Development and microbiological evaluation of chitosan and chitosan-alginate microspheres for vaginal administration of metronidazole

Metronidazole is the drug of choice in the treatment of bacterial vaginosis, but the oral therapy can induce several collateral effects. Aim of this work was the development of a vaginal multiparticulate system, loaded with metronidazole, able to improve its residence time allowing a complete drug release. Several kinds of MS were prepared using chitosan dissolved in different organic acids or alginate coated with chitosan. FTIR and DSC analyses were performed to study the interactions between the drug and the polymers, while MS morphology was investigated with optical and electron microscopy. All the formulations were characterized in terms of drug entrapment efficiency, mucoadhesion, swelling capacity and drug release behavior, demonstrating the best results for alginate MS coated with chitosan. The formulations evidenced a complete and rapid release of drug, compared with the commercial form: Zidoval®.The best formulations assayed for antibacterial activity confirmed the suitability of this new formulation for the vaginal treatment of local diseases.

Comparison of liposomal and NLC (nanostructured lipid carrier) formulations for improving the transdermal delivery of oxaprozin: Effect of cyclodextrin complexation

The combined strategy of drug-cyclodextrin (CD) complexation and complex loading into nanocarriers (deformable liposomes or nanostructured lipid carriers (NLC)), was exploited to develop effective topical formulations for oxaprozin transdermal administration. Oxaprozin was loaded as ternary complex with randomly-methylated-ßCD and arginine, selected as the best system in improving drug solubility. The colloidal dispersions, characterized for particle size, zeta-potential and entrapment efficiency, were investigated for drug permeation properties in comparison with a plain drug aqueous suspension, a ternary complex aqueous solution and a plain drug liposomal or NLC dispersion. Experiments with artificial membranes showed that the joined use of CD and both liposomes or NLC enabled a marked increase of the drug permeability (16 and 8 times, respectively) and was significantly more effective (P<0.05) than the drug as ternary complex (3.2 times increase), and the corresponding liposomal or NLC dispersion of plain drug (5.6 and 4.3 times increase, respectively). Experiments with excised human skin confirmed the significantly (P<0.05) better performance of deformable liposomes than NLC in promoting drug permeation; moreover, they evidenced a more marked permeability increase compared to the plain drug (24 and 12 fold, respectively), attributed to a possible enhancer effect of the nanocarriers components and/or of the randomly-methylated-ßCD.

Combined use of bile acids and aminoacids to improve permeation properties of acyclovir

The aim of this work was to develop a topical formulation with improved permeation properties of acyclovir. Ursodeoxycholic (UDC) and dehydrocholic (DHC) acids were tested as potential enhancers, alone or in combination with different aminoacids. Equimolar binary and ternary systems of acyclovir with cholic acids and basic, hydrophilic or hydrophobic aminoacids were prepared by co-grinding in a high vibrational micromill. Differential scanning calorimetry (DSC) was used to characterize the solid state of these systems, while their permeation properties were evaluated in vitro through a lipophilic artificial membrane. UDC was more than 2 times more effective than DHC in improving drug AUC and permeation rate. As for the ternary systems drug-UDC-aminoacid, only the combined use of l-lysine with UDC acid produced an evident synergistic effect in enhancing drug permeation properties, enabling an almost 3 and 8 times AUC increase compared to the binary UDC system or the pure drug, respectively. The best systems were selected for the development of topical cream formulations, adequately characterized and tested for in vitro drug permeation properties and stability on storage. The better performance revealed by acyclovir-UDC-l-lysine was mainly attributed to the formation of a more permeable activated system induced by the multicomponent co-grinding process.

Development of a new delivery system consisting in "drug--in cyclodextrin--in nanostructured lipid carriers" for ketoprofen topical delivery

A new delivery system based on drug cyclodextrin (Cd) complexation and loading into nanostructured lipid carriers (NLC) has been developed to improve ketoprofen therapeutic efficacy. The proposed strategy exploits both the solubilizing and stabilizing properties of Cds and the prolonged release, high tolerability and percutaneous absorption enhancer properties of NLC. Two different polymeric Cds, i.e. β-Cd-epichlorohydrin polymer (EPI-βCd) and carboxymethylathed-β-Cd-epichlorohydrin polymer (EPI-CMβCd) were tested and two different techniques to obtain solid ketoprofen-polymeric Cd complexes (i.e. co-grinding and co-lyophilization) were compared, to investigate the influence of the preparation method on the physicochemical properties of the end product. EPI-βCd was more effective than EPI-CMβCd in enhancing the solubility and dissolution properties of ketoprofen. Co-grinding in dry conditions was the best preparation technique of solid drug-Cd systems, allowing obtainment of homogeneous amorphous particles of nanometric range. NLC consisting in a mixture of Compritol® 888 ATO (glyceryl behenate) and Labrafac Lipophile were obtained by ultrasonication. Both empty and loaded NLC were suitably characterized for particle size, pH, entrapment efficiency and drug release behavior. The best (drug-Cd)-loaded NLC system, formulated into a xanthan hydrogel, exhibited drug permeation properties clearly better than those of the plain drug suspension or the plain drug-loaded NLC, in virtue of the simultaneous exploitation of the solubilizing effect of cyclodextrin and the penetration enhancer properties of NLC.

Improvement of oxaprozin solubility and permeability by the combined use of cyclodextrin, chitosan, and bile components

The effect of the combined use of randomly methylated β-cyclodextrin (RAMEB), chitosan (CS), and bile components (dehydrocholic (DHCA) or ursodeoxycholic (UDCA) acids and their sodium salts) on solubility and permeability through Caco-2 cells of oxaprozin (a very poorly water-soluble non-steroidal anti-inflammatory drug) has been investigated. Addition of CS, bile acids, and their sodium salts increased the RAMEB solubilizing power of 4, 2, and 5 times, respectively. Drug-RAMEB-CS co-ground systems showed very higher dissolution rate than corresponding drug-RAMEB systems. Addition of bile components further improved drug dissolution rate. The CS presence enabled a significant increase in drug permeability through Caco-2 cells with respect to drug-RAMEB systems. Moreover, CS and NaDHC showed a synergistic enhancer effect, enabling a 1.4-fold permeability increase in comparison with systems without bile salt. However, unexpectedly, no significant differences were found between physical mixtures and co-ground products, indicating that drug permeation improvement was due to the intrinsic enhancer effect of the carriers and not to drug-carrier interactions brought about by co-grinding, as instead found in dissolution rate studies. The combined use of RAMEB, CS, and NaDHC could be exploited to develop effective oral dosage forms of oxaprozin, with increased drug solubility and permeability, and then improved bioavailability.

Development of Enteric-coated Timed-release Matrix Tablets for Colon Targeting

A new oral drug delivery system for colon targeting has been developed based on enteric-coated matrix tablets which suitably exploits both pH-sensitive and time-dependent functions. Matrix-tablets were prepared by direct compression of mixtures of hydroxyethylcellulose (HEC), a hydrophilic swellable polymer, with the inert insoluble ethylcellulose (EC) or micro-crystalline cellulose (MCC) polymers, in which theophylline, selected as model drug, was dispersed. Eudragit S100, a methacrylic acid copolymer soluble at pH 7, was used as pH-sensitive coating polymer. The influence of varying the cellulose-derivative combinations and their relative ratios as well as the level of the coating polymer was investigated. Surface morphology of the tablets was monitored by SEM analysis before and after the release test. The results of release studies, performed according to the USP basket method using a sequence of dissolution media simulating the gastrointestinal physiological pH variation, indicated that the Eudragit S100 enteric-coated matrix tablets were successful in achieving gastric resistance and timed-release of the drug, assuring an adequate lag time for the intended colonic targeting, followed by a controlled-release phase. The enteric-coating level emerged as the critical factor in determining the duration of the lag-phase, whereas the release rate mainly depended on the matrix composition. Formulations with higher HEC content showed a faster drug release rate than those with greater content in inert polymer and the MCC-HEC combinations were more effective than the corresponding EC-HEC ones. The best results were given by the 27% coated 1:0.3:0.7 (w/w) drug/MCC/HEC tablets, which, after a 260 min lag time, regularly released the drug, achieving about 90% of release after 10 h.

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).

Liquid spray formulations of xibornol by using self-microemulsifying drug delivery systems

Xibornol is a lipophilic drug mainly used in Italy and Spain in spray dosage forms for the local treatment of infection and inflammation of the throat. Its poor water solubility makes difficult the development of aqueous formulations of the drug, thus giving rise to a limited number of stable and pharmaceutically accepted preparations. In fact, xibornol is actually marketed only as spray aqueous suspension. The aim of this work was to evaluate the possibility of developing a stable liquid formulation of the drug intended for oral spray administration using a self-microemulsifying drug delivery system (SMEDDS). These systems are able to adequately improve the drug solubility, allowing the introduction of relatively high concentration of drugs in the form of solution. Labrafil M1944, Labrafil M2125 and Labrafac CC were screened as oil phases, Labrasol and Labrafac PG as surfactants and Transcutol as co-surfactant. Pseudo-ternary phase diagrams were constructed, by titration with the aqueous phase of different oil phases and surfactant/co-surfactant mixtures in order to identify the self-microemulsification region and the optimal micro-emulsion composition. Then, complete pharmaceutical formulations were prepared and evaluated for stability and viscosity properties. The final selected formulations, containing Labrafil M1944, Transcutol, Labrafac PG and a hydrophilic co-solvent (propylene glycol or PEG 200) allowed complete solubilization of the required xibornol concentration (3%, w/v) and showed physical good stability up to 2 months at 25 and 4 degrees C, suitable viscosity and organoleptic properties.

Simultaneous effect of cyclodextrin complexation, pH, and hydrophilic polymers on naproxen solubilization

The effect of pH variation on complexation and solubilization of naproxen (pK(a) 4.2) with natural betaCyclodextrin (betaCyD) and various neutral, cationic and anionic betaCyD-derivatives has been investigated. The combined effect of pH variation and hydrophilic polymer addition on CyD solubilizing and complexing efficiency has also been determined. Phase-solubility analysis in buffered aqueous solutions (pH from 1.1 to 6.5) was used to study the interaction of the drug with each CyD, in the presence or not of the water-soluble polymer. A clear influence of the substituent type was observed, the methylderivative being the most efficient agent; on the contrary, unexpectedly, no influence of the CyD charge in the interaction with the ionizable drug was detected. As expected, total drug solubility increased with increasing pH; however, the solubility increment with respect to drug alone obtained by CyD complexation progressively decreased, with a parallel reduction of the complex stability, attributed to the reduced affinity of charged drug for the hydrophobic CyD cavity. The addition of the polymer in part counterbalanced the destabilizing effect obtained with increasing pH, by improving the CyD complexation power towards naproxen. In particular, the presence of PVP allowed an increase of the complex stability constant with hydroxypropyl betaCyD up to 60% with respect to the corresponding drug-CyD binary system. Therefore, the combined strategy of pH control and polymer addition to the CyD complexing medium can be successfully exploited to improve naproxen solubilization and reduce the amount of CyD needed. The construction of theoretical drug solubility curves as a function of pH for any given CyD and polymer concentration enables selection of the best experimental conditions for obtaining the desired drug solubility value.

Differential scanning calorimetry as a screening technique in compatibility studies of DHEA extended release formulations

Differential scanning calorimetry (DSC) was used as a screening technique for assessing the compatibility of DHEA as ternary complex with alpha-cyclodextrin and glycine (c-DHEA) with some excipients suitable for preparation of sustained-release matrix tablets by direct compression. The effect of sample mechanical treatment due to the compression process was also evaluated. In order to investigate the possible interactions between the components, the DSC curves of c-DHEA and each selected excipient were compared with those of their 1:1 w/w physical mixtures, before and after compression, in order to evaluate any possible solid state modification. FT-IR spectroscopy and X-ray powder diffractometry were used as complementary techniques to adequately implement and assist in interpretation of the DSC results. On the basis of DSC results, c-DHEA was found to be compatible with xanthan gum, hydroxypropylmethylcellulose, sodium starch glycolate (Explotab), polyvinylacetate-polyvinylpirrolidone (Kollidon SR) and sodium chloride. Some drug-excipient interaction was observed with dextrate hydrate (Emdex), mannitol and Magnesium stearate. Finally, the behaviour of the complete formulation, in the presence of all the excipients selected by means of the compatibility study, was investigated, in order to verify the absence of reciprocal interactions among the components.

Interaction of naproxen with ionic cyclodextrins in aqueous solution and in the solid state

The possible role of the cyclodextrin charge in the interaction with an acidic drug such as naproxen (pKa 4.8) has been evaluated. Sulfobutylether-beta-cyclodextrin (SBE-betaCyd) and trimethylammonium-beta-cyclodextrin (TMA-betaCyd) were selected as, respectively, anionically and cationically charged carriers and their performance was compared with that of the parent beta-cyclodextrin (betaCyd) and of its methyl-derivative (Me betaCyd) previously found as the best partner for the drug. Interactions in solution were investigated by phase-solubility, fluorescence and circular dichroism analyses. Equimolar drug-carrier products prepared by different techniques (blending, cogrinding, sealed-heating, colyophilization) were characterized by differential scanning calorimetry and X-ray powder diffractometry and tested for drug dissolution properties. Anionic charges of SBE-betaCyd did not negatively influence interactions in unbuffered aqueous solutions (pH approximately 5) with the acidic drug. In fact, it was a very effective carrier, exhibiting solubilizing and complexing properties considerably better than the parent betaCyd and comparable to those of Me betaCyd. On the contrary, the positive charges of TMA-betaCyd did not favour interactions with the counter-ionic drug (despite the presence of about 60% ionised drug) and it was less efficacious also than native betaCyd. Therefore, the role of the Cyd charge on the complexing and solubilizing properties towards naproxen was not important whereas other factors, such as steric hindrance effects and favourable hydrophobic interactions were significant in determining the drug affinity for the Cyd inclusion. Solid state studies evidenced similar amorphizing properties of both charged Cyds towards naproxen. On the other hand, dissolution tests, in agreement with solution studies, showed that all products with SBE-betaCyd exhibited significantly better dissolution properties than the corresponding ones with TMA-betaCyd. A clear influence of the preparation method of drug-Cyd solid systems on the performance of the end product was also observed. Colyophilization was the most effective technique, followed by the cogrinding one. Colyophilized product with SBE-betaCyd allowed a 10-times increase in drug dissolution efficiency (D.E.) (with respect to the five-times increase obtained with the corresponding coground product) and a reduction of t(50%) from about 60 min (for the coground product) to less than 2 min.

Determination of stability constant values of flurbiprofen-cyclodextrin complexes using different techniques

Three new experimental approaches for calculating the stability constant (K(st)) of complexes of flurbiprofen with natural beta-cyclodextrin (betaCyd) and the hydroxyethyl- (HEbetaCyd) and the methyl- (Me betaCyd) derivatives were tested and compared to the classic phase-solubility procedure: (a) the membrane permeation technique through a lipophilic synthetic membrane permeable to the drug but not to the Cyd molecules, by analysing the permeation profiles with a non-linear least-squares method; (b) the affinity capillary electrophoresis (ACE) technique, where K(st) were calculated from the relationship between Cyd concentration in solution and drug electrophoretic mobility, using three different linear plotting methods; (c) the molecular modeling technique, based on the relationship between the docking energies and the experimental K(st) values. The study allowed evaluation of the advantages and limits of each examined method, providing a useful guide for the choice of the most suitable one depending on the kind of host-guest system to be investigated. The K(st) values obtained with the various techniques were rather different, probably due to the very different experimental conditions required by each one. However, all the methods indicated the methyl-derivative as the most powerful complexing agent for the drug, showing the general trend: K(st)(Me betaCyd)>>K(st)(HEbetaCyd)>K(st)(betaCyd). Only in the case of the ACE method was an inversion of the trend found between HEbetaCyd and betaCyd; this was probably due to the lower molecular weight of the natural Cyd, which, in this case, became more important in determining the complex electrophoretic mobility than the different affinity of the drug for these two Cyds.

Influence of cyclodextrins and chitosan, separately or in combination, on glyburide solubility and permeability

The effect of chitosan and of different concentrations of beta- or hydroxypropyl-beta-cyclodextrins, separately or in various (w/w) combinations, on the dissolution characteristics of glyburide (an oral hypoglycemic agent subject to incomplete and variable bioavailability) and on its permeability through Caco-2 cells has been investigated. Cyclodextrins (and particularly the hydroxypropyl-derivative, in virtue of its higher water solubility) were clearly more effective than chitosan in enhancing the drug dissolution properties: the aqueous glyburide solubility was improved 40-fold in the presence of 25 mM hydroxypropyl-beta-cyclodextrin, 25-fold in the presence of 13 mM beta-cyclodextrin (saturation solubility) and only 3-fold in the presence of chitosan at its saturation concentration (0.5% w/v). When chitosan and cyclodextrin were simultaneously present, a strong reduction of the cyclodextrin solubilizing efficiency towards the drug was observed, and it was attributed to a possible competition effect of polymer and glyburide for the interaction with the macrocycle. By contrast, permeation studies revealed that chitosan was more powerful than cyclodextrins in enhancing the glyburide permeability through Caco-2 cells. This was probably in virtue of the polymer's favourable effect on the tight junctions opening, as demonstrated by the significant decrease in the transepithelial electrical resistance recorded in its presence. Moreover, interestingly, when using the carriers together, conversely from solubility studies, a significant (P < 0.05) synergistic effect in enhancing glyburide apparent permeability was revealed in permeation experiments.

Influence of formulation and process variables on in vitro release of theophylline from directly-compressed Eudragit matrix tablets

Extended-release theophylline (TP) matrix tablets were prepared by direct compression of drug and different pH-dependent (Eudragit L100, S100 and L100-55) and pH-independent (Eudragit RLPO and RSPO) polymer combinations. The influence of varying the polymer/polymer (w/w) ratio and the drug incorporation method (simple blend or solid dispersion) was also evaluated. Drug release, monitored using the Through Flow Cell system, markedly depended on both the kind of Eudragit polymer combinations used and their relative content in the matrix. Maintaining a constant 1:1 (w/w) drug/polymers ratio, the selection of appropriate mixtures of pH-dependent and pH-independent polymers enabled achievement of a suitable control of TP release. In particular, matrices with a 0.7:0.3 w/w mixture of Eudragit L100-Eudragit RLPO showed highly reproducible drug release profiles, with an almost zero-order kinetic, and allowed 100% released drug after 360 min. As for the effect of the drug incorporation method, simple blending was better than the solid dispersion technique, which not only did not improve the release data reproducibility, but also caused, unexpectedly, a marked slowing down in drug release rate.

Optimization of glibenclamide tablet composition through the combined use of differential scanning calorimetry and d-optimal mixture experimental design

A systematic analysis of the influence of different proportions of excipients on the stability of a solid dosage form was carried out. In particular, a d-optimal mixture experimental design was applied for the evaluation of glibenclamide compatibility in tablet formulations, consisting of four classic excipients (natrosol as binding agent, stearic acid as lubricant, sorbitol as diluent and cross-linked polyvinylpyrrolidone as disintegrant). The goal was to find the mixture component proportions which correspond to the optimal drug melting parameters, i.e. its maximum stability, using differential scanning calorimetry (DSC) to quickly obtain information about possible interactions among the formulation components. The absolute value of the difference between the melting peak temperature of pure drug endotherm and that in each analysed mixture and the absolute value of the difference between the enthalpy of the pure glibenclamide melting peak and that of its melting peak in the different analyzed mixtures, were chosen as indexes of the drug-excipient interaction degree.

Development and Evaluation of Glyburide Fast Dissolving Tablets Using Solid Dispersion Technique

Glyburide is a poorly water-soluble oral hypoglycemic agent, with problems of variable bioavailability and bio-inequivalence related to its poor water-solubility. This work investigated the possibility of developing glyburide tablets, allowing fast, reproducible, and complete drug dissolution, by using drug solid dispersion in polyethylene glycol. Phase-solubility studies were performed to investigate the drug-carrier interactions in solution, whereas differential scanning calorimetry, X-ray powder diffraction, and infrared spectroscopy were used to characterize the solid state of solid dispersions. The effects of several variables related to both solid dispersion preparation (cofusion or coevaporation technique, drug-to-carrier ratio, polyethylene glycol molecular weight) and tablet production (direct compression or previous wet-granulation, tablet hardness, drug, and solid dispersion particle size) on drug dissolution behavior were investigated. Tablets obtained by direct compression, with a hardness of 7-9 Kp, and containing larger sized solid dispersions (20-35 mesh, i.e., 850-500 microm) of micronized glyburide in polyethylene glycol 6000 prepared by the cofusion method gave the best results, with a 135% increase in drug dissolution efficiency at 60 min in comparison with a reference tablet formulation containing the pure micronized drug. Moreover, the glyburide dissolution profile from the newly developed tablets was clearly better than those from various commercial tablets at the same drug dosage.

Photostability studies on nicardipine–cyclodextrin complexes by capillary electrophoresis

Nicardipine (NC)-cyclodextrin solid systems were prepared in equimolar ratios and their photostability in aqueous solution under exposure to UV(A)-UV(B) radiations was evaluated. The photodegradation process was monitored by a capillary electrophoresis (CE) method able to provide the enantioresolution of the rac-nicardipine. Enantioresolution was achieved using the mixture 3.0% sulfate-beta-cyclodextrin (SbetaCD) and 2.0% heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TMbetaCD) as chiral selector in 20mM triethanolammonium phosphate solution (pH 3.0). The photostability studies were carried out on inclusion complexes of rac-nicardipine with alpha-cyclodextrin (alphaCD), beta-cyclodextrin (betaCD), gamma-cyclodextrin (gammaCD), hydroxypropyl-alpha-cyclodextrin (HPalphaCD), hydroxypropyl-beta-cyclodextrin (HPbetaCD), hydroxypropyl-gamma-cyclodextrin (HPgammaCD), (2-hydroxyethyl)-beta-cyclodextrin (HEbetaCD) and methyl-beta-cyclodextrin (MbetaCD). A photoprotective effect was observed by betaCD, HPalphaCD, HEbetaCD, whereas gammaCD, MbetaCD, HPbetaCD and HPgammaCD did not affect the nicardipine photostability. Conversely, alphaCD was found to favour the drug photodegradation. Evidences for CDs-mediated stereoselective photodegradation of rac-nicardipine were observed only for the beta-CD complex. In this case, two distinct photodegradation profiles, with two different kinetic constants (k), were observed for the nicardipine enantiomers.

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.

Enhancement of Dehydroepiandrosterone Solubility and Bioavailability by Ternary Complexation with α‐Cyclodextrin and Glycine

In the present work we investigated the possibility of improving dehydroepiandrosterone (DHEA) solubility and bioavailability by high-energy cogrinding with alpha-cyclodextrin (alpha-Cd) in the presence or absence of different auxiliary substances (glycine, biomaltodextrin, poly(vinyl pyrrolidone), poly(ethylene glycol) 400). In all cases, ternary products exhibited higher drug solubilizing properties than the binary DHEA-alpha-Cd coground system. Glycine was the most effective component. The best combinations, corresponding to 1:1:2 and 1:2:3 drug-alpha-Cd-glycine molar ratios, were characterized by differential scanning calorimetry and X-ray powder diffractometry and evaluated for dissolution rate. The presence of glycine favored destruction of DHEA crystalline structure during cogrinding, as evidenced by the strong reduction in both time and vibration frequency of milling necessary to obtain total drug amorphization. Both ternary products showed better dissolution properties than the drug alone, affording, respectively, a 40 and 60% increase of dissolution efficiency. The 1:2:3 coground product was then selected for in vivo bioavailability studies in women suffering from adrenocortical insufficiency. DHEA and DHEA sulfate blood levels were significantly higher (p < 0.001) after oral administration of the coground product than after oral administration of untreated drug, with a 100% increase in the area under the curve (AUC) of concentration versus time. Moreover, the time to reach maximum concentration (t(max)) decreased from 2.2 with the untreated drug to 0.5 h with the coground product, and the mean permanence time of DHEA within physiological levels was four times longer for the coground product compared with the untreated drug. These results indicate that the developed product is particularly suitable for oral DHEA formulations in hormone replacement therapies.

Investigation of the effects of grinding and co-grinding on physicochemical properties of glisentide

The purpose of the present study was to investigate the possibility of improving the dissolution properties of glisentide, a poorly water-soluble antidiabetic drug, by grinding in a high energy micromill, alone or in mixture with polyvinylpyrrolidone (PVP). Conventional and modulated differential scanning calorimetry (DSC, MDSC), thermogravimetry (TGA), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), hot-stage FT-IR thermomicroscopy and scanning electron microscopy (SEM) were used to characterize the drug solid state, whereas its dissolution rates were determined according to the dispersed amount method. The techniques utilized enabled exclusion of polymorphism phenomena as a consequence of mechanical treatment, and revealed a progressive drug amorphization during grinding. In particular, MDSC allowed a clear determination of the glass transition temperature of the amorphous drug, enabling separation of glass transition from enthalpic relaxation. The amorphous state of the ground drug was the main responsible factor for the obtained 100% dissolution efficiency increase in comparison with the untreated drug. Further significant increases in dissolution properties, directly related to the polymer content in the mixture, were obtained by co-grinding with PVP, whose presence clearly favored drug amorphization, allowing a strong reduction of time and frequency of grinding necessary for obtaining complete drug amorphization.