Preparation of a solid self-microemulsifying drug delivery system by hot-melt extrusion.

Hot-melt extrusion (HME) has gained increasing attention in the pharmaceutical industry; however, its potential in the preparation of solid self-emulsifying drug delivery systems (S-SMEDDS) is still unexplored. This study sought to prepare enteric S-SMEDDS by HME and evaluate the effects of the process and formulation variables on S-SMEDDS properties via Box-Behnken design. Liquid SMEDDS were developed, and carvedilol was used as a class II model drug. Mean size, polydispersity index (PdI) and zeta potential of the resulting microemulsions were determined. The extrudates were then obtained by blending the lipid mixture and HPMCAS using a twin-screw hot-melt extruder. SEM, optical microscopy and PXRD were used to characterize the extrudates. In vitro microemulsion reconstitution and drug release were also studied. L-SMEDDS gave rise to microemulsions with low mean size, PdI and zeta potential (140.04 ±â€¯7.22 nm, 0.219 ±â€¯0.011 and -9.77 ±â€¯0.86 mV). S-SMEDDS were successfully prepared by HME, and an HMPCAS matrix was able to avoid microemulsion reconstitution and retain drug release in pH 1.2 (12.97%-25.54%). Conversely, microemulsion reconstitution and drug release were gradual in pH 6.8 and complete for some formulations. Extrudates prepared at the lowest drug concentration and highest temperature and recirculation time promoted a complete and rapid drug release in pH 6.8 giving rise to small and uniform microemulsion droplets.

Comparison of Clobetasol Propionate Generics Using Simplified In vitro Bioequivalence Method for Topical Drug Products.

BACKGROUND: The aim of this paper is to evaluate a simple in vitro skin penetration experiment in which the drug is extracted from the whole skin piece as a test valid for formulation screening and optimization during development process, equivalence assessment during quality control or postapproval after changes to the product. METHODS: Twelve clobetasol propionate (CP) formulations (six creams and six ointments, being five generics and one reference from each formulation type) from the local market were used as a model to challenge the evaluated methodology in comparison to in vitro skin penetration following tape-stripping for drug extraction. To support the results, physicochemical tests for pH, viscosity, density and assay, as well as in vitro release were performed. RESULTS: Both protocols, extracting the drug from the skin using the tape-stripping technique or extracting from the full skin were capable of differentiating CP formulations. Only one formulation did not present statistical difference from the reference drug product in penetration tests and only other two oitments presented equivalent release to the reference. The protocol is straightforward and reproducible. CONCLUSION: Results suggest the bioinequavalence of tested CP formulations reinforcing the necessity of such evaluations.

Microparticles prepared with 50-190kDa chitosan as promising non-toxic carriers for pulmonary delivery of isoniazid.

Chitosan biocompatibility and mucoadhesiveness make it an ideal polymer for antituberculotic drugs microcapsulation for pulmonary delivery. Yet, previous study indicated toxicity problems to J-774.1-cells treated with some medium molecular weight (190-310kDa) chitosan microparticles. As polymer molecular weight is a crucial factor to be considered, this paper describes the preparation and characterization of chitosan (50-190kDa) microparticles containing isoniazid (INH). Cytotoxicity assays were also performed on murine peritoneal (J-774.1) and alveolar (AMJ2-C11) macrophages cell lines, followed by cytokines detection from AMJ2-C11 cells. Spray-drying process produced mucoadhesive microparticles from 3.2µm to 3.9µm, entrapping more than 89% of the drug and preserving their chemical stability. Drug release behavior could be controlled by the use of cross-linked or uncross-linked chitosan, the latter leading to a rapid drug release. Mucoadhesive potential of the microparticles was characterized following in vitro and ex vivo assays. Finally, a significant reduction on toxicity against peritoneal macrophages and no toxic effect on alveolar macrophages with use of such microparticles were observed. In conclusion, 50-190kDa chitosan microparticles may act as promising non-cytotoxic carriers for pulmonary delivery of INH showing marked alveoli macrophage activation.

Use of mixture design in drug-excipient compatibility determinations: Thymol nanoparticles case study.

The objective of this work was to access thymol-excipient compatibility using an alternative protocol of mixture design subsidizing the development of nanostructures lipid carriers containing this drug. Simultaneous DTA-TG analyses associated with infrared spectroscopy were performed according to simplex centroid mixture designs with three components. Two designs were used: the design A containing stearic acid (SA), soybean lecithin (LC), and sodium taurodeoxycholate (TAU) and the design B, where TAU was replaced by polysorbate 80 (P80). Assays allowed for a quantitative evaluation of thermal events involved with thymol (TML) - melting and evaporation -, as well as events related to excipients decomposition and overall system stability. Although the anionic surfactant TAU did not interact with TML in solid state, chemical and physical stability were compromised after drug melting. Alternatively, nonionic surfactant P80 could be a good excipient option, as TML formulation stability was not influenced by it. Fatty acid SA did not compromise TML stability alone, but, when in combination with other formulation components, negative interaction leading to a possible decomposition of the system was observed. Finally, phospholipid LC solubilizes TML extending its evaporation to higher temperatures; hence, drug stability may be increased. In conclusion, the use of mixture design in the evaluation of multicomponent systems is a valuable tool for identification of synergistic effects of excipients, providing more complete information on formulation development. In addition, the association of techniques employed allowed inferring with certainty if thermal interactions could compromise formulation stability.

Key Technical Aspects Influencing the Accuracy of Tablet Subdivision.

Tablet subdivision is a common practice used mainly for dose adjustment. The aim of this study was to investigate how the technical aspects of production as well as the method of tablets subdivision (employing a tablet splitter or a kitchen knife) influence the accuracy of this practice. Five drugs commonly used as subdivided tablets were selected. For each drug, the innovator drug product, a scored-generic and a non-scored generic were investigated totalizing fifteen drug products. Mechanical and physical tests, including image analysis, were performed. Additionally, comparisons were made between tablet subdivision method, score, shape, diluent composition and coating. Image analysis based on surface area was a useful tool as an alternative assay to evaluate the accuracy of tablet subdivision. The tablet splitter demonstrates an advantage relative to a knife as it showed better results in weight loss and friability tests. Oblong, coated and scored tablets had better results after subdivision than round, uncoated and non-scored tablets. The presence of elastic diluents such as starch and dibasic phosphate dehydrate conferred a more appropriate behaviour for the subdivision process than plastic materials such as microcrystalline cellulose and lactose. Finally, differences were observed between generics and their innovator products in all selected drugs with regard the quality control assays in divided tablet, which highlights the necessity of health regulations to consider subdivision performance at least in marketing authorization of generic products.

Solid effervescent formulations as new approach for topical minoxidil delivery.

Currently marketed minoxidil formulations present inconveniences that range from a grease hard aspect they leave on the hair to more serious adverse reactions as scalp dryness and irritation. In this paper we propose a novel approach for minoxidil sulphate (MXS) delivery based on a solid effervescent formulation. The aim was to investigate whether the particle mechanical movement triggered by effervescence would lead to higher follicle accumulation. Preformulation studies using thermal, spectroscopic and morphological analysis demonstrated the compatibility between effervescent salts and the drug. The effervescent formulation demonstrated a 2.7-fold increase on MXS accumulation into hair follicles casts compared to the MXS solution (22.0±9.7µg/cm2 versus 8.3±4.0µg/cm2) and a significant drug increase (around 4-fold) in remaining skin (97.1±29.2µg/cm2) compared to the drug solution (23.5±6.1µg/cm2). The effervescent formulations demonstrated a prominent increase of drug permeation highly dependent on the effervescent mixture concentration in the formulation, confirming the hypothesis of effervescent reaction favoring drug penetration. Clinically, therapy effectiveness could be improved, increasing the administration interval, hence, patient compliance. More studies to investigate the follicular targeting potential and safety of new formulations are needed.

Chromatographic method for clobetasol propionate determination in hair follicles and in different skin layers.

Clobetasol propionate (CLO) is a potent steroid used for the treatment of several dermatological diseases. Recent studies suggest its additional use in alopecia topical treatment, generating a demand for novel formulations with specific delivery into hair follicles. Hence, a selective analytical method for drug quantification in follicular structures and skin layers is required. For this, a simple HPLC-UV method was developed. Quantification was performed using a RP-C18 column (4.6 mm × 15 cm, 5 µm), with a mixture of methanol-acetonitrile-water (50:15:35 v/v) as mobile phase, a flow rate of 1.2 mL/min, oven temperature of 30°C, injection volume of 50 µL and detection at 240 nm. The optimized conditions enabled a 12 min running with CLO elution at 10.1 min and resolution of 2.424 from skin matrix interferences. Validation was performed in accordance with International Conference on Harmonization guidelines and fulfilled the criteria of selectivity, linearity (0.5-15.0 µg/mL), robustness, precision, accuracy and limits of detection and quantification (0.02 and 0.07 µg/mL, respectively). The validated method was successfully applied for CLO quantification following in vitro skin permeation experiments and differential tape-stripping for hair follicle deposition determination, demonstrating its suitability.

Preparation of benznidazole pellets for immediate drug delivery using the extrusion spheronization technique.

Recent advances in the treatment of Chagas disease have followed combinations of drugs that act synergistically against infection, predominantly including benznidazole (BNZ) and azoles derivatives. Possible incompatibilities between these drugs, slow dissolution of BNZ and dose adjustment difficulties are technological obstacles to the development of multidrug formulations. Thus, in the present study, BNZ pellets were developed using extrusion spheronization for immediate drug delivery. Preformulation studies were then performed using thermal analysis and infrared spectroscopy and compatibility between the drug and selected excipients (polyethylene glycol 6000, sodium starch glycolate, microcrystalline cellulose and sodium croscarmellose) was investigated. No chemical decomposition of BNZ was observed, even in samples submitted to wet granulation and thermal stress. Subsequently, formulations were elaborated according to a simplex lattice experimental design using polyethylene glycol, sodium starch glycolate and sodium croscarmellose as disintegrating agents. In these experiments, BNZ pellets showed appropriate physicochemical characteristics, including high drug load capacity and excellent flow properties. The mixture experimental design allowed identification of adequate compositions of disintegrating agents and achieved rapid disintegration and dissolution of pellets. Optimum performance was achieved using polyethylene glycol and sodium croscarmellose at 5.0% w/w each. The present BNZ pellets are versatile alternatives to treat Chagas disease and provide insights into the preparation of multidrug systems.

Development of carvedilol-cyclodextrin inclusion complexes using fluid-bed granulation: a novel solid-state complexation alternative with technological advantages.

OBJECTIVES: This study sought to evaluate the achievement of carvedilol (CARV) inclusion complexes with modified cyclodextrins (HPßCD and HPγCD) using fluid-bed granulation (FB). METHODS: The solid complexes were produced using FB and spray drying (SD) and were characterised by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction, SEM, flowability and particle size analyses and in vitro dissolution. KEY FINDINGS: The DSC, FTIR and powder X-ray diffraction findings suggested successful CARV inclusion in the modified ß- and γ-cyclodextrins, which was more evident in acidic media. The CARV dissolution rate was ~7-fold higher for complexes with both cyclodextrins prepared using SD than for raw CARV. Complexes prepared with HPßCD using FB also resulted in a significant improvement in dissolution rate (~5-fold) and presented superior flowability and larger particle size. CONCLUSIONS: The findings suggested that FB is the best alternative for large-scale production of solid dosage forms containing CARV. Additionally, the results suggest that HPγCD could be considered as another option for CARV complexation because of its excellent performance in inclusion complex formation in the solid state.

Development and validation of a selective HPLC-UV method for thymol determination in skin permeation experiments.

Thymol is a natural monoterpene, whose antioxidant and antimicrobial properties suggest a potential use in topical formulations. A simple, precise and selective HPLC method for thymol determination in skin penetration studies was developed and validated in this paper. Separation was achieved with a RP-C18 column, mobile phase comprised of acetonitrile:water (35:65v/v), flow rate of 1.5mL/min, oven temperature at 40°C, injection volume of 30µL and UV detection at 278nm. The validation procedure certified the method was selective for thymol determination even when extracted from skin matrix extracts. It was also linear in a range from 0.5 to 15.0µg/mL, robust, precise and accurate, with recovery rates from the skin layers higher than 90%. Limits of detection and quantification were 0.05 and 0.14µg/mL, respectively. The method showed, therefore, to be adequate for use in further skin permeation studies employing thymol topical formulations.

Simultaneous determination of benznidazole and itraconazole using spectrophotometry applied to the analysis of mixture: A tool for quality control in the development of formulations.

The aim of this work was the development of an analytical procedure using spectrophotometry for simultaneous determination of benznidazole (BNZ) and itraconazole (ITZ) in a medicine used for the treatment of Chagas disease. In order to achieve this goal, the analysis of mixtures was performed applying the Lambert-Beer law through the absorbances of BNZ and ITZ in the wavelengths 259 and 321 nm, respectively. Diverse tests were carried out for development and validation of the method, which proved to be selective, robust, linear, and precise. The lower limits of detection and quantification demonstrate its sensitivity to quantify small amounts of analytes, enabling its application for various analytical purposes, such as dissolution test and routine assays. In short, the quantification of BNZ and ITZ by analysis of mixtures had shown to be efficient and cost-effective alternative for determination of these drugs in a pharmaceutical dosage form.

Effect of storage conditions on the stability of ß-lapachone in solid state and in solution.

OBJECTIVES: In this work, the effects of several technological factors on the stability of ß-lapachone (ßLAP) in solution and in the solid state were investigated. METHODS: The effects of relative humidity and light on the stability of ßLAP in the solid state were studied. Samples were characterized by liquid chromatography, thermal analysis, X-ray powder diffraction and optical microscopy. In solution, the effects of light conditions and additives (cyclodextrins) were also evaluated. Molecular modelling was used to support the degradation mechanism involved. Additionally, the pH stability profile of ßLAP was established. KEY FINDINGS: The synergism of relative humidity and light promoted degradation of ßLAP in the solid state, with important consequences for the physical and chemical characteristics of the drug after storage. Random methyl-ß-cyclodextrin was able to protect the drug against the hydrolytic process in darkness. However, it accelerated the drug decomposition by photolysis in light conditions. According to the pH stability profile, ßLAP undergoes an alkaline hydrolysis, its maximum stability pH being over the range 2-4. CONCLUSIONS: These studies provide useful information regarding the optimal storage conditions and formulations of ßLAP.

Modulated dissolution rate from the inclusion complex of antichagasic benznidazole and cyclodextrin using hydrophilic polymer.

Benznidazole (BNZ) is the primary chemotherapeutic agent for treating Chagas' disease; however, its poor water solubility and irregular oral absorption lead to the treatment failure in the chronic phase. The aim of this work was to investigate the utility of the polymer hydroxypropyl methylcellulose (HPMC) in controlling the release of BNZ from solid inclusion complexes with cyclodextrin to overcome the problem of its bioavailability. Preliminary studies of solubility were conducted in solution using selected ß-cyclodextrin derivatives according to an experimental mixture design. The best cyclodextrin composition was used to produce solid-state systems by kneading in the presence or absence of HPMC. The formulations were characterized by different physico-chemical techniques, including the dissolution rate. Hydroxypropyl-ß-cyclodextrin (HPßCD) produced the greatest improvement in drug solubility and was selected for the development of solid systems. Assays confirmed the production of true inclusion complexes between BNZ and HPßCD. The dissolution rate of the BNZ-HPßCD system was markedly increased, while the presence of HPMC retarded drug release. An optimal formulation obtained by the combination of kneading systems developed in appropriate ratios could be a promising drug delivery system with a prolonged therapeutic effect coupled with more balanced bioavailability. The produced systems present interesting perspectives for Chagas' therapy.

Temperature-sensitive gels for intratumoral delivery of ß-lapachone: effect of cyclodextrins and ethanol.

This work evaluated the potential of Pluronics (varieties F127 and P123) in combination with solubilizing agents to be used as syringeable in situ gelling depots of intratumoral ß-lapachone (ßLAP). Pluronic dispersions prepared at various concentrations in the absence and the presence of ethanol and randomly methylated ß-cyclodextrin (RMßCD) were characterized regarding their rheological properties, drug solubilization capacity, and in vitro release. Pluronic F127 (18-23%) formulations combined high ability to solubilize ßLAP (enhancement solubility factor up to 50), adequate gel temperature range (over 25 °C), and gel strength at 37 °C enough to guarantee the permanence of the formulation in the administration site for a period of time. ßLAP release rate was finely tuned by the concentration of the polymer and the addition of RMßCD (diffusion coefficient ranging between 9 and 69 µg · cm(-2)). The ethanol increases ßLAP release rate but simultaneously led to weak gels. This paper shows that ßLAP formulations involving temperature-reversible Pluronic gels may be suitable for intratumoral drug delivery purposes.

Fast dissolving ß-lapachone particles and tablets: an approach using surface adsorption technique.

BACKGROUND: ß-lapachone (ßLAP) is obtained from natural resources with promising preliminary results against the etiologic agent of Chagas disease. ßLAP activity is associated with generation of free radical and inhibition of nucleic acids and protein synthesis leading an outstanding antichagasic action. Low water solubility and large therapeutic doses constitute the main problems to overcome in the development of dosage forms of this drug. OBJECTIVE: The purpose of the present research was to enhance the limited dissolution rate of ßLAP by promoting the spontaneous crystalline growth of ßLAP on the surface of an inert excipient. METHODS: Physicochemical characterization of the particles was carried out as well as the drug dissolution rate. Drug adsorbed particles were compared to the drug as supplied and its physical mixtures with the inner excipient. The utility of the ßLAP adsorbed particles in the development of tablets obtained by direct compression were also evaluated. RESULTS: Particles produced by spontaneous crystalline growth of ßLAP on microcrystalline cellulose (MCC) hydrophilic surface showed mean diameters between 55-65 µm and fast drug dissolution rate (90% drug dissolved at 50 min). Neither physical nor chemical instability of the drug were detected after the drug adsorption procedure. The compression process does not extensively deteriorate the dissolution behaviour of the systems when an adequate compression pressure is used. CONCLUSIONS: Surface adsorption technique offers a simple way to produce ßLAP powder and tablets with improved dissolution rate for oral administration.

Light effect on the stability of ß-lapachone in solution: pathways and kinetics of degradation.

OBJECTIVES: The purpose of this work was to study the chemical stability of the new antitumoral ß-lapachone (ßLAP) to determine the degradation pathway/s of the molecule and the degradation kinetics in addition to identifying several degradation products. METHOD: Samples of ßLAP in solution were stored under conditions of darkness and illumination at 40°C at which the pseudo-first order rate constants for the ßLAP degradation were determined. Furthermore, drug degraded solutions were concentrated and purified using Sephadex LH-20 and preparative thin-layer chromatography and degradation products were identified by nuclear magnetic resonance spectroscopy. KEY FINDINGS: The results revealed that ßLAP shows two different degradation routes: hydrolysis in the dark and photolysis under the light. The ßLAP exposure to light accelerated the drug degradation about 140 fold, compared with the samples stored in the absence of light. The hydrolysis produced hydroxylapachol as the main degradation product. The photolysis yielded phthalic acid, 6-hydroxy-3methylene-3H-isobenzofuran-1-one and a benzomacrolactone together with a complex mixture of other phthalate-derivatives such as 2-(2-carboxy-acetyl)-benzoic acid. CONCLUSIONS: This study provides useful information for the development of ßLAP dosage forms, their storage, manipulation and quality control.

Co-processed extracts of Cassia angustifolia Vahl, Fabaceae, and Maytenus ilicifolia (Schrad.) Planch., Celastraceae, for production of high load tablets

The aim of this study was to investigate the feasibility of a co-processing technique for improving the manufacturing properties of Maytenus ilicifolia (Schrad.) Planch., Celastraceae, and Cassia angustifolia Vahl, Fabaceae, extracts in order to obtain tablets containing a high dose of such extracts. An experimental mixture design was used to optimise the formulation composition. Flowability parameters, such as compressibility index, time flow and angle of repose, were determined. Additional important industrial parameters, such as granulometry, bulk density and moisture stability, were also studied. The results demonstrated that co-processing technique was able to improve the flowability of vegetal extracts, making these materials suitable for a direct compression process. The contour plots revealed that formulations with a higher amount of lactose produced the best flow results as well as a larger particle size and a greater bulk density. Tablets from co-processed extracts containing lactose as majority diluent showed appropriate physical-chemical characteristics and presented a more stable moisture sorption behaviour compared to commercial gelatine capsules.

Development of effervescent tablets containing benzonidazole complexed with cyclodextrin.

OBJECTIVES: Benznidazole (BNZ), the primary chemotherapy agent used to treat Chagas disease, has poor aqueous solubility, which results in low bioavailability. The purpose of this work was to develop stable effervescent tablets using an inclusion complex of BNZ with cyclodextrin (CD). METHOD: In the first phase, different CDs were evaluated according to their ability to improve the aqueous solubility of BNZ. Then, inclusion complexes of BNZ in the solid state were produced by the kneading method and the complexes were evaluated using several physical-chemical assays. Finally, effervescent tablets were prepared according to a complete 3(2) factorial design. The effects of the concentration of CD and effervescent mixture on the dissolution rate and physical stability of tablets were evaluated. KEY FINDINGS: Hydroxypropyl-ß-cyclodextrin produced the greatest improvement in the aqueous solubility of BNZ, almost 20-times greater than the water system. Solid systems produced with BNZ and CD showed physical-chemical interactions and increased the drug dissolution rate, suggesting the formation of a true solid inclusion complex. Moreover, the effervescent matrix of the tablets was effective in improving the dissolution behaviour of BNZ complexed with CD. CONCLUSIONS: Effervescent tablets produced using an inclusion complex of BNZ with CD suggest a possible improvement in the bioavailability of BNZ, and this could represent a relevant advance in Chagas therapy.

Benznidazole microcrystal preparation by solvent change precipitation and in vivo evaluation in the treatment of Chagas disease.

Benznidazole (BNZ) is traditionally used to treat Chagas disease. Despite its common use, BNZ has a poor water solubility and a variable bioavailability. The purpose of this study was to prepare BNZ microcrystals by solvent change precipitation and to study the effects of BNZ micronisation on therapeutic efficiency using a murine model of Chagas disease. The solvent change precipitation procedure was optimised in order to obtain stable and homogeneous particles with a small particle size, high yield and fast dissolution rate. The thermal and crystallographic analysis showed no polymorphic change in the microcrystals, and microscopy confirmed a significant reduction in particle size. A marked improvement in the drug dissolution rate was observed for micronised BNZ particles and BNZ tablets in comparison with untreated BNZ and commercial Rochagan. In vivo studies showed a significant increase in the therapeutic efficacy of the BNZ microparticles, corroborating the dissolution results.

Dissolution rate enhancement of the novel antitumoral beta-lapachone by solvent change precipitation of microparticles.

beta-Lapachone [betaLAP] is a novel antitumor drug, which was recently on clinical trials with promising preliminary results. Problems derived from its low water solubility, its instability in solution and its high therapeutic dose constitute some challenges for pharmaceutical researchers. The purpose of the present work is to enhance the limited dissolution rate of betaLAP by the design of particles using a solvent change precipitation process. The procedure induces the spontaneous crystalline growth of the betaLAP in the presence of a stabilizing polymer (Hydroxypropylmethylcellulose) that limits the size of the particles generated. Physicochemical characterization of microparticles and the betaLAP dissolution rate was carried out. The utility of the betaLAP microcrystals in the development of tablets with adequate dissolution properties was also stated. The procedure was optimized in order to obtain stable and homogeneous particles with a small mean particle size (approximately 3 microm) and a narrow particle size distribution. There were no differences between the drying methods evaluated (in an oven and freeze-drying) with regard to particle morphology or dissolution behaviour, which is almost instantaneous. Tablets having suitable mechanical properties were produced by dry granulation prior to compression. The compression process did not compromise betaLAP dissolution characteristics.