Synergistic Effect of Silver Nanoparticles with Antibiotics for Eradication of Pathogenic Biofilms.

BACKGROUND: The increase in nosocomial multidrug resistance and biofilm-forming bacterial infections led to the search for new alternative antimicrobial strategies other than traditional antibiotics. Silver nanoparticles [AgNP] could be a viable treatment due to their wide range of functions, rapid lethality, and minimal resistance potential. The primary aim of this study is to prepare silver nanoparticles and explore their antibacterial activity against biofilms. METHODS: AgNPs with specific physicochemical properties such as size, shape, and surface chemistry were prepared using a chemical reduction technique, and then characterized by DLS, SEM, and FTIR. The activity of AgNPs was tested alone and in combination with some antibiotics against MDR Gram-negative and Gram-positive planktonic bacterial cells and their biofilms. Finally, mammalian cell cytotoxicity and hemolytic activity were tested using VERO and human erythrocytes. RESULTS: The findings of this study illustrate the success of the chemical reduction method in preparing AgNPs. Results showed that AgNPs have MIC values against planktonic organisms ranging from 0.0625 to 0.125 mg/mL, with the greatest potency against gram-negative bacteria. It also effectively destroyed biofilm-forming cells, with minimal biofilm eradication concentrations [MBEC] ranging from 0.125 to 0.25 mg/ml. AgNPs also had lower toxicity profiles for the MTT test when compared to hemolysis to erythrocytes. Synergistic effect was found between AgNPs and certain antibiotics, where the MIC was dramatically reduced, down to less than 0.00195 mg/ml in some cases. CONCLUSION: The present findings encourage the development of alternative therapies with high efficacy and low toxicity.

Synergistic Antibacterial Effect of ZnO Nanoparticles and Antibiotics against Multidrug-Resistant Biofilm Bacteria.

BACKGROUND: The misuse of antibiotics leads to a global increase in antibiotic resistance. Therefore, it is imperative to search for alternative compounds to conventional antibiotics. ZnO nanoparticles (Zn NP) are one of these alternatives because they are an effective option to overcome biofilm bacterial cells and a novel way to overcome multidrug resistance in bacteria. The current research study aims to characterize the efficacy of ZnO nanoparticles alone and in combination with other antibacterial drugs against bacterial biofilms. METHODS: ZnO NPs were prepared by co-precipitation method, and their anti-biofilm and antibacterial activities alone or combined with four types of broad-spectrum antibacterial (Norfloxacin, Colistin, Doxycycline, and Ampicillin) were evaluated against E. coli and S. aureus bacterial strains. Finally, the cytotoxicity and the hemolytic activity were evaluated. RESULTS: ZnO NPs were prepared, and results showed that their size was around 10 nm with a spherical shape and a zeta potential of -21.9. In addition, ZnO NPs were found to have a strong antibacterial effect against Gram-positive and Gram-negative microorganisms, with a minimum inhibitory concentration (MIC) of 62.5 and 125 µg/mL, respectively. Additionally, they could eradicate biofilmforming microorganisms at a concentration of 125 µg/m. ZnO NPs were found to be non-toxic to erythrocyte cells. Still, some toxicity was observed for Vero cells at effective concentration ranges needed to inhibit bacterial growth and eradicate biofilm-forming organisms. When combined with different antibacterial, ZnO NP demonstrated synergistic and additive effects with colistin, and the MIC and MBEC of the combination decreased significantly to 0.976 µg/mL against planktonic and biofilm strains of MDR Gram-positive bacteria, resulting in significantly reduced toxicity. CONCLUSION: The findings of this study encourage the development of alternative therapies with high efficacy and low toxicity. ZnO nanoparticles have demonstrated promising results in overcoming multi-drug resistant bacteria and biofilms, and their combination with colistin has shown a significant reduction in toxicity. Further studies are needed to investigate the potential of ZnO nanoparticles as a viable alternative to conventional antibiotics.

The Formulation and Evaluation of Deep Eutectic Vehicles for the Topical Delivery of Azelaic Acid for Acne Treatment.

The current work was aimed at the development of a topical drug delivery system for azelaic acid (AzA) for acne treatment. The systems tested for this purpose were deep eutectic systems (DESs) prepared from choline chloride (CC), malonic acid (MA), and PEG 400. Three CC to MA and eight different MA: CC: PEG400 ratios were tested. The physical appearance of the tested formulations ranged from solid and liquid to semisolid. Only those that showed liquid formulations of suitable viscosity were considered for further investigations. A eutectic mixture made from MA: CC: PEG400 1:1:6 (MCP 116) showed the best characteristics in terms of viscosity, contact angle, spreadability, partition coefficient, and in vitro diffusion. Moreover, the MCP116 showed close rheological properties to the commercially available market lead acne treatment product (Skinorin®). In addition, the formula showed synergistic antibacterial activity between the MA moiety of the DES and the AzA. In vitro diffusion studies using polyamide membranes demonstrated superior diffusion of MCP116 over the pure drug and the commercial product. No signs of skin irritation and edema were observed when MCP116 was applied to rabbit skin. Additionally, the MCP116 was found to be, physically and chemically, highly stable at 4, 25, and 40 °C for a one-month stability study.

Design and Optimization of Pioglitazone Hydrochloride Self-Nanoemulsifying Drug Delivery System (SNEDDS) Incorporated into an Orally Disintegrating Tablet.

Pioglitazone Hydrochloride (PGZ) suffers from poor aqueous solubility. The aim of this research was to design orally disintegrating tablets with self-nanoemulsifying properties (T-SNEDDS) to improve the Pioglitazone solubility and dissolution rate. Three liquid self-nanoemulsifying systems (L-SNEDDS) were formulated and evaluated for transmittance percentage, emulsification time, particle size, Poly dispersity index (PDI), percentage of content, solubility and stability. The optimum L-SNEDDS formula was converted to a solidified self-nanoemulsifying drug delivery system (S-SNEDDS) by adsorption on Syloid (SYL). Powder characterization tests, such as flowability tests, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), were performed for the selected S-SNEDDS formulation. Orally disintegrating tablets (ODT) were formulated by blending S-SNEDDS with tableting excipients. The ODT tablet batch composed of Prosolv was selected for tablet quality control tests, such as hardness, friability, disintegration time, content uniformity, weight variation, in vitro release, in vivo studies and accelerated stability studies. ODT tablets showed accepted mechanical properties and rapid disintegration time (<30 s). No drug degradation was observed at 3 months into the accelerated stability study. The optimized L-SNEDDS, S-SNEDDS and ODT (T-SNEDDS), showed significant enhancement of PGZ in vitro dissolution profiles compared to the pure drug (p > 0.05). In vivo pharmacokinetic and pharmacodynamic evaluation of ODTs showed better behavior compared to the raw drug suspension and the commercial tablet (p > 0.05). Orally disintegrating tablets revealed a promising potential to improve Pioglitazone poor aqueous solubility, dissolution profile and bioavailability.

Enhancement of the Solubility of Asenapine Maleate Through the Preparation of Co-Crystals.

BACKGROUND: Asenapine maleate, an anti-schizophrenic drug, is a class II drug with low solubility and high permeability. This exerts a rate-limiting effect on drug bioavailability. OBJECTIVE: To improve the solubility/dissolution rate of asenapine maleate and hence the bioavailability using the co-crystal approach. METHODS: Co-crystals were prepared using the solvent evaporation method. Since the drug has Hbond acceptor count of 6, and H-bond donor count of 2, several co-formers (nicotinamide, urea, succinic, benzoic, and citric acid) were investigated in different ratios. The optimized co-crystals (drug-nicotinamide in a ratio of 1:3) were evaluated using PXRD, DSC, FTIR spectroscopy, and SEM. Additionally, in vitro dissolution and stability studies were conducted. RESULTS: Preparation of the co-crystals was successful except when citric and benzoic acids were used. PXRD patterns showed that the co-crystals were crystalline. FTIR spectroscopy confirmed the formation of H-bond between the drug and the co-former. DSC indicated a lower melting point than that of the components followed immediately by an exothermic peak, which confirmed the formation of co-crystals. SEM showed the formation of crystals with different size and habit. The dissolution of the drug from all the prepared co-crystals was almost similar and much enhanced compared to that of the unprocessed drug. The initial dissolution of the drug from the optimized batch was much faster than that from the other co-crystals and the physical mixture with the same ratio. The optimized batch exhibited long term stability. CONCLUSION: Co-crystals with improved solubility/dissolution rate of asenapine maleate were prepared successfully and were expected to enhance the bioavailability of the drug.

Solid self nano-emulsifying system for the enhancement of dissolution and bioavailability of Prasugrel HCl: in vitro and in vivo studies.

Prasugrel Hydrochloride (PHCl) is an antiplatelet drug. It is a class II drug with variable bioavailability. The objective of this work was to enhance the solubility and hence the bioavailability and efficacy of PHCl. A Self Nano-Emulsifying Drug Delivery System (SNEDDS) was prepared using Kolliphor El, Maisine 35-1, and Transcutol P as surfactant, oil, and co-surfactant, respectively in a ratio 10:72:18 v/v%. The SNEDDS was converted into solid by adsorption onto Neusilin. In vitro release of the drug from SNEDDS in (pH = 4) at 37 °C and 75 rpm for 45 min was studied. The results were compared to those from the unprocessed PHCl and Lexar® (the commercial drug). In-vivo studies (platelet Aggregation and bleeding time) were conducted using rats as animal models. It was found that the particle size of the SNEDDS ranged between 80 and 155 nm and EE% was in the range of 90.2% ± 0.4. The release from SNEDDS was about 84% compared to around 25% from unprocessed PHCl and 65% from Lexar® after 15 min. The platelet aggregation of the formula was lower than the PHCl, and Lexar® indicating higher bioavailability. In conclusion, SNEDDS with high EE% was prepared and was successful in enhancing the solubility, dissolution rate, and the bioavailability.

Preparation and Evaluation of Co-amorphous Formulations of Telmisartan-Amino Acids as a Potential Method for Solubility and Dissolution Enhancement.

Telmisartan (TLM) is a potent antihypertensive drug with pH-dependent aqueous solubility. This work aimed to enhance the solubility and dissolution rate of TLM by the co-amorphous drug amino acid (AA) approach by combining TLM, with different types and ratios of AAs. The co-amorphous TLM-AA blends were prepared by freeze-drying and investigated for solid-state characteristics like the dissolution rate enhancement of TLM. Among the prepared co-amorphous formulations, TLM-arginine (ARG) exhibited the greatest enhancement in solubility with increasing the molar ratio of ARG. The TLM-ARG at 1:2 ratio showed about a 57-fold increase in solubility of TLM and the highest dissolution percentage in phosphate buffer (pH7.5) (100% in 20 minutes) compared to both crystalline TLM (20% in 60 min) and physical mixture. Powder XRD, DSC, FTIR analysis and SEM demonstrated the formation of amorphous form within the co-amorphous formulations. Only TLM:ARG (1:0.5) were stable at (40°C, 75% RH) for a minimum of 90 days. In conclusion, ARG was able to stabilize the amorphous form of TLM and enhances its aqueous solubility and dissolution. The 1:2 w/w ratio of TLM-ARG co-amorphous showed the best solubility and dissolution rate while the 1:0.5 w/w ratio showed the best stability.

A Novel Eutectic-Based Transdermal Delivery System for Risperidone.

This paper reports for the first time the possible formation of a novel room temperature therapeutic deep eutectic solvent (THEDES) of risperidone (RIS) with some fatty acids, namely capric acid (C10; CA), lauric acid (C12; LA), and myristic acid (C14; MA). All mixtures of RIS and MA yielded a solid or pasty-like solid and were readily discarded. Some of the prepared THEDESs from RIS and CA or LA have spontaneously transformed into a transparent liquid, without any precipitate at room temperature by simple physical mixing of the components. From the DSC thermograms, phase diagrams of the eutectic systems were constructed and the lowest obtained melting point for a RIS:CA mixture was 17°C at 40:60% w/w ratio. While 22°C was recorded as the lowest melting point for RIS:LA at a ratio of 30:70% w/w, solubility improvement of RIS was up to 70,000-fold compared with water. Freeze-drying microscopy provided valuable information regarding the phase change and transitions the drug undergoes as a function of temperature and it clarifies the interpretation of the DSC results and provides valuable evidence of drug crystals co-melting within the fatty acid base. The presence of natural fatty acid as one component of THEDES and the depression in the melting point significantly (P < 0.05) enhanced RIS skin permeation. Rheological studies showed a viscosity temperature dependency of the DES and well fitted to the Arrhenius equation. Application of the obtained THEDES on the shaved skin of rats revealed the absence of any irritation or edema effects.

A Comparative Solubility Enhancement Study of Cefixime Trihydrate Using Different Dispersion Techniques.

This study aimed to investigate the effect of different polymers (polyethylene glycol 4000 and 6000 and Soluplus®) on the enhancement of solubility, dissolution, and stability of cefixime trihydrate as a selected class II model drug. Different solid dispersions have been prepared using conventional methods and supercritical fluid technology. The effect of co-solvent incorporation in supercritical fluid technology was also studied. Physicochemical properties for solid dispersions were investigated using Fourier transform infrared analysis, differential scanning calorimetry, thermogravimetric analysis, powder X-ray diffraction, and scanning electron microscopy. The solubility of the prepared solid dispersions increased except for those prepared with Soluplus® using supercritical fluid technology without co-solvent. The best enhancement in the release profile was recorded by Soluplus®-based solid dispersions prepared using a conventional method. The conventional methods of preparation and the presence of co-solvent in supercritical fluid technology converted cefixime into its amorphous form.

Preparation and characterization of co-processed starch/MCC/chitin hydrophilic polymers onto magnesium silicate.

It was aimed to investigate the compressibility, compactibility, powder flow and tablet disintegration of a new excipient comprising magnesium (Mg) silicate co-processed (5%-85% w/w) onto chitin, microcrystalline cellulose (MCC) and starch as the hydrophilic polymers of interest. Initially, the mechanism of tablet disintegration was studied by measuring water infiltration rate, moisture sorption, swelling capacity and hydration ability. Moreover, the powders compression behavior was carried out by applying Kawakita model of compression analysis in addition to porosity and radial tensile strength measurements. In vitro drug release of compacts made of 400 mg ibuprofen and 300 mg of the hydrophilic polymers containing 30% w/w Mg silicate co-precipitate was investigated in phosphate buffer (pH 7.8). This work demonstrated that the incorporation of Mg silicate to the hydrophilic polymers lead to the improvement of powder flowability, compactibility, stability (with regard to storage conditions), compacts crushing strength, and disintegration time in addition to faster drug release. The overall findings are practically advantageous in the context of finding a low cost and multifunctional co-processed excipient of natural origins.

Stabilization and Amorphization of Lovastatin Using Different Types of Silica.

Lovastatin (LOV), an antihyperlipidimic agent, is characterized by low solubility/poor dissolution and, thus, low bioavailability (<5%). A beneficial effect on its bioavailability could result from improving its dissolution. One of the most common methods used to enhance dissolution is the preparation of solid dispersions. Solid dispersions of LOV and silica with different surface areas were prepared. The effects of the type of silica, ratio of drug/silica, incubation period with silica, and the effect of surface area were all studied. Characterization of the prepared formulae for possible interaction between drug and polymer was carried out using differential scanning calorimetery, Fourier transform infrared spectroscopy, powder X-ray diffraction, surface area determination, and scanning electron microscopy. The dissolution profiles of all prepared formulae were constructed and evaluated. It was found that the formula made of LOV and Sylysia 350 FCP in a ratio of 1:5 after an incubation period of 48 h resulted in the best release, and it was stable after 3 months storage at 75% RH and 40°C.

Inulin and poly(acrylic acid) grafted inulin for dissolution enhancement and preliminary controlled release of poorly water-soluble Irbesartan drug.

In this article, inulin and poly(acrylic acid) grafted inulin copolymer were used to enhance the dissolution of poorly water-soluble Irbesartan drug and to control its drug release rate, respectively. Topological structure of inulin showed sleazy separable flower-like platelets and granules accumulated above each other, which adapt it to physically bind Irbesartan drug and enhance its dissolution. Consequently, the increase of inulin content in the polymeric matrix was found to increase the drug dissolution gradually until it reaches its maximum (∼90%) within the first 60 min. The release rate had followed zero-order transport mechanism. On the other hand, the poly(acrylic acid) grafted inulin copolymer, characterized using (1)H NMR, FTIR, TGA, and SEM techniques, was found to form highly consistent amorphous systems of two-dimensional surfaces with some voids topology. Such features adapted it to control Irbesartan drug dissolution (∼33%) and show Fickian diffusion mechanism.

Release behaviour of diclofenac sodium dispersed in Gelucire and encapsulated with alginate beads.

Sustained release polymeric particles containing diclofenac sodium dispersed in Gelucire matrix and encapsulated in calcium alginate shell were prepared with different drug-to-polymer ratios and also with different concentrations of sodium alginate for a fixed drug-to-polymer ratio in an aqueous environment. Spherical particles were formed by dropping an emulsion of diclofenac sodium in Gelucire matrix, emulsified with sodium alginate, into calcium chloride solution. The gelled beads formed by ionotropic gelation of alginate with calcium ions showed sustained release of the water soluble drug in in-vitro release study. Drug release was a function of square-root of time, suggesting a matrix diffusion release pattern. The rate of release was significantly suppressed with increasing proportions of Gelucire in the mixture. Sustained and complete release was achieved with Gelucire of low melting point and low HLB value. No significant drug release occurred in a dissolution medium of pH 1.5, whereas complete release was observed at pH 6.8, consistent with considerable swelling of the alginate gel at this pH.

Determination of the mechanism of uptake of organic vapors by chitoasn.

It was of interest to investigate the possible interactions that might occur between chitosan and various compounds of different polarities using solvent vapor sorption and Fourier Transform Infrared Spectroscopy (FTIR). The sorption system was composed of a gas inlet, a 2 meter gas cell and a gas outlet. The experimental set up allowed quantification of the free vapor and therefore the amount of the sorbed vapor by chitosan powder. The BET equation was applied to the experimental data to obtain the apparent monolayer sorption capacity (Sm) and the parameter C, which is related to the heat of interaction. Results demonstrated that the surface areas obtained for chitosan from the BET analyses for heptane, 1,4-dioxane and methanol were 421, 379 and 58 m(2)/g, respectively. These values were extremely higher than the value obtained from nitrogen vapor adsorption isotherm (4.56 m(2)/g). The difference is attributed to the partitioning of these compounds into the chitosan particles. The large difference in the Sm values between the nonpolar (heptane and 1,4-dioxane) and the semipolar compounds (methanol) also suggested that the polarity of the solvent might have a significant effect on the partitioning of the these compounds into the chitosan particles. The results obtained from this study also confirmed what was previously described regarding the ability of chitosan to act as a 'fat magnet' or a 'fat sponge'.

The sorption of ketotifen fumarate by chitosan.

The purpose of this investigation was to determine the mechanism of interaction between ketotifen fumarate and chitosan at different pH values. The specific surface area of chitosan was determined using gas sorption analyzer. The sorption experiments were conducted at pH 7 and 10 using two different particle size ranges of chitosan. The solutions were prepared at constant ionic strength and buffer concentration, with only varying the pH. The rotating bottle method was used for measuring the sorption. The average specific surface areas for the two different particle size ranges of chitosan were found to be 4.56 and 0.74 m(2)/g. The Langmuir-like equation and a model independent equation were both applied to the sorption experimental data. The extent of ketotifen uptake at pH 7 for small and large particles of chitosan was found to be 1,073 and 2,204 mg/g respectively. While the extent of ketotifen uptake at pH 10 for small and large particles of chitosan was found to be 4 and 11 mg/g respectively. The aforementioned results indicated that sorption of ketotifen fumarate at pH 7 is extremely high compared to pH 10 and that the sorption increases by decreasing the specific surface area of chitosan. Based on the results obtained, the following conclusions were reached. Ketotifen might be absorbed into the bulk structure of chitosan in addition to being adsorbed on the surface and the ability of chitosan to swell at pH 7 has a significant role in increasing its uptake.