Flexible New Dosage Forms Containing Carvedilol for the Treatment of Patients with Cardiovascular Disorders: Development, Stability, Palatability, and Microbiological Studies.

The development of formulations adapted to the patient's age is a challenge in the pharmaceutical industry. Pediatric and geriatric patients may have difficulties in swallowing oral medications when an adequate formulation is not available. Carvedilol is a poorly water-soluble drug used to treat cardiovascular problems; it is commercialized in several countries only as solid oral formulations, which are often manipulated at the point of administration to treat pediatric or geriatric patients. The purpose of this work was to obtain a new dosage form of Carvedilol using safe excipients, suitable for administration to pediatric and geriatric patients. To improve the solubility of Carvedilol, the effect of several factors was analyzed and optimized. Subsequently, to improve the physical stability of the formulations, two preparation methods were analyzed by adding HPMC. In "method 1," HPMC was dissolved in buffer and incorporated into a mixture of Carvedilol-PEG 400, while in "method 2," Carvedilol was solubilized in buffer containing PEG 400, and then, HPMC was added. Finally, microbiological tests were performed to the stable formulations. The factors "pH value" and "concentration of PEG" affected the solubility of Carvedilol. A formulation containing Carvedilol (3 mg/mL), pH=3, PEG 400 (15% v/v), and HPMC (0.25% w/v) prepared by method 2 was stable for 180 days at 4 °C while those containing Carvedilol (5 mg/mL), pH=3, PEG 400 (27% v/v), and HPMC (0.5% w/v), prepared by method 2, were stable for 180 days at 4 and 25°C. These oral liquid formulations were physicochemical and microbiologically stable for 6 months.

Miconazole Nitrate Microparticles in Lidocaine Loaded Films as a Treatment for Oropharyngeal Candidiasis.

Oral candidiasis is an opportunistic infection that affects mainly individuals with weakened immune system. Devices used in the oral area to treat this condition include buccal films, which present advantages over both oral tablets and gels. Since candidiasis causes pain, burning, and itching, the purpose of this work was to develop buccal films loaded with both lidocaine (anesthetic) and miconazole nitrate (MN, antifungal) to treat this pathology topically. MN was loaded in microparticles based on different natural polymers, and then, these microparticles were loaded in hydroxypropyl methylcellulose-gelatin-based films containing lidocaine. All developed films showed adequate adhesiveness and thickness. DSC and XRD tests suggested that the drugs were in an amorphous state in the therapeutic systems. Microparticles based on chitosan-alginate showed the highest MN encapsulation. Among the films, those containing the mentioned microparticles presented the highest tensile strength and the lowest elongation at break, possibly due to the strong interactions between both polymers. These films allowed a fast release of lidocaine and a controlled release of MN. Due to the latter, these systems showed antifungal activity for 24 h. Therefore, the treatment of oropharyngeal candidiasis with these films could reduce the number of daily applications with respect to conventional treatments.

The Effect of Different Formulations of Praziquantel in Reducing Worms in the Prepatent Period of Schistosomiasis in Murine Models.

Schistosomiasis is a widely distributed parasitic disease and one of the most important neglected tropical diseases globally, for which Praziquantel® (PZQ) is the only available treatment. In this context, tests with new PZQ formulations become relevant for disease control. This study evaluated the effects of PZQ treatment in the prepatent phase of schistosomiasis using two formulations: nanoencapsulated (PZQ-NANO) and active pharmaceutical ingredient (PZQ-API). Five experimental groups were established, for which the following serological parameters were evaluated: ALT, AST, ALP, and TP. Animals treated with PZQ-API at 15 and 30 days post-infection showed decreased eggs per gram of feces (EPG) compared to untreated infected animals. The same animals showed reductions of 63.6 and 65.1%, respectively, at 60 days post-infection. Animals treated with PZQ-NANO experienced no significant changes in EPG at any time of observation. Animals treated with either PZQ-API or PZQ-NANO had higher ALT and AST levels in the patent period (60 and 90 days post-infection). Treatment with PZQ, either API or NANO, at 15 days post-infection reduced AST, ALT, and TP levels. It is concluded that prepatent treatment with PZQ-API can reduce the parasite load of infected animals and that treatment at 15 days post-infection can prevent increased serum levels of ALT, AST, and TP.

Effect of sex and genotype of the host on the anthelmintic efficacy of albendazole microcrystals, in the CBi-IGE Trichinella infection murine model.

Albendazole (ABZ) is an anthelmintic pharmaceutical commonly used in the treatment of nematode infections. It is a Class II drug poorly water-soluble, with very low bioavailability, a feature particularly limiting to treat the trichinellosis chronic phase. Microcrystals obtained by controlled precipitation using hydroxyethyl cellulose and chitosan have previously been shown to improve ABZ biopharmaceutical properties. This investigation aimed to test the systems' in vivo efficacy in the CBi-IGE murine model of Trichinella spiralis infection in the infection's different phases and parasite' stages. Treatment in the enteral phase led to a 90% decrease in the larval muscle load, probably due to its effect on T. spiralis female fecundity. Both microcrystal systems given in the migratory phase halved muscle load in males, a response not observed in females. The chitosan-based microcrystals proved to be the best when administered in the chronic phase of the infection ­ an increased proportion of L1 dead larvae was found compared to controls, except in CBi+-treated females. Males and females from the highly susceptible CBi+ line presented a significantly different treatment response in this phase. In vivo efficacy depended on the host genotype and sex and was related to the parasite cycle stage in which the formulations were administered.

Orphan Formulations for Pediatric Use: Development and Stability Control of Two Sildenafil Citrate Solutions for the Treatment of Pulmonary Hypertension.

Sildenafil citrate causes vasodilatation, relaxation of the smooth muscle, and reduction of pulmonary arterial pressure. The latter property makes sildenafil citrate efficient for the treatment of cardiovascular diseases, including pulmonary arterial hypertension. Pediatric patients with pulmonary arterial hypertension are more susceptible to errors in drug administration than adults because of a lack of suitable drug dosages. Thus, the purpose of this study was to develop stable (chemically and microbiologically) sildenafil citrate drop liquid formulation, suitable for pediatric patients (including diabetics), ensuring safety during preparation and storing and improving palatability by using milk as a carrier for administration. The significant factors that affect the sildenafil solubility were evaluated by applying a Plackett-Burman design using two levels with six variables. The experiment showed that the type of buffer and glycerin content influenced the sildenafil solubility. The developed formulations proved to be stable for 6 months at all three assayed conditions (40± 2°C, 75 ± 5% RH; 25± 2°C, 60 ± 5% RH; and 4 ± 2°C). The microbiological tests fit with the requirement of the pharmacopeia at day 0 and 90 and even more at day 180. Finally, the palatability assay showed that 0.82 mL of the formulation containing buffer phosphate, 20% glycerin, and 4 mg mL-1 of sildenafil citrate diluted in 4.8 mL milk (which fits the medium pediatric dose) presented similar palatability to milk alone, and no precipitate or turbidity was observed. Graphical abstract.

Nanodelivery of nitazoxanide: impact on the metabolism of Taenia crassiceps cysticerci intracranially inoculated in mice.

Aim: To formulate nanocapsules and nanoemulsions of nitazoxanide (NTZ) and evaluate the metabolic effect on Taenia crassiceps cysticerci inoculated intracranially into mice. Materials & methods: NTZ nanosystems were formulated through solvent diffusion methodology. These nanoformulations were administered perorally and their impact on glycolysis, the tricarboxylic acid cycle and fatty acid metabolism in T. crassiceps cysticerci was investigated. Results: Gluconeogenesis and protein catabolism were significantly increased by the nanoformulations when compared with the control group and the NTZ-treated group. All the other metabolic pathways were inhibited by the nanoformulation treatments. Conclusion: The remarkable metabolic modifications that occur in this in vivo model through the application of these developed nanosystems confirm their capability to deliver NTZ into targeted tissues.

Effect of Genotype and Sex of the Host on the Bioavailability of Novel Albendazole Microcrystals Based on Chitosan and Cellulose Derivatives.

Albendazole (ABZ), an anthelmintic compound widely used in the treatment of systemic nematode infections, is included in the list of class II drugs based on the Biopharmaceutical Classification System. ABZ has limited effectiveness due to its poor water solubility and consequent low bioavailability. Bioavailability of novel ABZ microcrystals based on hydroxyethylcellulose (S4A) or chitosan (S10A) was studied in male and female mice of two inbred lines, from the murine CBi-IGE model of trichinellosis, differing in susceptibility to this parasitosis (line CBi/L, resistant; line CBi+, susceptible). ABZ microcrystals were administered orally, and albendazole sulfoxide (ABZSO) was quantified in plasma by high-performance liquid chromatography. Mice given the microcrystals showed a significant increase in maximum plasmatic concentration (Cmax) compared with those receiving pure ABZ (P < 0.01). In both genotypes, males and females given S4A had higher Cmax than those receiving S10A (P < 0.05). CBi/L showed a greater Cmax than CBi+ (significantly different only in females treated with S4A (P = 0.001)). CBi/L females attained a higher Cmax than males (P < 0.05). No sex effect was observed for this variable in CBi+ (P > 0.05). The results of the pharmacokinetic analysis indicate that the microcrystalline formulations optimize ABZ bioavailability, both in males and females, S4A being the best system in CBi/L mice and S10A in CBi+. In summary, the microcrystals increased ABZ bioavailability, and under the conditions of this investigation, both host genotype and sex influenced the pharmacokinetic parameters measured.

A Novel Prototype Device for Microencapsulation of Benznidazole: In Vitro/In Vivo Studies.

This study was aimed to design a simple and novel prototype device for the production of polymeric microparticles. To prove the effectiveness of this device, benznidazole microparticles using chitosan as carrier and NaOH, KOH, or SLS as counter ions were used. For comparison, benznidazole microparticles were prepared by the conventional dripping technique (syringe and gauge) using the same excipients. Microparticles were characterized in terms of encapsulation efficiency, particle shape, size and surface topography, crystallinity characteristics, thermal behavior, and dissolution rate. Then, the pharmacokinetic parameters were evaluated after the oral administration of the microparticles to healthy Wistar rats. The prepared formulations, by means of this device, showed good drug encapsulation efficiency (> 70%). Release studies revealed an increased dissolution of benznidazole from chitosan microparticles prepared using the novel device. It achieved more than 90% in 60 min, while those of the conventional microparticles and raw drug achieved 65% and 68%, respectively, during the same period. Almost spherical benznidazole microparticles with a smooth surface and size around 10-30 µm were observed using scanning electron microscopy. Thermal analysis and X-ray diffraction studies suggested a partial reduction of drug crystallinity. Moreover, the relative oral bioavailability of the novel benznidazole microparticles showed that the area under the curve for the microencapsulated drug was 10.3 times higher than the raw drug. Thus, these findings indicate that the designed glass prototype device is a useful alternative to formulate benznidazole polymeric microparticles with improved biopharmaceutical properties and could be useful for other therapeutic microparticulate systems.

Improving the Dissolution of Triclabendazole from Stable Crystalline Solid Dispersions Formulated for Oral Delivery.

Triclabendazole belongs to the class II/IV of the Biopharmaceuticals Classification System, and its low aqueous solubility represents a major drawback during the development of effective dosage forms. Therefore, the goal of this study was to elucidate whether polymeric solid dispersions would represent a suitable approach to overcome such disadvantage. Due to the lack of information on triclabendazole release, four different dissolution media were evaluated to analyze drug dissolution rate. The polymeric solid dispersions were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The selected final formulations were further stored for 24 months, and their physical stability was evaluated by means of X-ray diffraction and drug dissolution assays. Drug solubility studies indicated that poloxamer 407 (P407) solubilized a higher amount of drug than polyethylene glycol 6000. Drug-to-carrier ratio, nature of the selected carriers, and the type of dissolution media were important factors for increasing dissolution. By infrared spectroscopy, there were no specific interactions between the drug and polymers. The physicochemical characterization of the systems showed a detectable evidence of drug amorphization by increasing the carrier ratio. Micromeritic studies indicated that raw triclabendazole, physical mixtures, and reference formulation showed poor flow properties, in contrast to the triclabendazole:P407 solid dispersion sample. Both the crystalline properties and dissolution rate of selected samples were very similar after 24 months at room temperature. Thus, considering physical stability and dissolution studies, the development of the solid dispersion is a very suitable methodology to improve triclabendazole dissolution and, potentially, its biopharmaceutical performance.

Design and Characterization of Chitosan Nanoformulations for the Delivery of Antifungal Agents.

Among different Candida species triggering vaginal candidiasis, Candida albicans is the most predominant yeast. It is commonly treated using azole drugs such as Tioconazole (TIO) and Econazole (ECO). However, their low water solubility may affect their therapeutic efficiency. Therefore, the aim of this research was to produce a novel chitosan nanocapsule based delivery system comprising of TIO or ECO and to study their suitability in vaginal application. These systems were characterized by their physicochemical properties, encapsulation efficiency, in vitro release, storage stability, cytotoxicity, and in vitro biological activity. Both nanocapsules loaded with TIO (average hydrodynamic size of 146.8 ± 0.8 nm, zeta potential of +24.7 ± 1.1 mV) or ECO (average hydrodynamic size of 127.1 ± 1.5 nm, zeta potential of +33.0 ± 1.0 mV) showed excellent association efficiency (99% for TIO and 87% for ECO). The analysis of size, polydispersity index, and zeta potential of the systems at 4, 25, and 37 °C (over a period of two months) showed the stability of the systems. Finally, the developed nanosystems presented fungicidal activity against C. albicans at non-toxic concentrations (studied on model human skin cells). The results obtained from this study are the first step in the development of a pharmaceutical dosage form suitable for the treatment of vaginal candidiasis.

New approaches to identification and characterization of tioconazole in raw material and in pharmaceutical dosage forms.

Tioconazole (TCZ), a broad-spectrum antifungal agent, has significant activity against Candida albicans and other Candida species, and therefore, it is indicated for the topical treatment of superficial mycoses. The main goal of this work is to report an exhaustive identification and characterization procedure to improve and facilitate the online quality control and continuous process monitoring of TCZ in bulk material and loaded in two different dosage forms: ovules and nail lacquer. The methodologies were based on thermal (differential scanning calorimetry (DSC), melting point, and thermogravimetry (TG)), spectroscopic (ultraviolet (UV), Raman, near infrared (NIR), infrared spectroscopy coupled to attenuated total reflectance (FTIR-ATR), and nuclear magnetic resonance (NMR)), microscopic and X-ray diffraction (XRD). The TCZ bulk powder showed a high crystallinity, as observed by XRD, with a particles size distribution (3-95 µm) resolved by microscopic measurements. TCZ melting point (82.8 °C) and a degradation peak centered at 297.8 °C were obtained by DSC and DTG, respectively. An unambiguous structure elucidation of TCZ was obtained by mono- and two- dimensional 1H and 13C NMR spectral data analysis. The FTIR-ATR, Raman and NIR spectra of both the raw material and the commercial products were analyzed and their characteristic bands were tabulated. The best methods for TCZ identification in ovules were DSC, TG, XRD, NIR and Raman, while NIR and FTIR-ATR were the most appropriate techniques to analyze it in the nail lacquer. DSC, TG, DRX, Raman, FTIR-ATR and NIR spectroscopy are effective techniques to be used in online process analysis, because they do not require sample preparation, and they are considerably sensitive to analyze complex samples.

Synthesis and characterization of a new cyclodextrin derivative with improved properties to design oral dosage forms.

This work aimed to synthesize a novel ß-cyclodextrin derivative, itaconyl-ß-cyclodextrin to evaluate whether albendazole inclusion complexes with the new ß-cyclodextrin derivative-improved albendazole dissolution efficiency and its anthelminthic activity. The new derivative was thoroughly evaluated and characterized, and an average degree of substitution of 1.4 per cyclodextrin molecule was observed. Albendazole:itaconyl-ß-cyclodextrin complexes were prepared by spray drying procedures and investigated using phase solubility diagrams, dissolution efficiency, X-ray diffraction, differential scanning calorimetry, Fourier transform infrared, scanning electronic microscopy, mass spectrometry, and nuclear magnetic resonance spectroscopy. Phase solubility diagrams and mass spectrometry studies showed that the inclusion complex was formed in an equimolar ratio. Stability constant values were 602 M-1 in water, and 149 M-1 in HCl 0.1 N. Nuclear magnetic resonance experiments of the inclusion complex showed correlation signals between the aromatic and propyl protons of albendazole and the itaconyl-ß-cyclodextrin inner protons. The studies indicated solid structure changes of albendazole included in itaconyl-ß-cyclodextrin. The maximum drug release was reached at 15 min, and the inclusion complex solubility was 88-fold higher than that of the pure drug. The in vitro anthelmintic activity assay showed that the complex was significantly more effective than pure albendazole.

Chitosan-hydroxypropyl methylcellulose tioconazole films: A promising alternative dosage form for the treatment of vaginal candidiasis.

Vaginal candidiasis is considered a frequent opportunistic mucosal infection and the second most common cause of vaginitis after bacterial vaginosis. In this work, different vaginal films based on chitosan, hydroxypropyl methylcellulose and blends of these polymers containing tioconazole, were developed and thoroughly characterized to improve the conventional therapeutics of vaginal candidiasis. Mechanical properties, swelling, adhesiveness, morphology, antifungal activity, hemocompatibility and cytotoxicity were evaluated. The drug solid state in the films was analyzed by thermal and X-ray diffraction analysis. Films showed homogeneous surfaces and presented similar mechanical properties and adhesiveness. Time-kill studies displayed that films were more active than both tioconazole pure drug and traditional tioconazole ovule against Candida albicans, which is probably related to the fact that tioconazole is in amorphous state inside the films. Although all formulations proved to be hemocompatible, films based only on chitosan exhibited a certain degree of cytotoxicity and therefore they should be avoided. The system based on chitosan-hydroxypropyl methylcellulose with 40% PEG 400 as plasticizer presented fast antimicrobial activity as well as the lowest swelling. Additionally, this formulation did not produce substantial hemolytic and cytotoxic effects, indicating that films based on chitosan-hydroxypropyl methylcellulose could be a promising alternative dosage form for the treatment of vaginal candidiasis.

Chitosan-based nanodelivery systems applied to the development of novel triclabendazole formulations.

Triclabendazole is a poorly-water soluble (0.24 µg/mL) compound classified into the Class II/IV of the Biopharmaceutical Classification System. It is the drug of choice to treat fascioliasis, a neglected parasitic disease worldwide disseminated. Triclabendazole is registered as veterinary medicine and it is only available for human treatment as 250 mg tablets. Thus, the aim of this work was to develop novel drug delivery systems based on nanotechnology approaches. The chitosan-based nanocapsules and nanoemulsions of triclabendazole were fully characterized regarding their particle size distribution, polydispersity index and zeta potential, in-vitro release and stability in biological media. Cytotoxicity evaluation and cellular uptake studies using CaCo-2 cell line were also investigated. The results indicated an average hydrodynamic size around ~160 nm were found for unloaded nanoemulsions which were slightly increased up to ~190 nm for loaded one. In contrast, the average hydrodynamic size of the nanocapsules increased from ~160 nm up to ~400 nm when loaded with triclabendazole. The stability studies upon 30 days storage at 4, 25 and 37°C showed that average size of nanoemulsions was not modified with varying amounts of loaded TCBZ while an opposite result was seen in case of loaded nanocapsules. In addition, a slight reduction of zeta potential values over time was observed in both triclabendazole nanosystems. Release of TCBZ from nanoformulations over 6 h in simulated gastric fluid was 9 to 16-fold higher than with untreated TCBZ dispersion. In phosphate buffer saline solution there was no drug release for neither nanocapsules nor nanoemulsions. Cell viabilities studies indicated that at certain concentrations, drug encapsulation can lower its cytotoxic effects when compared to untreated drug. Confocal laser scanning microscopy study has shown that nanocapsules strongly interacted with Caco-2 cells in vitro which could increase the passage time of triclabendazole after oral administration. The results of this study constitute the first step towards the development of nanoformulations intended for the oral delivery of anti-parasitic drugs of enhanced bioavailability.

Repositioning of Anti-parasitic Drugs in Cyclodextrin Inclusion Complexes for Treatment of Triple-Negative Breast Cancer.

Drug repositioning refers to the identification of new therapeutic indications for drugs already approved. Albendazole and ricobendazole have been used as anti-parasitic drugs for many years; their therapeutic action is based on the inhibition of microtubule formation. Therefore, the study of their properties as antitumor compounds and the design of an appropriate formulation for cancer therapy is an interesting issue to investigate. The selected compounds are poorly soluble in water, and consequently, they have low and erratic bioavailability. In order to improve their biopharmaceutics properties, several formulations employing cyclodextrin inclusion complexes were developed. To carefully evaluate the in vitro and in vivo antitumor activity of these drugs and their complexes, several studies were performed on a breast cancer cell line (4T1) and BALB/c mice. In vitro studies showed that albendazole presented improved antitumor activity compared with ricobendazole. Furthermore, albendazole:citrate-ß-cyclodextrin complex decreased significantly 4T1 cell growth both in in vitro and in vivo experiments. Thus, new formulations for anti-parasitic drugs could help to reposition them for new therapeutic indications, offering safer and more effective treatments by using a well-known drug.

Correction to: First Development, Optimization, and Stability Control of a Pediatric Oral Atenolol Formulation.

In the INTRODUCTION section, Atenolol is defined in parenthesis as (ATN, Fig. 1.) The correct definition is (ATN). Fig 1 corresponds to the RESULTS section.

Solving the Delivery Problems of Triclabendazole Using Cyclodextrins.

Triclabendazole is the first-line drug of choice to treat and control fasciolasis, a neglected parasitic human disease. It is a class II/IV compound according to the Biopharmaceutics Classification System. Thus, the aim of this study was to improve aqueous solubility and dissolution rate of triclabendazole complexed with 2-hydroxylpropyl-ß-cyclodextrin (HP-ß-CD) and methyl-ß-cyclodextrin (Me-ß-CD) at 1:1 and 1:2 M ratio. The impact of storage on the solubility, dissolution profile, and solid-state properties of such complexes was also investigated. Drug-carrier interactions were characterized by infrared spectroscopy, differential scanning calorimetry, X-ray diffractometry, and scanning electron microscopy. The solubility of triclabendazole improved up to 256- and 341-fold using HP-ß-CD and Me-ß-CD, respectively. In particular, the drug complexed with Me-ß-CD showed a positive deviation from linearity, suggesting that its solubility increases with an increasing concentration of Me-ß-CD concentration in a nonlinear manner. The drug dissolution was found to be improved through complex formation with HP-ß-CD and Me-ß-CD. In particular, the 1:2 M ratio complexes exhibited higher dissolution than the corresponding 1:1 M ratio complexes. The physicochemical characterization of the systems showed strong evidence of amorphous phases and/or of the formation of an inclusion complex. Stored at 25 °C, 60% RH for 24 months, drug complexed with ß-cyclodextrins (CDs) at 1:2 M ratio remained amorphous. Based on these findings, it is postulated that the formation of triclabendazole-CD inclusion complexes produced significant enhancement in both the dissolution and solid-state properties of the drug, which may lead to the development of triclabendazole novel formulations with improved biopharmaceutical characteristics.

First Development, Optimization, and Stability Control of a Pediatric Oral Atenolol Formulation.

Liquid formulations can be used in children of different ages by varying the volume of the administered dose in order to ensure an exact dosage. The aim of this work was to develop and to optimize a safe liquid atenolol formulation and to carry out the corresponding chemical and microbiological stability studies. A Plackett-Burman design was used to determine the factors that could be critical in the development of the formulations, and a central composite design was used to determine the optimal working conditions. As a result of these analyses, three formulations were selected and their stability studied in three storage conditions, 4, 25, and 40°C. After 6 months of stability testing, the optimal systems showed no pH change or atenolol loss; however, only glycerin-based formulations showed no microbial development. These systems, employing excipients in a range that the EMA has recommended, showed chemical and microbiological stability for at least 6 months even at the worst storage conditions.

Structural Elucidation of Poloxamer 237 and Poloxamer 237/Praziquantel Solid Dispersions: Impact of Poly(Vinylpyrrolidone) over Drug Recrystallization and Dissolution.

Praziquantel (PZQ) is the recommended, effective, and safe treatment against all forms of schistosomiasis. Solid dispersions (SDs) in water-soluble polymers have been reported to increase solubility and bioavailability of poorly water-soluble drugs like PZQ, generally due to the amorphous form stabilization. In this work, poloxamer (PLX) 237 and poly(vinylpyrrolidone) (PVP) K30 were evaluated as potential carriers to revert PZQ crystallization. Binary and ternary SDs were prepared by the solvent evaporation method. PZQ solubility increased similarly with PLX either as binary physical mixtures or SDs. Such unpredicted data correlated well with crystalline PZQ and PLX as detected by solid-state NMR (ssNMR) and differential scanning calorimetry in those samples. Ternary PVP/PLX/PZQ SDs showed both ssNMR broad and narrow superimposed signals, thus revealing the presence of amorphous and crystalline PZQ, respectively, and exhibited the highest PZQ dissolution efficiency (up to 82% at 180 min). SDs with PVP provided a promising way to enhance solubility and dissolution rate of PZQ since PLX alone did not prevent recrystallization of amorphous PZQ. Based on ssNMR data, novel evidences on PLX structure and molecular dynamics were also obtained. As shown for the first time using ssNMR, propylene glycol and ethylene glycol constitute the PLX amorphous and crystalline components, respectively.

Application of Fluorescence Emission for Characterization of Albendazole and Ricobendazole Micellar Systems: Elucidation of the Molecular Mechanism of Drug Solubilization Process.

Albendazole (ABZ) and ricobendazole (RBZ) are referred to as class II compounds in the Biopharmaceutical Classification System. These drugs exhibit poor solubility, which profoundly affects their oral bioavailability. Micellar systems are excellent pharmaceutical tools to enhance solubilization and absorption of poorly soluble compounds. Polysorbate 80 (P80), poloxamer 407 (P407), sodium cholate (Na-C), and sodium deoxycholate (Na-DC) have been selected as surfactants to study the solubilization process of these drugs. Fluorescence emission was applied in order to obtain surfactant/fluorophore (S/F) ratio, critical micellar concentration, protection efficiency of micelles, and thermodynamic parameters. Systems were characterized by their size and zeta potential. A blue shift from 350 to 345 nm was observed when ABZ was included in P80, Na-DC, and Na-C micelles, while RBZ showed a slight change in the fluorescence band. P80 showed a significant solubilization capacity: S/F values were 688 for ABZ at pH 4 and 656 for RBZ at pH 6. Additionally, P80 micellar systems presented the smallest size (10 nm) and their size was not affected by pH change. S/F ratio for bile salts was tenfold higher than for the other surfactants. Quenching plots were linear and their constant values (2.17/M for ABZ and 2.29/M for RBZ) decreased with the addition of the surfactants, indicating a protective effect of the micelles. Na-DC showed better protective efficacy for ABZ and RBZ than the other surfactants (constant values 0.54 and 1.57/M, respectively), showing the drug inclusion into the micelles. Entropic parameters were negative in agreement with micelle formation.