Tablet formulation containing meloxicam and beta-cyclodextrin: mechanical characterization and bioavailability evaluation

Short Review on the Biological Activity of Cyclodextrin-Drug Inclusion Complexes Applicable in Veterinary Therapy

Cyclodextrins (CDs) are a family of carrier molecules used to improve the pharmacokinetic parameters of therapeutic molecules. These cyclic oligosaccharides have medical and pharmaceutical applications by being able to form inclusion complexes with molecules that are poorly soluble in water. The benefits of these complexes are directed towards improving the chemical and biological properties-i.e., solubility, bioavailability, stability, non-toxicity and shelf life of drug molecules. Since the 1960s, the first inclusion complexes used in therapeutics were those with α-, β- and γ-CD, which proved their usefulness, but had certain degrees of particularly renal toxicity. Currently, to correct these deficiencies, β-CD derivatives are most frequently used, such as sulfobutylether-β-CD, hydroxypropyl-β-CD, etc. Therefore, it is of interest to bring to the attention of those interested the diversity of current and potential future clinical applications of inclusion complexes in veterinary medicine and to present the contribution of these inclusion complexes in improving drug efficacy. The most important biological activities of β-CD complexed molecules in the veterinary field are summarized in this short review.

Synthesis of PEG-4000-co-poly (AMPS) nanogels by cross-linking polymerization as highly responsive networks for enhancement in meloxicam solubility

Poor solubility is an ongoing issue and the graph of poorly soluble drugs has increased markedly which critically affect their dissolution, bioavailability, and clinical effects. This common issue needs to be addressed, for this purpose a series of polyethylene glycol (PEG-4000) based nanogels were developed by free radical polymerization technique to enhance the solubility, dissolution, and bioavailability of poorly soluble drug meloxicam (MLX), as improved solubility is the significant application of nanosystems. Developed nanogels formulations were characterized by FTIR, XRD, SEM, zeta sizer, percent equilibrium swelling, drug loaded content (DLC), drug entrapment efficiency (DEE), solubility studies, and in vitro dissolution studies. Furthermore, cytotoxicity studies were conducted in order to determine the bio-compatibility of the nanogels drug delivery system to biological environment. Nanogels particle size was found to be 156.19 ± 09.33 d.nm. Solubility study confirmed that the solubility of poorly soluble drug MLX was significantly enhanced up to 36 folds as compared to reference product (Mobic^®). The toxicity study conducted on rabbits and MTT assay endorsed the safety of the developed nanogels formulations to the biological system.

The role of pH and dose/solubility ratio on cocrystal dissolution, drug supersaturation and precipitation

Cocrystals that are more soluble than the constituent drug, generate supersaturation levels during dissolution and are predisposed to conversion to the less soluble drug. Drug release studies during cocrystal dissolution generally compare several cocrystals and their crystal structures. However, the influence of drug dose and solubility in different dissolution media has been scarcely reported. The present study aims to investigate how drug dose/solubility ratio (Do=C_dose/S_drug), cocrystal solubility advantage over drug (SA=S_cocrystal/S_drug), and dissolution media affect cocrystal dissolution-drug supersaturation and precipitation (DSP) behavior. SA and K_sp values of 1:1 cocrystals of meloxicam-salicylic acid (MLX-SLC) and meloxicam-maleic acid (MLX-MLE) were determined at cocrystal/drug eutectic points. Results demonstrate that both cocrystals enhance SA by orders of magnitude (20 to 100 times for the SLC and over 300 times for the MLE cocrystal) in the pH range of 1.6 to 6.5. It is shown that during dissolution, cocrystals regulate the interfacial pH (pH_int) to 1.6 for MLX-MLE and 4.5 for MLX-SLC, therefore diminishing the cocrystal dissolution rate dependence on bulk pH. Do values ranged from 2 (pH 6.5) to 410 (pH 1.6) and were mostly determined by the drug solubility dependence on pH. Drug release profiles show that maximum supersaturation (σ_max=C_max/S_drug)and AUC increased with increasing Do as pH decreased. When Do>>SA, the cocrystal solubility is not sufficient to dissolve the dose so that a dissolution-precipitation quasi-equilibrium state is able to sustain supersaturation for the extent of the experiment (24 h). When Do<<SA, cocrystal solubility is more than adequate to dissolve the dose. Low σ_max values (1.7 and 1.5) near the value of Do (2.3 and 2.4) were observed, where a large fraction of the cocrystal added is dissolved to reach σ_max. Two different cocrystal to drug conversion pathways were observed: (1) surface nucleation of the metastable MLX polymorph IV on the dissolving cocrystal preceeded formation of the stable MLX polymorph I in bulk solution (in all conditions without FeSSIF), and (2) bulk nucleation of the stable MLX polymorph (in FeSSIF). The interplay between cocrystal SA, Do_, and drug precipitation pathways provide a framework to interpret and understand the DSP behavior of cocrystals.

Intermolecular interaction as a direct measure of water solubility advantage of meloxicam cocrystalized with carboxylic acids

The solubility advantage (SA) of meloxicam cocrystalized with mono- and dicarboxylic acids was expressed in terms of equilibrium constants involving active pharmaceutical ingredient and coformer in aqueous solutions. It is argued that SA can be quantified by concentration of pairs formed in water. The pH and concentration of dissolved components is included explicitly in the model. The alternative behavior of mono- and dicarboxylic acids was emphasized and addressed to different structural motifs. The structural and energetic properties of meloxicam and its complexes with carboxylic acids were characterized, including tautmerism and dissociation in aqueous media. In particular, performed in silico modeling confirmed experimental observation that meloxicam dissolved in water or modest acidic solutions is expected to be a mixture of anionic form in equilibrium with at least five neutral isomers. Tautomer-related diversity of pairs formation and the possibility of salt formation is also discussed. Graphical abstract Two types of motifs found in meloxicam cocrystals reveal two sources of solubility advantage.

Amorphous Solid Dispersion of Meloxicam Enhanced Oral Absorption in Rats With Impaired Gastric Motility

Meloxicam (MEL) shows a slow onset of action in severe pain patients on account of delayed gastric motility. This study aimed to develop an amorphous solid dispersion (ASD) of MEL to achieve rapid oral absorption in severe pain patients. ASD formulations of MEL with hydroxypropylmethylcellulose (ASD-MEL/HPMC) and polyacrylates and polymethacrylates (ASD-MEL/EUD) were prepared and physicochemically characterized. Oral absorption behavior of MEL samples was also clarified in both normal and propantheline (PPT)-pretreated rats with impaired gastric motility. MEL in the formulations was amorphous, and ASD formulations of MEL exhibited high dissolution behavior in acidic solution. After oral administration of crystalline MEL (1 mg-MEL/kg), a 69% reduction in AUC_0-4 was observed between normal and PPT-pretreated rats. For orally dosed ASD-MEL/HPMC (1 mg-MEL/kg), there were approximately 9- and 12-fold increases of AUC_0-4 in normal and PPT-pretreated rats, respectively, in comparison with crystalline MEL (1 mg-MEL/kg). However, the oral absorption behavior of ASD-MEL/EUD (1 mg-MEL/kg) was low and similar to that of crystalline MEL. The infrared spectroscopic study revealed potent interactions between MEL and EUD, possibly leading to marked attenuation of MEL absorption. This ASD approach might provide rapid oral absorption of MEL in severe pain patients, possibly leading to better clinical outcomes.

Physicochemical and Pharmacokinetic Characterization of Amorphous Solid Dispersion of Meloxicam with Enhanced Dissolution Property and Storage Stability

The aim of the present study was to develop amorphous solid dispersion (ASD) of meloxicam (MEL) for providing rapid onset of action. ASDs of MEL with polyvinylpyrrolidone (PVP) K-30 (MEL/PVP), HPC-SSL (MEL/HPC), and Eudragit EPO (MEL/EPO) were prepared. The physicochemical properties were characterized by focusing on morphology, crystallinity, dissolution properties, stability, and the interaction of MEL with coexisting polymers. MEL/EPO was physicochemically stable after storage at 40°C/75% RH for 30 days. In contrast, recrystallization of MEL was observed in MEL/PVP and MEL/HPC at 40°C/50% RH for 30 days. Infrared spectroscopic studies and (1)H NMR analyses of MEL/EPO revealed that Eudragit EPO interacted with MEL and reduced intermolecular binding between MEL molecules. Intermolecular interaction of drug molecules is necessary for the formation of crystalline. Thus, the interaction of MEL with Eudragit EPO and interruption of the formation of supramolecular interaction between MEL molecules might lead to the inhibition of crystal growth of MEL. Of all the MEL solid dispersions prepared, MEL/EPO showed the largest improvement in dissolution behavior. Oral administration of MEL/EPO to rats showed rapid and enhanced MEL exposure with a 2.4-fold increase in bioavailability compared with crystalline MEL. Based on these findings, MEL/EPO was physicochemically stable and provided a rapid onset of action and enhanced bioavailability after oral administration.

Acyclovir-loaded sorbitan esters-based organogel: development and rheological characterization

Herein, a nanoemulsion-based organogel (NEOG) system loaded with acyclovir has been developed for the effective treatment of herpes simplex virus infection via topical delivery. Pseudo-ternary phase diagram exhibited increase in non-birefrigent, optically isotropic region of organogel with Smix (K_w) ratio. The NEOG C showed good storage (G') and loss moduli (G″), and more compact network structures. Gel-sol transition temperature (Tg) and fractal dimension (D_f) of NEOG system revealed increased density of the tubular network with K_w. Hence, high gelling ability of the developed NEOG system may attribute to the combination of sustained and site-specific delivery of drugs.

Characterization of omega-3 tablets

Omega-3 nutraceuticals are extensively used as health supplements worldwide. Various administration forms for delivery of omega-3 are available. However, the niche omega-3 tablets have so far remained unexplored. In this work tablets containing 25-40% (w/w) omega-3 oil as triglycerides or ethyl esters were prepared utilizing a direct compaction grade powder with β-cyclodextrin as encapsulating agent. It was found that powders with up to 35% (w/w) triglyceride oil and 30% (w/w) ethyl ester oil, respectively, can be directly compressed into tablets of excellent quality. Physical properties of omega-3 containing powders and tablets are described. The powder X-ray diffractograms of the powders and crushed tablets show evidence of the formation of new crystalline phases not present in β-cyclodextrin. In addition, (1)H NMR data suggest that the ethyl esters form inclusion complexes with β-cyclodextrin. Compaction of other, commercially available, omega-3 powders was performed as a comparison and deemed unsuccessful.

Enhanced analgesic activity by cyclodextrins - a systematic review and meta-analysis

INTRODUCTION

Analgesics can be ineffective in treating some types of pain, hence, improved drug delivery systems could optimize their efficacy.

AREA COVERED

The authors conducted a systematic review to evaluate the analgesic activity of compounds complexed in cyclodextrins, analyzing whether these complexes improved analgesic efficacy. The search terms 'analgesics', 'cyclodextrins' and 'drug effects' were used to retrieve articles in SCOPUS, PUBMED and EMBASE. A total of 22 papers were identified. In the clinical studies, there was greater efficacy in the complexed drug when compared with control groups, with differences ranging from 25 to 83%. Through a meta-analysis, the preclinical studies showed that the complexed drug had a significantly (p < 0.01) greater effect than the non-complexed drug.

EXPERT OPINION

The use of cyclodextrins can improve the efficacy of analgesic compounds, and they are an important tool in the search for greater analgesic effect. They may also be a way to reduce the therapeutic doses, and hence increasing the potential of the drug.

Compactible powders of omega-3 and β-cyclodextrin

Omega-3 fatty acids are used in both nutraceuticals and pharmaceuticals in the form of triglycerides and ethyl esters. Administration forms available for omega-3 include bulk oil, soft gel capsules, emulsions and some powder compositions. Cyclodextrins are substances well known for their ability to encapsulate lipophilic molecules. In the present work, powders loaded with omega-3 oil, ranging from 10 to 40% (w/w), have been prepared by vacuum drying, freeze drying or spray granulation of aqueous mixtures of omega-3 oil and β-cyclodextrin. The powders were found to be partially crystalline by powder X-ray diffraction and to contain crystalline phases not present in pure β-cyclodextrin, indicating true complexation. The compactibility of the powders has been explored, revealing that a dry and compactible powder can be prepared from various omega-3 oils and β-cyclodextrin. Spray granulation was found to be the superior drying method for the preparation of compactible powders.

Formulation and evaluation of meloxicam oral disintegrating tablet with dissolution enhanced by combination of cyclodextrin and ion exchange resins

CONTEXT

The bitter taste of drug is masked by the exchange of ionized drugs with counter ions of ion exchange resin, forming "resinate". Cyclodextrin reduces the unpleasant taste and enhances the drug solubility by encapsulating drug molecules into its central cavity.

OBJECTIVE

Oral disintegrating tablets (ODTs) using the combination of ion exchange resin and cyclodextrin was developed, to mask the bitter taste and enhance drug dissolution.

METHODS

Meloxicam (MX) was selected as a model drug. Formulations containing various forms of MX (free drug, MX-loaded resin or resinate, complexes of MX and 2-hydroxypropyl-β-cyclodextrin (HPβCD) or MX/HPβCD complexes, and a mixture of resinate and MX/HPβCD complexes) were made by direct compression. The ODTs were evaluated for weight variation, thickness, diameter, hardness, friability, disintegration time, wetting time, MX content, MX release, degree of bitter taste and stability.

RESULTS AND DISCUSSION

The tablet hardness was ∼3 kg/in(2), and the friability was <1%. Tablets formulated with resinate and the mixture of resinate and MX/HPβCD complexes disintegrated rapidly within 60 s, which is the acceptable limit for ODTs. These results were corresponded to the in vivo disintegration and wetting times. However, only tablets containing the mixture of resinate and MX/HPβCD complexes provided complete MX dissolution and successfully masked the bitter taste. In addition, this tablet was stable at least 6 months.

CONCLUSIONS

The combination of ion exchange resin and cyclodextrin could be used in ODTs to mask the bitter taste and enhance the dissolution of drugs that are weakly soluble in water.

An innovative hydrogel of gemcitabine-loaded lipid nanocapsules: when the drug is a key player of the nanomedicine structure

A new method to form a nanoparticle-structured hydrogel is reported; it is based on the drug being loaded into the nanoparticles to form a solid structure. A lipophilic form of gemcitabine (modified lauroyl), an anti-cancer drug, was encapsulated in lipid nanocapsules (LNCs), using a phase-inversion temperature process. A gel was formed spontaneously, depending on the LNC concentration. The drug loading, measured with total entrapment efficiency, and the rheological properties of the gel were assessed. Physical studies (surface tension measurements) showed that modified gemcitabine was localised at the oil-water interface of the LNC, and that the gemcitabine moieties of the prodrug were exposed to the water phase. This particular assembly promoted inter-LNC interactions via hydrogen bonds between gemcitabine moieties that led to an LNC gel structure in water, without a matrix, like a tridimensional pearl necklace. Dilution of the gel produced a gemcitabine-loaded LNC suspension in water, and these nanoparticles presented cytotoxic activity to various cancer cell lines to a greater degree than the native drug. Finally, the syringeability of the formulation was successfully tested and perspectives of its use as a nanomedicine (intratumoural or subcutaneous injection) can be foreseen.

Meloxicam taste-masked oral disintegrating tablet with dissolution enhanced by ion exchange resins and cyclodextrin

The purpose of this study was to develop taste-masked oral disintegrating tablets (ODTs) using the combination of ion exchange resin and cyclodextrin, to mask the bitter taste and enhance drug dissolution. Meloxicam (MX) was selected as a model drug with poor water solubility and a bitter taste. Formulations containing various forms of MX (free drug, MX-loaded resin or resinate, complexes of MX and 2-hydroxypropyl-β-cyclodextrin (HPβCD) or MX/HPβCD complexes, and a mixture of resinate and MX/HPβCD complexes) were made and tablets were prepared by direct compression. The ODTs were evaluated for weight variation, thickness, diameter, hardness, friability, disintegration time, wetting time, MX content, MX release, degree of bitter taste, and stability. The results showed that thickness, diameter, weight, and friability did not differ significantly for all of these formulations. The tablet hardness was approximately 3 kg/in.(2), and the friability was less than 1%. Tablets formulated with resinate and the mixture of resinate and MX/HPβCD complexes disintegrated rapidly within 60 s, which is the acceptable limit for ODTs. These results corresponded to the in vivo disintegration and wetting times. However, only tablets containing the mixture of resinate and MX/HPβCD complexes provided complete MX dissolution and successfully masked the bitter taste of MX. In addition, this tablet was stable at least 6 months. The results from this study suggest that the appropriate combination of ion exchange resin and cyclodextrin could be used in ODTs to mask the bitter taste of drug and enhance the dissolution of drugs that are weakly soluble in water.

Enhanced dissolution and stability of lansoprazole by cyclodextrin inclusion complexation: preparation, characterization, and molecular modeling

In this study, lansoprazole (LSP)/cyclodextrin (CD) inclusion complexes were prepared using a fluid bed coating technique, with β-cyclodextrin (β-CD) and 2-hydroxypropyl-β-cyclodextrin (HPCD) as the host molecules, respectively, to simultaneously improve the dissolution and stability of LSP. The dissolution rate and stability of LSP was dramatically enhanced by inclusion complexation regardless of CD type. LSP/HPCD inclusion complex was more stable under illumination than LSP/β-CD inclusion complex. Differential scanning calorimetry and powder X-ray diffractometry proved the absence of crystallinity in both LSP/CD inclusion complexes. Fourier transform infrared spectroscopy together with molecular modeling indicated that the benzimidazole of LSP was included in the cavity of both CDs, while LSP was more deeply included in HPCD than β-CD. The enhanced photostability was due to the inclusion of the sulfinyl moiety into the HPCD cavity. CD inclusion complexation could improve the dissolution and stability of LSP.

Enhanced dissolution, stability and physicochemical characterization of ATRA/2-hydroxypropyl-β-cyclodextrin inclusion complex pellets prepared by fluid-bed coating technique

The aim of this work was to prepare stable all-trans-retinoic acid (ATRA)/2-hydroxypropyl-β-cyclodextrin (HPCD) inclusion complex pellets with industrial feasible technology, the fluid-bed coating technique, using PVP K30 simultaneously as binder and reprecipitation retarder. The coating process was fluent with high coating efficiency. In vitro dissolution of the inclusion complex pellets in 5% w/v Cremopher EL solution was dramatically enhanced with no reprecipitation observed, and significantly improved stability against humidity (92.5% and 75% RH) and illumination (4500 lx ± 500 lx) was achieved by HPCD inclusion. Differential scanning calorimetry and powder X-ray diffractometry confirmed the absence of crystallinity of ATRA. Fourier transform-infrared spectrometry revealed interaction between ATRA and HPCD adding evidence on inclusion of ATRA moieties into HPCD cavities. Solid-state (13)C NMR spectrometry indicated possible inclusion of ATRA through the polyene chain, which was the main reason for the enhanced photostability. It is concluded that the fluid-bed coating technique has the potential use in the industrial preparation of ATRA/HPCD inclusion complex pellets.

Stability Indicating HPTLC Determination of Meloxicam

A simple, selective, precise and stability-indicating high-performance thin layer chromatographic method of analysis of meloxicam both as a bulk drug and in formulation has been developed. The mobile phase selected was ethyl acetate:cyclohexane:glacial acetic acid (6.5:3.5:0.02% v/v/v). The calibration curve of the drug was linear in the range of 100-500 ng. The spectrodensitometric analysis was carried out in the absorbance mode at 353 nm. The mean (±RSD) values of slope, correlation coefficient and intercept were 3183.8±0.358, 0.9996±0.0321 and 13012±7.1 respectively. The system precision and the method precision studies were carried out with RSD of 0.83 and 1.89 respectively. The limit of detection and quantitation were 30 ng and 99 ng respectively. The mean percent recovery was found to be 100.3%. The method was used to analyze meloxicam from marketed tablet formulation in the presence of commonly used excipients.

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.

Development and evaluation of fast-dissolving tablets of meloxicam-β-cyclodextrin complex prepared by direct compression

The aim of this study was to prepare fast-dissolving tablets of meloxicam after its complexation with β-cyclodextrin (β-CD) and to investigate the effect of using different superdisintegrants on the disintegration and release of meloxicam from the tablets. A complex of meloxicam with β-CD was prepared by spray drying and then compressed in the form of tablets utilizing the direct compression technique. Three superdisintegrants were employed at various levels - sodium starch glycolate, croscarmellose sodium, and crospovidone. Co-spray dried micro-crystalline cellulose and mannitol (Avicel HFE-102) were used as diluents in the tablets. Prior to compression, the pre-compression parameters showed satisfactory flow properties. Post-compression parameters showed that all tablet formulations had acceptable mechanical properties. Wetting and disintegration times were prolonged by increasing the level of sodium starch glycolate in the tablets. This was attributed to the formation of a viscous gel layer around the tablets by sodium starch glycolate whereas this effect was not observed with croscarmellose sodium and crospovidone. Dissolution studies showed fast release of meloxicam except in tablets containing a high level of sodium starch glycolate. Complexation of meloxicam with β-CD significantly improved the solubility of the drug and improved the mechanical properties of tablets produced by direct compression.

Coformer selection in pharmaceutical cocrystal development: a case study of a meloxicam aspirin cocrystal that exhibits enhanced solubility and pharmacokinetics

Meloxicam is a nonsteroidal anti-inflammatory drug with low aqueous solubility and high permeability. Because of its low solubility under acidic conditions (e.g., pH 1-5), it can take more than 2 h for meloxicam to reach its therapeutic concentration in humans. Although the slow onset of meloxicam does not necessarily impact the current label indications, the slow onset does prevent meloxicam from its potential application for the relief of mild-to-medium-level acute pain. Pharmaceutical cocrystallization of meloxicam, which represents a promising approach to generate diverse novel crystal forms, could be used to improve the aqueous solubility and accelerate the onset of action. In this contribution, we describe how a novel method can be used for coformer selection to enable the efficient and effective development of a pharmaceutical cocrystal with desired physicochemical and pharmacokinetic properties. Aspirin was selected as the coformer for meloxicam based upon this alternative route, which combines the supramolecular synthon approach with findings in the previous pharmacological and toxicological studies of meloxicam. The resulting cocrystal of meloxicam and aspirin exhibited superior kinetic solubility and possessed the potential to significantly decrease the time required to reach the human therapeutic concentration compared with the parent drug, meloxicam.

Response surface methodology to optimize novel fast disintegrating tablets using β cyclodextrin as diluent

The objective of this work was to apply response surface approach to investigate main and interaction effects of formulation parameters in optimizing novel fast disintegrating tablet formulation using β cyclodextrin as a diluent. The variables studied were diluent (β cyclodextrin, X (1)), superdisintegrant (Croscarmellose sodium, X (2)), and direct compression aid (Spray dried lactose, X (3)). Tablets were prepared by direct compression method on B2 rotary tablet press using flat plain-face punches and characterized for weight variation, thickness, disintegration time (Y (1)), and hardness (Y (2)). Disintegration time was strongly affected by quadratic terms of β cyclodextrin, croscarmellose sodium, and spray-dried lactose. The positive value of regression coefficient for β cyclodextrin suggested that hardness increased with increased amount of β cyclodextrin. In general, disintegration of tablets has been reported to slow down with increase in hardness. However in the present study, higher concentration of β cyclodextrin was found to improve tablet hardness without increasing the disintegration time. Thus, β cyclodextrin is proposed as a suitable diluent to achieve fast disintegrating tablets with sufficient hardness. Good correlation between the predicted values and experimental data of the optimized formulation validated prognostic ability of response surface methodology in optimizing fast disintegrating tablets using β cyclodextrin as a diluent.

Risperidone solid dispersion for orally disintegrating tablet: its formulation design and non-destructive methods of evaluation

The focus of present investigation was to assess the utility of non-destructive techniques in the evaluation of risperidone solid dispersions (SD) with methyl-β-cyclodextrin (MBCD) and subsequent incorporation of the SD into orally disintegrating tablets (ODT) for a faster release of risperidone. The SD was prepared by a solvent evaporation method and evaluated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), near infrared spectroscopy (NIR), NIR-chemical imaging (NIR-CI), powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC). DSC and XRD analysis indicated that crystallinity of SD has reduced significantly. FTIR showed no interaction between risperidone and MBCD. Partial least square (PLS) was applied to the NIR data for the construction of chemometric models to determine both components of the SD. Good correlations were obtained for calibration and prediction as indicated by correlation coefficients >0.9965. The model was more accurate and less biased in predicting the MBCD than risperidone as indicated by its lower mean accuracy and mean bias values. SD-3 (risperidone:MBCD, 1:3) was incorporated into ODT tablets containing diluent (D-mannitol, FlowLac(®) 100 or galenIQ™-721) and superdisintegrant (Kollidon(®) CL-SF, Ac-Di-Sol or sodium starch glycolate). Disintegration time, T(50) and T(90) were decreased in the formulations containing mannitol and Kollidon(®) CL-SF, but increased with galenIQ™-721 and sodium starch glycolate, respectively. NIR-CI images confirmed the homogeneity of SD and ODT formulations.

A pilot human pharmacokinetic study and influence of formulation factors on orodispersible tablet incorporating meloxicam solid dispersion using factorial design

Meloxicam (MLX) suffers from poor aqueous solubility leading to slow absorption following oral administration; hence, immediate release MLX tablet is unsuitable in the treatment of acute pain. This study aims to overcome such a drawback by increasing MLX solubility and dissolution using PEG solid dispersion (SD), then, to investigate the feasibility of incorporating the SD into orodispersible tablets (ODTs). A 2(3) full factorial design was employed to investigate the influence of three formulation variables on MLX ODTs. The selected factors: camphor (X(1)) as pore-forming material, and croscarmellose sodium (X(2)) as superdisintegrant, showed significant positive influence, while PEG content (X(3)) was proved to negatively affect both disintegration and wetting times. In addition, isomalt increased disintegration and wetting times when compared to mannitol as diluents. The pharmacokinetic assessment of the optimum ODT formulation in healthy human subjects proved that the faster MLX dissolution by using PEG solid dispersion at pH 6.8 resulted in more rapid absorption of MLX. The rate of absorption of MLX from ODT was significantly faster (p = 0.030) with a significantly higher peak plasma concentration (P = 0.037) when compared to the marketed immediate release MLX tablet with a mean oral disintegration time of 17 ± 3 s.

Immune receptor signaling, aging and autoimmunity

Aging is associated with a myriad of changes including alterations in glucose metabolism, brain function, hormonal regulation, muscle homeostasis and the immune system. Aged dividuals, generally still defined as over 65 years old, differ from middle-aged or young donors in many features of the immune system. The major observation is that the elderly population is not able to cope with infections as well as younger adults and recovery generally takes longer. Moreover, some diseases first appear with advancing age and are likely associated with dysfunction of the immune system. Thus, Alzheimer's disease, atherosclerosis, type II diabetes and some autoimmune disorders are linked to changes in immune function. One major immune cell population implicated as being responsible for the initiation and chronicity of immune dysfunction leading to diseases or immunosuppression is the T-cell. Although many changes in B-cell and innate immune function in aging are associated with the appearance of disease, they are not as well studied and clearly demarcated as changes in the T-cell compartment. The adaptive immune system is coordinated by T-cells, the activation of which is required for the initiation, maintenance and termination of responses against pathogens. Changes in the expression and functions of the T-cell receptor (TCR) for antigen and its co-receptors are closely associated with immunosenescence. Certain similar changes have also been found in some other disease states, e.g., rheumatoid arthritis, systemic lupus erythematosus and cancer. In this chapter, we will summarize our knowledge about multichain immune recognition receptor signaling, mainly the TCR, in aging and autoimmune diseases.

Fast-dissolving tablets of glyburide based on ternary solid dispersions with PEG 6000 and surfactants

Marketed glyburide tablets present unsatisfying dissolution profiles that give rise to variable bioavailability. With the purpose of developing a fast-dissolving tablet formulation able to assure a complete drug dissolution, we investigated the effect of the addition to a reference tablet formulation of different types (anionic and nonionic) and amounts of hydrophilic surfactants, as well as the use of a new technique, based on ternary solid dispersions of the drug with an hydrophilic carrier (polyethylene glycol [PEG] 6000) and a surfactant. Tablets were prepared by direct compression or previous wet granulation of suitable formulations containing the drug with each surfactant or drug:PEG:surfactant ternary dispersions at different PEG:surfactant w/w ratios. The presence of surfactants significantly increased (p<0.01) the drug dissolution rate, but complete drug dissolution was never achieved. On the contrary, in all cases tablets containing ternary solid dispersions achieved 100% dissolved drug within 60 min. The best product was the 10:80:10 w/w ternary dispersion with PEG 6000 and sodium laurylsulphate, showing a dissolution efficiency 5.5-fold greater than the reference tablet formulation and 100% drug dissolution after only 20 min.

In vitro release and in vivo absorption in beagle dogs of meloxicam from Eudragit® FS 30 D-coated pellets

The objective of this study was to develop meloxicam-loaded colon-specific pellets coated with Eudragit FS 30 D and further evaluate their in vitro release and in vivo absorption in beagle dogs. Meloxicam-loaded cores (drug loading, 4.8%, w/w) were prepared by layering drug-binder (HPMC)-solubilizer (beta-cyclodextrin) solution onto nonpareils (710-850 microm) and then coated with a copolymer of methyl acrylate, methyl methacrylate and methacrylic acid (Eudragit FS 30 D). The obtained pellets with 15% (w/w) coating level had a spherical form and a smooth surface with coating thickness approximately 28 microm. The in vitro drug release from the pellets was pH-dependent with sufficient gastric resistance (pH 1.2: no release; pH 6.8: 6%; pH 7.0: 52%; pH 7.2: 100%; pH 7.4: 100%, after 3 h incubation). In vivo study was carried out using pentagastrin-pretreated beagle dogs. The onset of meloxicam absorption from the coated pellets with 15% (w/w) Eudragit FS 30 D (3.0+/-0.8 h) was significantly delayed (p<0.05) compared to that from the uncoated drug-layered cores (0.6+/-0.3 h). The area under the meloxicam plasma concentration-time curve (AUC(0-->96)(h) was not significantly different between the two preparations (p>0.05), although AUC(0-->96)(h) obtained after oral administration of coated pellets (142.5+/-59.6 microg h/ml) was lower than that obtained after administration of uncoated drug-layered cores (180.8+/-61.9 microg h/ml). These results suggested that meloxicam could be delivered to the colon with 15% (w/w) coating level of Eudragit FS 30 D and this polymer coating had no significant influence on the relative bioavailability of meloxicam of the pellets.

Improved absorption of meloxicam via salt formation with ethanolamines

The present study aimed to investigate the effect of ethanolamine salt formation on the dissolution as well as in vivo pharmacokinetics of meloxicam. Three meloxicam-ethanolamine salts were prepared and their in vitro dissolution profiles were examined at pH 1.2 and 6.8. The pharmacokinetic profiles of meloxicam following an oral administration of meloxicam or its ethanolamine salts were also evaluated in rats. The dissolution rates of meloxicam and its ethanolamine salts were similarly slow at pH 1.2, however, at pH 6.8, ethanolamine salt formation significantly enhanced the dissolution rate of meloxicam. Meloxicam diethanolamine salt exhibited the highest dissolution rate at pH 6.8. The faster dissolution of meloxicam via ethanolamine salt formation at pH 6.8 appeared to be correlated well with more rapid absorption of meloxicam in rats. Tmax of meloxicam was significantly (p<0.05) shortened following an oral administration of ethanolamine salts. Furthermore, ethanolamine salts exhibited a trend toward the increase in AUC0-4 (initial exposure), while the overall exposure (AUC0-24) was similar between meloxicam and its salts. In conclusion, the ethanolamine salts of meloxicam, particularly diethanolamine salt of meloxicam, facilitated the rapid absorption of meloxicam while maintaining the prolonged exposure and may be used for the earlier onset of action for meloxicam.

Adsorption of meloxicam on porous calcium silicate: characterization and tablet formulation

The purpose of the present study was characterization of microparticles obtained by adsorption of poorly water soluble drug, meloxicam, on a porous silicate carrier Florite RE (FLR) and development of a tablet formulation using these microparticles, with improved drug dissolution properties. The study also reveals the use of FLR as a pharmaceutical excipient. Meloxicam was adsorbed on the FLR in 2 proportions (1:1 and 1:3), by fast evaporation of solvent from drug solution containing dispersed FLR. Drug adsorbed FLR microparticles were evaluated for surface topography, thermal analysis, X-ray diffraction properties, infrared spectrum, residual solvent, micromeritic properties, drug content, solubility, and dissolution studies. Microparticles showed bulk density in the range of 0.10 to 0.12 g/cm(3). Dissolution of drug from microparticles containing 1:3, drug:FLR ratio was faster than microparticles containing 1:1, drug:FLR ratio. These microparticles were used for formulating directly compressible tablets. Prepared tablets were compared with a commercial tablet. All the prepared tablets showed acceptable mechanical properties. Disintegration time of prepared tablets was in the range of 18 to 38 seconds, and drug dissolution was much faster in both acidic and basic medium from prepared tablets as compared with commercial tablet. The results suggest that FLR provides a large surface area for drug adsorption and also that a reduction in crystallinity of drug occurs. Increase in surface area and reduction in drug crystallinity result in improved drug dissolution from microparticles.

Architecture of a Biocompatible Supramolecular Material by Supersaturation-Driven Fabrication of its Fiber Network

The architecture of a biocompatible organogel formed by gelation of a small molecule organic gelator, N-lauroyl-L-glutamic acid di-n-butylamide, in isostearyl alcohol was investigated based on a supersaturation-driven crystallographic mismatch branching mechanism. By controlling the supersaturation of the system, the correlation length that determines the mesh size of the fiber network was finely tuned and the rheological properties of the gel were engineered. This approach is of considerable significance for many gel-based applications, such as controlled release of drugs that requires precise control of the mesh size. A direct cryo-transmission electron microscopy (TEM) imaging technique capable of preserving the network structure was used to visualize its nanostructure.