculated by the theoretical model based on the thermodynamic properties of pure component of Au and Cu NPs, respectively. The thermodynamic parameters of Au-Cu system at various nanoscales were optimized on the basis of experimental and theoretical results in this work and previous results in literature. Based on the obtained the thermodynamic data set, the nano phase diagrams of the Au-Cu system at nanoscale were calculated, and the thermodynamic properties of Au-Cu nanometer system were obtained. The results show that the calculated results agree well with experimental work.

3-Aminophenylboronic acid-mediated aggregation of gold nanoparticles for colorimetric sensing of iohexol in environmental and biological samples

Iohexol (IHO), as one of iodinated X-ray contrast, is often used as not only a chemical marker for tracking wastewater contamination in aquatic environment, but also an ideal glomerular filtration rate marker for explorating kidney disease. To these aims, it is important to establish reliable, fast, and cheap methods to detect IHO in environmental and biological samples. This work describes for the first time the development of a selective, sensitive and reliable colorimetric sensing assay for the fast determination of IHO in environmental and biological samples based on 3-aminophenylboronic acid (3-APBA) mediated aggregation of gold nanoparticles (AuNPs). In this approach, 3-APBA can assemble on the AuNPs surface through electrostatic interaction between its amino groups with the negatively charged citrate stabilizer of AuNPs to form AuNP@3-APBA. Subsequently, the aggregation and visual color change of the assembled AuNP@3-APBA are induced by the covalent reaction between boronic acid ligands of 3-APBA and cis-diols of IHO. The developed assay presented a very simple operating procedure and a rapid analysis time of around 10 min. The developed assay also exhibited good selectivity and a low limit of detection (LOD) of 0.005 mM for detecting IHO. Moreover, the developed assay showed comparable accuracy and precision to the high-performance liquid chromatography-diode array detector (HPLC-DAD) method when used for the rapid determination of IHO in river water and human urine samples. The recoveries of IHO at three spiking levels were in the range of 91.5–106.3% with relative standard deviation (RSD) values below 6.39%.

Study of the Stability of Citrate Capped AgNPs in Several Environmental Water Matrices by Asymmetrical Flow Field Flow Fractionation.

Asymmetrical flow field-flow fractionation (AF4) coupled to UV-Vis and dynamic light scattering (DLS) detectors in series, was tested for stability studies of dispersions of citrate-capped silver nanoparticles (AgNPs) in several water matrices. The main goal is to provide knowledge to understand their possible behavior in the environment for short times since mixturing (up to 180 min). Ultrapure (UPW), bottled (BW1, BW2), tap (TW), transitional (TrW) and sea water (SW) matrices were assayed. Observations were compatible with the aggregation of AgNPs, a change in the plasmon band and a size growth with time were done. Fractograms showed different evolution fingerprints in the function of the waters and batches. The aggregation rate order was BW2, SW, TrW, BW1 and TW, being BW2 the lowest and TW the highest. NP aggregation can be induced by increasing the salt concentration of the medium, however transitional and sea waters did not follow the rule. Both matrices presented a lower aggregation rate in comparison with other aqueous matrices with much lower ionic strength (BW1 and TW), which can be explained by the potential presence of dissolved organic matter and/or the high concentration of halides providing their stabilization and passivation, respectively. AF4 provides relevant information with respect to static DLS and UV-Vis Spectroscopy showing that at least two populations of aggregates with different sizes between them, depending on both, the mixture time for a given matrix and type of water matrix for the same time.

Synthesis and Characterization of Plasmon-Enhanced SERS Substrate Based on Au-Ag Alloy-Coated, Large-Area Photonic (Methyl Methacrylate+Styrene) Co-Polymer

Enhancement of surface-enhanced Raman scattering (SERS) by metal nanoparticles has attracted considerable interest on account of their widespread popularity of SERS-based measurements and devices ranging from life science until materials science. Current study focuses on noble metal SERS substrates with attempting to achieve high and enhanced effect by describe a plasmon-enhanced SERS substrate based on gold-silver, alloy-coated co-polymer (methyl methacrylate-styrene) colloidal sphere. Copolymer was synthesised via surfactant-free emulsion polymerization and was successfully produced a homogeneous colloidal spheres. The homogenous spheres of copolymer would promote periodic array upon fabrication and more, introducing the copolymer medium had improved the thermal degradation of the material compare to single polymer. Gold-silver alloy nanospheres was synthesised via one pot reduction method using citrate stabilizer. The nanoalloy obtained are well within the nanoscale domain (<100 nm) supported by the maximum surface plasmon resonance peak at 436 nm using UV-Visible spectroscopy. The perfect combination of our proposed alloy nanoparticles and copolymer present an ability to enhance Raman scattering by higher than 90 %. The region of high electron density of the substrate is expected to develop a new opportunities for SERS detections in wide analytical area.

The Citrus Flavonoid Naringenin Protects the Myocardium from Ageing-Dependent Dysfunction: Potential Role of SIRT1.

Sirtuin 1 (SIRT1) enzyme plays a pivotal role in the regulation of many physiological functions. In particular, it is implicated in ageing-related diseases, such as cardiac hypertrophy, myocardial infarct, and endothelial dysfunction; moreover, its expression decreases with age. Therefore, an effective strategy to extend the lifespan and improve cardiovascular function is the enhancement of the expression/activity of SIRT1 with exogenous agents. The Citrus flavonoid naringenin (NAR) presents structural similarity with the natural SIRT1 activator resveratrol. In this study, we demonstrate through in vitro assays that NAR significantly activates SIRT1 enzyme and shows antisenescence effects. The binding mode of NAR into SIRT1 was detailed investigated through in silico studies. Moreover, chronic administration (for six months) of NAR (100 mg/kg/day) to 6-month-old mice leads to an enhancement of SIRT1 expression and a marked reduction of reactive oxygen species production in myocardial tissue. Furthermore, at the end of the treatment, the plasma levels of two well-known markers of cardiovascular inflammation, TNF-α and IL6, are significantly reduced in 12-month-old mice treated with NAR, as well as the cardiovascular risk (total cholesterol/HDL ratio) compared to control mice. Finally, the age-associated fibrotic remodeling, which is well detected through a Mallory trichrome staining in the vehicle-treated 12-month-old mice, is significantly reduced by the chronic treatment with NAR. Moreover, an improvement of myocardium functionality is highlighted by the enhancement of citrate synthase activity and stabilization of the mitochondrial membrane potential after NAR treatment. Taken together, these results suggest that a nutraceutical approach with NAR may have positive impacts on many critical hallmarks of myocardial senescence, contributing to improve the cardiac performance in aged subjects.

Kinetic study of functionalization of citrate stabilized silver nanoparticles with catechol and its anti-biofilm activity

Silver nanoparticles (Ag-NPs) and catechol are extensively used in various purposes for the benefits of human needs. Thus, functionalization of Ag-NPs with catechol is demanding for better prospects but a difficult task. In this paper, we have attempted to functionalize Ag-NPs indirectly and report the functionalization of citrate-capped Ag-NPs (cit-Ag-NPs), which was prepared by the citrate reduction and stabilization method, with catechol in the aqueous solution. The change of surface Plasmon resonance (SPR) of cit-Ag-NPs at 443 nm was monitored in the presence of the catechol using time-scan UV–Vis spectroscopy. The study evidences that the catechol molecules interact kinetically with the surface adsorbed citrate ions without the onset of any aggregations. The actual rate of the functionalization was determined to be 2.52 m−1 s−1. The optimum concentration of the catechol for functionalization of cit-Ag-NPs under study is 35μM. The particle sizes determined using a transmission electron microscope (TEM) of cit-Ag-NPs in absence and presence of catechol, are nearly equal to 51 ± 1 nm. The neutral catechol forms association complex with the surface adsorbed citrate ions through H-bonds, and the evaluated association constant is found to be (4.61 ± 0.5)×107 M−1. The catechol functionalized cit-Ag-NPs show significant anti-biofilm activity against gram-negative Pseudomonas aeruginosa and gram positive Bacillus subtilis bacteria. So, cit-Ag-NPs coupled with catechol molecules would be the attractive material for the purposes they have been independently employed.

Size-Selective Electrophoretic Deposition of Gold Nanoparticles Mediated by Hydroquinone Oxidation.

Here we describe the size-selective, hydroquinone (HQ)-mediated electrophoretic deposition of 4 and 15 nm diameter citrate-stabilized Au nanoparticles (NPs) onto a glass/indium-tin-oxide (ITO) electrode. Protons liberated from HQ during electrochemical oxidation at the Au NP surface during collisions with the glass/ITO electrode lead to Au NP deposition through neutralization of the citrate stabilizer surrounding the Au NPs, protonation of the glass/ITO electrode, or some combination of the two. Interestingly, the 4 nm Au NPs deposit at about 300-400 mV more negative potential than that of 15 nm diameter Au NPs because of faster HQ oxidation kinetics at the 4 nm NPs, leading to lower overpotentials. This allows for selective deposition of the 4 nm Au NPs over 15 nm Au NPs in a solution containing a mixture of the two by controlling the electrode potential. Controlled pH experiments indicate that significant NP deposition occurs on glass/ITO at a pH of ∼3, giving insight into the local pH needed from HQ oxidation in order to deposit the Au NPs. Experiments performed at different ionic strengths confirm that migration is a major mode of mass transport of the NPs to the glass/ITO. Long deposition times lead to films of densely packed Au NPs that are mostly free from NP-NP contact, indicating that some electrostatic repulsion between the NPs remains during the deposition. This simple method of Au NP deposition may find use for separation of Au NPs and electrode device preparation for a variety of sensor and electrocatalysis applications.

Rapid and sensitive surface‐enhanced resonance Raman spectroscopy detection for norepinephrine in biofluids

AbstractNorepinephrine (NE) is a kind of catecholamine neurotransmitter that participates significant function in living organism. Rapid and sensitive detection target in complex system is crucial in analytical science. A facile ferric citrate (CA‐Fe (III)) sensor was designed successfully for sensitive detection of NE by surface‐enhanced resonance Raman spectroscopy (SERRS) method. This CA‐Fe (III) sensor was prepared by modifying Fe (III) on the surface of uniform Au nanoparticles (NPs) wrapped with citrate (CA) stabilizer. The implementation of NE selective detection is attributed to significant enhancement provided by Au NPs and additional enhancement provided by ligand‐to‐metal charge transfer between chromophore and analyte. In addition, a universal CH3OH, HCl, and petroleum ether added in sequence pretreatment method was developed and applied to purify and enrich the target in practical biological sample, realizing selective detection of NE in biofluids. This novel sensor combined with SERRS and pretreatment strategy not only amplifies the Raman signal of NE but also paves the way for pretreating sample in complex system.

Density, Structure, and Stability of Citrate3– and H2citrate– on Bare and Coated Gold Nanoparticles

We simulate the packing of citrate3– and H2citrate– onto gold nanoparticles (AuNPs) to understand how citrate anions cap and stabilize AuNPs. We determine the molecular configurations of citrate on 4, 6, and 8 nm AuNP surfaces as a function of charge state and packing density and find that both the distribution of configurations and maximum packing density are independent of AuNP size. A combination of molecular dynamics simulations and in situ Fourier transform infrared spectroscopy (FTIR) is employed to compare the molecular configurations, stability, and density of citrate on 4 nm citrate-coated (cit-AuNPs) and within polycation-wrapped 4 nm cit-AuNPs. FTIR experiments indicate the presence of H2citrate– within polycation-wrapped cit-AuNPs with coordination between the H2citrate– layer and polycation layer in agreement with simulations. Intermolecular hydrogen bonding between terminal carboxylic acid groups of H2citrate– stabilizes the anionic layer at the interface between cit-AuNPs and adsorbing char...

STABILITY OF SYNTHESIZED SILVER NANOPARTICLES IN CITRATE AND MIXED GELATIN/CITRATE SOLUTION

The study focuses on an investigation of the influence of both citrate and mixed gelatin/citrate as a reductant and stabilizer on the colloidal stability of silver nanoparticles (AgNPs)synthesized by a chemical reduction of Ag<sup>+</sup> ions after a short - (7th day) - and long - (118th day) - term storage. Formed AgNPs were characterized by a UV–vis Spectroscopy, Transmission Electron Microscope (TEM), Dynamic light scattering (DLS) and Zeta-potential (ZP). The obtained results revealed that a short-term stability of the synthesized AgNPs was greatly influenced by a citrate stabilizer with the absence of gelatin. Smaller-sized AgNPs (average particle diameter of 3 nm), roughly spherical in a shape, were obtained with a narrow size distribution. The very negative value of the Zeta-potential confirmed a strong stability of the citrate capped AgNPs. However, a surface coating of the AgNPs by a gelatin/citrate stabilizer was found to be a dominant contributor in improving a long-term stability of the AgNPs (average particle diameter of 26 nm). The use of gelatin in mixed stabilizer solution provided the AgNPs with higher monodispersity and a controllable size after both the short and long-term storage.

Multifunctional hybrid nanoconstruct of zerovalent iron and carbon dots for magnetic resonance angiography and optical imaging: An In vivo study

In magnetic resonance imaging (MRI), gadolinium (Gd) complexes are very often used as contrast agents to enhance the signal from soft tissue deformities and vascular anomalies, to improve the accuracy of diagnosis. The safety concern of using Gd complexes in renally compromised patients pose limitations on its application. To overcome this scenario, we introduce a nontoxic zerovalent iron based nanoparticle as a novel contrast agent for MR angiography and a hybrid version of the same to serve as a dual function contrast agent for targeted liver imaging. The synthesized zerovalent iron (ZVI) nanoparticles after citrate stabilization (C@ZVI) had an average size of 10 nm and exhibited paramagnetic property which is a prerequisite for a positive MRI contrast agent. The longitudinal magnetic relaxivity, r1 of C@ZVI was 4.93 mM−1s−1 which is much higher than that of clinically used Gd based agent, gadoterate meglumine (3.6 mM−1s−1). For multimodal imaging of the liver, initially the ZVI nanoparticle was tailored with a highly liver specific polysaccharide pullulan, and later with fluorescent carbon dots (Cdts) facilitating both optical and MR imaging. The magnetic relaxivity was retained in P@ZVI-Cdts for T1 contrast imaging with an r1 value of 3.48 mM−1s−1. The in vivo MR angiogram using C@ZVI and the liver targeted MRI and optical imaging using P@ZVI-Cdts were successfully demonstrated proving their potential as MRA contrast agent and a liver specific multimodal imaging agent.

Tailoring the Synthesis of LnF3 (Ln = La-Lu and Y) Nanocrystals via Mechanistic Study of the Coprecipitation Method.

Here, 15 LnF3 nanocrystals are synthesized using coprecipitation method with citrate stabilization to allow the fast, easy, and reproducible synthesis of several nanoscaled structures in water. General trends related to the behavior of LnF3 nanocrystals are highlighted due to their broad range of application in several fields (e.g., medical applications). The same nature for all Ln3+ cations is expected due to the internal role of f orbitals. However, we found that the use of different lanthanide elements is crucial in the final size, shape, assembly, and crystalline structure. In addition, the decrease of the cation size of the lanthanide series changes the behavior of these compounds, resulting in hexagonal, orthorhombic, and cubic crystalline structures. In addition, we are able to tune the cubic crystalline phase to pure orthorhombic by modifying the pH of the system using HBF4 instead of tetramethylammonium citrate. Via 11B NMR, we demonstrated the mechanism of HBF4 as fluorinating agent if an additional source of F- is not added during the synthesis. 1H NMR and IR techniques were performed to unravel the picture of the surface chemistry of the two representative metal cations (Y and La). Finally, HRTEM and SAED were performed to uncover the shape of the obtained nanocrystals and the preferential orientation of the assembled particles, giving crucial information on the involved mechanisms. This study reveals not only the dependence of the crystalline structure on the used metal and pH but also ability to achieve LnF3 assembled particles depending on the final shape and temperature.

Formulation and Clinical Evaluation of Orphenadrine citrate as a Plain Tablet

Orphenadrine is an anticholinergic ,antimuscarinic , centrally acting skeletal muscle relaxant .It presents in the form of citrate and HCl salts which are used in treatment of the symptoms of mild Parkinson's disease and also it is used as adjuvant with other drugs in the therapy .
 Many trials were made to formulate Orphenadrine citrate as a plain tablet using wet granulation or direct compression technique in order to get a satisfactory formula through studying the effect of various factors such as binders , diluents and disintegrants types .
 The best formula was obtained by using Poly Vinyl Pyrolidine (PVP) as a binder also the results indicated that starch and mannitol gave acceptable physical properties to the tablets when they were used as diluents . At the same time , the results showed that Avicel which was used as a disintegrant gave an acceptable disintegration and dissolution time in comparison with the reference tablet DISIPAL Ò. In addition , the selected formula was used to study the effect of method of incorporation of disintegrant on the physical properties of tablets .It was found that the intragranular incorporation resulted in a shorter disintegration and dissolution times .The stability of Orphenadrine citrate prepared tablets was also studied upon storage at 50°C, 60°C and 70°C for four months .The drug was fairly stable and the expiration date for the prepared tablet was considered to be equal for 5 years .On the other hand , the results of clinical study on patients suffering from Parkinson's disease indicated that patients with tremor (regular rhythmic oscillation of extremities especially hand and finger ) and mild symptoms of Parkinson's disease showed a good response to the prepared tablets , but it had no effect on patients of dystonia ( fixed upward gaze , neck twisting ,clenching jaws ) and akinesia ( slow down of movement of voluntary muscle and difficulty of initiation of movement ).
 The overall results of this study indicate that the drug can be prepared as tablets , which fit the requirements of British Pharmacopoeia since the prepared tablets gave satisfactory results .