Effect of glucosamine HCl on dissolution and solid state behaviours of piroxicam upon milling

Controllable Synthesis and Biological Application of Schiff Bases from d-Glucosamine and Terephthalaldehyde

Theoretically, the two aldehydes of terephthalaldehyde (TPA) are equivalent, so the single or double Schiff base from TPA and d-glucosamine (Glc) may be formed at the same time. However, it is preferred to produce separately a single Schiff base (L₁ ) or double Schiff base (L₂ ) for different synthesis systems of anhydrous methanol or water-methanol. We calculated the Δ_r G of the formation of compounds L₁ and L₂ by density functional theory (DFT). In an anhydrous methanol system, the Δ_r G values of L₁ and L₂ are both below zero and L₂ is lower, suggesting the spontaneous formation of the two Schiff bases. Though adjusting the molar ratio of Glc to TPA, L₁ and L ₂ both were separately formed in anhydrous methanol. However, in the water-methanol system, L₂ was absent, which is most likely due to higher Δ_r G (4.95 eV) and better water solubility. The results also exhibits that the positive charge of C in -CHO for TPA is smaller in a mixed solvent than that in methanol, which confirms that the nucleophilic reaction of the Schiff base is more difficult in a mixed solvent. Therefore, we could realize to control the synthesis of a pure single or double Schiff base from Glc and TPA by adjusting the molar ratio and solvent. The as-prepared two kinds of Schiff bases have strong optical properties, high bacteriostatic activity, and can be used as fluorescent probes for tumor cell imaging.

Imaging of the Effect of Alcohol-Containing Media on the Performance of Hypromellose Hydrophilic Matrix Tablets: Comparison of Direct Compression and Regular Grades of Polymer

As the ingestion of drug products with alcohol could have adverse effects on the release of drugs from dosage forms, it is important to understand the mechanisms underpinning the influence on drug release by evaluating the effect of alcohol-containing media on the behaviour of pharmaceutical excipients. In this work, the effect of hydroalcoholic media containing up to 40% v/v absolute ethanol was evaluated, employing both the regular (CR) and direct compression grades (DC) of hypromellose. X-ray microtomography (XµT) and magnetic resonance imaging (MRI) were used as complementary techniques in determining the influence of the media composition on the ability of the CR and DC polymers to form and evolve the gel layer that controls drug release. Particle and powder properties of the polymer were characterised to determine any relationship to performance in hydroalcoholic media. Triboelectrification results showed the CR grade formulation to charge electropositively whereas the DC grade charged electronegatively. The flow properties also showed the DC grade to have a superior flow as compared to its CR counterpart. Differences in particle morphology between the grades influenced charging and flow behaviour of the powders; however, it did not seem to impact significantly either on the mechanical strength or the drug release properties of the compacted formulation using the model drug propranolol HCl. XµT and MRI imaging were successfully used as complementary techniques in determining the gel layer/hydration layer thickness measurements as the layer developed, as well as following ingress of hydroalcoholic media and its impact on the dry core. The result showed that although differences were present in the gel layer thickness potentially due to differences in particle morphology, this also did not impact significantly on the dissolution process, especially in acidic and hydroalcoholic media.

Mechanical and release behaviour of theophylline from matrix tablets containing psyllium powder in combination with grewia polysaccharides

This study was aimed at investigating the effect of grewia polysaccharides on the mechanical and release properties of tablet matrices containing binary mixtures of the polysaccharide with psyllium. Two grades of grewia polysaccharides (GG and GDS) were extracted and binary mixtures of the polysaccharides with psyllium were formulated into tablet matrices containing theophylline as the model drug. The true, bulk and tapped densities, Carr's compressibility index of the powders and binary composites were determined before tablet compression. Tablet properties (hardness, porosity, and drug release from the matrices) were investigated. The dissolution test was carried out in 0.1 M HCl (pH 1.2) and phosphate buffer (pH 6.8). The results show that GG and GDS produced tablets with good mechanical strength (108.33 N and 95.70 N, respectively) while psyllium produced softer tablets (7.13 N). The combination of psyllium and grewia polysaccharides in the matrices resulted in a significant increase in the mechanical strength of the matrices when compared to matrices containing psyllium alone as the matrix former. The results also showed that GG and GDS reduced the dissolution rate and effectively eliminated the burst release of theophylline from the psyllium matrices at both pHs. The matrices of GG or GDS and the binary mixtures conform to non-Fickian anomalous diffusion with n > 0.45. When overcoming the burst release of drug from matrices such as psyllium, grewia polysaccharides may provide an effective reduction and a more sustained drug release from such matrices.

Effect of preparation method on the surface properties and UV imaging of indomethacin solid dispersions

This work explores the use of UV imaging in solid dispersion systems. Solid dispersions are one of the common strategies used in improving the dissolution of poorly soluble drugs. Three manufacturing techniques (spray drying (SD), freeze drying (FD) and homogenising (HG)) are investigated. Differential Scanning Calorimetry (DSC) and X-Ray Powder Diffraction (XRPD) was used in characterising the solid dispersions. Advanced imaging was implemented to give an insight into how these solid dispersions performed. The DSC and XRPD results showed that all three methods and the various ratios studied produced amorphous solid dispersions. Ultra-Violet (UV) imaging of the pseudo Intrinsic Dissolution Rate (IDR) deduced only two samples to have superior pseudo IDR values to the IDR of the parent drug indomethacin (INDO). The whole dose imaging of the capsule formulation however showed all the samples (SD, FD and HG) to have superior dissolution to that of INDO which was in contrast to the IDR results. The UV images obtained from the determination of the pseudo IDR also showed a phenomenon the authors are reporting for the first time where increased polymer (Soluplus) content produced "web-like" strands that migrated to the top of the quartz cell which may have been responsible for the low pseudo IDR values. The authors also report for the first time using this UV imaging technique, the tip of a capsule coming off for drug to go into solution. The area under the curve suggested the best five samples dissolution wise to be 1:3 SD > 1:1 HG > 1:1 SD > 1:3 FD > 1:3 HG meaning a ratio of INDO to SOL in these dispersion of up to 1:3 being sufficient to produce significant dissolution increases. The developed interfacial (surface) area ratio (Sdr) highlighted how the surface area of the IDR compacts varied between the batches, in particular highlighting larger surface area gains for the FD and HG compacts. A choice of instrumentation/techniques to use in making solid dispersions may well come down to cost or instrument availability for a formulator as all three techniques were successful in improving the dissolution of indomethacin. This work thus highlights the importance of having both complimentary IDR and whole dosage imaging techniques in giving a better understanding of solid dispersion systems.

Glucosamine-paracetamol spray-dried solid dispersions with maximized intrinsic dissolution rate, bioavailability and decreased levels of in vivo toxic metabolites

Purpose

This study is aimed at preparing and testing physicochemical, pharmacokinetic and levels of toxic metabolites of paracetamol and glucosamine solid dispersions intended for multiple deliveries via the parenteral or per oral route.

Methods

Solid dispersions were prepared using the spray drying technique at different molar ratios of paracetamol and glucosamine. Characterization of the solid dispersions was carried out using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), equilibrium solubility and intrinsic dissolution rate. In vivo pharmacokinetics and toxic metabolites of the prepared dispersions were evaluated and compared to those of pure drugs and physical mixtures.

Results

Instant water solubility and more than 7-fold increase in dissolution rate led to significantly high plasma drug concentration (>6.5-fold) compared to paracetamol alone. More than 2-fold increase in area under the curve from 0 to 24 h from the dispersions was noticed on the third day of oral dosing to animals. Lower number and concentration followed by the complete disappearance of toxic pathway metabolites were observed on second and third days of dosing with solid dispersions and physical mixtures, respectively.

Conclusions

The spray-dried dispersions support safer and more effective delivery of multiple doses of paracetamol, leading to an acceleration of its analgesic actions. Synergism between the analgesic actions of paracetamol and joint protective actions of glucosamine in this combination is expected to facilitate effective treatment of persistent pain-related illnesses such as osteoarthritis.

Direct imaging of the dissolution of salt forms of a carboxylic acid drug

The optimisation of the pharmaceutical properties of carboxylic acid drugs is often conducted by salt formation. Often, the salt with the best solubility is not chosen due to other factors such as stability, solubility, dissolution and bioavailability that are taken into consideration during the preformulation stage. This work uses advanced imaging techniques to give insights into the preformulation properties that can aid in the empirical approach often used in industry for the selection of salts. Gemfibrozil (GEM) was used as a model poorly soluble drug. Four salts of GEM were made using cyclopropylamine (CPROP), cyclobutylamine (CBUT), cyclopentylamine (CPENT) and cyclohexylamine (CHEX) as counterions. DSC, XRD and SEM were used to confirm and characterise salt formation. IDR obtained using UV-imaging up to 10 min for all the salts showed that an increase in the chain length of the counterion caused a decrease in the IDR. Past the 10 min mark, there was an increase in the IDR value for the CPROP salt, which was visualised using UV-imaging. The developed interfacial (surface) area ratio (Sdr) showed significant surface gains for the compacts. Full dosage form (capsule) imaging showed an improvement over the GEM for all the salts with an increase in chain length of the counterion bringing about a decrease in dissolution which correlated with the obtained UV-imaging IDR data.

The influence of hydroalcoholic media on the performance of Grewia polysaccharide in sustained release tablets

Co-administration of drugs with alcohol can affect the plasma concentration of drugs in patients. It is also known that the excipients used in the formulation of drugs may not always be resistant to alcohol. This study evaluates effect of varying alcohol concentrations on theophylline release from two grades of Grewia mollis polysaccharides. X-ray microtomography showed that native polysaccharide formulation compacts were not homogenous after the mixing process resulting in its failure in swelling studies. Removal of starch from the native polysaccharide resulted in homogenous formulation compacts resistant to damage in high alcoholic media in pH 6.8 (40%v/v absolute ethanol). Destarched polymer compacts had a significantly higher hardness (375N) than that of the native polysaccharide (82N) and HPMC K4M (146N). Dissolution studies showed similarity at all levels of alcohol tested (f₂=57-91) in simulated gastric media (pH 1.2). The dissolution profiles in the simulated intestinal fluids were also similar (f₂=60-94), with the exception of the native polysaccharide in pH 6.8 (40%v/v absolute ethanol) (f₂=43). This work highlights the properties of Grewia polysaccharide as a matrix former that can resist high alcoholic effects therefore; it may be suitable as an alternative to some of the commercially available matrix formers with wider applications for drug delivery as a cheaper alternative in the developing world.

Anti-proliferative potential of Glucosamine in renal cancer cells via inducing cell cycle arrest at G0/G1 phase

Background

Renal cell carcinoma (RCC) is one of the most common types of cancer in urological system worldwide. Recently, the anticancer role of Glucosamine has been studied in many types of cancer. The aim of this study was to investigate the effects of Glucosamine on RCC.

Methods

The effects of Glucosamine on RCC cell proliferation and apoptosis were investigated by MTT assay and Annexin V-FITC Apoptosis assay, respectively in vitro. Cell cycle was detected by flow cytometry after treatment with Glucosamine. Protein levels of several cell cycle associated markers were examined by Western Blot.

Results

Our data showed that Glucosamine significantly inhibited the proliferation of renal cancer 786-O and Caki-1 cells in a dose-dependent manner. Besides, Glucosamine treatment resulted in cell cycle arrest at G0/G1 phase in both cell lines. Meanwhile, the expression of several regulators that contribute to G1/S phased transition, such as Cyclin D1, CDK4 and CDK6, were significantly down-regulated with the up-regulation of cell cycle inhibitors, p21 and p53, after treatment with glucosamine. However, the apoptosis rate of RCC cells was down-regulated when treatment with Glucosamine at 1 mM and 5 mM, while up-regulated at 10 mM.

Conclusions

Our findings indicated that Glucosamine inhibited the proliferation of RCC cells by promoting cell cycle arrest at G0/G1 phase, but not promoting apoptosis. The present results suggested that Glucosamine might be a potential therapeutic agent in RCC treatment in the future.

The dissolution and solid-state behaviours of coground ibuprofen-glucosamine HCl

The cogrinding technique is one of most effective methods for improving the dissolution of poorly water-soluble drugs and it is superior to other approaches from an economical as well as an environmental standpoint, as the technique does not require any toxic organic solvents. Present work explores the role of d-glucosamine HCl (GL) as a potential excipient to improve dissolution of a low melting point drug, ibuprofen (Ibu), using physical mixtures and coground formulations. The dissolution of the poorly soluble drug has been improved by changing the ratio of Ibu:GL and also grinding time. The results also showed that although GL can enhance the solubility of Ibu, it also reduces pH around the Ibu particles which led to poor dissolution performance when the concentration of GL is high. The effect of GL on the solubility of Ibu could be misleading if the pH of the final solution was not measured. Grinding reduced the particle size of GL significantly but in case of Ibu it was less effective. Solid state analysis (XRPD, DSC, and FT-IR) showed that ibuprofen is stable under grinding conditions, but the presence of high concentration of GL in samples subjected to high grinding times caused changes in FT-IR spectrum of Ibu which could be due to intermolecular hydrogen bond or esterification between the carboxylic acid group in the ibuprofen and hydroxyl group in the GL.