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Biomedical subjects

J R Moyano

Publications and source records attributed to J R Moyano.

13 recordsLinked to original sources
PubMed2005

Characterization and dissolution properties of ketoprofen in binary and ternary solid dispersions with polyethylene glycol and surfactants.

The effect of incorporation of an anionic [sodium dodecyl sulfate (SDS) or dioctylsulfosuccinate (DSS)] or nonionic [Tween 60 (TW60)] surfactant on the properties of ketoprofen solid dispersions in polyethylene glycol 15000 (PEG) has been investigated. Physicochemical and morphological properties of the various solid systems were determined by differential scanning calorimetry, hot stage microscopy, X-ray powder diffraction analysis, and scanning electron microscopy. The results from dissolution studies, performed according to the USP 24 basket method, indicated that all ternary dispersed systems were significantly (p < 0.001) more efficacious than the corresponding binary ones, by virtue of the additive wetting and solubilizing effect due to the presence of the surfactant. The relative effectiveness of the incorporated surfactant was in the same order as found in phase-solubility studies (i.e., SDS > DSS > TW60). With regard to the solid dispersion preparation method, coevaporated products always gave better results than the corresponding cofused ones; however, this effect was statistically significant (p < 0.001) only in the initial phase of the dissolution process. The most effective solid dispersion was the 10-80-10 w/w drug-PEG-SDS ternary coevaporate, which allowed dissolution of 50% drug after only 6 min (in comparison with > 120 min for drug alone and 17 min for the binary coevaporate) and dissolution of about 100% drug after 30 min (in comparison with > 120 min for the binary coevaporate).

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2004

Characterization of ibuproxam binary and ternary dispersions with hydrophilic carriers.

This work investigates the possibility of increasing the dissolution properties of ibuproxam (a poorly water-soluble anti-inflammatory drug) using hydrophilic carriers such as polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), or urea, alone or in combination. Phase-solubility studies showed that the carrier solubilizing power was in the order PEG>PVP>urea and evidenced a synergistic effect in drug solubility improvement when using carrier combinations. Binary and ternary systems, at 20/80 or 20/40/40 (w/w) drug/carrier(s) ratios, prepared by coevaporation of their ethanolic solutions or by cogrinding physical mixtures in a high-energy vibrational micromill, were characterized by differential scanning calorimetry (DSC), hot stage microscopy (HSM), and scanning electron microscopy (SEM) analyses. The results of dissolution tests (USP paddle method), in terms of Dissolution Efficiency, indicated that ternary systems were up to 35% more effective than the corresponding binary preparations and coevaporated products were up to 45% more efficacious than the corresponding coground ones. The IBUX-PEG-PVP coevaporated was the best product, allowing a more than three-times increase in Dissolution Efficiency with respect to drug alone; moreover, t50% (> 60 min for pure ibuproxam) was < 10 min, and 90% dissolution was achieved after 30 min, whereas only 40% was obtained after 60 min for pure drug. The best performance of this system was attributed to a joined effect of the strong amorphizing power of PVP (as demonstrated by solid state analyses) with the high solubilizing efficacy of PEG (as emerged from phase-solubility studies). The drug dissolution rate from solid dispersions remained practically unchanged after one-year storage at room temperature in closed containers.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2003

Study of glimepiride-b-cyclodextrin complex.

The interaction of glimepiride with b-cyclodextrin (b-CD) has been studied by several analytical techniques, including 1H NMR, infrared spectroscopy (FTIR), powder x-ray diffractometry (XRD), thermal analysis (DSC) and scanning electron microscopy (SEM). The existence of an inclusion complex was proved in solution by phase solubility techniques and 1H NMR, and in the solid state by DSC, FTIR and XRD, being isolated by sealed heating and freeze drying procedures.

Calorimetry, Differential Scanning↗
PubMed2001

Polymorphism of rac-5,6-diisobutyryloxy-2-methylamino-1,2,3,4-tetrahydro-naphthalene hydrochloride (CHF 1035). I. Thermal, spectroscopic, and X-ray diffraction properties.

The polymorphism of rac-5,6-diisobutyryloxy-2-methylamino-1,2,3,4-tetrahydro-naphthalene hydrochloride (CHF 1035) was investigated. Three different crystal forms (Form I, Form II, and Form III) were obtained by recrystallization procedures from common organic solvents. The polymorphs were characterized by Raman and carbon-13 nuclear magnetic resonance ((13)C NMR) spectroscopy, in solution and in solid state (cross polarization-magic angle spinning), powder X-ray diffractometry, and thermal methods (differential scanning calorimetry, hot stage microscopy, and thermogravimetry). Moreover, the diffraction patterns of Form I, collected at controlled temperatures, gave evidence of the presence of two reversible structural rearrangements at approximately 60 and approximately 75 degrees C. These structural variations were confirmed by the results obtained by differential scanning calorimetry and hot stage microscopy techniques. The analysis of the Raman spectra allowed the identification of peculiar absorption bands for each polymorph. Form III was the stable crystal form at room temperature as determined by the basis of slurry conversion method.

Calorimetry, Differential Scanning↗
PubMed2000

Study of omeprazole-gamma-cyclodextrin complexation in the solid state.

The possibility of obtaining inclusion complexes between omeprazole (OME) and gamma-cyclodextrin (gamma-CD) by kneading, spray-drying, coprecipitation, and freeze-drying was evaluated. All these methods lead to the isolation of a true inclusion compound, as evidenced by differential scanning calorimetry (DSC), infrared spectroscopy, and X-ray diffractometry on powder (PXRD). Moreover, PXRD and scanning electron microscopy (SEM) afforded data concerning crystallinity and surface characteristics of the solid phases obtained. In all cases, a significant increase of the release rate with respect to the drug alone was found, and it was attributed to the formation of an inclusion compound. Among the solid phases obtained, the comprecipitated product presented the highest dissolution rate.

Anti-Ulcer Agents↗
PubMed1999

Complexation of ursodeoxycholic acid with beta-cyclodextrin-choline dichloride coprecipitate.

The inclusion complexes of ursodeoxycholic acid (UDCA) with beta-cyclodextrin (betaCD) coprecipitated with choline dichloride (CDC) or beta-cyclodextrin were investigated to evaluate the effect of the presence of choline for UDCA inclusion in betaCD. The inclusion complexes were investigated in solution by phase solubility diagrams and 1H NMR spectrometry and in solid state (kneading, freeze-drying, sealed heating and spray-drying) by DSC, SEM, HSM, XRD and IR spectroscopy. Stability constants were determined at pH 5.5 and 7.0 to simulate the environmental pH of the first intestinal tract and at different temperatures (25, 30 and 37 degrees C) to obtain the thermodynamic parameters of inclusion. Both betaCD-CDC and betaCD increased the water solubility of UDCA particularly betaCD-CDC. All complexes showed a high dissolution rate particularly the spray-dried complexes obtained in the presence of betaCD-CDC.

Calorimetry, Differential Scanning↗
PubMed1999

Effects of the host cavity size and the preparation method on the physicochemical properties of ibuproxam-cyclodextrin systems.

The effect of cyclodextrin (Cd) complexation on ibuproxam (IBUX) dissolution properties was studied by evaluating both the influence of Cd cavity size and the preparation method used for obtaining solid inclusion complexes. Binary systems of IBUX with natural Cds, prepared using different techniques (kneading, sealed-heating, spray-drying), were studied by differential scanning calorimetry (DSC), hot-stage microscopy (HSM), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and their dissolution behavior was evaluated according to the dispersed amount method. The nature and the dissolution performance of the end product appeared to be related to both steric factors of host molecule and preparation method of the solid system. The alpha Cd cavity size was less suitable for accommodating the IBUX molecule, whereas spray-drying and sealed-heating methods led to a true inclusion complex of IBUX in the beta Cd and gamma Cd cavity. In contrast, the kneading method did not lead in any case to a real inclusion complex. Spray-dried systems with beta Cd and gamma Cd were the most effective in achieving the enhancement of the IBUX dissolution rate.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1998

Crystal forms of piroxicam pivalate: preparation and characterization of two polymorphs.

This study investigates the polymorphism of piroxicam ester with pivalic acid. Two crystal modifications were prepared by recrystallization from toluene (form 1) and ethyl acetate (form 2). Data regarding preparation conditions, solid state properties, and physicochemical characterization of two polymorphs by means of FT/IR spectroscopy, X-ray diffractometry on powder, and thermal analysis are reported. Heat of fusion rule and thermodynamic formulas consistently indicate an enantiotropic stability relationship of forms 1 and 2 with a calculated transition point (32 degrees C) near the ambient temperature. The phase diagrams of each polymorph with piroxicam were also investigated in order to gain information about the thermal behavior of their solid mixtures. Liquidus curves calculated by the Schröder-Van Laar equation from fusion enthalpies and temperatures were found to agree satisfactorily with experimental results obtained by first heating runs with differential scanning calorimetry.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1997

Nuclear magnetic resonance investigations of the inclusion complexation of gliclazide with beta-cyclodextrin.

The formation of the gliclazide-beta-cyclodextrin (GL-beta-CD) inclusion compound has been studied in the liquid state by phase solubility techniques and by 1H and 13C NMR spectroscopy. From the initial straight portion of the solubility curve (Bs type), the value of the apparent stability constant (Kc) was calculated as 1094 M(-1). The nuclear magnetic resonance studies confirm that GL yields a complex with beta-CD in aqueous medium, which is mainly due to the penetration of the azabicyclooctyl group of GL into the cavity of beta-CD. The study of the monodimensional nuclear Overhauser effect (NOE) of the H3 proton of CD has shown that the tolyl group also interacts with CD, but to a lesser extent than the azabicyclooctyl moiety. Finally, the application of the continous variation technique confirmed the 1:2 drug:CD stoichiometry of the complex.

Cyclodextrins↗
PubMed1996

Dissolution properties and in vivo behaviour of triamterene in solid dispersions with polyethylene glycols.

The applicability of the solid dispersion technique as a method for enhancing the GI absorption of a drug has been explored in order to procure better dissolution characteristics and better bioavailability for triamterene. The physicochemical characterization of the systems has shown the absence of chemical reaction between the drug and the polymers during the solid dispersion elaboration process (melting carrier method). In vitro release profiles have been studied and quantified in terms of dissolution efficiency over the first 30 min (DE30) and dissolution percentage over the first 30 min (DP30). The results have shown that there were no significant differences between the three polyethylene glycols (PEGs) under test. The in vivo effectiveness of the different preparations was also investigated by means of the urinary volumetric excretion (UVE)--pharmacologic effect--and by the estimation of Ke, tmax, and MRT-pharmacokinetic parameters. At end, an analysis of the relative bioavailabilities between formulations has been performed.

Animals↗
PubMed1994

The application of solid dispersion technique with D-mannitol to the improvement in oral absorption of triamterene.

Present paper proposes a new system to administer triamterene, a sparing potassium diuretic which presents absorption problems when administered as a free powder, due to its low solubility in water. To increase the dissolution rate and subsequent oral bioavailability of this drug, it has been formulated as solid dispersion. This method involves preparation by the melting carrier method using D-mannitol as matrix. These systems were subjected to USP XXII dissolution rate determination. The results revealed a marked dissolution rate increase of included triamterene in solid dispersions when compared with micronized drug. Further in vivo assays have demonstrated the absorption efficiency for the proposed systems when referred to pure drug. In vitro-in vivo correlation between the parameter T80% (from dissolution rate studies) and the pharmacokinetic one Ke, has found to be acceptable. All the results obtained make this system suited for further formulation in the pharmaceutical industry.

Administration, Oral↗
PubMedDate not supplied

Improvement of the diuretic effect of triamterene via solid dispersion technique with PEG 4000.

The present investigation was designed and undertaken in order to substantiate further contention concerning the universality of the utilization of PEG polymers as matrix carriers. This study could then be considered an attempt to enhance the dissolution rate of triamterene, with the subsequent enhancement in its absorption rate, via solid dispersion using PEG 4000. The approach of solid dispersions was found useful for optimizing the pharmacokinetic of triamterene in rats.

Administration, Oral↗