Physicochemical characterization and dissolution of norfloxacin/cyclodextrin inclusion compounds and PEG solid dispersions

Exploring paediatric oral suspension development: Challenges, requirements, and formulation advancements

Oral suspension is the most preferred dosage form for the paediatric population because of the difficulties related to solid medications, such as the swallowing limitations, bitter taste, and poor oral bioavailability, which can cause serious impairment to attain a successful treatment. Given the importance of successful therapies, there is a need for safe and effective commercially-available paediatric oral suspension and their characterization. For the latter, it is important to identify safe excipients and preservatives. The paediatric group is a diverse category which includes infants and teenagers, with major pharmacokinetics and pharmacodynamics differences, mainly because of physiological and behavioral variations. Therefore, finding a single formulation for paediatric population remains a challenge, as well asthe formulation of stable-in-time suspension. In addition, drug's dissolving characteristic and permeation, are the main determinants for oral absorption, which are closely related to drug release kinetics from the pharmaceutical form. In this context, drug release profile is an important and limiting step in oral bioavailability, particularly for BCS class II drugs; thus, it is possible to increase bioavailability and minimize adverse effects by changing the release rate of such drugs. This review covers all the aspects for paediatric oral suspension development, and analyses the considerations for excipients selection as a crucial task for effectively choosing a safe and effective pharmaceutical form and correctly dosing paediatric patients.

Prediction of enhanced drug solubility related to clathrate compositions and operating conditions: Machine learning study

Although complexation technique has been documented as a promising strategy to enhance the dissolution rate and bioavailability of water-insoluble drugs, prediction of the enhanced drug solubility related to clathrate compositions and operating conditions is still a challenge. Herein, clathrate compositions (drug content (DC), drug molecular weight (M) and molar ratio (Ratio)), operating conditions (drug concentration (C), pH, pressure (P), temperature (T) and dissolution time (t)) under the different excipients (PEG, PVP, HPMC and cyclodextrin) as main solubilizers of the clathrates condition as input parameters were used to predict two indexes (drug dissolved percentage and dissolution efficiency) simultaneously through machine learning methodfor the first time. The results show that PVP as the main solubilizer of clathrates had higher prediction accuracy to the drug dissolved percentage, and HPMC as the main solubilizer of clathrates had higher prediction accuracy to the drug dissolution efficiency. In addition, the influence of various factors and interactions on the target variables were analyzed. This study affords achievable hints to the quantitative prediction of the drug solubility affected by various compositions and different operating conditions.

Optimized Rapid Disintegrating Tablets produced through Central Composite Design

The work is aimed at producing fast disintegrating diclofenac potassium tablets to relieve pain and tenderness by applying a quality-by-design approach. Diclofenac potassium (DP) is of BCS class II and has issues of minimal oral bioavailability. This can be overcome by complexing DP with β-cyclodextrin (β-CD) and sodium starch glycolate (SSG). The attempt was to optimize DP tablets by applying central composite design (CCD). Nine different DP tablet formulations were created and assessed for physicochemical constraints, disintegration time and drug dissolution at the end of 30 min. The separate and mutual consequences of β-CD and SSG on the disintegration time of DP tablets are highly significant (P<0.01). The DP tablets made with β-CD in 150 mg disintegrated rapidly within 39±2 sec, and gave very rapid drug dissolution (96.35±2.36%) at the end of 30 min. These DP tablets (F-8) contain β-CD (150 mg) and SSG at 32.07 mg. The intermittent levels of β-CD and higher levels of SSG gave good dissolution of DP tablets. The polynomial equation linking the response, i.e. disintegration time in sec (Y1) and the levels of β-CD (A) and SSG (B) based on the pragmatic results, is Y1=45-3.14277A- 2.46599B-1.25AB+1.75A2-0.5B2. In contrast, the DP release at the end of 30 min was expressed as Y2 = 88.57 + 4.09333A + 3.27837B + 1.2525AB - 2A2 + 0.8875B2. The study concludes that SSG decreases the disintegration time with its concentration and β-CD concentration ingresses the drug release from the formulation.

Cyclodextrin Inclusion Complexes with Antibiotics and Antibacterial Agents as Drug-Delivery Systems—A Pharmaceutical Perspective

Cyclodextrins (CDs) are a family of cyclic oligosaccharides, consisting of a macrocyclic ring of glucose subunits linked by α-1,4 glycosidic bonds. The shape of CD molecules is similar to a truncated cone with a hydrophobic inner cavity and a hydrophilic surface, which allows the formation of inclusion complexes with various molecules. This review article summarises over 200 reports published by the end of 2021 that discuss the complexation of CDs with antibiotics and antibacterial agents, including beta-lactams, tetracyclines, quinolones, macrolides, aminoglycosides, glycopeptides, polypeptides, nitroimidazoles, and oxazolidinones. The review focuses on drug-delivery applications such as improving solubility, modifying the drug-release profile, slowing down the degradation of the drug, improving biological membrane permeability, and enhancing antimicrobial activity. In addition to simple drug/CD combinations, ternary systems with additional auxiliary substances have been described, as well as more sophisticated drug-delivery systems including nanosponges, nanofibres, nanoparticles, microparticles, liposomes, hydrogels, and macromolecules. Depending on the desired properties of the drug product, an accelerated or prolonged dissolution profile can be achieved when combining CD with antibiotics or antimicrobial agents.

Physicochemical Characterization, Molecular Docking, and In Vitro Dissolution of Glimepiride-Captisol Inclusion Complexes

This present study investigated the effect of Captisol, a chemically modified cyclodextrin, on the in vitro dissolution of glimepiride. We prepared glimepiride-Captisol complexes of different mass ratios (1:1, 1:2, and 1:3 w/w) by a physical mixing or freeze-drying technique, and found that complexation with Captisol enhanced the water solubility of glimepiride. Molecular docking and dynamic simulation predicted complex formation; at the same time, Fourier transform infrared spectroscopy, differential scanning calorimetry, powder X-ray diffractometry, and scanning electron microscope indicated molecular interactions that support complexation. We also found that an inclusion complex was better than a physical mixture in enhancing the complexation of glimepiride with Captisol and enhancing water solubility. Phase solubility study of the glimepiride-Captisol complex showed an A_L-type profile, implying the formation of a 1:1 inclusion complex. The study also revealed that pH influenced the stability of the complex because the stability constant of the glimepiride-Captisol complex was higher in distilled water of pH ∼6.0 than in phosphate buffer of pH 7.2.

Thermal Extrusion 3D Printing for the Fabrication of Puerarin Immediate-Release Tablets

Thermal extrusion (TE) 3D printing is a thermoplastic semisolid-based rapid prototyping process, which is capable of building complex structures. The aim of this study was to manufacture rapid-release puerarin tablets without solvent through TE 3D printing. Novel rapid-release tablets were fabricated with polyethylene glycol (PEG 4000) as the carrier at appropriate puerarin/PEG 4000 ratios, assessed through differential scanning calorimetry (DSC), solubility, and dissolution tests. The novel structures of 3D-printed tablets with five different values were formed by printing paths, which established a flexible way of adjusting in vitro drug release. An obvious acceleration (85% of cumulative release about 7.5 min at the soonest) was observed for the tablets with internal structural design. It was inferred that puerarin formed simple eutectic mixtures with PEG 4000 and that puerarin dispersed into the carrier based on DSC and X-Ray powder diffraction (XRD). This highlights the combined advantage of PEG as a soluble polymer with TE 3D printing and provides a suitable system for rapid puerarin release.

A thermo-responsive polyurethane organogel for norfloxacin delivery

A facile organogel was developed to improve drug release and transdermal delivery, and to increase bactericidal activity over 80% in vivo.

Ion-pair complexes formation between fluoroquinolone antibiotics and methyl red and their use for the extraction-spectrophotometric analysis

The new spectrophotometric methods of fluoroquinolones: enrofloxacin, norfloxacin, and ofloxacin determination with the methyl red are based on ion-pair complex formation between fluoroquinolones and methyl red in acidic medium at pH 3–4 and subsequent three times extraction of the reaction products by chloroform. The obtained orange extract has an absorbance maximum at λmax = 492 nm. Optimum conditions for the formation as well as for the extraction of ion-pair complexes between fluoroquinolones and methyl red at the presence of acetate buffer and potassium chloride solutions have been established: C (CH3COONa) = 0.85 M, C (KCl) = 2 M, pH = 3.8. Effective molar absorbtivity of ion-pair complexes chloroform extracts is ɛ492∼3·103 l mol−1 cm−1. New extraction-spectrophotometric methods for fluoroquinolone determination with methyl red were developed on the basis of the optimum reaction conditions. Concentration range for the system fluoroquinolone – methyl red is (2.5–25)·10−6 M; limit of detection for enrofloxacin is Cmin = 2.48·10−6 M, for norfloxacin – Cmin = 3.07·10−6 M, for ofloxacin – Cmin = 3.17·10−6 M.

Fusion Method for Solubility and Dissolution Rate Enhancement of Ibuprofen Using Block Copolymer Poloxamer 407

Aim of current research was to prepare ibuprofen-poloxamer 407 binary mixtures using fusion method and characterize them for their physicochemical and performance properties. Binary mixtures of ibuprofen and poloxamer were prepared in three different ratios (1:0.25, 1:0.5, and 1:0.75, respectively) using a water-jacketed high shear mixer. In vitro dissolution and saturation solubility studies were carried out for the drug, physical mixtures, and formulations for all ratios in de-ionized water, 0.1 N HCl (pH = 1.2), and phosphate buffer (pH = 7.2). Thermal and physical characterization of samples was done using modulated differential scanning calorimetry (mDSC), X-ray powder diffraction (XRD), and infrared spectroscopy (FTIR). Flow properties were evaluated using a powder rheometer. Maximum solubility enhancement was seen in acidic media for fused formulations where the ratio 1:0.75 had 18-fold increase. In vitro dissolution studies showed dissolution rate enhancement for physical mixtures and the formulations in all three media. The most pronounced effect was seen for formulation (1:0.75) in acidic media where the cumulative drug release was 58.27% while for drug, it was 3.67%. Model independent statistical methods and ANOVA based methods were used to check the significance of difference in the dissolution profiles. Thermograms from mDSC showed a characteristic peak for all formulations with T_peak of around 45°C which suggested formation of a eutectic mixture. XRD data displayed that crystalline nature of ibuprofen was intact in the formulations. This work shows the effect of eutectic formation and micellar solubilization between ibuprofen and poloxamer at the given ratios on its solubility and dissolution rate enhancement.

Investigation of the in vitro performance difference of drug-Soluplus® and drug-PEG 6000 dispersions when prepared using spray drying or lyophilization

Purpose: To evaluate the physicochemical and in vitro characteristics of solid dispersions using BCS II model drugs with Soluplus® and one of its component homopolymers, PEG 6000. Methods: Nifedipine (NIF) and sulfamethoxazole (SMX) of 99.3% and 99.5% purity, respectively, were selected as BCS II model drugs, such that an improved dissolution rate and concentration in the gastrointestinal tract should increase oral bioavailability. Soluplus® is an amorphous, tri-block, graft co-polymer with polyvinyl caprolactam, polyvinyl acetate, and polyethylene glycol (PCL:PVAc:PEG6000) in the ratio 57:30:13. PEG 6000 (BASF) is a waxy material with melting point of about 60 °C. Solid dispersions were prepared using lyophilization or spray drying techniques. Dissolution study, crystallinity content, and analysis for new chemical bond formation have been used to evaluate the dispersed materials. Results: Although each polymer improved the drug dissolution rate, dissolution from Soluplus® was slower. Enhanced dissolution rates were observed with NIF solid dispersions, but the dissolution profiles were quite different due to the selected technique, polymer, and dissolution medium. For SMX, there was similarity across the dissolution profiles despite the medium, polymer, or applied technique. Each polymer was able to maintain an elevated drug concentration over the three hour duration of the dissolution profile, i.e., supersaturation was supported by the polymer. DSC thermograms revealed no melting endotherm, suggesting that the drug is amorphous or molecularly dispersed. Conclusion: NIF and SMX solid dispersions were successfully prepared by spray drying and lyophilization using Soluplus® or PEG 6000. Each polymer enhanced the drug dissolution rate; NIF dissolution rate was improved to a greater extent. Dispersions with PEG 6000 had a faster dissolution rate due to its hydrophilic nature. DSC analysis showed that no crystalline material exists in the dispersions.

Computational investigation on the host-guest inclusion process of norfloxacin into β-cyclodextrin

A theoretical (1)H NMR spectroscopy and thermodynamic analysis of the host-guest inclusion process involving the norfloxacin (NFX) into β-cyclodextrin (β-CD) was carried out. DFT structure and stabilization energies were obtained in both gas and aqueous phases. We could establish that the complex formation is enthalpy driven, and the hydrogen bonds established between NFX and β-CD play a major role in the complex stabilization. Besides, a theoretical (1)H NMR analysis has shown to be a supplementary proceeding to predict appropriately the inclusion mode of norfloxacin molecule into the β-CD. In this work, a theoretical study of the NFX@β-CD complex is reported for the first time, seeking a deep understanding of topology and thermodynamics of the inclusion complex formation. Graphical Abstract Topology, thermodynamic and (1)H NMR analysis of NFX@β-CD host-guest complexes.

Solid-state flurbiprofen and methyl-β-cyclodextrin inclusion complexes prepared using a single-step, organic solvent-free supercritical fluid process

The aim of this study was to enhance the apparent solubility and dissolution properties of flurbiprofen through inclusion complexation with cyclodextrins. Especially, the efficacy of supercritical fluid technology as a preparative technique for the preparation of flurbiprofen-methyl-β-cyclodextrin inclusion complexes was evaluated. The complexes were prepared by supercritical carbon dioxide processing and were evaluated by solubility, differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, practical yield, drug content estimation and in vitro dissolution studies. Computational molecular docking studies were conducted to study the possibility of molecular arrangement of inclusion complexes between flurbiprofen and methyl-β-cyclodextrin. The studies support the formation of stable molecular inclusion complexes between the drug and cyclodextrin in a 1:1 stoichiometry. In vitro dissolution studies showed that the dissolution properties of flurbiprofen were significantly enhanced by the binary mixtures prepared by supercritical carbon dioxide processing. The amount of flurbiprofen dissolved into solution alone was very low with 1.11±0.09% dissolving at the end of 60min, while the binary mixtures processed by supercritical carbon dioxide at 45°C and 200bar released 99.39±2.34% of the drug at the end of 30min. All the binary mixtures processed by supercritical carbon dioxide at 45°C exhibited a drug release of more than 80% within the first 10min irrespective of the pressure employed. The study demonstrated the single step, organic solvent-free supercritical carbon dioxide process as a promising approach for the preparation of inclusion complexes between flurbiprofen and methyl-β-cyclodextrin in solid-state.

Poloxamer-based solid dispersions for oral delivery of docetaxel: Differential effects of F68 and P85 on oral docetaxel bioavailability

Development of an oral docetaxel formulation has been hindered mainly due to its poor solubility and oral bioavailability. The aim of this study was to develop poloxamer F68/P85-based solid dispersions (SDs) for the oral delivery of docetaxel and investigate their in vivo pharmacokinetic impacts on the systemic absorption of docetaxel given orally, in comparison with a SD based on F68 alone. The F68 and/or P85-based docetaxel SDs were prepared with varying the contents of poloxamers and then evaluated in terms of morphology, crystallinity, solubility, dissolution, permeation across rat intestinal segments, and oral pharmacokinetics in rats. As a result, the SDs successfully changed the crystalline properties of docetaxel and enhanced the drug solubility and dissolution. The SD prepared with F68 alone significantly enhanced the dissolution but not intestinal permeation of docetaxel, leading to only limited enhancement of oral bioavailability (1.39-fold increase). Notably, however, the F68/P85-based SD significantly enhanced both the dissolution and intestinal permeation of docetaxel, achieving a markedly improved oral bioavailability (2.97-fold increase). Therefore, the present results suggest that the intestinal permeation factor should be taken into account when designing SD formulations for the oral delivery of BCS class IV drugs including docetaxel, and that P85 could serve as a potential formulation excipient for enhancing the intestinal permeation of docetaxel.

Investigation of β-cyclodextrin-norfloxacin inclusion complexes. Part 1. Preparation, physicochemical and microbiological characterization

INTRODUCTION

Drugs classified as class IV by the Biopharmaceutical Classification System present significant problems in relation to effective oral administration. In the case of antibiotics, the subsequently high doses required can enhance the emergence of microorganism resistance and lead to a low rate of patient treatment adherence.

OBJECTIVE

In an attempt to improve physicochemical properties and microbiological activity of norfloxacin, the aim of this study was to investigate different methods (coevaporation, kneading followed by freeze-drying or spray-drying) to obtain complexes of norfloxacin and different cyclodextrins.

METHODS

Guest-host interactions were investigated through a complete physical-chemical characterization and the dissolution profile and microbiological activity were determined.

RESULTS

The formation of a complex of norfloxacin and β-cyclodextrin (1:1), obtained by kneading followed by freeze drying, led to increased drug solubility, which could maximize the oral drug absorption.

CONCLUSION

Moreover, the microbiological activity was enhanced by around 23.3%, demonstrating that the complex formed could represent an efficient drug delivery system.

Influence of β-cyclodextrin on the Properties of Norfloxacin Form A

Cyclodextrins are able to form host-guest complexes with hydrophobic molecules to result in the formation of inclusion complexes. The complex formation between norfloxacin form A and β-cyclodextrin was studied by exploring its structure affinity relationship in an aqueous solution and in the solid state. Kneading, freeze-drying, and physical mixture methods were employed to prepare solid complexes of norfloxacin and β-cyclodextrin. The solubility of norfloxacin significantly increased upon complexation with β-cyclodextrin as demonstrated by a solubility isotherm of the AL type along with the results of an intrinsic dissolution study. The complexes were also characterized in the solid stated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffractometry, scanning electron microscopy (SEM), and solid-state nuclear magnetic resonance (ssNMR) spectrometry. The thermal analysis showed that the thermal stability of the drug is enhanced in the presence of β-cyclodextrin. Finally, the microbiological studies showed that the complexes have better potency when compared with pure drug.

Preparation and Characterization of Solid Dispersions of Artemether by Freeze-Dried Method

Solid dispersions of artemether and polyethylene glycol 6000 (PEG6000) were prepared in ratio 12 : 88 (group-1). Self-emulsified solid dispersions of artemether were prepared by using polyethylene glycol 6000, Cremophor-A25, olive oil, Transcutol, and hydroxypropyl methylcellulose (HPMC) in ratio 12 : 75 : 5 : 4 : 2 : 2, respectively (group-2). In third group, only Cremophor-A25 was replaced with Poloxamer 188 compared to group-2. The solid dispersions and self-emulsified solid dispersions were prepared by physical and freeze dried methods, respectively. All samples were characterized by X-ray diffraction, attenuated total reflectance Fourier transform infrared spectroscopy, differential scanning calorimeter, scanning electron microscopy, and solubility, dissolution, and stability studies. X-ray diffraction pattern revealed artemether complete crystalline, whereas physical mixture and freeze-dried mixture of all three groups showed reduced peak intensities. In attenuated total reflectance Fourier transform infrared spectroscopy spectra, C–H stretching vibrations of artemether were masked in all prepared samples, while C–H stretching vibrations were representative of polyethylene glycol 6000, Cremophor-A25, and Poloxamer 188. Differential scanning calorimetry showed decreased melting endotherm and increased enthalpy change (ΔH) in both physical mixture and freeze-dried mixtures of all groups. Scanning electron microscopy of freeze-dried mixtures of all samples showed glassy appearance, size reduction, and embedment, while their physical mixture showed size reduction and embedment of artemether by excipients. In group-1, solubility was improved up to 15 times, whereas group-2 showed up to 121 times increase but, in group-3, when Poloxamer 188 was used instead of Cremophor-A25, solubility of freeze-dried mixtures was increased up to 135 times. In fasted state simulated gastric fluid at pH 1.6, the dissolution of physical mixture was increased up to 12 times and freeze-dried mixtures up to 15 times. The stability of artemether was substantially enhanced in freeze-dried mixtures by using polyethylene glycol 6000, Cremophor-A25, and Poloxamer 188 of self-emulsified solid dispersions of artemether in Hank's balanced salt solution at pH 7.4.

Nanosuspension: An Emerging Trend for Bioavailability Enhancement of Etodolac

Etodolac (ET) (poorly soluble drug) nanosuspensions were prepared by both pH shift method and antisolvent techniques in order to increase its dissolution rate. Various stabilizers were used, namely, Tween 20 and 80, HPMC, PVP K44, PVA, PEG 400, NaCMC, andβ-cyclodextrin. The prepared nanosuspensions were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) and evaluated for their particle size, particle size distribution, andin vitrodissolution rate. In general, it was found that the antisolvent method for the preparation of ET nanosuspensions reduced the drug particle size to a higher extent compared to the pH shift method. The dissolution rate of ET in distilled water was markedly enhanced in the nanosized system, as more than 65% of drug dissolved in 10 min from all the nanosuspension formulations except F5 (stabilized with PVP K44) and F8 (stabilized with Tween 20), as compared to less than 20% of crude drug. Nanoparticles prepared by antisolvent method using Tween 80 as a stabilizer were selected for furtherin vivostudy. Thein vivotest demonstrated that nanoparticles of ET were well absorbed with a percentage drug absorption value 2.7 times more than that of micrometric size of crude ET.

Enhancement of carvedilol solubility by solid dispersion technique using cyclodextrins, water soluble polymers and hydroxyl acid

Aim of the present work is to enhance aqueous solubility of carvedilol (CV) by solid dispersion technique using wide variety of carriers such as: β-cyclodextrin (βCD), hydroxypropyl-β-cyclodextrin (HPβCD), tartaric acid (TA), polyvinyl pyrrolidone K-30 (PVP K-30) and poloxamer-407 (PLX-407). Various products of 'CV-solid dispersion' had been studied extensively in various pH conditions to check enhancement of solubility and dissolution characteristics of carvedilol. Any physical change upon interaction between CV and carriers was confirmed by instrumental analysis: XRD, DSC, FTIR and SEM. Negative change of Gibb's free energy and complexation constants (Kc, 75-240M(-1), for cyclodextrins and 1111-20,365M(-1), for PVP K-30 and PLX-407) were the evidence of stable nature of the binding between CV and carriers. 'Solubility enhancement factor' of ionized-CV was found high enough (340 times) with HPβCD in presence of TA. TA increases the binding efficiency of cyclodextrin and changing the pH of microenvironment in dissolution medium. In addition, ionization process was used to increase the apparent intrinsic solubility of drug. In vitro, dissolution time of CV was remarkably reduced in the solid dispersion system compared to that of pure drug. This may be attributed to increased wettability, dispersing ability and transformation of crystalline state of drug to amorphous one.

Strategies to address low drug solubility in discovery and development

Drugs with low water solubility are predisposed to low and variable oral bioavailability and, therefore, to variability in clinical response. Despite significant efforts to "design in" acceptable developability properties (including aqueous solubility) during lead optimization, approximately 40% of currently marketed compounds and most current drug development candidates remain poorly water-soluble. The fact that so many drug candidates of this type are advanced into development and clinical assessment is testament to an increasingly sophisticated understanding of the approaches that can be taken to promote apparent solubility in the gastrointestinal tract and to support drug exposure after oral administration. Here we provide a detailed commentary on the major challenges to the progression of a poorly water-soluble lead or development candidate and review the approaches and strategies that can be taken to facilitate compound progression. In particular, we address the fundamental principles that underpin the use of strategies, including pH adjustment and salt-form selection, polymorphs, cocrystals, cosolvents, surfactants, cyclodextrins, particle size reduction, amorphous solid dispersions, and lipid-based formulations. In each case, the theoretical basis for utility is described along with a detailed review of recent advances in the field. The article provides an integrated and contemporary discussion of current approaches to solubility and dissolution enhancement but has been deliberately structured as a series of stand-alone sections to allow also directed access to a specific technology (e.g., solid dispersions, lipid-based formulations, or salt forms) where required.

Preparation and characterization of progesterone dispersions using supercritical carbon dioxide

CONTEXT

Supercritical fluid methods offer an alternative to conventional mixing methods, particularly for heat sensitive drugs and where an organic solvent is undesirable.

OBJECTIVE

To design, develop and construct a unit for the particles from a gas-saturated suspension/solution (PGSS) method and form endogenous progesterone (PGN) dispersion systems using SC-CO2.

MATERIALS AND METHODS

The PGN dispersions were manufactured using three selected excipients: polyethylene glycol (PEG) 400/4000 (50:50), Gelucire 44/14 and D-α-tocopheryl PEG 1000 succinate (TPGS). Semisolid dispersions of PGN prepared by PGSS method were compared to the conventional methods; comelting (CM), cosolvent (CS) and physical mixing (PM). The dispersion systems made were characterized by Raman and Fourier transform infrared (FTIR) spectroscopies, X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), PGN recovery, uniformity and in vitro dissolution, analyzed by high-performance liquid chromatography (HPLC).

RESULTS

Raman spectra revealed no changes in the crystalline structure of PGN treated with SC-CO2 compared to that of untreated PGN. XRPD and FTIR showed the presence of peaks and bands for PGN confirming that PGN has been incorporated well with each individual excipient. All PGN dispersions prepared by the PGSS method resulted in the improvement of PGN dissolution rates compared to that prepared by the conventional methods and untreated PGN after 60 min (p value < 0.05).

CONCLUSION

The novel PGN dispersions prepared by the PGSS method offer the great potential to enhance PGN dissolution rate, reduce preparation time and form stable crystalline dispersion systems over those prepared by conventional methods.

Pharmaceutical development and optimization of azithromycin suppository for paediatric use

Pharmaceutical development and manufacturing process optimization work was undertaken in order to propose a potential paediatric rectal formulation of azithromycin as an alternative to existing oral or injectable formulations. The target product profile was to be easy-to-use, cheap and stable in tropical conditions, with bioavailability comparable to oral forms, rapidly achieving and maintaining bactericidal concentrations. PEG solid solution suppositories were characterized in vitro using visual, HPLC, DSC, FTIR and XRD analyses. In vitro drug release and in vivo bioavailability were assessed; a study in rabbits compared the bioavailability of the optimized solid solution suppository to rectal solution and intra-venous product (as reference) and to the previous, non-optimized formulation (suspended azithromycin suppository). The bioavailability of azithromycin administered as solid solution suppositories relative to intra-venous was 43%, which compared well to the target of 38% (oral product in humans). The results of 3-month preliminary stability and feasibility studies were consistent with industrial production scale-up. This product has potential both as a classical antibiotic and as a product for use in severely ill children in rural areas. Industrial partners for further development are being sought.

Cyclodextrin-grafted cellulose: physico-chemical characterization

Cyclodextrins (CDs) can form inclusion complexes with a wide variety of molecules making them very attractive in different areas, such as pharmaceutics, biochemistry, food chemistry and textile. In this communication we will report on the physico-chemical characterization of cellulose modified with CDs by means of infra-red spectroscopy (FTIR), cross polarization magic angle spinning solid state nuclear magnetic resonance (CP-MAS NMR), polarized optical microscopy (POM) and thermal gravimetric analysis (TGA). Both CP-MAS NMR and FTIR indicate that CDs are chemically attached to cellulose backbone through the formation of ester bonds. Furthermore, the CD-grafted cellulose was dissolved in a "superphosphoric" acid solution but, despite the increase of hydrophilicity due to the modification, POM revealed that grafted cellulose was less soluble when compared to the unmodified polymer. The formation of a complex CD-cellulose network is suggested.

Preparation and in vitro, in vivo evaluations of norfloxacin-loaded solid lipid nanopartices for oral delivery

This work aims to develop norfloxacin-solid lipid nanoparticles (NFX-SLN) as an oral delivery formulation. Hot homogenization and ultrasonic technique was employed to prepare NFX-SLN using stearic acid as lipid matrix and polyvinyl alcohol as surfactant. The physicochemical characteristics of SLN were investigated by optical microscope scanning electron microscopy and photon correlation spectroscopy. Antibacterial experiments of NFX-SLN were carried out by broth dilution technique. Pharmacokinetics was studied after oral administration in male Sprague-Dawley rats. The results showed that NFX-SLN was spherical and the SLN of the optimized formulation had diameters 301 ± 16.64 nm, polydispersity index 0.15 ± 0.04, zeta potential -30.8 ± 0.69 mv, loading capacity 8.58 ± 0.21% and encapsulation efficiency 92.35 ± 2.24% with good stability at 4 °C. The NFX-SLN had sustained release effect and sustained bactericidal activity. Cytotoxicity studies in cell culture demonstrated that the nanoparticles were not toxic. NFX-SLN resulted in significantly higher plasma drug concentration than native NFX. The SLN increased the relative bioavailability of NFX by 12 folds, prolonged the plasma drug level above the average minimum inhibition concentration from 14 to 168 h. These studies demonstrate that NFX-SLN could be a promising oral formulation for enhanced bioavailability and pharmacological activities.

Physicochemical characterisation, drug polymer dissolution and in vitro evaluation of phenacetin and phenylbutazone solid dispersions with polyethylene glycol 8000

Poor water solubility leads to low dissolution rate and consequently, it can limit bioavailability. Solid dispersions, where the drug is dispersed into an inert, hydrophilic polymer matrix can enhance drug dissolution. Solid dispersions were prepared using phenacetin and phenylbutazone as model drugs with polyethylene glycol (PEG) 8000 (carrier), by melt fusion method. Phenacetin and phenylbutazone displayed an increase in the dissolution rate when formulated as solid dispersions as compared with their physical mixture and drug alone counterparts. Characterisation of the solid dispersions was performed using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). DSC studies revealed that drugs were present in the amorphous form within the solid dispersions. FTIR spectra for the solid dispersions of drugs suggested that there was a lack of interaction between PEG 8000 and the drug. However, the physical mixture of phenacetin with PEG 8000 indicated the formation of hydrogen bond between phenacetin and the carrier. Permeability of phenacetin and phenylbutazone was higher for solid dispersions as compared with that of drug alone across Caco-2 cell monolayers. Permeability studies have shown that both phenacetin and phenylbutazone, and their solid dispersions can be categorised as well-absorbed compounds.

Preparation of meloxicam-β-cyclodextrin-polyethylene glycol 6000 ternary system: characterization, in vitro and in vivo bioavailability

Ternary complexes of meloxicam (ML), a poorly water-soluble anti-inflammatory drug, with β-cyclodextrin (βCD) and polyethylene glycol (PEG) 6000 were prepared from an equimolar (ML-βCD) and 10% of PEG. Characterization of the ternary complex was carried out by differential scanning calorimetry and X-ray diffractometry. The solubility of ML increased as a function of increasing the concentration of βCD and PEG 6000. Ternary system increased significantly ML solubility in water. Ternary complexes improved drug release compared with ML and ML-βCD. The oral bioavailability of ML-βCD-PEG was investigated by administration to rat and compared with ML and ML-βCD. The results confirmed that the oral bioavailability of ML was significantly improved by complexation with βCD in the presence of PEG.

Systems biology approach to study permeability of paracetamol and its solid dispersion

Physiological changes that take place at cellular level are usually reflective of their level of gene expression. Different formulation excipients have an impact on physiological behavior of the exposed cells and in turn affect transporter genes, enterocyte-mediated metabolism and toxicity biomarkers. The aim of this study was to prepare solid dispersion of paracetamol and evaluate genetic changes that occur in Caco-2 cell lines during the permeability of paracetamol alone and paracetamol solid dispersion formulations. Paracetamol-PEG 8000 solid dispersion was prepared by melt fusion method and the formulation was characterised using differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Formulation of solid dispersion resulted in the conversion of crystalline drug into an amorphous form. Permeability studies showed that paracetamol absorption was higher from the solid dispersion formulation. DNA microarrays analysis was carried out in order to investigate the involvement of any efflux/uptake transporters in paracetamol or its solid dispersion permeability. Neither transporter carriers nor efflux proteins were found to be involved in the absorption of paracetamol or its PEG solid dispersion. Gene expression analysis established that paracetamol toxicity was potentially reduced upon formulation into solid dispersion when ATP binding cassette (ABC) and solute carrier transporter (SLC) genes were analyzed.

Genomic evaluation during permeability of indomethacin and its solid dispersion

Drug resistance was first identified in cancer cells that express proteins known as multidrug resistance proteins that extrude the therapeutic agents out of the cells resulting in alteration of pharmacokinetics, tissue distribution, and pharmacodynamics of drugs. To this end studies were carried out to investigate the role of pharmacological inhibitors and pharmaceutical excipients with a primary focus on P-glycoprotein (P-gp). The aim of this study was to investigate holistic changes in transporter gene expression during permeability upon formulation of indomethacin as solid dispersion. Initial characterization studies of solid dispersion of indomethacin showed that the drug was dispersed within the carrier in amorphous form. Analysis of permeability data across Caco-2 monolayers revealed that drug absorption increased by 4-fold when reformulated as solid dispersion. The last phase of the work involved investigation of gene expression changes of transporter genes during permeability. The results showed that there were significant differences in the expression of both ATP-binding cassette (ABC) transporter genes as well as solute carrier transporter (SLC) genes suggesting that the inclusion of polyethylene glycol as well as changes in molecular form of drug from crystalline to amorphous have a significant bearing on the expression of transporter network genes resulting in differences in drug permeability.

Physicochemical characterization of artemether solid dispersions with hydrophilic carriers by freeze dried and melt methods

Solid dispersions of artemether (ARM), a poorly soluble drug, were prepared using polyvinylpyrrolidone (PVPK25, MW 25000) and polyethyleneglycol (PEG4000, MW 4000) as excipients. These dispersions were studied by physical mixture, freeze-drying, and melting methods. They were characterized by X-ray diffraction pattern, fourier transform infrared spectrophotometry, differential scanning calorimetery, and dissolution studies. X-ray diffraction pattern revealed the complete crystalline nature of artemether, whereas physical mixtures, melt mixtures (MM), and freeze-dried solid dispersions (FDSD) of ARM-PVP and ARM-PEG showed reduced peak intensities with increased PVP/PEG content. PEG showed lower decreases in intensity than PVP preparations. Differential scanning calorimetery also confirmed this finding by showing either a small or absent endotherm. Red shifts in O-H stretching vibrations of ARM were higher in the MM of ARM-PVP than its FDSD as exhibited by fourier transform infrared spectrophotometry. The carbonyl peak of PEG was blue shifted in MM and FDSD, whereas the C=O peak of PVP was red shifted in FDSD and MM, indicating different H-bonding by PEG and PVP with ARM. The rate of dissolution (phosphate buffer at pH 4.5) was improved up to 4-fold in MM and FDSD compared to artemether, and up to 50% compared to physical mixtures. The preparation of solid dispersions influenced the rate of dissolution at various drug-carrier ratios, i.e., the dissolution order of 1:1-1:4 ratio was MM > FDSD; FDSD > MM at 1:6-1:8 ratios of both ARM-PVP and ARM-PEG; and FDSD of ARM-PEG > FDSD of ARM-PVP > MM of ARM-PEG > MM of ARM-PVP at a 1:10 ratio.