Piroxicam Loading onto Mesoporous Silicas by Supercritical CO2 Impregnation

Piroxicam (PRX) is a commonly prescribed nonsteroidal anti-inflammatory drug. Its efficacy, however, is partially limited by its low water solubility. In recent years, different studies have tackled this problem and have suggested delivering PRX through solid dispersions. All these strategies, however, involve the use of potentially harmful solvents for the loading procedure. Since piroxicam is soluble in supercritical CO₂ (scCO₂), the present study aims, for the first time, to adsorb PRX onto mesoporous silica using scCO₂, which is known to be a safer and greener technique compared to the organic solvent-based ones. For comparison, PRX is also loaded by adsorption from solution and incipient wetness impregnation using ethanol as solvent. Two different commercial mesoporous silicas are used (SBA-15 and Grace Syloid^® XDP), which differ in porosity order and surface silanol population. Physico-chemical analyses show that the most promising results are obtained through scCO₂, which yields the amorphization of PRX, whereas some crystallization occurs in the case of adsorption from solution and IWI. The highest loading of PRX by scCO₂ is obtained in SBA-15 (15 wt.%), where molecule distribution appears homogeneous, with very limited pore blocking.

Electrospun Gelatin Nanocontainers for Enhanced Biopharmaceutical Performance of Piroxicam: In Vivo and In Vitro Investigations

BACKGROUND

Piroxicam exhibits low oral bioavailability, due to its meager solubility in water. The intent of this study was to ameliorate the bioavailability of the drug by employing a solubility-enhancing encapsulation technique.

METHODS

Seven samples were formulated with piroxicam and gelatin using both solvent evaporation and electrospraying together. Evaluation of solubility and release rate in water and assessment of bioavailability in rats were carried out in comparison with piroxicam plain drug powder (PPDP). Other in vitro explorations were accomplished using powder X-ray diffraction analysis, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and Fourier-transform infrared spectroscopy.

RESULTS

All piroxicam-loaded gelatinnanocontainers (PLGNs) enhanced solubility and release of the payload in water. In particular, a PLGN formulation consisting of piroxicam and gelatin at a 1:8 (w:w) ratio presented about 600-fold the drug solubility of that shown by PPDP. Moreover, 85.12%±10.96% of the payload was released from this formulation in 10 minutes which was significantly higher than that dissolved from PPDP in 10 minutes (11.81%±5.34%). Drug content, drug loading, and encapsulation efficiency of this formulation were 93.41%±0.56%, 10.45%±0.06%, and 66.74%±6.87%, respectively. The drug loaded in PLGNs existed in the amorphous state, as confirmed by X-ray diffraction and differential scanning-calorimetry analyses, and was more stable when analyzed by thermogravimetric analysis. Moreover, Fourier-transform infrared spectroscopy analysis suggested nonexistence of any piroxicam-gelatin interaction in the formulation. In the scanning electron-microscopy image, PLGNs appeared as round, smooth particles, with particle size of <1,000 nm. Amelioration in bioavailability of piroxicam with the aforementioned PLGN formulation was fourfold that of PPDP.

CONCLUSION

The PLGN formulation fabricated with piroxicam and gelatin at 1:8 (w:w) might be a promising system for enhanced biopharmaceutical performance of the drug.

Identification of hub genes and discovery of promising compounds in gastric cancer based on bioinformatics analysis

Aim: To explore the mechanism of gastric carcinogenesis by mining potential hub genes and to search for promising small-molecular compounds for gastric cancer (GC). Materials & methods: The microarray datasets were downloaded from Gene Expression Omnibus database and the genes and compounds were analyzed by bioinformatics-related tools and software. Results: Six hub genes (MKI67, PLK1, COL1A1, TPX2, COL1A2 and SPP1) related to the prognosis of GC were confirmed to be upregulated in GC and their high expression was correlated with poor overall survival rate in GC patients. In addition, eight candidate compounds with potential anti-GC activity were identified, among which resveratrol was closely correlated with six hub genes. Conclusion: Six hub genes identified in the present study may contribute to a more comprehensive understanding of the mechanism of gastric carcinogenesis and the predicted potential of resveratrol may provide valuable clues for the future development of targeted anti-GC inhibitors.

Understanding Surface Interaction and Inclusion Complexes between Piroxicam and Native or Crosslinked β-Cyclodextrins: The Role of Drug Concentration

Drug concentration plays an important role in the interaction with drug carriers affecting the kinetics of release process and toxicology effects. Cyclodextrins (CDs) can solubilize hydrophobic drugs in water enhancing their bioavailability. In this theoretical study based on molecular mechanics and molecular dynamics methods, the interactions between β-cyclodextrin and piroxicam, an important nonsteroidal anti-inflammatory drug, were investigated. At first, both host–guest complexes with native β-CD in the 1:1 and in 2:1 stoichiometry were considered without assuming any initial a priori inclusion: the resulting inclusion complexes were in good agreement with literature NMR data. The interaction between piroxicam and a β-CD nanosponge (NS) was then modeled at different concentrations. Two inclusion mechanisms were found. Moreover, piroxicam can interact with the external NS surface or with its crosslinkers, also forming one nanopore. At larger concentration, a nucleation process of drug aggregation induced by the first layer of adsorbed piroxicam molecules is observed. The flexibility of crosslinked β-CDs, which may be swollen or quite compact, changing the surface area accessible to drug molecules, and the dimension of the aggregate nucleated on the NS surface are important factors possibly affecting the kinetics of release, which shall be theoretically studied in more detail at specific concentrations.

Biological and Spectroscopic Investigations of New Tenoxicam and 1.10-Phenthroline Metal Complexes

In the present work, tenoxicam (H₂Ten) reacted with Mn(II), Co(II), Ni(II), Cu(II) and Zn (II) ions in the presence of 1.10-phenthroline (Phen), forming new mixed ligand metal complexes. The properties of the formed complexes were depicted by elemental analyses, infrared, electronic spectra, proton nuclear magnetic resonance (¹H NMR), mass spectrometry, thermogravimetric (TGA) and differential thermogravimetric (DTG) analysis, molar conductance and magnetic moment. IR spectra demonstrated that H₂Ten acted as a neutral bidentate ligand, coordinated to the metal ions via the pyridine-N and carbonyl group of the amide moiety, and Phen through the nitrogen atoms. Kinetic thermodynamics parameters activation energy (E*), enthalpy of activation (ΔH*), entropy of activation (ΔS*), Gibbs, free energy (ΔG*) associated to the complexes have been evaluated. Antibacterial screening of the compounds was carried out in vitro against Clavibacter michiganensis, Xanthomonas campestris and Bacillus megaterium. Antifungal activity was performed in vitro against Monilinia fructicola, Penicillium digitatum and Colletotrichum acutatum. The possible phytotoxic effect of the studied compounds was also investigated on Solanum lycopersicum (tomatoes) and Lepidium sativum (garden cress) seeds. The anticancer activity was screened against cell cultures of HCT-116 (human colorectal carcinoma), HepG2 (human hepatocellular carcinoma) and MCF-7 (human breast adenocarcinoma).

Effect of low melting hydrophilic carriers on the solubility and dissolution rate of Piroxicam using solid dispersion technique

The present study was aimed to enhance the solubility and dissolution rate of Piroxicam, a poorly water soluble drug from BCS class II. Solid dispersions (SDs) of Piroxicam Solutol and Gelucire were prepared by applying fusion method. The prepared SDs were tested for their aqueous solubility and dissolution rate. These dispersions were characterized by PXRD and FTIR for any physical or chemical change, respectively. From the results it was revealed that the solubility value of drug was increased by 20-25 times (with Solutol) and 6-10 times (with Gelucire). Dissolution rate of piroxicam was 7-8 times quicker in SDs with Solutol while with Gelucire a slow drug release in first 20 min was noted that was further enhanced by adding a ternary component, i.e. silica. The real time stability studies show that the solid dispersions are quite stable after 6 months in terms of solubility and dissolution rate. The study concludes that binary solid dispersion with Solutol has effectively increased the solubility of piroxicam that in turn has increased its dissolution rate, therefore useful in enhancing the bioavailability of this poorly soluble drug. In case of piroxicam: Gelucire solid dispersion; a ternary component is required to achieve quick release of drug.

Metal-Ligand Recognition Index Determination by NMR Proton Relaxation Study

In this study, we developed and validated a new proposed parameter quantifying the interaction strength between natural and/or synthetic molecules with paramagnetic metal ions. The Metal ion Recognition Index, Miri, is a quantitative parameter to describe the proton environment and to define their involvement in the inner and/or outer sphere of the paramagnetic metal ion. The method is based on the analysis of NMR proton spin-lattice relaxation rates of a specific ligand in both the diamagnetic and paramagnetic conditions. The proposed procedure is also useful to calculate the ligand proton spin-lattice relaxation rate in the paramagnetic bound conditions, which is typically very difficult to determine experimentally. Miri was used to compare the ligand proton involvement toward different paramagnetic species, in particular the Copper(II)-Piroxicam system. Copper(II)-Piroxicam complex is one of the most active anti-inflammatory and anti-arthritic species. Miri provides an opportunity to improve our knowledge of metal-ligand complexes that play a fundamental role in bioinorganic interactions.

Degradation of the Nonsteroidal Anti-Inflammatory Drug Piroxicam by Iron Activated Persulfate: The Role of Water Matrix and Ultrasound Synergy

This work examined the oxidation of Piroxicam (PIR), a representative nonsteroidal anti-inflammatory drug using iron activated persulfate. The effect of persulfate dosing was vital for the efficiency of the process. The addition of 20 mg/L sodium persulfate (SPS) eliminated 500 μg/L of PIR in less than 20 min at natural pH. PIR decomposition followed pseudo-first-order kinetics, and the observed kinetic constant increased by 2.1 times when the initial concentration of PIR decreased from 2000 to 250 μg/L. Acidic pH favored the PIR destruction, while both sulfate and hydroxyl radicals are involved in PIR destruction at natural pH. The effect of inorganic ions like bicarbonate and chlorides was almost insignificant on PIR removal. The presence of humic acid reduced PIR removal from 100% to 67% after 20 min of treatment with 2 mg/L Fe2+ and 20 mg/L SPS. The experiment that was performed with bottled water showed similar efficiency with ultrapure water, while in the case of secondary effluent, PIR removal decreased by 26% after 30 min of treatment. The Fe2+/SPS/ultrasound hybrid process showed a low degree of synergy (18.3%). The ecotoxicity of aqueous solution using the Vibrio fischeri as an indicator was reduced during the treatment, although with a different trend from the removal of PIR, possibly due to byproducts derived from the oxidation of secondary effluent and PIR.

A high-throughput multi-microfluidic crystal generator (MMicroCryGen) platform for facile screening of polymorphism and crystal morphology for pharmaceutical compounds

In this work, a novel multi-microfluidic crystallization platform called MMicroCryGen is presented, offering a facile methodology for generating individual crystals for fast and easy screening of the polymorphism and crystal habit of solid compounds. The MMicroCryGen device is capable of performing 8 × 10 cooling crystallization experiments in parallel using 8 disposable microcapillary film strips, each requiring less than 25 μL of solution. Compared to traditional microfluidic systems, the MMicroCryGen platform does not require complex fluid handling; it can be directly integrated with a 96-well microplate and it can also work in a "dipstick" mode. The produced crystals can be safely and directly observed inside the capillaries by optical and spectroscopic techniques. The platform was validated by performing a number of independent experimental runs for: (1) polymorph and hydrate screening of ortho-aminobenzoic acid, succinic acid and piroxicam; (2) co-crystal form screening of the p-toluenesulfonamide/triphenylphosphine oxide system; (3) studying the effect of o-toluic acid on ortho-aminobenzoic cooling crystallization (effect of structurally related additives). In all three cases, all known solid forms were identified with a single experiment using ∼200 μL of solvent and just a few micrograms of the solid material. The MMicroCryGen is simple to use, inexpensive and it provides increased flexibility compared to traditional crystallization techniques, being an effective new microfluidic solution for solid form screening in pharmaceutical, fine chemicals, food and agrochemical industries.

Synthesis, spectral, DFT modeling, cytotoxicity and microbial studies of novel Zr(IV), Ce(IV) and U(VI) piroxicam complexes

The Zr(IV), Ce(IV) and U(VI) piroxicam anti-inflammatory drug complexes were prepared and characterized using elemental analyses, conductance, IR, UV-Vis, magnetic moment, ^IHNMR and thermal analysis. The ratio of metal: Pir is found to be 1:2 in all complexes estimated by using molar ratio method. The conductance data reveal that Zr(IV) and U(VI) chelates are non-electrolytes except Ce(IV) complex is electrolyte. Infrared spectroscopic confirm that the Pir behaves as a bidentate ligand co-ordinated to the metal ions via the oxygen and nitrogen atoms of ν(CO)_carbonyl and ν(CN)_pyridyl, respectively. The kinetic parameters of thermogravimetric and its differential, such as activation energy, entropy of activation, enthalpy of activation, and Gibbs free energy evaluated using Coats-Redfern and Horowitz-Metzger equations for Pir and complexes. The geometry of the piroxicam drug in the Free State differs significantly from that in the metal complex. In the time of metal ion-drug bond formation the drug switches-on from the closed structure (equilibrium geometry) to the open one. The antimicrobial tests were assessed towards some types of bacteria and fungi. The in vitro cell cytotoxicity of the complexes in comparison with Pir against colon carcinoma (HCT-116) cell line was measured.

Supramolecular Metal-Phenolic Gels for the Crystallization of Active Pharmaceutical Ingredients

The use of supramolecular gel media for the crystallization of active pharmaceutical ingredients (APIs) is of interest for controlling crystal size, morphology, and polymorphism, as these features determine the performance of pharmaceutical formulations. In contrast to supramolecular systems prepared from synthetic gelators, herein, supramolecular metallogels based on a natural polyphenol (tannic acid) are used for the crystallization of APIs. The gel-grown API crystals exhibit considerable differences in size, morphology, and polymorphism when compared with those formed in solutions. These physical features can also be tailored by varying the gel composition and additives, suggesting an influence of the gel medium on the crystallization outcomes. Furthermore, these gel-API crystal composites can be used for sustained drug release, indicating their potential as drug delivery systems. The facile preparation of these supramolecular gels and the use of naturally abundant components in their synthesis provide a generic platform for studying gel-mediated crystallization of diverse APIs.

Forced and long-term degradation assays of tenoxicam, piroxicam and meloxicam in river water. Degradation products and adsorption to sediment

The fate of the pharmaceutical drugs tenoxicam, piroxicam and meloxicam in river water is evaluated here for first time. So, biological, photochemical and thermal degradation assays have been conducted to estimate their degradation rates and know their degradation products. Results indicated that the direct sunlight irradiation, without any protection, promoted a fast degradation of the oxicams while the chemical reactions in solution were less important. The biological degradation in water was negligible except for tenoxicam in whose case its influence was scarce. When the exposition of river water to sunlight was partially limited and kept under the natural day-night cycle, as occurs inside a body of water, tenoxicam, piroxicam and meloxicam (at 2 μg L^-1) were detected during a period of 15, 27 and 45 days, respectively. Residues were monitored by ultra-pressure liquid chromatography/quadrupole time-of-flight/mass spectrometry after solid-phase extraction and several degradation products were found (10 for tenoxicam, 9 for piroxicam and 7 for meloxicam) and monitored over time. Their structures were proposed from the molecular formulae and fragmentation observed in high-resolution tandem mass spectra; the nature of the transformation products found in the long-term resulted to be very variable for each oxicam. Furthermore, the degradation in presence of river sediment was also monitored over time, with some differences being noted; the adsorption coefficients of the compounds on sediment were calculated, meloxicam exhibited a higher sorption capacity. The ecotoxicity of the different compounds in aquatic ecosystems was predicted, too.

A QUALITY BY DESIGN APPROACH: FABRICATION, CHARACTERIZATION AND EVALUATION OF OPTIMIZED TRANSDERMAL THERAPEUTIC SYSTEM FOR ANTIRHEUMATIC LORNOXICAM

Microemulsion was prepared using several concentrations of selected oil (pine oil), surfactant (cre- mophor RH40), co-surfactant (isopropanol) and water to improve bioavailability by increasing solubility and permeability of lomoxicam, which was then incorporated to carbomer 940 gel base to fabricate microemulsion based gel (MEBG) to sustained permeability for transdermal delivery. Initially, the formulations were investi- gated for physicochemical characteristics, i.e., pH, conductivity, viscosity, refractive index, zeta size, poly-dis- persity index and Atomic Force Microscopy. Also, the significance of the components on in vitro permeability was observed to find out optimum microemulsion (ME,) using Box-Behnken-Design (BBD). MEBG was com- pared for in vitro permeation, stability, skin irritation and anti-inflammatory studies using control gel and in vivo bioavailability study with oral tablet. Microemulsions exhibited the physiological pH (5.35-5.99), oil in water nature (139-185 tsiemens/cm), isotropic (1.3390-1.4166), narrow size (62 nm), homogeneity, Newtonian flow (52-160 centipoise) and spherical shape. Predicted values (Q2, flux, lag time) of optimized microemulsions derived from BBD were in reasonable agreement with experimental values. The formulations were stable and non-irritating to the skin. Significant difference was investigated when comparing percent inhibition of edema of MEBG (80%) and control gel (40%) with respect to standard. The MEBG behavior differed significantly from oral tablet formulation in vivo bioavailability. Such BBD based estimation will reduce time and cost in drug designing, delivery and targeting.

In vivo Piroxicam Metabolites: Possible Source for Synthesis of Central Nervous System (CNS) Acting Depressants

BACKGROUND

Piroxicam has been reported to be convertible to Central Nervous System (CNS) acting agents. It has serious depressant effects at high doses.

OBJECTIVE

In view of this, structures of piroxicam metabolites were assessed for possible conversion to CNS depressants.

METHODS

Literature search was carried out with intent to identifying piroxicam metabolites and the possibility of converting them to CNS acting depressants.

RESULTS

Piroxicam is convertible to hydroxymethylated metabolite which may be converted to barbiturates such as thiopentone and thiamylal. Whereas cyclodehydrated metabolite may be converted to acetylcyclodehydrated compound that may be in turn converted to acetylacetone and cyclohexamide. However, carboxybenzothiazine metabolite may be converted to carboxamide compound, benzolactone which is convertible to phenazone. Carboxybenzothiazine is also convertible to 2-aminopyridine mepyramine and triplenamine. Conversion of carboxybenzothiazine to gamma aminobutyric acid and phenothiazines such as chlorpromazine, thioridazine, fluphenazine and perphenazine is highly possible.

CONCLUSION

Structurally, barbituric compounds, carboxamide, cyclodehydrated, benzothiazine and carboxybenzothiazine metabolites may act via dopamine and adrenergic receptors causing depression of CNS activities. Piroxicam metabolites may also act via histamine, melatonin and potassium channel receptors causing CNS depression.

Transdermal Lipid Nanocarriers: A Potential Delivery System for Lornoxicam

BACKGROUND

Lornoxicam, is a NSAID of the oxicam class. Its short duration of action owing to rapid elimination and gastrointestinal side effects limits its usefulness when administered orally.

OBJECTIVE

The primary objective of the proposed work is to develop suitable lipid nanocarriers for transdermal delivery of Lornoxicam with increased drug residence time at local site of inflamation and in systemic circulation, overcoming undesired gastrointestinal side effects.

METHOD

Lornoxicam loaded lipid nanocarriers like solid lipid nanocarriers (SLN), nano-structured lipid carriers (NLC) & nanoemulsions (NE) were prepared by high-speed homogenization technique.

RESULT

The particle size, zeta potential, and polydispersity index as obtained, were in the range of 140- 193 nm, -22 to -32 mV, and 0.354-0.301 for SLN formulations and 146-201 nm, -23 to -30 mV, and 0.355-0.354 for NLC formulations respectively. Characterization of stable NE revealed that globule size, zeta potential and polydispersity index were within the range of 138 to 195 nm, -26.1±0.123 mV and 0.195 ± 1.231 respectively. It was also observed that entrapment efficacy and drug loading improved as the lipid concentration was increased. The results obtained from the in vitro permeation study and in vivo anti-inflammatory study showed controlled drug permeation, increased bioavailability, longer retention and better therapeutic potential of Lornoxicam after transdermal application of lipid nanoparticles as compared to conventional gel.

CONCLUSION

It can be concluded that the developed lipid nanoparticle loaded gel was found to be a suitable drug delivery carrier for transdermal delivery of Lornoxicam to increase the residence time of drug in systemic circulation and to combat the gastrointestinal side effects.

DETERMINATION OF TENOXICAM IN THE PLASMA BY REVERSE PHASE HPLC METHOD USING SINGLE STEP EXTRACTION TECHNIQUE: A RELIABLE AND COST EFFECTIVE APPROACH

A simple and cost effective RPLC-UV bio-analytical method was developed and used for tenoxicam quantification on ODS Hypersil C-18 column using classical liquid-liquid extraction technique for sample preparation. Acetonitrile was used as precipitating agent for plasma proteins and supernatant was taken for injection without any further modification. The bio-analytical method depends upon isocratic elution using binary mixture of aqueous 0.1 M potassium dihydrogen phosphate and acetonitrile in 6 : 4 ratio. The pH of mobile phase was adjusted to 2.8 which favor tenoxicam to remain undissociated throughout the analysis. The optimized flow rate of 1.0 mL/min provided proper separation of peaks and column clean up within 5 min. The UV detection was achieved at 381 nm and 4.29 min. Reproducible calibration curve gave 0.325 μg/mL LOQ, linear dynamic range from 0.325 to 20 μg/mL and recovery from plasma was 98.5% with %CV 0.2314 achieved. After validation, the method was applied in pharmacokinetic study in healthy human volunteers (n = 8). The pharmacokinetic parameters were evaluated using kinetica version 4.1.1. The values of C. and area under curve for current study were 1.776 ± 0.003 pg/mL and 179.97 ± 0.0681 (mean ± SEM) pg x h/mL. The values of t, and volume of distribution for tenoxicam in current study were 74.103 0.167 h (mean ± SEM) and 11.962 ± 0.0677 L/kg (mean ± SEM), respectively. This method was simple, sensitive and successfully applied in pharmacokinetic studies. It can be extended to bioequivalence studies and evaluation of tenoxicam in different clinical situations.

Ultrasound influence on the solubility of solid dispersions prepared for a poorly soluble drug

Solid dispersions have been successfully used to enhance the solubility of several poorly water soluble drugs. Solid dispersions are produced by melting hydrophilic carriers and mixing in the poorly water soluble drug. Supersaturation is obtained by quickly cooling the mixture until it solidifies, thereby entrapping the drug. The effects of using ultrasound to homogenize the molten carrier and drug mixture were studied. In particular, the increase in drug solubility for the resulting solid dispersions was analyzed. Piroxicam, which has very low water solubility, was used as a model drug. A full factorial design was used to analyze how sonication parameters affected the solubility and in vitro release of the drug. The results show that the use of ultrasound can significantly increase the solubility and dissolution rate of the piroxicam solid dispersion. Pure piroxicam presented a solubility of 13.3 μg/mL. A maximum fourfold increase in solubility, reaching 53.8 μg/mL, was observed for a solid dispersion sonicated at 19 kHz for 10 min and 475 W. The in vitro dissolution rate test showed the sonicated solid dispersion reached a maximum rate of 18%/min, a sixfold increase over the piroxicam rate of 2.9%/min. Further solid state characterization by thermal, X-ray diffraction and Fourier transform infrared analyses also showed that the sonication process, in the described conditions, did not adversely alter the drug or significantly change its polymorphic form. Ultrasound is therefore an interesting technique to homogenize drug/carrier mixtures with the objective of increasing the solubility of drugs with poor water solubility.

Stability indicating RP-HPLC method for simultaneous determination of piroxicam and ofloxacin in binary combination

A simple and precise RP-HPLC method was developed for simultaneous determination of piroxicam and ofloxacin in pharmaceutical formulations and human serum. Optimum separations of piroxicam, ofloxacin and stress-induced degradation products were achieved by use of Hypersil BDS C8 column (250 x 4.6mm, 5 μm). The mobile phase was a mixture of acetonitrile: 0.012M K2HPO4: 0.008M sodium citrate (both buffers mixed and pH adjusted to 2.8) (50:25:25 v/v/v) delivered at flow rate of 1.5 mL min⁻¹ using DAD at 254 nm. Response was linear function of concentration over the ranges of 70-130 mg mL⁻¹ for piroxicam and ofloxacin (r² ≥ 0.999). The method efficiently separated the analytical peaks from degradation products with acceptable tailing and resolution. The developed method was successfully used for concurrent analysis of piroxicam and ofloxacin in pharmaceutical formulations, human serum and in vitro drug interaction studies.

Synthesis of piroxicam loaded novel electrospun biodegradable nanocomposite scaffolds for periodontal regeneration

Development of biodegradable composites having the ability to suppress or eliminate the pathogenic micro-biota or modulate the inflammatory response has attracted great interest in order to limit/repair periodontal tissue destruction. The present report includes the development of non-steroidal anti-inflammatory drug encapsulated novel biodegradable chitosan (CS)/poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) electro-spun (e-spun) composite nanofibrous mats and films and study of the effect of heat treatment on fibers and films morphology. It also describes comparative in-vitro drug release profiles from heat treated and control (non-heat treated) nanofibrous mats and films containing varying concentrations of piroxicam (PX). Electrospinning was used to obtain drug loaded ultrafine fibrous mats. The physical/chemical interactions were evaluated by Fourier Transform Infrared (FT-IR) spectroscopy. The morphology, structure and pore size of the materials were investigated by scanning electron microscopy (SEM). The thermal behavior of the materials was investigated by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Control (not heat treated) and heat treated e-spun fibers mats and films were tested for in vitro drug release studies at physiological pH7.4 and initially, as per requirement burst release patterns were observed from both fibers and films and later sustained release profiles were noted. In vitro cytocompatibility was performed using VERO cell line of epithelial cells and all the synthesized materials were found to be non-cytotoxic. The current observations suggested that these materials are potential candidates for periodontal regeneration.

Polypyrrole nanoparticles for tunable, pH-sensitive and sustained drug release

We report the development of a generalized pH-sensitive drug delivery system that can release any charged drug preferentially at the pH range of interest. Our system is based on polypyrrole nanoparticles (PPy NPs), synthesized via a simple one-step microemulsion technique. These nanoparticles are highly monodisperse, stable in solution over the period of a month, and have good drug loading capacity (∼15 wt%). We show that PPy NPs can be tuned to release drugs at both acidic and basic pH by varying the pH, the charge of the drug, as well as by adding small amounts of charged amphiphiles. Moreover, these NPs may be delivered locally by immobilizing them in a hydrogel. Our studies show encapsulation within a calcium alginate hydrogel results in sustained release of the incorporated drug for more than 21 days. Such a nanoparticle-hydrogel composite drug delivery system is promising for treatment of long-lasting conditions such as cancer and chronic pain which require controlled, localized, and sustained drug release.

Vibrational spectra (FT-IR, FT-Raman), frontier molecular orbital, first hyperpolarizability, NBO analysis and thermodynamics properties of Piroxicam by HF and DFT methods

The solid phase FT-IR and FT-Raman spectra of 4-Hydroxy-2-methyl-N-(2-pyridinyl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide (Piroxicam) have been recorded in the region 4000-400 and 4000-100cm(-1) respectively. The molecular geometry, harmonic vibrational frequencies and bonding features of piroxicam in the ground state have been calculated by Hartree-Fock (HF) and density functional theory (DFT) methods using 6-311++G(d,p) basis set. The calculated harmonic vibrational frequencies are scaled and they are compared with experimental obtained by FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of the title compound has been made on the basis of the calculated potential energy distribution (PED). The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MESP) are also performed. The linear polarizability (α) and the first order hyper polarizability (β) values of the title compound have been computed. The molecular stability arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis.

A mononuclear zinc(II) complex with piroxicam: crystal structure, DNA- and BSA-binding studies; in vitro cell cytotoxicity and molecular modeling of oxicam complexes

A new mononuclear Zn(II) complex, trans-[Zn(Pir)2(DMSO)2], where Pir(-) is 4-hydroxy-2-methyl-N-2-pyridyl-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide (piroxicam), has been synthesized and characterized. The crystal structure of the complex was obtained by the single crystal X-ray diffraction technique. The interaction of the complex with DNA and BSA was investigated. The complex interacts with FS-DNA by two binding modes, viz., electrostatic and groove binding (major and minor). The microenvironment and the secondary structure of BSA are changed in the presence of the complex. The anticancer effects of the seven complexes of oxicam family were also determined on the human K562 cell lines and the results showed reasonable cytotoxicities. The interactions of the oxicam complexes with BSA and DNA were modeled by molecular docking and molecular dynamic simulation methods.

New metal based drugs: spectral, electrochemical, DNA-binding, surface morphology and anticancer activity properties

The NSAID piroxicam (PRX) drug was used for complex formation reactions with Cu(II), Zn(II) and Pt(II) metal salts have been synthesized. Then, these complexes have been characterized by spectroscopic and analytical techniques. Thermal behavior of the complexes were also investigated. The electrochemical properties of all complexes have been investigated by cyclic voltammetry (CV) using glassy carbon electrode. The biological activity of the complexes has been evaluated by examining their ability to bind to fish sperm double strand DNA (FSFSdsDNA) with UV spectroscopy. UV studies of the interaction of the PRX and its complexes with FSdsDNA have shown that these compounds can bind to FSdsDNA. The binding constants of the compounds with FSdsDNA have also been calculated. The morphology of the FSdsDNA, PRX, metal ions and metal complexes has been investigated by scanning electron microscopy (SEM). To get the SEM images, the interaction of compounds with FSdsDNA has been studied by means of differential pulse voltammetry (DPV) at FSdsDNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals has been used as an indicator for the interaction mechanism. The effect of proliferation PRX and complexes were examined on the HeLA and C6 cells using real-time cell analyzer with four different concentrations.

Formulation and evaluation of mini-tablets-filled-pulsincap delivery of lornoxicam in the chronotherapeutic treatment of rheumatoid arthritis

In this present research work, we have designed a pulsincap formulation comprising mini-tablets, which to the best of our knowledge this combination has not been reported yet. We successfully combined the advantages of mini-tablets technology to meet the optimized requirements of our pulsincap formulation. Our main aim was to target lornoxicam to treat rheumatoid arthritis as per the chronotherapeutic pattern of the disease. Directly compressing method was used to prepare mini-tablets. The drug, polymers and combine mixtures of drug and polymers was evaluated for pre-formulation testing. Prepared mini-tablets were also evaluated for physicochemical, dissolution and stability studies. From FTIR and DSC evaluation, we found no interaction between the drug and polymers used. For mini-tablets, all the physico-chemical parameters were in limit. The mini-tablets of lornoxicam were filled into an insoluble body of capsule, and its opening was sealed by plugging it with a polymer. The complete capsule body after sealing with a cap was given enteric coating. Different polymers in various concentrations were used as a plug, to identify the most suitable which gives a complete lag time of 5 hours when combined with 5% CAP coating. HPMC-K100M in 30% and sodium alginate in 40% concentrations were identified as the most suitable plugs. Our optimized pulsincap formulations releases lornoxicam after a lag time of 5 hrs and maximum portion of the drug will be released in the early morning hours. It was also found to be stable for a period of 6 months as per ICH guidelines.

Modulating drug release from gastric-floating microcapsules through spray-coating layers

Floating dosage forms with prolonged gastric residence time have garnered much interest in the field of oral delivery. However, studies had shown that slow and incomplete release of hydrophobic drugs during gastric residence period would reduce drug absorption and cause drug wastage. Herein, a spray-coated floating microcapsule system was developed to encapsulate fenofibrate and piroxicam, as model hydrophobic drugs, into the coating layers with the aim of enhancing and tuning drug release rates. Incorporating fenofibrate into rubbery poly(caprolactone) (PCL) coating layer resulted in a complete and sustained release for up to 8 h, with outermost non-drug-holding PCL coating layer serving as a rate-controlling membrane. To realize a multidrug-loaded system, both hydrophilic metformin HCl and hydrophobic fenofibrate were simultaneously incorporated into these spray-coated microcapsules, with metformin HCl and fenofibrate localized within the hollow cavity of the capsule and coating layer, respectively. Both drugs were observed to be completely released from these coated microcapsules in a sustained manner. Through specific tailoring of coating polymers and their configurations, piroxicam loaded in both the outer polyethylene glycol and inner PCL coating layers was released in a double-profile manner (i.e. an immediate burst release as the loading dose, followed by a sustained release as the maintenance dose). The fabricated microcapsules exhibited excellent buoyancy in simulated gastric fluid, and provided controlled and sustained release, thus revealing its potential as a rate-controlled oral drug delivery system.

Synthesis of new piroxicam derivatives and their influence on lipid bilayers

A novel series of potentially biologically active 1,2-benzothiazine 1,1-dioxides--analogs of piroxicam (a recognized non-steroidal anti-inflammatory drug) were synthesized from commercially available saccharin. All of the synthesized compounds were subjected to preliminary evaluation for their ability to interact with lipid bilayers. The influence of the new derivatives of piroxicam on liposomes made of EYPC was investigated by fluorescence spectroscopy with two fluorescent probes--Laurdan and Prodan. All the studied compounds showed an interaction with model membranes.

The interaction of new piroxicam analogues with lipid bilayers--a calorimetric and fluorescence spectroscopic study

The purpose of the present paper was to assess the ability of new piroxicam analogues to interact with the lipid bilayers. The results of calorimetric and fluorescence spectroscopic experiments of two new synthesized analogues of piroxicam, named PR17 and PR18 on the phase behavior of phospholipid bilayers and fluorescence quenching of fluorescent probes (Laurdan and Prodan), which molecular location within membranes is known with certainty, are shown in present work. The presented results revealed that, depending on the details of chemical structure, the studied compounds penetrated the lipid bilayers.

Sensitive and selective spectrophotometric assay of piroxicam in pure form, capsule and human blood serum samples via ion-pair complex formation

A simple, accurate and highly sensitive spectrophotometric method has been developed for the rapid determination of piroxicam (PX) in pure and pharmaceutical formulations. The proposed method involves formation of stable yellow colored ion-pair complexes of the amino derivative (basic nitrogen) of PX with three sulphonphthalein acid dyes namely; bromocresol green (BCG), bromothymol blue (BTB), bromophenol blue (BPB) in acidic medium. The colored species exhibited absorption maxima at 438, 429 and 432 nm with molar absorptivity values of 9.400×10(3), 1.218×10(3) and 1.02×10(4) L mol(-1) cm(-1) for PX-BCG, PX-BTB and PX-BPB complexes, respectively. The effect of optimum conditions via acidity, reagent concentration, time and solvent were studied. The reactions were extremely rapid at room temperature and the absorbance values remained constant for 48h. Beer's law was obeyed with a good correlation coefficient in the concentration ranges 1-100 μg mL(-1) for BCG, BTB complexes and 1-95 μg mL(-1) for BPB complex. The composition ratio of the ion-pair complexes were found to be 1:1 in all cases as established by Job's method. No interference was observed from common additives and excipients which may be present in the pharmaceutical preparations. The proposed method was successfully applied for the determination of PX in capsule and human blood serum samples with good accuracy and precision.

Tenoxicam-kollicoat IR binary systems: physicochemical and biological evaluation

Tenoxicam (TNX) binary systems in Kollicoat IR (KL) matrix were prepared in different drug: polymer ratios using kneading and spray-drying method. The prepared binary systems were characterized for drug dissolution rate, differential scanning calorimetry (DSC), IR spectroscopy and x-ray diffractometry. The results showed that the drug dissolution rate was remarkably enhanced by incorporating it in the KL matrix either by kneading or spray-drying, and the dissolution rate was increased by decreasing the drug weight ratio. The DSc and x-ray studies revealed the presence of TNX in less crystalline or amorphous state in its-KL binary systems. Moreover, the spray-dried TNX-KL system in 1:4 ratio, that exhibited the faster dissolution rate, was formulated in oral disintegrating tablets (ODTs). The data indicated that a fast disintegration and higher drug dissolution rate was achieved in case of the ODTs containing the spray-dried form compared to the ODTS containing untreated drug or the commercial tablet (Epicotil). Also, the drug exhibited significantly (p < 0.01) faster onset of the anti-inflammatory analgesic activities in case of the ODTs containing the spray-dried form, that was superior to that observed with both the commercial tablet product and the ODTS containing untreated drug.

Spectroscopic studies of the binding of Cu(II) complexes of oxicam NSAIDs to alternating G-C and homopolymeric G-C sequences

Drugs belonging to the Non-steroidal anti-inflammatory (NSAID) group are not only used as anti-inflammatory, analgesic and anti-pyretic agents, but also show anti-cancer effects. Complexing them with a bioactive metal like copper, show an enhancement in their anti-cancer effects compared to the bare drugs, whose exact mechanism of action is not yet fully understood. For the first time, it was shown by our group that Cu(II)-NSAIDs can directly bind to the DNA backbone. The ability of the copper complexes of NSAIDs namely meloxicam and piroxicam to bind to the DNA backbone could be a possible molecular mechanism behind their enhanced anticancer effects. Elucidating base sequence specific interaction of Cu(II)-NSAIDs to the DNA will provide information on their possible binding sites in the genome sequence. In this work, we present how these complexes respond to differences in structure and hydration pattern of GC rich sequences. For this, binding studies of Cu(II) complexes of piroxicam [Cu(II)-(Px)2 (L)2] and meloxicam [Cu(II)-(Mx)2 (L)] with alternating GC (polydG-dC) and homopolymeric GC (polydG-polydC) sequences were carried out using a combination of spectroscopic techniques that include UV-Vis absorption, fluorescence and circular dichroism (CD) spectroscopy. The Cu(II)-NSAIDs show strong binding affinity to both polydG-dC and polydG-polydC. The role reversal of Cu(II)-meloxicam from a strong binder of polydG-dC (Kb=11.5×10(3) M(-1)) to a weak binder of polydG-polydC (Kb=5.02×10(3) M(-1)), while Cu(II)-piroxicam changes from a strong binder of polydG-polydC (Kb=8.18×10(3) M(-1)) to a weak one of polydG-dC (Kb=2.18×10(3) M(-1)), point to the sensitivity of these complexes to changes in the backbone structures/hydration. Changes in the profiles of UV absorption band and CD difference spectra, upon complex binding to polynucleotides and the results of competitive binding assay using ethidium bromide (EtBr) fluorescence indicate different binding modes in each case.

Coordination modes of bidentate lornoxicam drug with some transition metal ions. Synthesis, characterization and in vitro antimicrobial and antibreastic cancer activity studies

The NSAID lornoxicam (LOR) drug was used for complex formation reactions with different metal salts like Cr(III), Mn(II), Fe(III) and Ni(II) chlorides and Fe(II), Co(II), Cu(II) and Zn(II) borates. Mononuclear complexes of these metals are obtained that coordinated to NO sites of LOR ligand molecule. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, IR, UV-Vis, (1)H NMR, mass, electronic spectra, magnetic susceptibility and ESR spectral studies, conductivity measurements, thermogravimetric analyses (TG-DTG) and further confirmed by X-ray powder diffraction. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. The data show that the complexes have composition of ML2 type except for Fe(II) where the type is [ML3]. The electronic absorption spectral data of the complexes suggest an octahedral geometry around the central metal ion for all the complexes. The antimicrobial data reveals that LOR ligand in solution show inhibition capacity less or sometimes more than the corresponding complexes against all the species under study. In order to establish their future potential in biomedical applications, anticancer evaluation studies against standard breast cancer cell lines (MCF7) was performed using different concentrations. The obtained results indicate high inhibition activity for Cr(III), Fe(II) and Cu(II) complexes against breast cancer cell line (MCF7) and recommends them for testing as antitumor agents.

In vitro release of model compounds with different hydrophilicity from poly(ester-anhydride) microspheres

Poly(ester-anhydride) microspheres were prepared using emulsion solvent evaporation technique from two copolymers obtained by polycondensation of sebacic acid (SBA) and oligo(3-allyloxy-1,2-propylene succinate) terminated with carboxyl groups (OSAGE). The SBA content in copolymers was 90 or 70 w/w %, respectively. The size of microspheres obtained was in the range of 2-4 microm (small microspheres) or 12-31 microm (large ones) and depended on stirring conditions used in emulsion formulation process, as well as on concentration of polymer solution used. Poly(ester-anhydride) microspheres were loaded with three model compounds (rhodamine B, p-nitroaniline and piroxicam) with different water solubility. The loading efficiency was dependent on kind of model compound, polymer composition and size of microparticles. Each of three model compounds also exhibited different release profiles. Rhodamine was released very quickly. The release of p-nitroaniline was more prolonged, but showed only little dependence on microsphere size and polymer composition, whereas the piroxicam-loaded microspheres exhibited the most interesting release profile, showing that release rate as well as transport mechanism can be adjusted by changing microsphere size and poly(ester-anhydride) compositions.

Evaluation and enhancement of physical stability of semi-solid dispersions containing piroxicam into hard gelatin capsules

The aim of the study was to investigate the physical stability of the semi-solid dispersions into the hard gelatine capsules prepared with Gelucire 44/14, Labrasol and different additives such as microcrystalline cellulose (MCC), mannitol and lactose (alpha-monohydrate) used for enhancing the stability of the formulations. The master dispersion prepared with only Gelucire 44/14 (20% w/w) and Labrasol (80% w/w) was stored in a refrigerator (5 +/- 3 degrees C), while the modified dispersions with the additives (2% w/w) were kept in a climatic chamber (25 +/- 2 degrees C / 60 +/- 5% RH) for 12 months. Dissolution tests of the semi-solid dispersions were performed in media with different pH's immediatly after preparation and after 3, 6 and 12 months of storage. FTIR and DSC studies were also carried out at the same time points. The ideal storage condition for the master dispersion was found to be at 5 degrees C. The addition of MCC, mannitol and lactose (alpha-monohydrate) to the original dispersion afforded a solidification effect on the formulation at room temperature and showed the same dissolution behavior (not less than 85% of piroxicam within 30 min in pH 1.2, 4.5 and 6.8; and water) with the master. The dispersion including lactose was stable at 25 degrees C for 12 months. However, the ideal period of storage for the modified dispersions including MCC and mannitol was 6 months at 25 degrees C. FTIR and DSC results both confirmed the amorphous state of piroxicam in all semi-solid dispersions under storage conditions for 12 months.

Phase behaviour and formation of fatty acid esters nanoemulsions containing piroxicam

Fatty acid esters are long-chain esters, produced from the reaction of fatty acids and alcohols. They possess potential applications in cosmetic and pharmaceutical formulations due to their excellent wetting behaviour at interfaces and a non-greasy feeling when applied on the skin surfaces. This preliminary work was carried out to construct pseudo-ternary phase diagrams for oleyl laurate, oleyl stearate and oleyl oleate with surfactants and piroxicam. Then, the preparation and optimization study via 'One-At-A-Time Approach' were carried out to determine the optimum amount of oil, surfactants and stabilizer using low-energy emulsification method. The results revealed that multi-phase region dominated the three pseudo-ternary phase diagrams. A composition was chosen from each multi-phase region for preparing the nanoemulsions systems containing piroxicam by incorporating a hydrocolloid stabilizer. The results showed that the optimum amount (w/w) of oil for oleyl laurate nanoemulsions was 30 and 20 g (w/w) for oleyl stearate nanoemulsions and oleyl oleate nanoemulsions. For each nanoemulsions system, the amount of mixed surfactants and stabilizer needed for the emulsification to take place was found to be 10 and 0.5 g (w/w), respectively. The emulsification process via high-energy emulsification method successfully produced nano-sized range particles. The nanoemulsions systems passed the centrifugation test and freeze-thaw cycle with no phase failures, and stable for 3 months at various storage temperatures (3°C, 25°C and 45°C). The results proved that the prepared nanoemulsions system cannot be formed spontaneously, and thus, energy input was required to produce nano-sized range particles.

Detection of cocrystal formation based on binary phase diagrams using thermal analysis

PURPOSE

Although a number of studies have reported that cocrystals can form by heating a physical mixture of two components, details surrounding heat-induced cocrystal formation remain unclear. Here, we attempted to clarify the thermal behavior of a physical mixture and cocrystal formation in reference to a binary phase diagram.

METHODS

Physical mixtures prepared using an agate mortar were heated at rates of 2, 5, 10, and 30 °C/min using differential scanning calorimetry (DSC). Some mixtures were further analyzed using X-ray DSC and polarization microscopy.

RESULTS

When a physical mixture consisting of two components which was capable of cocrystal formation was heated using DSC, an exothermic peak associated with cocrystal formation was detected immediately after an endothermic peak. In some combinations, several endothermic peaks were detected and associated with metastable eutectic melting, eutectic melting, and cocrystal melting. In contrast, when a physical mixture of two components which is incapable of cocrystal formation was heated using DSC, only a single endothermic peak associated with eutectic melting was detected.

CONCLUSION

These experimental observations demonstrated how the thermal events were attributed to phase transitions occurring in a binary mixture and clarified the relationship between exothermic peaks and cocrystal formation.

Preparation, structural analysis, and properties of tenoxicam cocrystals

Cocrystals of tenoxicam, a non-steroidal anti-inflammatory drug, are screened, prepared, and characterized in this study. Nine tenoxicam cocrystals were identified using solvent-drop grinding (SDG) techniques. Structural characterization was performed using powder X-ray diffraction (PXRD), differential scanning calorimetry, and multinuclear solid-state NMR (SSNMR). Thermal analysis, PXRD, and 1D SSNMR are used to detect solvates and phase mixtures encountered in SDG cocrystal screening. 2D SSNMR methods are then used to confirm cocrystal formation and determine structural aspects for selected cocrystals formed with saccharin, salicylic acid, succinic acid, and glycolic acid in comparison to Forms I and III of tenoxicam. Molecular association is demonstrated using cross-polarization heteronuclear dipolar correlation (CP-HETCOR) methods involving (1)H and (13)C nuclei. Short-range (1)H-(13)C CP-HETCOR and (1)H-(1)H double-quantum interactions between atoms of interest, including those engaged in hydrogen bonding, are used to reveal local aspects of the cocrystal structure. (15)N SSNMR is used to assess ionization state and the potential for zwitterionization in the selected cocrystals. The tenoxicam saccharin cocrystal was found to be similar in structure to a previously-reported cocrystal of piroxicam and saccharin. The four selected cocrystals yielded intrinsic dissolution rates that were similar or reduced relative to tenoxicam Form III.

Dissolution rate enhancement of piroxicam by ordered mixing

Micronized piroxicam was mixed with lactose, mannitol, sorbitol, maltitol and sodium chloride to produce ordered mixture in a glass vial by manual hand shaking method. The effect of excipients, surfactant, superdisintegrant, drug concentration and carrier particle size on dissolution rate was investigated. Dissolution rate studies of the prepared ordered mixtures revealed that all water soluble excipients increased the dissolution rate of piroxicam when compared to the dissolution rate of piroxicam or its suspension. Ordered mixture formulation PLF4, consisting of lactose as water soluble excipient, SSG (8% w/s) and SLS (1% w/w), released piroxcam at a very fast rate so much so that about 90% of the composition had passed into solution within 2 min. The order of the dissolution rate enhancement for ordered mixtures of various water soluble excipients was: lactose > mannitol > maltitol > sorbitol > sodium chloride. Carrier granules of size 355-710 µm were most effective in increasing the dissolution rate of drug from ordered mixtures. Decreasing the carrier particle size reduced drug dissolution from ordered mixtures. The dissolution rate of ordered mixtures consisting of 1-5% w/w piroxicam was superior to dissolution rate of piroxicam suspension. The dissolution data fitting and the resulting regression parameters indicated Hixson Crowell, cube root law, as the best fit to drug release data of ordered mixtures.

Study of surface activity of piroxicam at the interface of palm oil esters and various aqueous phases

The surface activity of some non-steroidal anti-inflammatory agents like ibuprofen was investigated extensively. This fact has attracted the researchers to extend this behavior to other agents like piroxicam. Piroxicam molecules are expected to orient at the interface of oil and aqueous phase. The aim of this study was, firstly, to assess the surface and interfacial tension behaviour of newly synthesised palm oil esters and various pH phosphate buffers. Furthermore, the surface and interfacial tension activity of piroxicam was studied. All the measurements of surface and interfacial tension were made using the tensiometer. The study revealed that piroxicam has no effect on surface tension values of all pH phosphate buffers and palm oil esters. Similarly, various concentrations of piroxicam did not affect the interfacial tensions between the oil phase and the buffer phases. Accordingly, the interfacial tension values of all mixtures of oil and phosphate buffers were considerably high which indicates the immiscibility. It could be concluded that piroxicam has no surface activity. Additionally, there is no surface pressure activity of piroxicam at the interface of plam oil esters and phosphate buffers in the presence of Tweens and Spans.

Development and validation of a stability indicating HPLC method for the analysis of lornoxicam in powder for injection

A rapid, isocratic stability indicating high performance liquid chromatographic method was developed and validated for the estimation of lornoxicam in its powder for injection. The analysis was performed on a Shimadzu VP-ODS (4. 6 mm x 15 cm, 5 µm) column. The mobile phase consisted of sodium acetate (pH 5.8; 0.05 M) and methanol (45:55) flowed at 1.0 ml/min. Detection was carried out at 290 nm. The developed method had the good ability to separate lornoxicam well from the degradation products. The regression data showed good linear relationship at the concentration range of 4.04-20.20 μ/mL with r(2)=0.9999. Specificity, linearity, accuracy, precision and robustness of the method were evaluated to validate the proposed method. Stressed degradation studies were conducted to provide an indication of its stability indicating property. The limits of detection and quantitation were 9.70 and 33.94 ng /ml, respectively. Lornoxicam was found to be stable in the mobile phase in 24 h. The co-existed excipients had no interference with the analytical procedure. Additional peaks appeared in the chromatograms of five kinds of forced degraded samples (light, heat, acid, base and oxidation degradation). Mean recovery assessed at three levels was from 99. 7 to 100.3%, indicating the good accuracy of the method. Repeatability and inter-day RSD of the method was determined to be 0.38% and 0.81%, respectively. The HPLC method was demonstrated to be robust for intentional minor changes of ratio, pH change, salt concentration and column temperature. The method should be utilized as the routine analysis and quality control of lornoxicam in injectable formulation.

Effect of the surfactant on the availability of piroxicam as a poorly hydrosoluble drug from suppositories

The use of surfactants in suppository formulations has been suggested to improve availability of poorly soluble drugs. In the present study, different kinds of surfactants have been investigated to clarify the influence on piroxicam release from suppositories formulated with both lipophilic and hydrophilic bases. Two hydrophilic glucose-derivate surfactants, and a polyoxylglyceride amphiphilic surfactant, all with high HLB values, were investigated for their use in improving drug availability. The two glucose derivate surfactants reduced drug availability from both lipophilic suppositories and hydrophilic formulations, according to longer disintegration times and drug micellization. The more complex surfactant, a lauroyl macrogolglyceride, showed an increase in piroxicam availability from lipophilic suppositories at the higher tested concentrations (15% and 20%). Otherwise, when used in hydrophilic formulations, it was less effective in promoting drug release and even reduced drug availability.

A new method for a quantitative determination of piroxicam in pharmaceutical formulations using FT-IR spectrometry

A Fourier transform infrared (FT-IR) spectrometric method was developed for the rapid, and direct measurement of piroxicam (Pir) in pharmaceutical drugs. Pir is a well known and very effective antiinflammatory drug. Pir can be determined by various methods and now we are adding a new one that uses a Fourier transform infrared spectrophotometric technique. Conventional spectra were compared for best determination of active substance in pharmaceutical formulations. The Beer-Lambert law and two chemometric approaches, partial least squares (PLS) and principal component regression (PCR+) methods, were tried in data processing.

Effect of lipid molecule headgroup mismatch on non steroidal anti-inflammatory drugs induced membrane fusion

Membrane fusion is an essential process guiding many important biological events, which most commonly requires the aid of proteins and peptides as fusogenic agents. Small drug induced fusion at low drug concentration is a rare event. Only three drugs, namely, meloxicam (Mx), piroxicam (Px), and tenoxicam (Tx), belonging to the oxicam group of non steroidal anti-inflammatory drugs (NSAIDs) have been shown by us to induce membrane fusion successfully at low drug concentration. A better elucidation of the mechanism and the effect of different parameters in modulating the fusion process will allow the use of these common drugs to induce and control membrane fusion in various biochemical processes. In this study, we monitor the effect of lipid headgroup size mismatch in the bilayer on oxicam NSAIDs induced membrane fusion, by introducing dimyristoylphosphatidylethanolamine (DMPE) in dimyristoylphosphatidylcholine (DMPC) small unilamellar vesicles (SUVs). Such headgroup mismatch affects various lipid parameters which includes inhibition of trans-bilayer motion, domain formation, decrease in curvature, etc. Changes in various lipidic parameters introduce defects in the membrane bilayer and thereby modulate membrane fusion. SUVs formed by DMPC with increasing DMPE content (10, 20, and 30 mol %) were used as simple model membranes. Transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) were used to characterize the DMPC-DMPE mixed vesicles. Fluorescence assays were used to probe the time dependence of lipid mixing, content mixing, and leakage and also used to determine the partitioning of the drugs in the membrane bilayer. How the inhibition of trans-bilayer motion, heterogeneous distribution of lipids, decrease in vesicle curvature, etc., arising due to headgroup mismatch affect the fusion process has been isolated and identified here. Mx amplifies these effects maximally followed by Px and Tx. This has been correlated to the enhanced partitioning of the hydrophobic Mx compared to the more hydrophilic Px and Tx in the mixed bilayer.

Nanocrystals as tool to improve piroxicam dissolution rate in novel orally disintegrating tablets

In this paper, orally disintegrating tablets (ODT) were prepared using nanocrystal formulations in order to optimise dissolution properties of lipophilic, poorly soluble drug piroxicam (PRX). Different nanocrystal formulations were prepared using a high pressure homogenisation technique and poloxamer 188 as stabiliser. Characterisation of PRX nanocrystal ODT was carried out by infrared spectroscopy (FTIR), X-ray powder diffractometry (XRPD), differential scanning calorimetry and photon correlation spectroscopy. Dissolution study of PRX ODT was performed in distilled water (pH 5.5) and was compared to that of PRX coarse suspension ODT, PRX/poloxamer 188 physical mixture and bulk PRX samples. The XRPD and FTIR studies demonstrated that the homogenisation process led to a polymorphic transition from form I (bulk commercial PRX) to form III and monohydrate form of the nanocrystals. All ODT formulations prepared using PRX nanosuspensions showed a higher PRX dissolution rate compared with the ODT prepared with the coarse PRX. Since the solubility of the different PRX polymorphic forms increased only slightly from bulk PRX (form I) to monohydrate, form II and form III, we can conclude that the improvement in PRX dissolution rate is mainly caused by the increased surface-to-volume ratio due to the submicron dimension of the drug particles.

Effect of compressional forces on piroxicam polymorphs

The effect of compressional force on the polymorphic transition in piroxicam has been examined, using pure polymorph, by differential scanning calorimetery, powder X-ray diffractometry and by determination of dissolution rates from tablets of the individual polymorphs. The needle shaped polymorph was found to undergo transition to the cubic polymorph during compression.

[Amorphous form in pharmaceutical technological research]

Detecting and analysing of the amorphous phase are increasingly important in pharmaceutical technology. The amorphous or glassy state has a several advantages and disadvantages. The amorphous form can be applied in deliberate amorphization, when active pharmaceutical ingredient (API) is formulated in glassy state, or this form can appear accidentally during formulation or storage. The aim of this study was to characterize glass-forming properties of 13 different materials. Differential Scanning Calorimetry (DSC) was used as an analytical technique and T(g) and T(m) values were determined. The equation of T(g)/T(m) (K/K) was applied to determine the glass-forming tendencies. We made 2 groups of investigated substances. The first group was that we could not amorphized: tenoxicam, mannitol, niflumic acid, theophyllin and lidocain. The second group contains materials, which could be prepared in glassy form. This group can be divided into 2 sub-groups: poor-glass formers and good-glass formers. Poor-glass formers are following: meloxicam, ibuprofen and piroxicam. Good-glass formers are lacidipine, gemfibrosil, sorbitol, loratadine, chlorhexidine and clopidogrel hydrogensulfate.

Measurement of the principal values of the chemical-shift tensors of overlapping protonated and unprotonated carbons with the 2D-SUPER technique and dipolar dephasing (DD-SUPER)

A modified 2D-SUPER technique is demonstrated to allow independent measurement of the principal values of the chemical-shift tensors of overlapping protonated and unprotonated carbons. The insertion of a dipolar-dephasing period into the sequence causes loss of signal from protonated carbons. The spectrum obtained with this modification allows one to determine the principal values of the unprotonated carbons with high precision. Subsequent fitting of the usual 2D-SUPER spectrum, with the chemical-shift parameters of the unprotonated carbons fixed, gives the parameters of the overlapped resonances of the protonated carbons. As an example, we report the determination of the (13)C chemical-shift parameters of the carbons of form II of piroxicam. The experimental results are compared with those obtained from calculations using the DFT/GIAO method. Potential applications of this method are discussed.

[Construction and characterization of a selective membrane electrode for tenoxicam determination]

This paper describes the construction and characterization of a selective membrane electrode which can be used for determination of tenoxicam.

MATERIAL AND METHOD

The electroactive compound is a precipitate obtained in 2 N hydrocloric acid solution containing tenoxicam in which a solution of iodine is added. The membrane is made by mixing the electroactive compound with polyethylene using tetrahydrofurane as solvent. The solution is evaporated in order to obtain a thick membrane, which is attached at one end of a PVC tube and is fixed with the same polymeric solution. In this tube an internal Ag/AgCl reference electrode is inserted. The assembly is filled with an internal solution containing tenoxicam. The electrode was characterized (electrode slope, selectivity, optimal pH range, response time, life time). The developed method was validated.

RESULTS

The method showed a good liniarity in the range of 10(-6)-10(-1) M (the correlation coefficient r = 0.9999). The detection limit (LD) was 7.347 x 10(-7) M and the quantification limit (LQ) was 1.017 x 10(-6) M. There were established the precision (RSD = 1.79%) and the accuracy (mean recovery is 100.17%)

CONCLUSIONS

The experimental results demonstrated a good sensibility.

A theoretical and spectroscopic study of conformational structures of piroxicam

Piroxicam (PRX) has been widely studied in an attempt to elucidate the causes and mechanisms of its side effects, mainly the photo-toxicity. In this paper fluorescence spectra in non-protic solvents and different polarities were carried out along with theoretical calculations. Preliminary potential surfaces of the keto and enol forms were obtained at AM1 level of theory providing the most stable conformers, which had their structure re-optimized through the B3LYP/CEP-31G(d,p) method. From the optimized structures, the electronic spectra were calculated using the TD-DFT method in vacuum and including the solvent effect through the PCM method and a single water molecule near PRX. A new potential surface was constructed to the enol tautomer at DFT level and the most stable conformers were submitted to the QST2 calculations. The experimental data showed that in apolar media, the solution fluorescence is raised. Based on conformational analysis for the two tautomers, keto and enol, the results indicated that the PRX-enol is the main tautomer related to the drug fluorescence, which is reinforced by the spectra results, as well as the interconvertion barrier obtained from the QST2 calculations. The results suggest that the PRX one of the enol conformers presents great possibility of involvement in the photo-toxicity mechanisms.

[Turbidimetric determination of tenoxicam using molybdophosphoric acid]

A turbidimetric method was developed for tenoxicam quantification using the complexing reaction with molybdophosphoric acid in hydrochloric acid medium; the complex has a maximum of absorbance at 369 nm.

MATERIALS AND METHOD

The practical working conditions were established. In the 2.5 division by 15.0 microg/mL concentration range of tenoxicam in 1N hydrochloric acid, were added 1 mL of 1% molybdophosphoric acid solution and 1 mL of 0.1% sodium lauryl sulphate. The stability of product was evaluated over 60 minutes. The developed method was validated.

RESULTS

The method showed a good linearity in the range of 2.5 division by 15.0 microg/mL (the correlation coefficient r = 0.9996). The detection limit (LD) was 0.44 microg/mL and the quantification limit (LQ) was 1.47 microg/mL. There were established the precision (RSD = 1.82%) and the accuracy (mean recovery is 100.79% in 97.55 division by BY 04.41% the range).

CONCLUSIONS

The experimental results demonstrated a good sensibility. The specific absorptivity for this method is A(1cm,369nm)(1%) higher than tenoxicam in hydrochloric acid medium A(1cm,354nm)(1%).

Microemulsion system with improved loading of piroxicam: a study of microstructure

Formulation of a new oil-in-water (o/w) microemulsion composed of castor oil/Tween 80/ethanol/phosphate buffer for enhancing the loading capacity of an anti-inflammatory drug piroxicam has been accomplished. The pseudo-ternary phase diagram has been delineated at constant surfactant/cosurfactant ratio (1:2). The internal structure of so created four-component system was elucidated by means of an analysis of isotropic area magnitudes in the phase diagram. Conductivity (sigma), kinematic viscosity (keta), and surface tension (gamma) studies with the variation in Phiw (weight fraction of aqueous phase) show the occurrence of structural changes from water-in-oil (w/o) microemulsion to oil-in-water (o/w). Along with the solubility and partition studies of piroxicam in microemulsion components, the changes in the microstructure of the microemulsion after incorporation of drug have been evaluated using pH, sigma, gamma, keta, and density studies. Piroxicam, a poorly water-soluble drug displayed high solubility (1.0%) in an optimum microemulsion formulation using ethanol (55.0%), Tween 80 (26.5%), castor oil (7.5%), and phosphate buffer (11.0%). The results have shown that the microemulsion remained stable after the incorporation of piroxicam. Fluorescence spectra analysis taking pyrene as fluorescent probe was performed, and the results showed that pyrene was completely solubilized in the oil phases of the bicontinuous microemulsions. The fluorescence spectrum of the model drug piroxicam was used to probe the intramicellar region of nonionic microemulsion. The results showed that the piroxicam was localized in the interfacial film of microemulsion systems more deeply in the palisade layer with ethanol as the cosurfactant.