Evaluation of modified gum karaya as carrier for the dissolution enhancement of poorly water-soluble drug nimodipine

Synthesis and bio-medical applications of multifunctional phosphorester cyclic amide anchored sterculia network

The main focus of the present research is to design network hydrogels derived from natural polymers to promote a sustainable future. Multifunctional hydrogels were prepared by combining sterculia gum (SG), phosphorester -cyclic amide polymers for bio-medical applications including drug delivery (DD). The antibiotic drug ceftriaxone was incorporated into hydrogels to enhance wound healing potential. The surface morphology of copolymers was investigated by using FESEM and AFM techniques. FTIR and 13C NMR spectroscopic techniques provided insight into the formation of network structures. In FTIR analysis, distinctive bands were identified: at 1649 cm-1 attributed to CO stretching of the cyclic amide of PVP, at 1147 cm-1 and 974 cm-1 representing PO stretching and P-O-C of poly(BMEP), respectively. In the 13C NMR spectrum, a prominent peak at 63.272 ppm revealed the presence of (O-CH2) linkage of poly(BMEP). XRD demonstrated amorphous characteristics of hydrogels. The interactions of copolymer with blood, bio-membrane and encapsulated drug illustrated their biocompatibility, bio-adhesion and controlled DD properties. The dressings expressed a hemolytic index value of 2.58 ± 0.03 %. The hydrogels exhibited mucoadhesive character, revealed from the adhesion force of 50.0 ± 5 mN needed to separate polymer dressing from the mucosa. Dressings exhibited antioxidant properties and displayed 33.73 ± 0.3 % radical scavenging in the DPPH assay. Protein adsorption test of copolymer illustrated 9.48 ± 0.970 % of albumin adsorption. The tensile strength of the dressing was found 0.54 ± 0.03 N mm-2 while the burst strength 9.92 ± 0.27 N was observed. The sustained release of the drug was provided by supra-molecular interactions. Drug release followed a non-Fickian diffusion mechanism and the release profile was best described by the Higuchi kinetic model. Additionally, hydrogel dressings revealed permeability to H2O vapors and O2 and antimicrobial activity. These findings suggest the suitability of sterculia gum-based hydrogels for DD uses.

Determination of Alteration in Micromeritic Properties of a Solid Dispersion: Brunauer-Emmett-Teller Based Adsorption and Other Structured Approaches

The present study is focused on the use of solid dispersion technology to triumph over the solubility-related problems of bexarotene which is currently used for treating various types of cancer and has shown potential inhibitory action on COVID-19 main protease and human ACE2 receptors. It is based on comparison of green locust bean gum and synthetic poloxamer as polymers using extensive mechanistic methods to explore the mechanism behind solubility enhancement and to find suitable concentration of drug to polymer ratio to prepare porous 3rd generation solid dispersion. The prepared solid dispersions were characterized using different studies like X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), differential scanning calorimetry (DSC), and particle size analysis in order to determine the exact changes occurred in the product which are responsible for enhancing solubility profiles of an insoluble drug. The results showed different profiles for particle size, solubility, dissolution rate, porosity, BET, and Langmuir specific surface area of prepared solid dispersions by using different polymers. In addition to the comparison of polymers, the BET analysis deeply explored the changes occurred in all dispersions when the concentration of polymer was increased. The optimized solid dispersion prepared with MLBG using lyophilization technique showed reduced particle size of 745.7±4.4 nm, utmost solubility of 63.97%, pore size of 211.597 Å, BET and Langmuir specific surface area of 5.6413 m2/g and 8.2757 m2/g, respectively.

Solubility enhancement of some poorly soluble drugs by solid dispersion using Ziziphus spina-christi gum polymer

A high percentage of marketed drugs suffer from poor water solubility and require an appropriate technique to increase their solubility. This study aims to compare physically modified and unmodified gum polymers extracted from Ziziphus spina-christi fruits as solid dispersion carriers for some drugs. Taguchi Orthogonal Design (L9) was chosen for the screening and optimization of the solid dispersions. The design has four factors: type of drug, type of polymer, type of solid dispersion process, and drug to polymer ratio. Each factor was varied in three stages and the total number of runs was 9 in triplicate. The polymer was physically modified by heating (M1ZG) or freeze-drying (M2ZG). The drugs were selected according to the biopharmaceutical classification system, namely loratadine and glimepiride (class II) and furosemide (class IV). Drugs were dispersed in the polymer in three different ratios 1: 1, 1: 2, and 1: 3. Solid dispersions were made by co-grinding, solvent evaporation, and kneading methods. Modified and unmodified polymers were characterized in terms of their organoleptic properties, solubility, powder flowability, density, viscosity, swelling index, and water retention capacity. Solid dispersions were characterized in terms of percentage practical yield, solubility improvement, and drug compatibility. The results showed that the organoleptic properties of polymers were not changed by the gum modification. The swelling index of the polymer was doubled in M1ZG. The viscosity and water retention capacity of the polymer was increased in both modified polymers. All solid dispersions showed a high practical percentage yield of more than 93%, the higher values ​​being more associated with loratadine and furosemide than with glimepiride. The improvement in solubility was observed in all solid dispersions prepared, the values ​​varying with the pH of the medium and the method of modification. The FTIR results indicated that there was no chemical interaction between these drugs and the polymer used. Analysis of the results according to the Taguchi orthogonal design indicated 51 folds aqueous solubility enhancement for loratadine using M2ZG polymer at a ratio of 1: 3 of Drug: polymer. This study showed the possibility of improving the solubility of other poorly soluble drugs.

Using X-ray Diffraction Techniques for Biomimetic Drug Development, Formulation, and Polymorphic Characterization

Drug development is a decades-long, multibillion dollar investment that often limits itself. To decrease the time to drug approval, efforts are focused on drug targets and drug formulation for optimal biocompatibility and efficacy. X-ray structural characterization approaches have catalyzed the drug discovery and design process. Single crystal X-ray diffraction (SCXRD) reveals important structural details and molecular interactions for the manifestation of a disease or for therapeutic effect. Powder X-ray diffraction (PXRD) has provided a method to determine the different phases, purity, and stability of biological drug compounds that possess crystallinity. Recently, synchrotron sources have enabled wider access to the study of noncrystalline or amorphous solids. One valuable technique employed to determine atomic arrangements and local atom ordering of amorphous materials is the pair distribution function (PDF). PDF has been used in the study of amorphous solid dispersions (ASDs). ASDs are made up of an active pharmaceutical ingredient (API) within a drug dispersed at the molecular level in an amorphous polymeric carrier. This information is vital for appropriate formulation of a drug for stability, administration, and efficacy purposes. Natural or biomimetic products are often used as the API or the formulation agent. This review profiles the deep insights that X-ray structural techniques and associated analytical methods can offer in the development of a drug.

Preparation and characterization of dexamethasone lipid nanoparticles by membrane emulsification technique, use of self-emulsifying lipids as a carrier and stabilizer

Self-emulsifying lipids (SEL) were used as a stabilizer for the preparation of dexamethasone lipid nanoparticles by membrane emulsification employing Shirasu porous glass. The effect of process and formulation parameters on the size and polydispersity and dexamethasone solubility in lipids and its release from lipid nanoparticles were investigated. Lipid phase pressure (40-80 kPa), membrane pore-size (0.1 - 0.4 µm) and agitation speed (300 - 900 rpm) did not affect the size and polydispersity of SEL. However, the size was increased with increasing lipid content and fatty acid chain of the lipid. Sizes of < 250 nm were achieved from TEGO^® care:Gelucire^® blend and it increased to 487 nm by adding 20% w/w of hard fat. The highest solubility of dexamethasone was found in TEGO^® care 450 (29 mg/g). Release from the lipid nano-dispersions was extended with no burst effect and the absolute release was increased with increasing lipid content.

Antibacterial and cytotoxic properties from esterified Sterculia gum

Sterculia gums, as karaya and chicha gum, are complex branched and polydisperse heteropolysaccharides which can have their applications extended by improving their characteristics through chemical modifications. The objective of this work was to increase the antimicrobial activity of karaya and chicha gum through chemical modification with maleic anhydride. The incorporation of anhydride in the gum structure was confirmed by the characterization techniques. The derived biopolymers were synthesized and characterized by FTIR, X-ray diffraction, Thermogravimetric analysis and elemental analysis. Antimicrobial activity was evaluated against the Staphylococcus aureus strain (ATCC 25923). Mammalian cytotoxicity assays were also performed by MTT and hemolysis tests. The derivatives showed excellent antibacterial action inhibiting almost 100% of bacterial growth and did not present significant cytotoxicity in mammalian cells. The results showed that the derivatives are promising for biomedical applications aiming the control of infectious diseases caused by S. aureus.

A Review on Solid Dispersion and Carriers Used Therein for Solubility Enhancement of Poorly Water Soluble Drugs

A large number of hydrophilic and hydrophobic carriers in pharmaceutical excipients are available today which are used for formulation of solid dispersions. Depending on nature of carriers the immediate release solid dispersions and/or controlled release solid dispersions can be formulated. Initially crystalline carriers were used which are transformed into amorphous solid dispersions with enhanced properties. The carriers used previously were mostly synthetic one. Recent trend towards the use of natural carriers have replaced the use of synthetic carriers. This review is the overview of various synthetic, natural, semisynthetic, modified natural hydrophilic carriers used for formulation of solid dispersions.

Formulation and Characterization of Solid Dispersions of Etoricoxib Using Natural Polymers

Objectives

The main objective of the present investigation to develop and evaluate solid dispersions of BCS Class II drugs etoricoxib employing various natural polymers, compatible with conventional manufacturing method to enhance solubility of poorly soluble drugs.

Materials and Methods

In this study, etoricoxib solid dispersion were prepared using xanthan gum, gaur gum and acacia and their combinations by solvent evaporation method. Solid dispersions and pure etoricoxib in the form of powder were characterized in comparison with pure drug and corresponding physical mixtures in the same ratios by Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC), powder X-ray diffractogram, and in vitro drug release.

Results

Solid dispersion (ET11) prepared with 1: 2: 2: 2 drug carrier ratios were showed highest solubility in different solvents. Hence the solid dispersion (ET11) of 1: 2: 2: 2 ratios were selected for characterization. The DSC study indicated that the crystalline nature of etoricoxib was reduced to amorphous. The diffraction pattern of the solid dispersions in each figure indicates that diffraction peaks at 2ɵ values has less intensity than that of pure drugs. This indicated that the crystalline nature of drug sample was converted to amorphous with ET11. Scanning electron microscope photographs of solid dispersion seem to be more porous in nature. From the in vitro drug release profile, it can be seen that formulation ETM11 shows higher dissolution rate i.e. 98.2±1.3% compared with other formulations. It is predicted that, increasing concentration of carrier, increases the drug dissolution rate.

Conclusion

This study has shown that the solid dispersion of etoricoxib using natural carrier can be promising formulation for solubility and dissolution enhancement. Natural polymers used have shown promising results in the modification of drug release from the formulations.

Novel propyl karaya gum nanogels for bosentan: In vitro and in vivo drug delivery performance

The amphiphilic propyl Karaya gum (KG) with a degree of propyl group substitution of 3.24 was synthesized to design self-assembled nanogels as carriers for bosentan monohydrate, a poorly soluble antihypertensive drug. The drug was physically hosted into the hydrophobic core of the micellar nanogels by solvent evaporation method. TEM images revealed spherical shape and core-shell morphology of the nanogels. Depending upon polymer: drug weight ratio, the drug entrapment efficiency of >85% was attained. The carriers had hydrodynamic diameter in the range of 230-305 nm with narrow size distribution. The zeta potential of -23.0 to -24.9 mV and low critical association concentration (CAC) of 8.32 mg/l provided evidence that the colloidal nanogel system was physically stable. Thermodynamics of the propyl KG system in water favored spontaneous self-assembly of propyl KG. FTIR, thermal and x-ray analyses suggested that the drug was compatible in the hydrophobic confines of the nanogels. The micellar nanogels liberated their contents in simulated gastrointestinal condition in a pH-dependent manner over a period of 10 h. Peppas-Sahlin modeling of in vitro drug release data suggested that the polymer relaxation/swelling mechanism dominated the drug release process. Pre-clinical testing of the mucoadhesive nanogel formulations exhibited that the system could monitor the anti-hypertensive activity for a prolonged period. Overall, this propyl KG micellar nanogel system had a great potential and splendid outlook to serve as novel oral controlled release carriers for poorly soluble drugs with outstanding pharmacodynamics.

Enhancement of solubility and bioavailability of ambrisentan by solid dispersion using Daucus carota as a drug carrier: formulation, characterization, in vitro, and in vivo study

Ambrisentan is an US FDA approved drug, it is the second oral endothelin A receptor antagonist known for the treatment of pulmonary arterial hypertension, but its oral administration is limited due to its poor water solubility. Hence, the objective of the investigation was focused on enhancement of solubility and bioavailability of ambrisentan by solid dispersion technique using natural Daucus carota extract as drug carrier. Drug carrier was evaluated for solubility, swelling index, viscosity, angle of repose, hydration capacity, and acute toxicity test (LD₅₀). Ambrisentan was studied for the saturation solubility, phase solubility, and Gibbs free energy change. Compatibility of drug and the natural carrier was confirmed by DSC, FTIR, and XRD. Solid dispersions were evaluated for drug content, solubility, morphology, in vitro, and in vivo study. Screening of the natural carrier showed the desirable properties like water solubility, less swelling index, less viscosity, and acute toxicity study revealed no any clinical symptoms of toxicity. Drug and carrier interaction study confirmed the compatibility to consider its use in the formulation. Formed particles were found to be spherical with smooth surface. In vitro studies revealed higher drug release from the solid dispersion than that of the physical mixture. Bioavailability study confirms the increased absorption and bioavailability by oral administration of solid dispersion. Hence, it can be concluded that the natural Daucus carota extract can be the better alternative source for the preparation of solid dispersion and/or other dosage forms for improving solubility and bioavailability.

Extensive Diminution of Particle Size and Amorphization of a Crystalline Drug Attained by Eminent Technology of Solid Dispersion: A Comparative Study

The present study emphasized on the use of solid dispersion technology to triumph over the drawbacks associated with the highly effective antihypertensive drug telmisartan using different polymers (poloxamer 188 and locust bean gum) and methods (modified solvent evaporation and lyophilization). It is based on the comparison between selected polymers and methods for enhancing solubility through particle size reduction. The results showed different profiles for particle size, solubility, and dissolution of formulated amorphous systems depicting the great influence of polymer/method used. The resulting amorphous solid dispersions were characterized using x-ray diffraction (XRD), differential scanning calorimetry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and particle size analysis. The optimized solid dispersion (TEL 19) prepared with modified locust bean gum using lyophilization technique showed reduced particle size of 184.5 ± 3.7 nm and utmost solubility of 702 ± 5.47 μg/mL in water, which is quite high as compared to the pure drug (≤1 μg/mL). This study showed that the appropriate selection of carrier may lead to the development of solid dispersion formulation with desired solubility and dissolution profiles. The optimized dispersion was later formulated into fast-dissolving tablets, and further optimization was done to obtain the tablets with desired properties.

Effect of carboxymethylation on rheological and drug release characteristics of locust bean gum matrix tablets

This study was undertaken to investigate correlation between the carboxymethylation-induced rheological changes and drug release characteristics of locust bean gum (LBG) matrix tablets. LBG was derivatized to carboxymethyl LBG (CMLBG) and characterized by (13)C NMR, FTIR and elemental analyses. Rheological studies revealed that LBG, in contact with water, produced a strong elastic gel which swelled less due to lower penetration of water resulting in slower drug release. On the other hand, CMLBG formed a viscous polymer solution through which higher influx of water resulted in rapid swelling of the matrix and faster drug release. Although the release from a particular matrix was dependent on drugs' solubilities, CMLBG matrix tablet produced faster release of all the drugs than LBG matrix tablets. In conclusion, rheological study appeared to be an useful tool to predict release of drugs from polysaccharide matrix tablets.

Characterization and Pharmacokinetic Study of Aprepitant Solid Dispersions with Soluplus®

Solid dispersions are a useful approach to improve the dissolution rate and bioavailability of poorly water-soluble active pharmaceutical ingredients (APIs). The aim of this study was to improve the physicochemical properties and bioavailability of a poorly water-soluble aprepitant by preparation of solid dispersions. The solid dispersions were characterized by dissolution, FTIR, XRPD, DSC, SEM and pharmacokinetic studies in rats. The dissolution rate of the aprepitant was significantly increased by solid dispersions, and XRD, DSC, and SEM analysis indicated that the aprepitant existed in an amorphous form within the solid dispersions. The result of dissolution study showed that the dissolution rate of SDs was nearly five-fold faster than aprepitant. FTIR spectrometry suggested the presence of intermolecular hydrogen bonds between the aprepitant and polymer. Pharmacokinetic studies in rats indicated that the degree drug absorption was comparable with that of Emend^®. Aprepitant exists in an amorphous state in solid dispersions and the solid dispersions can markedly improve the dissolution and oral bioavailability of the aprepitant. The AUC_0–t of the SDs was 2.4-fold that of the aprepitant. In addition, the method and its associated techniques are very easy to carry out.

Physico-chemical and structural characterization of mucilage isolated from seeds of Diospyros melonoxylon Roxb

Mucilage was isolated from the seeds of Diospyros melonoxylonRoxb., a plant growing naturally in the forests of India. Various physico-chemical methods like particle analysis, scanning electron microscopy, differential scanning calorimetry, differential thermal analysis, thermogravimetry analysis, molecular weight by gel permeation chromatography, rheometry, elemental analysis, x-ray diffraction spectrometry, zeta potential, fourier transform infrared spectroscopy, 1D(1H and 13C) (NMR) have been employed to characterize this gum in the present study. Particle analyses suggest that mucilage had particle size in nanometer. SEM analysis suggested that the mucilage had irregular particle size. The glass transition temperature of the gum observed was 78 °C and 74 °C by DSC and DTA respectively. The Thermogravimetry analysis suggested that mucilage had good thermal stability with two stage decomposition. The molecular weight of mucilage was determined to be 8760, by gel permeation chromatography, while the viscosity of mucilage was observed to be 219.1 cP. The XRD pattern of the mucilage indicated a complete amorphous nature. Elemental analysis of the gum revealed specific contents of carbon, hydrogen, nitrogen and sulfur. The major functional groups identified from FT-IR spectrum include 3441 cm-1 (-OH), 1632 cm-1 (-COO-), 1414 cm-1 (-COO-) and 1219 cm-1 (-CH3CO). Analysis of mucilage by paper chromatography and 1D NMR indicated the presence of sugars.

Novel swellable polymer of orchidaceae family for gastroretentive drug delivery of famotidine

This study aimed to develop hydrophilic, gastroretentive matrix tablets of famotidine with good floating and swelling properties. A novel gastroretentive drug delivery formulation was designed using salep, also known as salepi, a flour obtained from grinding dried palmate tubers of Orchis morio var mascula (Orchidaceae family). The main polysaccharide content of salep is glucomannan, highly soluble in cold and hot water, which forms a viscous solution. Salep was characterized for physicochemical properties, thermal stability, chemical interaction, and surface morphology using X-ray diffraction analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy. Ten different formulations (S1–S10) were prepared using famotidine to salep ratios from 1:0.5 to 1:5. Results demonstrated that all formulations were able to sustain the drug release for more than 24 hours. The S5 formulation, with a famotidine to salep ratio of 1:2.5, had the shortest floating lag time of 35 seconds and 100% drug release within 24 hours. The dissolution data were fitted into popular mathematical models to assess the mechanism of drug release. S5 showed Zero order release (R=0.9746) with Higuchi diffusion (R=0.9428). We conclude that salep, a novel polymer, can be used in controlled release formulations to sustain release for 24 hours, due to inherent swelling and gelling properties.

Solubility and bioavailability enhancement of poorly aqueous soluble atorvastatin: in vitro, ex vivo, and in vivo studies

The objective of this investigation was to improve the solubility of the poorly water soluble drug atorvastatin (ATR), using solid dispersion (SD) techniques, with Neem Gum (NG) as a hydrophilic carrier. The effects of the polymer concentration and method of preparation on the solubility and dissolution rate were studied. The results showed that the solubility of ATR increases with increasing NG concentration. However, dissolution rate of ATR from its SD was dependent on the method used to prepare SD. An in vitro drug release study revealed that the solvent evaporation technique is a more convenient and effective method of preparing SD than kneading method. The SD was characterized using DSC, SEM, and XRD study. An in vivo study was performed in which the 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG CoA) reductase inhibition activity was measured. A significant reduction in HMG CoA reductase activity was observed with SD of ATR compared with the plain drug. An ex vivo absorption study was carried out using modified apparatus developed in our laboratory. The in vitro drug release and in vivo and ex vivo studies clearly demonstrated the potential of hydrophilic NG in enhancing the solubility, dissolution rate, and bioavailability of ATR.

Studies on gum of Moringa oleifera for its emulsifying properties

Background:

Emulsion has been a form of presenting water insoluble substances for a long period of time. Now a day, it has been a way of presenting various intravenous additives and diagnostic agents in X-ray examinations. Various substances can be used as emulsifying agent, which can be operationally defined as a stabilizer of the droplets formed of the internal phase.

Materials and Methods:

Gum from Moringa oleifera was evaluated for its emulsifying properties. Castor oil emulsions 30 percent (o/w), containing 2 to 4% Moringa oleifera gum was prepared. Emulsions containing equivalent concentration of acacia were also prepared for comparison. All the emulsions prepared were stored at room temperature and studied for stability at various time intervals for 8 weeks. The prepared emulsions were evaluated for creaming rate, globule size and rate of coalescence. 23 factorial design was chosen to investigate the effects of centrifugation, pH, temperature changes and electrolytes on the creaming rate and globule size.

Results:

The results of the investigations show that the gum of Moringa oleifera possesses better emulsifying properties as compared to gum acacia.

Conclusion:

Gum of Moringa oleifera could be used in pharmaceutical and non-pharmaceutical preparation.

Manilkara zapota (Linn.) Seeds: A Potential Source of Natural Gum

Mucilage isolated from seeds of Manilkara zapota (Linn.) P. Royen syn. is a plant growing naturally in the forests of India. This mucilage is yet to be commercially exploited, and characterized as polymer. Various physicochemical methods like particle size analysis, scanning electron microscopy, thermal analysis, gel permeation chromatography, X-ray diffraction spectrometry, zeta potential, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy have been employed to characterize this gum in the present study. Particle size analyses suggest that mucilage has particle size in nanometer. Scanning electron microscopy analysis suggests that the mucilage has irregular particle size. The glass transition temperature of the gum was observed to be 138°C and 136°C by differential scanning calorimetry and differential thermal analysis, respectively. The thermogravimetric analysis suggested that mucilage had good thermal stability. The average molecular weight of mucilage was determined to be 379180, by gel permeation chromatography, while the viscosity of mucilage was observed to be 219.1 cP. The X-ray diffraction spectrometry pattern of the mucilage indicates a completely amorphous structure. Elemental analysis of the gum revealed the contents of carbon, hydrogen, nitrogen, and sulfur to be 80.9 (%), 10.1 (%), 1.58 (%), and 512 (mg/kg), respectively. Mucilage had specific content of calcium, magnesium, potassium, lower concentrations of aluminum, cadmium, cobalt, lead, and nickel. The major functional groups identified from FT-IR spectrum include 3441 cm⁻¹ (–OH), 1660 cm⁻¹ (Alkenyl C–H & C=C Stretch), 1632 cm⁻¹ (–COO–), 1414 cm⁻¹ (–COO–), and 1219 cm⁻¹ (–CH₃CO). Analysis of mucilage by paper chromatography and 1D NMR, indicated the presence of rhamnose, xylose, arabinose, mannose, and fructose.

Enhancement of solubility and dissolution rate of poorly water soluble raloxifene using microwave induced fusion method

The objective of the present work was to enhance the solubility and dissolution rate of the drug raloxifene HCl (RLX), which is poorly soluble in water. The solubility of RLX was observed to increase with increasing concentration of hydroxypropyl methylcellulose (HPMC E5 LV). The optimized ratio for preparing a solid dispersion (SD) of RLX with HPMC E5 LV using the microwave-induced fusion method was 1:5 w/w. Microwave energy was used to prepare SDs. HPMC E5 LV was used as a hydrophilic carrier to enhance the solubility and dissolution rate of RLX. After microwave treatment, the drug and hydrophilic polymer are fused together, and the drug is converted from the crystalline form into an amorphous form. This was confirmed through scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) studies. These results suggested that the microwave method is a simple and efficient method of preparing SDs. The solubility and dissolution rate of the SDs were increased significantly compared with pure RLX due to the surfactant and wetting properties of HPMC E5 LV and the formation of molecular dispersions of the drug in HPMC E5 LV. It was concluded that the solubility and dissolution rate of RLX are increased significantly when an SD of the drug is prepared using the microwave-induced fusion method.

Solubility Enhancement of Raloxifene Using Inclusion Complexes and Cogrinding Method

The objective of the present work was to enhance the solubility and dissolution of practically water-insoluble drug raloxifene HCl (RLX), for the same two approaches that were used. In the first approach, drug was kneaded with hydroxypropyl-β-cyclodextrin (HPβCD), and in the second one drug was cogrinded with modified guar gum (MGG). The drug-cyclodextrin complex and drug-MGG cogrind mixtures were characterized by differential scanning calorimetry, X-ray diffraction studies, scanning electron microscopy, and Fourier transform infrared spectroscopy. The solubility and dissolution study reveals that solubility and dissolution rate of RLX remarkably increased in both methods. It was concluded that the prepared inclusion complex showed a remarkable increase in solubility and dissolution of poorly water-soluble drug raloxifene. In the cogrinding mixture, a natural modified gum is used as a surfactant and enhances the solubility and dissolution of RLX without requiring addition of organic solvent or high temperature for its preparation; thus, process is less cumbersome and cost effective. But when both methods were compared; HPβCD complexation method showed significant enhancement of drug solubility.

Design, Development, and Optimization of Sterculia Gum-Based Tablet Coated with Chitosan/Eudragit RLPO Mixed Blend Polymers for Possible Colonic Drug Delivery

The purpose of this study is to explore the possible applicability of Sterculia urens gum as a novel carrier for colonic delivery system of a sparingly soluble drug, azathioprine. The study involves designing a microflora triggered colon-targeted drug delivery system (MCDDS) which consists of a central polysaccharide core and is coated to different film thicknesses with blends of chitosan/Eudragit RLPO, and is overcoated with Eudragit L00 to provide acid and intestinal resistance. The microflora degradation property of gum was investigated in rat caecal medium. Drug release study in simulated colonic fluid revealed that swelling force of the gum could concurrently drive the drug out of the polysaccharide core due to the rupture of the chitosan/Eudargit coating in microflora-activated environment. Chitosan in the mixed film coat was found to be degraded by enzymatic action of the microflora in the colon. Release kinetic data revealed that the optimized MCDDS was fitted well into first-order model, and apparent lag time was found to be 6 hours, followed by Higuchi release kinetics. In vivo study in rabbits shows delayed T max, prolonged absorption time, decreased C max, and absorption rate constant (Ka), indicating a reduced systemic toxicity of the drug as compared to other dosage forms.

Design, development and optimization of oral colon targeted drug delivery system of azathioprine using biodegradable polymers

The present study was aimed at designing a microflora triggered colon targeted drug delivery system (MCDDS) based on swellable polysaccharide, Sterculia gum in combination with biodegradable polymers with a view to specifically deliver azathioprine in the colonic region for the treatment of IBD with reduced systemic toxicity. The microflora degradation properties of Sterculia gum was investigated in rat caecal phosphate buffer medium. The polysaccharide tablet cores were coated to different film thicknesses with blends of Eudragit RLPO and chitosan and overcoated with Eudragit L00 to provide acid and intestinal resistance. Swelling and drug release studies were carried out in simulated gastric fluid, SGF (pH 1.2), simulated intestinal fluid, SIF (pH 6.8) and simulated colonic fluid, SCF (pH 7.4 under anaerobic environment), respectively. Drug release study in SCF revealed that swelling force of the Sterculia gum could concurrently drive the drug out of the polysaccharide core due to the rupture of the chitosan/Eudargit coating in microflora activated environment. The degradation of chitosan was the rate-limiting factor for drug release in the colon. Drug release from the MCDDS was directly proportional to the concentration of the pore former (chitosan), but inversely related to the Eudragit RLPO coating thickness.

Microwave-generated bionanocomposites for solubility and dissolution enhancement of poorly water-soluble drug glipizide: in-vitro and in-vivo studies

Objectives

In oral absorption of a drug, the drug first dissolves and then is absorbed by diffusion through gastrointestinal membranes. The gastrointestinal environment is aqueous in nature and it is well-known that one-third of the drug population is water insoluble. Hence, there is a need for enhancement of the solubility and dissolution of such drugs. In this work, enhancement of the solubility and dissolution of the practically insoluble drug glipizide was achieved by formation of bionanocomposites (BNCs) using microwave-induced diffusion (MIND), which ultimately leads to bioavailability enhancement.

Methods

BNCs were formed by using natural carriers such as gelatin, acacia, cassia and ghatti gum, with the help of microwaves. Selection of carriers was based on their surfactant and wetting properties. Solubility studies were carried out to establish the solubility-enhancing property of the BNCs. To support solubility analysis results, dissolution studies (i.e. powder dissolution and in-vitro dissolution) were carried out. The BNCs were characterized by Fourier transform infra-red spectroscopy, differential scanning calorimetry, X-ray diffraction studies, scanning electron microscopy and transmission electron microscopy. In-vivo performance of the optimised formulation was assessed by glucose-induced hyperglycaemia test in male albino Wistar rats.

Key findings

It was found that as the concentration of polymer in the composite increased the solubility and dissolution of glipizide were enhanced. The optimised ratio (drug : polymer) for all the composites was found to be 1:9. In the glucose-induced hyperglycemia test in rats, the optimized formulation demonstrated a significant reduction in hyperglycemia compared with a marketed formulation, Glynase.

Conclusions

The novelty of this work is the green and cost-effective way of forming drug nanocomposites with the help of microwave, which can be scaled up to an industrial level. The method gives an immaculate means of solubilisation by generating drug dispersion at the micro and nanoscale level in natural biodegradable stabilising media. Hence, this study demonstrates the use of BNCs in solubility and dissolution enhancement.

Dissolution enhancement of glimepiride using modified gum karaya as a carrier

OBJECTIVE

The aim of present investigation is to enhance in vitro dissolution of poorly soluble drug glimepiride by preparing solid dispersions using modified gum karaya.

MATERIALS AND METHODS

Solid dispersions of drug were prepared by solvent evaporation method using modified gum karaya as carrier. Four batches of solid dispersion (SD1, SD4, SD9, and SD14) and physical mixture (PM1, PM4, PM9, and PM14) were prepared and characterized by differential scanning colorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, powder X-Ray diffraction (X-RD), and scanning electron microscopy (SEM) studies. Equilibrium solubility studies were carried out in shaker incubator for 24 h and in vitro drug release was determined using USP Dissolution Apparatus-II.

RESULTS

Maximum solubility and in vitro dissolution were observed with Batch SD4. No significant enhancement of dissolution characteristics were observed in the corresponding physical mixture PM4. Low viscosity with comparable swelling characteristics as compared to GK of modified form of gum karaya may lead to improvement in dissolution behavior of solid dispersion batches. Also, the conversion of crystalline form of drug to amorphous form may be a responsible factor, which was further confirmed by DSC, FTIR studies, and X-RD studies. SEM photographs of batch SD4 revealed porous nature of particle surface.

CONCLUSION

Modified forms of natural carriers prove beneficial in dissolution enhancement of poorly soluble drugs and exhibited a great potential in novel drug delivery systems.

Development, characterization and solubility study of solid dispersions of Cefuroxime Axetil by the solvent evaporation method

Cefuroxime Axetil (Poorly water soluble drug), when prepared as solid dispersion showed improved solubility and dissolution. Therefore, the main purpose of this investigation was to increase the solubility and dissolution rate of Cefuroxime Axetil by the preparation of its solid dispersion with urea, using the solvent evaporation method. Physical mixtures and solid dispersions of Cefuroxime Axetil were prepared by using urea as a water-soluble carrier in various proportions (1:1, 1:2, 1:3, 1:4, 1:5, 1:6, and 1:7 by weight), by employing the solvent evaporation method. The drug release profile was studied and it was found that the dissolution rate and the dissolution parameters of the drug from the physical mixture as well as solid dispersion were higher than those of the intact drug. The Fourier Transform Infrared (FTIR) spectra revealed no chemical incompatibility between the drug and urea. Drug-polymer interactions were investigated using differential scanning calorimetry (DSC) and Powder X-Ray Diffraction (PXRD).

Improvement in solubility of poor water-soluble drugs by solid dispersion

This article is intended to combine recent literature on solid dispersion technology for solubility enhancement with special emphasis on mechanism responsible for the same by solid dispersion, various preparation methods, and evaluation parameters. Solubility behavior is the most challenging aspect for various new chemical entities as 60% of the new potential products possess solubility problems. This is the biggest reason for new drug molecules not reaching to the market or not reaches to full potential. There are various techniques to enhance the drug solubility such as particle size reduction, nanosuspension, use of surfactants, salt formation, solid dispersion, etc. From this article it may be concluded that solid dispersion is an important approach for improvement of bioavailability of poor water-soluble drugs.

Resolving issues of content uniformity and low permeability using eutectic blend of camphor and menthol

The aim of present study were to arrest the problem of content uniformity without the use of harmful organic solvent and to improve ex vivo permeability of captopril, a low dose class III drug as per biological classification system. Eutectic mixture of camphor and menthol was innovatively used in the work. Captopril solution in eutectic mixture was blended with Avicel PH 102 and then the mixture was blended with mannitol in different ratios. Formulated batches were characterized for angle of repose and Carr's index. A selected batch was filled in hard gelatin capsule. Tablet dosage form was also developed. Capsules and tablets were characterized for in vitro drug release in 0.1N HCl. Additionally, the captopril tablets were analyzed for content uniformity and ex vivo drug permeation study using rat ileum in modified apparatus. The measurement of angle of repose and Carr's index revealed that the powder blend exhibited good flow property and compressibility. The captopril capsules and tablets exhibited immediate drug release in 0.1 N HCl. The captopril tablets passed content uniformity test as per IP 1996. Ex vivo permeation of captopril, formulated with eutectic mixture, was faster than control. The permeation was increased by 15% at the end of 3 h. Tablets and capsule exhibited reasonable short term stability with no considerable change in performance characteristics.

A kinetic study of the polymorphic transformation of nimodipine and indomethacin during high shear granulation

The objective of the present study was to investigate the mechanism, kinetics, and factors affecting the polymorphic transformation of nimodipine (NMD) and indomethacin (IMC) during high shear granulation. Granules containing active pharmaceutical ingredient, microcrystalline cellulose, and low-substituted hydroxypropylcellulose were prepared with ethanolic hydroxypropylcellulose solution, and the effects of independent process variables including impeller speed and granulating temperature were taken into consideration. Two polymorphs of the model drugs and granules were characterized by X-ray powder diffraction analysis and quantitatively determined by differential scanning calorimetry. A theoretical kinetic method of ten kinetic models was applied to analyze the polymorphic transformation of model drugs. The results obtained revealed that both the transformation of modification I to modification II of NMD and the transformation of the α form to the γ form of IMC followed a two-dimensional nuclei growth mechanism. The activation energy of transformation was calculated to be 7.933 and 56.09 kJ·mol(-1) from Arrhenius plot, respectively. Both the granulating temperature and the impeller speed affected the transformation rate of the drugs and, in particular, the high shear stress significantly accelerated the transformation process. By analyzing the growth mechanisms of granules in high-shear mixer, it was concluded that the polymorphic transformation of NMD and IMC took place in accordance with granule growth in a high-shear mixer.