Enhancement of dissolution rate through eutectic mixture and solid solution of posaconazole and benznidazole

An empirical predictive model for determining the aqueous solubility of BCS class IV drugs in amorphous solid dispersions

CONTEXT

Determining solubility of drugs is laborious and time-consuming process that may not yield meaningful results. Amorphous solid dispersion (ASD) is a widely used solubility enhancement technique. Predictive models could streamline this process and accelerate the development of oral drugs with improved aqueous solubilities.

OBJECTIVE

This study aimed to develop a predictive model to estimate the solubility of a compound from the ASDs in polymer matrices.

METHODS

ASDs of model drugs (acetazolamide, chlorothiazide, furosemide, hydrochlorothiazide, sulfamethoxazole) with model polymers (PVP, PVPVA, HPMC E5, Soluplus) and a surfactant (TPGS) were prepared using hotmelt process. The prepared ASDs were characterized using DSC, FTIR, and XRD. The aqueous solubility of the model drugs was determined using shake-flask method. Multiple linear regression was used to develop a predictive model to determine aqueous solubility using the molecular descriptors of the drug and polymer as predictor variables. The model was validated using Leave-One-Out Cross-Validation.

RESULTS

The ASDs' drug components were identified as amorphous via DSC and XRD Studies. There were no significant chemical interactions between the model drugs and the polymers based on FTIR studies. The ASDs showed a significant (p < 0.05) improvement in solubility, ranging from a 3-fold to 118-fold, compared with the pure drug. The developed empirical model predicted the solubility of the model drugs from the ASDs containing model polymer matrices with an accuracy greater than 80%.

CONCLUSION

The developed empirical model demonstrated robustness and predicted the aqueous solubility of model drugs from the ASDs of model polymer matrices with an accuracy greater than 80%.

Two into one does go: Formulation development of a multipurpose combination vaginal ring releasing dapivirine and metronidazole for prevention of HIV infection and treatment of bacterial vaginosis

Bacterial vaginosis (BV) is a common but often asymptomatic dysbiosis of the human vagina characterized by an imbalance in the normal vaginal microbiota due to loss of lactobacilli and an overgrowth of certain anaerobic bacteria. While BV itself is not a sexually transmitted infection, it is associated with an increased risk in women of various sexually acquired infections, including human immunodeficiency virus (HIV) infection. There is, therefore, a strong rationale for pursuing new multipurpose products that seek to treat or prevent BV alongside preventing HIV infection. With the dapivirine-releasing vaginal ring for HIV prevention now approved in several African countries, here we report formulation development of a next-generation ring product that releases both dapivirine (DPV) and the antibiotic drug metronidazole (MET). Following thermal analysis studies to characterize the phase behaviour of DPV-MET mixtures and rheological analysis to assess the cure characteristics of the active silicone elastomer mixes, matrix-type rings were manufactured containing 25 or 200 mg DPV in combination with 100, 250, 500, 1000 or 2000 mg MET. The results for drug content, in vitro release, mechanical testing, and Gardnerella vaginalis time-kill experiments demonstrate the feasibility of incorporating both DPV and MET in a matrix-type ring formulation and indicate that clinically effective release rates may be possible.

Eutectic phase transition during tablet manufacture: effect of melting point of eutectic forming drug

The aim was to investigate eutectic transition during tableting and storage. Mixtures of lidocaine and series of NSAIDs with increasing melting point were used as model systems to guide formulators to scaleup eutectic forming materials gaining enhanced dissolution while avoiding deleterious physical changes. Physical mixtures of NSAIDs with lidocaine were prepared at eutectic forming ratio. These were directly compressed, dry co-ground before compression, or compressed after wet granulation. Dissolution of tablets was compared to corresponding dry co-ground mixture. Thermograms of direct compressed tablet were compared to co-ground mixture and pure compound. Stability of direct compressed tablets was assessed. Tableting initiated eutexia which enhanced dissolution of NSAIDs. Eutexia was associated with tablet softening in case of low melting point ketoprofen and aceclofenac. Wet granulation hastened eutexia developing unacceptable tablet in case ketoprofen and aceclofenac. Tablets prepared by direct compression of physical mixtures underwent gradual eutectic transition upon storage with the magnitude of eutectic transition reducing with increased melting point of NSAIDs. Ketoprofen was physically unstable but aceclofenac degraded chemically as well. Tenoxicam and meloxicam tablets were physically and chemically stable. Direct compression after physical mixing is the best tableting technique, but low melting point drugs should consider different strategy before compression.

Amorphous solid dispersions in high-swelling, low-substituted hydroxypropyl cellulose for enhancing the delivery of poorly soluble drugs

Amorphous solid dispersions (ASDs) based on water-insoluble hydrophilic polymers can sustain supersaturation in their kinetic solubility profiles (KSPs) compared to soluble carriers. However, in the limit of very high swelling capacity, the achievable extent of drug supersaturation has not been fully examined. This study explores the limiting supersaturation behavior of ASDs of poorly soluble indomethacin (IND) and posaconazole (PCZ) based on a high-swelling excipient, low-substituted hydroxypropyl cellulose (L-HPC). Using IND as a reference, we showed that the rapid initial supersaturation buildup in the KSP of IND ASD can be simulated through sequential IND infusion steps, however at large times the KSP of IND release from ASD appears more sustained than direct IND infusion. This has been attributed to potential trapping of seed crystals generated in the L-HPC gel matrix thus limiting their growth and rate of desupersaturation. Similar result is also expected in PCZ ASD. Furthermore, the current drug loading process for ASD preparation resulted in the agglomeration of L-HPC based ASD particles, producing granules of up to 300-500µm (cf. 20µm individual particle), with distinct kinetic solubility profiles. This feature makes L-HPC particularly suitable as ASD carriers for fine tuning of supersaturation to achieve enhanced bioavailability for poorly soluble drugs.

Melting point depression for enhanced dissolution rate of eslicarbazepine acetate

BACKGROUND

Eslicarbazepine acetate (ESL) is antiepileptic agent which is approved for use as single therapy or in combination with other drugs. However, it suffers from poor oral bioavailability. Modulation of drug crystallinity can be utilized as an approach for enhancing drug dissolution.

OBJECTIVE

Accordingly, the aim of this study was to investigate possible eutectic system formation between eslicarbazepine with either tartaric acid or citric acid.

METHODOLOGY

Eslicarbazepine acetate was subjected to wet co-grinding with tartaric acid or citric acid at different molar ratios. The prepared formulations were assessed using Fourier-transform infrared (FTIR), X-ray powder diffraction (XRPD), differential scanning calorimetry in addition to dissolution studies.

RESULTS

The characterization techniques confirmed eutectic system formation with tartaric and citric acid with the optimum molar ratio for eutexia being 1:1 for both substances. Development of eutectic systems significantly enhanced the dissolution rate of ESL. Increasing the ratio of tartaric acid higher than the optimum ratio for eutexia resulted in additional increase in drug dissolution rate. This suggested the impact of pH modification on drug dissolution rate. The enhanced dissolution rate in case of the formulations containing ESL and citric acid was accredited to combined effect of eutaxia and pH modulation. These explanations were proven from investigating the dissolution rate of the physical mixtures which were inferior in their dissolution rate compared with the prepared formulations.

CONCLUSION

co-processing of ESL with either citric acid or tartaric acid resulted in hastened dissolution rate which was accredited to combined effect of eutexia with pH modification.

A co-crystal berberine-ibuprofen improves obesity by inhibiting the protein kinases TBK1 and IKKɛ

Berberine (BBR) exerts specific therapeutic effects on various diseases such as diabetes, obesity, and other inflammation-associated diseases. However, the low oral bioavailability (below 1%) of berberine due to its poor solubility and membrane permeability limits its clinical use. In this paper, we have prepared a 1:1 co-crystal berberine-ibuprofen (BJ) using drug salt metathesis and co-crystal technology. Pharmacokinetic studies demonstrate a 3-fold increase in vivo bioavailability of BJ compared to that of BBR, and BJ is more effective in treating obesity and its related metabolism in vitro and in vivo. We also find that BJ promotes mitochondrial biogenesis by inhibiting TBK1 and inducing AMP-activated protein kinase (AMPK) phosphorylation, and BJ increases adipocyte sensitivity to catecholamine by inhibiting IKKε. Together, our findings support that co-crystal BJ is likely to be an effective agent for treating obesity and its related metabolic diseases targeting TBK1 and IKKε.

Eutectic Formation of Naproxen with Some Dicarboxylic Acids

Eutectic formation with additives is one of the established methods to improve the dissolution behaviors of active pharmaceutic ingredients (APIs). The improvement is mainly due to the increase in the surface area for dissolution, which originates from the finely divided micro-domains generated through the phase separation of the miscible liquid components upon solidification. The present study is to identify eutectic-forming additives for naproxen (NPX), a class II API of the biopharmaceutical classification system. A particular aim was to develop a eutectic mixture with NPX at least over 20 wt%, a minimum to be practical for oral delivery. Screening based on the proximity of the solubility parameter values identified dicarboxylic acids (succinic acid, glutaric acid, and suberic acid) as desirable additives for NPX. Binary melting diagrams were constructed to confirm the eutectic compositions, and the eutectic mixture with suberic acid (NPX 55 wt%) was further investigated. The dissolution (at pH 5.0) of the melt crystallized eutectics was enhanced compared to the simple physical mixture of the same compositions and neat NPX, which was attributed to the microscopically observed lamellar structures. The current study should support the systematic investigations of API eutectic mixtures by selecting appropriate eutectic-forming additives.

Synthesis, Characterization, and Intrinsic Dissolution Studies of Drug-Drug Eutectic Solid Forms of Metformin Hydrochloride and Thiazide Diuretics

The mechanochemical synthesis of drug–drug solid forms containing metformin hydrochloride (MET·HCl) and thiazide diuretics hydrochlorothiazide (HTZ) or chlorothiazide (CTZ) is reported. Characterization of these new systems indicates formation of binary eutectic conglomerates, i.e., drug–drug eutectic solids (DDESs). Further analysis by construction of binary diagrams (DSC screening) exhibited the characteristic V-shaped form indicating formation of DDESs in both cases. These new DDESs were further characterized by different techniques, including thermal analysis (DSC), solid state NMR spectroscopy (SSNMR), powder X-ray diffraction (PXRD) and scanning electron microscopy–energy dispersive X-ray spectroscopy analysis (SEM–EDS). In addition, intrinsic dissolution rate experiments and solubility assays were performed. In the case of MET·HCl-HTZ (χ_MET·HCl = 0.66), we observed a slight enhancement in the dissolution properties compared with pure HTZ (1.21-fold). The same analysis for the solid forms of MET·HCl-CTZ (χ_MET·HCl = 0.33 and 0.5) showed an enhancement in the dissolved amount of CTZ accompanied by a slight improvement in solubility. From these dissolution profiles and saturation solubility studies and by comparing the thermodynamic parameters (ΔH_fus and ΔS_fus) of the pure drugs with these new solid forms, it can be observed that there was a limited modification in these properties, not modifying the free energy of the solution (ΔG) and thus not allowing an improvement in the dissolution and solubility properties of these solid forms.

Ternary Eutectic Ezetimibe-Simvastatin-Fenofibrate System and the Physical Stability of Its Amorphous Form

In this study, the phase diagram of the ternary system of ezetimibe–simvastatin–fenofibrate was established. It has been proven that the ternary composition recommended for the treatment of mixed hyperlipidemia forms a eutectic system. Since eutectic mixtures are characterized by greater solubility and dissolution rate, the obtained result can explain the marvelous medical effectiveness of combined therapy. Considering that another well-known method for improving the aqueous solubility is amorphization, the ternary system with eutectic concentration was converted into an amorphous form. Thermal properties, molecular dynamics, and physical stability of the obtained amorphous system were thoroughly investigated through various experimental techniques compared to both: neat amorphous active pharmaceutical ingredients (considered separately) and other representative concentrations of ternary mixture. The obtained results open up a new way of selecting the therapeutic concentrations for combined therapies, a path that considers one additional variable: eutecticity.

Novel amorphous solid dispersion based on natural deep eutectic solvent for enhancing delivery of anti-tumor RA-XII by oral administration in rats

At present, oral chemotherapy showing the advantages of non-invasiveness, convenience, and high patient compliance, is gradually replacing traditional intravenous chemotherapy to treat patients with cancer. RA-XII, a unique natural cyclopeptide, exhibits various biological activities, such as anti-tumor, anti-angiogenic, and anti-metastatic activities. Designing an orally available formulation of RA-XII is of great importance in the development of clinically useful anticancer agents. However, RA-XII shows low oral bioavailability in rats due to its poor solubility and low permeability. To overcome these limitations, in this work, a natural deep eutectic solvent (NADES) was designed to efficiently deliver RA-XII by oral administration. A novel NADES composed of betaine and mandelic acid in the molar ratio of 1:1 (Bet-Man NADES) was successfully prepared based on a binary phase diagram of Bet and Man. Acute toxicity studies indicated that Bet-Man NADES was well tolerated with acceptable toxicity. In Bet-Man NADES solutions, the solubility of RA-XII was increased by up to 17.54-fold, and the diffusion and permeability of RA-XII carried out in a Franz cell was also significantly improved 10.35 times. In terms of biopharmaceutical classification this is translated into a change for RA-XII from class IV to class II systems. More importantly, Bet-Man NADES was transferred into the solid formulation by the inclusion of a polymer, and amorphous solid dispersions based on Bet-Man NADES (PVP K30/NADES/RA-XII, ASDs) were successfully prepared to improve uniformity, apparent solubility, dissolution, and cytotoxicity in vitro. Consequently, the oral bioavailability of RA-XII in NADES solutions and ASDs was enhanced by approximately 11.58 and 7.56 times compared with that of pure RA-XII in 0.5% CMCNa. Thus, it can be seen that a natural deep eutectic solvent and its modified amorphous solid dispersions are appropriate novel strategies for improving dissolution rate and bioavailability of poor soluble natural products such as RA-XII.

Characterisation and fundamental insight into the formation of new solid state, multicomponent systems of propranolol

The physiochemical properties of acidic or basic active pharmaceutical ingredients (APIs) can be optimised by forming salts with different counterions. The aim of this work was to synthesise a novel salt of propranolol (PRO) using sebacic acid (SEBA) as the counterion and to gain mechanistic understanding of not only the salt formation, but also its eutectic phase formation with SEBA. Thermal analysis showed a solid-state reaction occurring between PRO and SEBA leading to the formation of dipropranolol sebacate (DPS) melting at app. 170 °C and the eutectic composed of DPS and SEBA melting at app. 103 °C, comprising 0.33 mol fraction of PRO as determined by the Tammann plot. X-ray diffraction and Fourier-transform infrared spectroscopy (FTIR) confirmed the identity of the new multicomponent phases of PRO. DPS can be conveniently obtained by heat-induced crystallisation, grinding and conventional solvent crystallisation. Detailed analysis by FTIR revealed H-bond interactions between DPS and SEBA at the inter-phase in the eutectic. Bravais, Friedel, Donnay and Harker crystal morphology coupled with full interaction maps analysis allowed to understand further the nature of interactions which led to formation of the eutectic phase. This work contributes to furthering research on multicomponent pharmaceutical systems to harness their full potential.

Mechanochemistry: A Green Approach in the Preparation of Pharmaceutical Cocrystals

Mechanochemistry is considered an alternative attractive greener approach to prepare diverse molecular compounds and has become an important synthetic tool in different fields (e.g., physics, chemistry, and material science) since is considered an ecofriendly procedure that can be carried out under solvent free conditions or in the presence of minimal quantities of solvent (catalytic amounts). Being able to substitute, in many cases, classical solution reactions often requiring significant amounts of solvents. These sustainable methods have had an enormous impact on a great variety of chemistry fields, including catalysis, organic synthesis, metal complexes formation, preparation of multicomponent pharmaceutical solid forms, etc. In this sense, we are interested in highlighting the advantages of mechanochemical methods on the obtaining of pharmaceutical cocrystals. Hence, in this review, we describe and discuss the relevance of mechanochemical procedures in the formation of multicomponent solid forms focusing on pharmaceutical cocrystals. Additionally, at the end of this paper, we collect a chronological survey of the most representative scientific papers reporting the mechanochemical synthesis of cocrystals.

Enhanced Dissolution of Naproxen by Combining Cocrystallization and Eutectic Formation

Improving dissolution properties of active pharmaceutical ingredients (APIs) is a critical step in drug development with the increasing occurrence of sparingly soluble APIs. Cocrystal formation is one of the methods to alter the physicochemical properties of APIs, but its dissolution behavior in biorelevant media has been scrutinized only in recent years. We investigated the combined strategy of cocrystallization and eutectic formation in this regard and utilized the cocrystal model system of naproxen and three pyridinecarboxamide isomers. Binary melting diagrams were constructed to discover the eutectic compositions of the three cocrystals with excess amounts of pyridinecarboxamides. The melt-crystallized eutectics and cocrystals were compared in their dissolution behaviors with respect to neat naproxen. The eutectics enhanced the early dissolution rates of the cocrystals in both the absence and presence of biologically relevant bile salt and phospholipid components, whereas the cocrystal dissolution was expedited and delayed, respectively. The combined strategy in the present study will be advantageous in maximizing the utility of the pharmaceutical cocrystals.

Multicomponent crystalline solid forms of aripiprazole produced via hot melt extrusion techniques: An exploratory study

Multicomponent crystalline solid forms (salts, cocrystals and eutectics) are a promising means of enhancing the dissolution behavior of poorly soluble drugs. The present study demonstrates the development of multicomponent solid forms of aripiprazole (ARP) prepared with succinic acid (SA) and nicotinamide (NA) as coformers using the hot melt extrusion (HME) technique. The HME-processed samples were characterized and analyzed using differential scanning calorimetry (DSC), hot stage microscopy (HSM), Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The DSC and HSM analyses revealed a characteristic single melting temperature in the solid forms, which differed from the melting points of the individual components. The discernible changes in the FTIR (amide C=O stretching) and PXRD results for ARP-SA confirm the formation of new crystalline solid forms. In the case of ARP-NA, these changes were less prominent, without the appearance or disappearance of peaks, suggesting no change in the crystal lattice. The SEM images demonstrated morphological differences between the HME-processed samples and the individual parent components. The in vitro dissolution and microenvironment pH measurement studies revealed that ARP-SA showed a higher dissolution rate, which could be due to the acidic microenvironment pH imparted by the coformer. The observations of the present study demonstrate the applicability of the HME technique for the development of ARP multicomponent solid forms.

Emerging Multi-Drug Eutectics: Opportunities and Challenges

Complexity and heterogeneous nature of most diseases have posed greater challenges in the modern healthcare system. Fixed-dose combination can offer an ideal way to improve patient compliance and higher therapeutic efficacy. However, biopharmaceutical issues associated with the drug combinations remain unaddressed. Multidrug eutectics (MDE) have demonstrated significant promise in improving the biopharmaceutical attributes with synergistic therapeutic action. Eutectic mixtures are the multicomponent solid forms that possess lesser melting point than the individual components at a fixed composition. Non-covalent linking of drug combinations as MDE is an innovative strategy with enhanced solubility, dissolution, and mechanical and potential therapeutic efficacy. This review provides a comprehensive overview of the design of MDE, rational selection of drugs, characterization tools, and their therapeutic potential. Besides, the futuristic perspective where MDE could make a significant impact on combination therapy is briefly outlined. Graphical Abstract.

Microfluidics-enabled particle engineering of monodisperse solid lipid microparticles with uniform drug loading and diverse solid-state outcomes

Lipids serve as excellent excipients for drug products. Solid lipid microparticles (SLMs) are relatively underexplored in drug delivery; these particles are conventionally prepared using processes yielding polydisperse size distributions, such as spray congealing or emulsification. In this paper, we demonstrate a microfluidics-enabled process for particle engineering of monodisperse solid lipid microparticles with size and content uniformity. To overcome low solubility, we use a volatile solvent to increase drug loading, making the drug-lipid solution a single phase, enabling identical drug loading across particles. We use microfluidic flow extrusion of the solution to generate uniform drug-loaded SLMs, substantially enhancing monodispersity. This method generalises across three drugs-ibuprofen, 5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile (ROY), and naproxen, and two lipids-beeswax and hard fat (Suppocire NAI 25A), forming particles of various solid states: amorphous naproxen in crystalline lipids, crystalline ROY in crystalline lipids, and a eutectic mixture of ibuprofen-hard fat. In vitro dissolution studies on the ibuprofen-hard fat SLMs reveal gradual release, fitting the Higuchi model with 50-65% drug released over 72 h. This work expands the drug particle engineering toolbox to enable the formulation of SLMs with high precision in particle size and drug loading. Moreover, the diverse solid-state outcomes enabled by our method makes it applicable to various drugs having different formulation requirements (crystalline/amorphous).

Investigating Cocrystallization of Carbamazepine with Structurally Compatible Coformers: New Cocrystal and Eutectic Phases with Enhanced Dissolution

In this work, carbamazepine (CBZ), an anticonvulsant drug was cocrystallized with several structurally complement coformers (coformers with amide, acid and hydrazide functional groups) to enhance its dissolution. CBZ formed a cocrystal phase with acetamide (ACE) when mixtures of CBZ and ACE (containing CBZ mole fractions, X_CBZ of 0.25, 0.33, 0.5, and 0.67) were subjected to solid-state grinding (SSG), evaporative crystallization (EC), slurry conversion (SC), and slow cooling crystallization (SLC). Upon heating, the CBZ-ACE cocrystal phase formed from CBZ-ACE mixtures containing X_CBZ of 0.25, 0.33 and 0.67 underwent solid-state phase transition to CBZ form I and CBZ cocrytsal phase obtained from the CBZ-ACE mixture containing X_CBZ of 0.5 converted to CBZ form III. Interestingly, slow cooling cocrystallization experiments resulted in crystallization of a cocrystal as well as the CBZ dihydrate forms. The powder dissolution studies demonstrated that among the different CBZ-ACE-SSG cocrystal phases, CBZ-ACE-SSG-X_CBZ-0.33 cocrystal exhibited 7.47 times improved dissolution whereas the CBZ eutectic phase with nicotinic acid hydrazide (NAH) exhibited 4.93 times increased dissolution when compared to raw CBZ.

Solubility improvement of curcumin with amino acids

Eutectic, co-amorphous, cocrystal, and physical mixtures of curcumin with basic amino acids are prepared and characterized by PXRD, DSC, NMR, FT-IR, and SEM; solubility and dissolution improvement achieved in 40% ethanol–water system.

A Novel Eutectic-Based Transdermal Delivery System for Risperidone

This paper reports for the first time the possible formation of a novel room temperature therapeutic deep eutectic solvent (THEDES) of risperidone (RIS) with some fatty acids, namely capric acid (C10; CA), lauric acid (C12; LA), and myristic acid (C14; MA). All mixtures of RIS and MA yielded a solid or pasty-like solid and were readily discarded. Some of the prepared THEDESs from RIS and CA or LA have spontaneously transformed into a transparent liquid, without any precipitate at room temperature by simple physical mixing of the components. From the DSC thermograms, phase diagrams of the eutectic systems were constructed and the lowest obtained melting point for a RIS:CA mixture was 17°C at 40:60% w/w ratio. While 22°C was recorded as the lowest melting point for RIS:LA at a ratio of 30:70% w/w, solubility improvement of RIS was up to 70,000-fold compared with water. Freeze-drying microscopy provided valuable information regarding the phase change and transitions the drug undergoes as a function of temperature and it clarifies the interpretation of the DSC results and provides valuable evidence of drug crystals co-melting within the fatty acid base. The presence of natural fatty acid as one component of THEDES and the depression in the melting point significantly (P < 0.05) enhanced RIS skin permeation. Rheological studies showed a viscosity temperature dependency of the DES and well fitted to the Arrhenius equation. Application of the obtained THEDES on the shaved skin of rats revealed the absence of any irritation or edema effects.

Eutectic mixtures as an approach to enhance solubility, dissolution rate and oral bioavailability of poorly water-soluble drugs

Eutectic mixtures have been known for a long time in the pharmaceutical field. However, its potential as a system to improve the solubility and dissolution of poorly water-soluble drugs remains little explored. Studies involving the microstructural characterization and the preparation of solid dosage forms containing eutectic mixtures are also an issue to be developed. Recently, the number of studies involving the preparation of eutectic mixtures to improve the solubility and oral bioavailability of poorly soluble drugs has increased considerably, including drug-carrier and drug-drug mixtures. In this review is discussed the potential of eutectic mixtures as an alternative pharmaceutical solid system to enhance drugs solubility, dissolution rate or oral bioavailability. Different aspects like history, physico-chemical, microstructural properties, preparation methods, mechanisms involved in solubility/dissolution enhancement, techniques for solid state characterization, in vivo studies, advantages, limitations and formulation perspective are also discussed.

Synthesis and characterization of meloxicam eutectics with mandelic acid and saccharin for enhanced solubility

Meloxicam (MLX) is a non-steroidal anti-inflammatory which is practically insoluble in water, requiring high concentrations to reach therapeutic levels and causing frequently gastrointestinal effects. In this way, the aim of this study was to synthesize two eutectic mixtures of MLX with mandelic acid (MND) and saccharin (SAC) by liquid-assisted grinding resulting in a multicomponent material with enhanced solubility. Mixtures were studied in different stoichiometric and eutectic point was found for each eutectic by Binary phase diagram and Tamman's triangle, with 0.33 molar fraction of MLX for SAC and MND. Eutectics were characterized by thermoanalytical techniques (TG-DSC, EGA, DSC, and DSC microscopy), infrared spectroscopy, and X-ray powder diffraction. Thermal behavior was studied and videos of the materials being heated were available. A polymorphic transition was discovered and studied for MLX-MND eutectic. Each new system was evaluated by solubility, dissolution, and hygroscopicity tests. Eutectics showed an increase in solubility of 1.7× (MLX-MND1), 3.1× (MLX-MND2), and 1.3× (MLX-SAC) with slower dissolution profile when compared with MLX. All new solid forms showed high hygroscopicity at 98% relative humidity with 27.9 and 58.9% increase in mass at day four for MLX-SAC and MLX-MND, deliquescence occurs at day 6. The experiments and analysis in this study help to understand the behavior of eutectics and evaluate them as an approach to modify properties in drugs.

Eutectics and Salt of Dapsone With Hydroxybenzoic Acids: Binary Phase Diagrams, Characterization and Evaluation

Poor solubility and low dissolution rate of pharmaceuticals in many cases largely limit their bioavailability and efficacy. One of the promising approaches to improve dissolution behavior is to develop new multicomponent solid forms. Herein we use this strategy to synthesize new multicomponent solids of dapsone (DAP), which belongs to BCS class IV, with a series of hydroxybenzoic acid coformers. A new salt of DAP with 2,6-dihydroxybenzoic acid (26DHBA) and 4 eutectics with other hydroxybenzoic acids were reported through comprehensive characterizations using powder X-ray diffraction DSC, and vibrational spectroscopy techniques. The salt formation was evidenced by the presence of ionic interactions detected using FT-IR and Raman spectroscopy, and the stoichiometric ratio was determined to be 1:1. Binary phase diagrams were established to determine the composition of eutectics. The cause for salt and eutectic selection was further understood by computing molecular electrostatic potential (MEP) surface where 26DHBA shows the greatest acidity. Moreover, the powder dissolution study and microenvironment pH measurement reveal that both salt and eutectics of DAP display improvements on the dissolution rate and equilibrium concentration in which the acidity of coformers plays a dominant role. Our findings provide a direction for future coformer screening of multicomponent solids with improved pharmaceutical properties.

Characterization and therapeutic efficacy evaluation of glimepiride and L-arginine co-amorphous formulation prepared by supercritical antisolvent process: Influence of molar ratio and preparation methods

The glimepiride/L-arginine (GA) binary systems were prepared at various molar ratios by using a supercritical antisolvent (SAS) process. For comparison, the GA system was also prepared by physical mixing (PM), melt quenching (MQ), and solvent evaporation (SE) methods. Analyses by DSC and PXRD showed that only the GA binary mixture at 1:1 M ratio prepared by the SAS process was a pure co-amorphous mixture with an excellent content uniformity. On the other hand, GA mixture prepared by PM and SE were not pure co-amorphous systems and contained crystalline eutectic mixture, and MQ method at 170 °C induced the decrease in drug content due to decomposition of glimepiride. The positive deviation of experimentally measured glass transition temperature (T_g) compared to predicted T_g by the Gordon Taylor equation suggests specific molecular interactions between glimepiride and L-arginine in solid-state GA co-amorphous (GACA) mixture. The intermolecular interactions between glimepiride and L-arginine in GACA system were characterized by FT-IR and solid-state NMR analyses. Improved glimepiride dissolution rate of GACA formulation were confirmed using the solubility test, contact angle measurement, and dissolution test. Furthermore, the evaluation of pharmacodynamic hypoglycemic effect demonstrated that GACA prepared by the SAS process significantly improved the therapeutic efficacy of glimepiride.

Avocado-derived polyols for use as novel co-surfactants in low energy self-emulsifying microemulsions

Avocado (Persea americana Mill.; Lauraceae) seed-derived polyhydroxylated fatty alcohols (PFAs) or polyols (i.e., avocadene and avocadyne) are metabolic modulators that selectively induce apoptosis of leukemia stem cells and reverse pathologies associated with diet-induced obesity. Delivery systems containing avocado polyols have not been described. Herein, natural surface active properties of these polyols are characterized and incorporated into self-emulsifying drug delivery systems (SEDDS) that rely on molecular self-assembly to form fine, transparent, oil-in-water (O/W) microemulsions as small as 20 nanometers in diameter. Mechanistically, a 1:1 molar ratio of avocadene and avocadyne (i.e., avocatin B or AVO was shown to be a eutectic mixture which can be employed as a novel, bioactive, co-surfactant that significantly reduces droplet size of medium-chain triglyceride O/W emulsions stabilized with polysorbate 80. In vitro cytotoxicity of avocado polyol-SEDDS in acute myeloid leukemia cell lines indicated significant increases in potency and bioactivity compared to conventional cell culture delivery systems. A pilot pharmacokinetic evaluation of AVO SEDDS in C57BL/6J mice revealed appreciable accumulation in whole blood and biodistribution in key target tissues. Lastly, incorporation of AVO in SEDDS significantly improved encapsulation of the poorly water-soluble drugs naproxen and curcumin.

Sketching neoteric solvents for boosting drugs bioavailability

Emerging neoteric solvents are being the subject of growing attention due to their lower cost and environmental impact, so they are being applied in a broad spectrum of industries. Among them, the pharmaceutical sector is demanding new environmentally friendly and non-toxic solvents able to enhance drugs solubility and stability. The introduction of ionic liquids turned out to be a breakthrough in the field of Green Chemistry opening up new separation and catalysis opportunities. In this sense, the options represented by Deep Eutectic Solvents make up an attractive alternative due to the low cost of their raw material, simple synthesis, and eco-friendly character. In line with these findings, Therapeutic Deep Eutectic Solvents and Natural Deep Eutectic Solvents are new and promising alternatives to improve the bioavailability of drugs in pharmaceutical formulations. This leading article is focused on providing a general picture of the advantages and drawbacks of these new solvents as well as the main research lines and perspectives to achieve efficient drugs delivery systems.

How tenofovir disoproxil fumarate can impact on solubility and dissolution rate of efavirenz?

Efavirenz (EFZ) and tenofovir disoproxil fumarate (TDF) can be used simultaneously in the treatment of human immunodeficiency virus type1 infection. In this work the impact of TDF, a hydrophilic drug, on the solubility and dissolution rate of EFZ, a poorly water-soluble drug, was evaluated. EFZ/TDF binary mixtures in different molar ratios were prepared. Differential scanning calorimetry (DSC) results indicate the formation of a eutectic mixture, the molar ratio of 65/35 being the eutectic point. It was observed an increase in the EFZ solubility in water and acidic conditions (0.1 N HCl and biorelevant medium), in the presence of TDF. On the other hand, there was a decreasing on EFZ solubility in phosphate buffer pH 6.8, probably influenced by the lower solubility of TDF in this medium. The high solubility of TDF in water and acidic medium may have contributed to improve the solubility of EFZ, as well as the formation of a eutectic mixture, supported by X-ray powder diffraction (XRPD) and Fourier Transform infrared spectroscopy (FTIR) analyses. However, TDF solubility and dissolution rate was not significantly influenced by the presence of EFZ.

Combining amorphous solid dispersions for improved kinetic solubility of posaconazole simultaneously released from soluble PVP/VA64 and an insoluble ammonio methacrylate copolymer

The aim of this study was to evaluate the potential of combining multiple ASDs based on water soluble and insoluble polymers to reach and maintain poorly soluble posaconazole (PCZ) supersaturation over time. ASDs of PCZ were obtained with PVP/VA64 or an ammonio methacrylate copolymer by solvent evaporation method with a fixed 20% (wt/wt%) drug loading ratio and physical mixtures of these ASDs were prepared at various proportions. ASDs were characterized by Fourier transform infrared spectroscopy (FT-IR) and powder X-ray diffraction (PXRD) and compared to their respective physical mixture with crystalline PCZ. Crystalline PCZ equilibrium solubility was determined at pH 1.2-2 range. Dissolution profiles were constructed under non-sink condition with an adapted dissolution system. PXRD analysis demonstrated that both ASDs were at the amorphous state and FT-IR spectroscopy revealed that the analytical signal of PCZ was also absent in both ASDs. Equilibrium solubility of crystalline PCZ varied between 26.36 ± 0.32 (pH 2) to 609.33 ± 3.68 (pH 1.2) μg/mL. All ASDs reached higher concentrations than the equilibrium solubility of crystalline PCZ during dissolution. PVP/VA64 ASDs showed dominance over PCZ dissolution and recrystallization rates whereas Eudragit RS PO ASD alone did not cause PCZ recrystallization whatsoever. The combination containing 20 mg PVP/VA64 + 80 mg Eudragit RS PO as PCZ carriers obtained the highest AUC, suggesting that even after the PVP/VA64 part was completely dissolved, reaching a concentration above crystalline PC C_s, the insoluble polymer could still release PCZ slowly and maintain supersaturation over time. The research demonstrated a potential of combining multiple ASDs to achieve distinct dissolution profiles while increasing the kinetic solubility of poorly soluble drugs.

Drug Solubility Enhancement through the Preparation of Multicomponent Organic Materials: Eutectics of Lovastatin with Carboxylic Acids

Lovastatin (LOV) is a drug used to treat hypercholesterolemia. Recent studies have identified its antioxidant effects and potential use in the treatment of some types of cancer. However, the low bioavailability related to its poor water solubility limits its use in solid oral dosage forms. Therefore, to improve the solubility of LOV three eutectic systems of LOV with the carboxylic acids benzoic (BEN), salicylic (SAL) and cinnamic (CIN) were obtained. Both binary phase and Tammann diagrams were constructed using differential scanning calorimetry (DSC) data of mixtures prepared from 0.1 to 1.0 molar ratios. Binary mixtures and eutectics were prepared by liquid-assisted grinding. The eutectics were further characterized by DSC and powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The LOV-BEN, LOV-SAL and LOV-CIN system formed a eutectic at an LOV mole fraction of 0.19, 0.60 and 0.14, respectively. The systems exhibited improvements in LOV solubility, becoming more soluble by five-fold in the LOV-SAL system and approximately four-fold in the other two systems. Considering that the solubility enhancements and the carboxylic acids used are generally recognized as safe by the U.S. Food and Drug Administration (FDA), the LOV eutectic systems are promising materials to be used in a solubility enhancement strategy for pharmaceutical product formulation.

Development and characterization of benznidazole nano- and microparticles: A new tool for pediatric treatment of Chagas disease?

Benznidazole (BNZ) is the drug of choice for the treatment of Chagas disease in many countries. However, its low water solubility produces low and/or variable oral bioavailability. Thus, the aim of this work was to formulate micro- and nanoparticles based on Eudragit^® RS PO and Eudragit^® RL PO as a convenient approach to increase the dissolution rate of BNZ. The microparticles were obtained by means of spray-drying process while the nanoparticles were prepared through the nanoprecipitation technique and further freeze-drying. The results indicated that nanoparticles were obtained in 86% yield while microparticles were obtained in 68% yield. In both cases, the encapsulation efficiency of particles was greater than 78% while drug loading capacity was nearly 24% w/w and 18% w/w, after spray-drying and freeze-drying procedures, respectively. Images of scanning electron microscopy showed that the particles obtained by spray-drying and freeze-drying were in the micrometer and nanometer scale, respectively. FT-IR spectra of BNZ-loaded particles obtained by both methods showed characteristic bands of BNZ confirming that part of drug remained on their surface. Thermal analysis revealed that the drug crystallinity after both methods decreased. Physical stability evaluation of the nanoparticles confirmed that Pluronic^® F68 was suitable to keep the particles size in a range of 300 nm after 70 days storage at 4 ± 2 °C. In-vitro release studies showed increased dissolution rate of drug from the particles obtained by both methods respect to untreated BNZ. The kinetics of drug release in acid media followed the Higuchi kinetics indicating drug diffusion mechanism from particles.

Enhanced delivery of fixed-dose combination of synergistic antichagasic agents posaconazole-benznidazole based on amorphous solid dispersions

Posaconazole (PCZ) and benznidazole (BNZ) are known to show synergetic effect in treating the acute and chronic phases of Chagas disease, a neglected parasitic disease. However, as both compounds are poorly water soluble, the development of amorphous solid dispersions (ASDs) of a PCZ/BNZ fixed-dose combination in a water-soluble polymer becomes an attractive option to increase their apparent solubility and dissolution rate, potentially improving their oral bioavailability. The initial approach was to explore solvent evaporated solid dispertion (SD) systems for a PCZ/BNZ 50:50 (wt%) combination at several total drug loading levels (from SD with 10% to 50% drug loading) in water-soluble carriers, including polyvinylpyrrolidone (PVP K-30) and vinylpyrrolidone-vinyl acetate copolymer (PVPVA 64). Based on comparison of non-sink in vitro dissolution performance, ASD systems based on PVPVA was identified as the most effective carrier for a 50:50 (w/w %) fixed-dose combination of PCZ/BNZ to increase their apparent solubility and dissolution rate, mainly at 10% drug loading, which shows more expressive values of area under the curve (AUC) (7336.04 ± 3.77 min.μL/mL for PCZ and 15,795.02 ± 7.29 min.μL/mL for BNZ). Further characterization with polarized microscopy, powder X-ray diffraction, and thermal analysis reveals that there exists a threshold drug loading level at about 30% PCZ/BNZ, below which ASDs are obtained and above which a certain degree of crystallinity tends to result. Moreover, infrared spectroscopic analysis reveals the lack of hydrogen bonding interactions between the drugs (PCZ and BNZ) and the polymer (PVPVA) in the ASD, this is also confirmed through molecular dynamics simulations. The molecular modeling results further show that even in the absence of meaningful hydrogen bonding interactions, there is a greater tendency for PVPVA to interact preferentially with PCZ and BNZ through electrostatic interactions thereby contributing to the stability of the system. Thus, the present SD system has the advantage of presenting a fixed-dese combination of two synergistic antichagasic agents PCZ and BNZ together in amorphous form stabilized in the PVPVA matrix with enhanced dissolution, potentially improving their bioavailability and therapeutic activity in treating Chagas disease.

Ultrasonic assisted dispersive liquid-liquid microextraction method based on deep eutectic solvent for speciation, preconcentration and determination of selenium species (IV) and (VI) in water and food samples

A novel ultrasound-assisted liquid phase microextraction (UALPME) based on environmental friendly extractants, deep eutectic solvent (DES) was first time presented for speciation of selenium. In present study, five DES solvents of different composition was prepared and used as efficient extractive medium for hydrophobic chelate of Se(IV) with 3,3'-Diaminobenzidine (DAB). The total inorganic Se species were determined after pre-reduction of Se(VI) to Se(IV), prior to applying developed method. The concentration of Se(VI) was calculated by the difference of Se(IV) values and total selenium contents. The concentration of Se in DES rich phase was measured with electrothermal atomic absorption spectrometer (ETAAS). The effects of different parameters on extraction efficiency of study analyte, including pH, ligand concentration, type and volume of DES, sonication time, volumes tetrahydrofuran and aqueous samples were examined. At the optimum conditions, limit of detection and quantification, preconcentration factor, and relative standard deviation (RSD %) were determined as 4.61ngL^-1, 15.4ngL^-1, 50% and 4.1%, respectively. The accuracy of the presented method was confirmed by analysis of certified reference material and standard addition method for different water and ice tea samples. The developed method was effectively applied to real water and food samples.