Contribution of Crystal Lattice Energy on the Dissolution Behavior of Eutectic Solid Dispersions

Cocrystal Prediction of Nifedipine Based on the Graph Neural Network and Molecular Electrostatic Potential Surface

Nifedipine (NIF) is a dihydropyridine calcium channel blocker primarily used to treat conditions such as hypertension and angina. However, its low solubility and low bioavailability limit its effectiveness in clinical practice. Here, we developed a cocrystal prediction model based on Graph Neural Networks (CocrystalGNN) for the screening of cocrystals with NIF. And scoring 50 coformers using CocrystalGNN. To validate the reliability of the model, we used another prediction method, Molecular Electrostatic Potential Surface (MEPS), to verify the prediction results. Subsequently, we performed a second validation using experiments. The results indicate that our model achieved high performance. Ultimately, cocrystals of NIF were successfully obtained and all cocrystals exhibited better solubility and dissolution characteristics compared to the parent drug. This study lays a solid foundation for combining virtual prediction with experimental screening to discover novel water-insoluble drug cocrystals.

Quantum Chemistry and Pharmacy: Diagnostic Check of the Thermochemistry of Ibuprofen

The thermodynamic data on ibuprofen available in the literature shows that the disarray of experimental results is unacceptable for this very important drug. The data on ibuprofens available in the literature were collected, combined with our complementary experimental results and evaluated. The enthalpies of combustion and formation of the crystalline RS-(±)- and S-(+)-ibuprofens were measured using high-precision combustion calorimetry. The temperature dependence of the vapour pressure of S-(+)-ibuprofen was measured using the transpiration method and the enthalpy of vaporization was derived from this measurement. The enthalpies of fusion of both compounds were measured using DSC. The G4 calculations have been carried out to determine the enthalpy of formation in the gaseous state of the most stable conformer. Thermochemical properties of the compounds studied were evaluated and tested for consistency with the "centerpiece approach". A set of reliable and consistent values of thermodynamic properties of ibuprofens at 298.15 K is recommended for thermochemical calculations of the pharmaceutical processes. The diagnostic protocol was developed to distinguish between the "sick" or "healthy" thermodynamic data. This diagnostic is also applicable to other drugs with a different structure than ibuprofen.

Preparation and characterisation of kaempferol composite carrier solid dispersion: evaluation of its application in preventing soybean oil spoilage

Kaempferol (KPF) can be used as a natural antioxidant and food additive in food processing. However, the poor solubility of KPF limited its bioavailability and application. In order to improve the solubility of KPF, kaempferol composite carrier solid dispersion (KPF-CC-SD) was prepared and the process was optimised. When the ratio of KPF: CA (citric acid): Soluplus reached 1:4:6, the dissolution rate was the highest, and the sample was stable over 12 weeks. The characterisation results indicated that KPF-CC-SD exists in an amorphous form. Peroxidation value and acid value of soybean oil showed that the preservation effect of KPF-CC-SD was better than that of KPF, and the inhibition effect of KPF-CC-SD on acid value was better than that of butylated hydroxytoluene. In conclusion, KPF-CC-SD can change the solubility, crystal form and spatial stability of KPF through the carrier, which has a great application prospect in the field of food preservation.

Simple preparation and greatly improved oral bioavailability: The supersaturated drug delivery system of quercetin based on PVP K30

Quercetin, as a representative flavonoid, is widely present in daily diet and has been developed as a dietary supplement due to its beneficial physiological activities. However, the application of quercetin is limited due to its poor water solubility and extensive metabolism. So far, the nano-drug delivery systems designed to improve its bioavailability generally have the shortcomings of low drug loading content and difficulty in industrial production. In order to tackle these problems, quercetin supersaturated drug delivery system (QSDDS) was successfully prepared using solvent method, for which PVP K30 was employed as a crystallization and precipitation inhibitor to maintain the supersaturated state of quercetin in aqueous system. The obtained QSDDS, with a relative high drug loading content of 13%, could quickly disperse in water and form colloidal system with the mean particle size of about 200 nm, meanwhile induce the generation of supersaturated quercetin solution more than 12 h. In vivo pharmacokinetic study proved that QSDDS achieved a high absolute bioavailability of 36.05%, 10 times as that of physical quercetin suspension, which was dose-dependent with higher bioavailability at higher dose. Considering the simple preparation method, QSDDS provided a feasible strategy and a simple way to improve oral absorption of insoluble flavonoids.

Saquinavir-Piperine Eutectic Mixture: Preparation, Characterization, and Dissolution Profile

The dissolution rate of the anti-HIV drug saquinavir base (SQV), a poorly water-soluble and extremely low absolute bioavailability drug, was improved through a eutectic mixture formation approach. A screening based on a liquid-assisted grinding technique was performed using a 1:1 molar ratio of the drug and the coformers sodium saccharinate, theobromine, nicotinic acid, nicotinamide, vanillin, vanillic acid, and piperine (PIP), followed by differential scanning calorimetry (DSC). Given that SQV-PIP was the only resulting eutectic system from the screening, both the binary phase and the Tammann diagrams were adapted to this system using DSC data of mixtures prepared from 0.1 to 1.0 molar ratios in order to determine the exact eutectic composition. The SQV-PIP system formed a eutectic at a composition of 0.6 and 0.40, respectively. Then, a solid-state characterization through DSC, powder X-ray diffraction (PXRD), including small-angle X-ray scattering (SAXS) measurements to explore the small-angle region in detail, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and a powder dissolution test were performed. The conventional PXRD analyses suggested that the eutectic mixture did not exhibit structural changes; however, the small-angle region explored through the SAXS instrument revealed a change in the crystal structure of one of their components. FT-IR spectra showed no molecular interaction in the solid state. Finally, the dissolution profile of SQV in the eutectic mixture was different from the dissolution of pure SQV. After 45 min, approximately 55% of the drug in the eutectic mixture was dissolved, while, for pure SQV, 42% dissolved within this time. Hence, this study concludes that the dissolution rate of SQV can be effectively improved through the approach of using PIP as a coformer.

Design of Ascorbic Acid Eutectic Mixtures With Sugars to Inhibit Oxidative Degradation

L-Ascorbic acid (ASC), commonly known as vitamin C, acts as an anti-oxidant in the biological system. It is extensively used as an excipient in pharmaceutical industry, food supplements in fruit juices, and food materials due to its free radicals scavenging activity. Main drawback of ASC is its poor aqueous stability owing to the presence of lactone moiety that is easily oxidized to dehydroascorbic acid and further degraded. To improve aqueous stability and inhibit oxidative degradation, ASC was co-crystallized to constitute binary eutectic compositions with mono and di-saccharides such as glucose, sucrose, lactose, and mannitol. The eutectics were confirmed by their (single) lower melting endotherm compared to ASC and sugars, although Powder X-ray diffraction (PXRD) and Fourier transform Infrared spectroscopy (FT-IR) data confirmed the characteristics of their physical mixture. Scanning electron microscope (SEM) images of the binary eutectics confirmed their irregular morphology. The ASC eutectics exhibited improved shelf-life by 2–5-fold in weakly acidic (pH 5) and neutral (pH 7) aqueous buffer medium, whereas the eutectic with glucose enhanced shelf-life only by 1.1–1.2-fold in acidic medium (pH 3.3 and 4). Notably, stabilizing effect of the sugar eutectics decreased with increasing acidity of the medium. In addition, higher binding energy of the disaccharide eutectics partially supports the aqueous stability order of ASC in the neutral pH medium due to more number of non-bonded interactions than that of monosaccharides.

Pharmacotechnical Evaluation by SeDeM Expert System to Develop Orodispersible Tablets

Sediment delivery model (SeDeM) system is innovative tool to correlate micromeritic properties of powders with compressibility. It involves computation of indices which facilitate direct compressibility of solids and enable corrective measures through particle engineering. Study had multiple objectives, viz, (i) to enhance solubility of BCS class II, nevirapine using solid dispersions; (ii) SeDeM analyses of excipients and solid dispersions to analyze direct compressibility; and (iii) prepare orodispersible tablets (ODT). Solid dispersions were prepared by solvent evaporation. Superdisintegrants and solid dispersions were analyzed for primary indices of dimension, compressibility, flowability, stability, and disgregability derived from micromeritic properties. Radar diagrams were constructed to provide visual clues to deficient properties for direct compressibility. ODTs were prepared using excipients which passed criteria for direct compressibility and evaluated for tablet properties. Solid dispersions with Eudragit S100 revealed 6 to 10 fold increase in solubility in various dissolution media including biorelevant media in comparison with plain drug. Solubility was found to be pH dependent. SeDeM analyses facilitated identification of superdisintegrants and excipients with unfavorable compressibility. Radar diagrams provided a clear pictorial evidence of lacunae in powder properties. Based on SeDeM results, tablets were formulated by direct compression using crosspovidone, croscarmellose sodium, and mannitol. All batches showed 40% release in first minute in simulated salivary fluid.

Evaluation of Piperine as Natural Coformer for Eutectics Preparation of Drugs Used in the Treatment of Cardiovascular Diseases

Piperine (PIP) was evaluated as a natural coformer in the preparation of multicomponent organic materials for enhancing solubility and dissolution rate of the poorly water-soluble drugs: curcumin (CUR), lovastatin (LOV), and irbesartan (IBS). A screening based on liquid assisted grinding technique was performed using 1:1 drug-PIP molar ratio mixtures, followed by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) analyses. Three eutectic mixtures (EMs) composed of CUR-PIP, LOV-PIP, and IBS-PIP were obtained. Therefore, binary phase and Tamman's diagrams were constructed for each system to obtain the exact eutectic composition, which was 0.41:0.59, 0.29:0.71, and 0.31:0.69 for CUR-PIP, LOV-PIP, and IBS-PIP, respectively. Further, bulk materials of each system were prepared to characterize them through DSC, PXRD fully, Fourier transform infrared spectroscopy (FT-IR), and solution-state nuclear magnetic resonance (NMR) spectroscopy. In addition, the contact angle, solubility, and dissolution rate of each system were evaluated. The preserved characteristic in the PXRD patterns and FT-IR spectra of the bulk material of each system confirmed the formation of EM mixture without molecular interaction in solid-state. The formation of EM resulted in improved aqueous solubility and dissolution rate associated with the increased wettability observed by the decrease in contact angle. In addition, solution NMR analyses of CUR-PIP, LOV-PIP, and IBS-PIP suggested no significant intermolecular interactions in solution between the components of the EM. Hence, this study concludes that PIP could be an effective coformer to improve the solubility and dissolution rate of CUR, LOV, and IBS.

Neoteric deep eutectic solvents: history, recent developments, and catalytic applications

Deep eutectic solvents (DESs) are modified versions of ionic liquids (ILs) and are formed by the fusion of polar components (liquids or solids) via hydrogen bonding interactions. DESs are prepared by the simple mixing of two or three cheap constituents (that are capable of self-association) with gentle heating, which leads to a drastic decrease in their melting points. The resultant clear homogeneous mixture consists of cations, anions, as well as neutral molecules; this will contribute both ionic and molecular solvent properties to the DESs. DESs have emerged as alternatives to conventional organic solvents and ILs, which meet different criteria such as availability, low cost, low toxicity, biodegradability, recyclability, ease of preparation method, tunable, and designer physiochemical properties. Many of them have attracted considerable attention and haave been applied in distinct fields of chemistry. To summarize the full-scale development of DESs, this review discusses the history, classifications, various methods of preparation, properties, and some major applications in catalysis in the last three years. This review is expected to be helpful for the further development of DESs based on a summary of the fundamental research in the field.

Accelerating pre-formulation investigations in early drug product life cycles using predictive methodologies and computational algorithms

Precisely developed computational methodologies can allow the drug product lifecycle process to be time-efficient, cost-effective and reliable through a thorough fundamental understanding at the molecular level. Computational methodologies include computational simulations, virtual screening, mathematical modeling and predictive tools. In light of current trends and increased expectations of product discovery in early pharmaceutical development, we have discussed different case studies. These case studies clearly demonstrate the successful application of predictive tools alone or in combination with analytical techniques to predict the physicochemical properties of drug substances and drug products, thereby shortening research and development timelines. The overall goal of this report is to summarize unique predictive methodologies, which can assist pharmaceutical scientists in achieving time-sensitive research goals and avoiding associated risks that can potentially affect the drug product quality.

Brain Delivery of Curcumin Through Low-Intensity Ultrasound-Induced Blood-Brain Barrier Opening via Lipid-PLGA Nanobubbles

Background

Parkinson's disease (PD) is a progressive neurodegenerative disorder. Owing to the presence of blood-brain barrier (BBB), conventional pharmaceutical agents are difficult to the diseased nuclei and exert their action to inhibit or delay the progress of PD. Recent literatures have demonstrated that curcumin shows the great potential to treat PD. However, its applications are still difficult in vivo due to its poor druggability and low bioavailability through the BBB.

Methods

Melt-crystallization methods were used to improve the solubility of curcumin, and curcumin-loaded lipid-PLGA nanobubbles (Cur-NBs) were fabricated through encapsulating the curcumin into the cavity of lipid-PLGA nanobubbles. The bubble size, zeta potentials, ultrasound imaging capability and drug encapsulation efficiency of the Cur-NBs were characterized by a series of analytical methods. Low-intensity focused ultrasound (LIFU) combined with Cur-NB was used to open the BBB to facilitate curcumin delivery into the deep brain of PD mice, followed by behavioral evaluation for the treatment efficacy.

Results

The solubility of curcumin was improved by melt-crystallization methods, with 2627-fold higher than pure curcumin. The resulting Cur-NBs have a nanoscale size about 400 nm and show excellent contrast imaging performance. Curcumin drugs encapsulated into Cur-NBs could be effectively released when Cur-NBs were irradiated by LIFU at the optimized acoustic pressure, achieving 30% cumulative release rate within 6 h. Importantly, Cur-NBs combined with LIFU can open the BBB and locally deliver the curcumin into the deep-seated brain nuclei, significantly enhancing efficacy of curcumin in the Parkinson C57BL/6J mice model in comparison with only Cur-NBs and LIFU groups.

Conclusion

In this work, we greatly improved the solubility of curcumin and developed Cur-NBs for brain delivery of curcumin against PD through combining with LIFU-mediating BBB. Cur-NBs provide a platform for these potential drugs which are difficult to cross the BBB to treat PD disease or other central nervous system (CNS) diseases.

Improvement in Solubility and Absorption of Nifedipine Using Solid Solution: Correlations between Surface Free Energy and Drug Dissolution

Ternary solid solutions composed of nifedipine (NDP), amino methacrylate copolymer (AMCP), and polysorbate (PS) 20, 60, or 65 were prepared using a solvent evaporation method. The dissolution profiles of NDP were used to study the effect of the addition of polysorbate based on hydrophilic properties. A solid solution of NDP and AMCP was recently developed; however, the dissolution of NDP was <70%. In the present study, polysorbate was added to improve the dissolution of the drug by altering its hydrophilicity. The suitable formulation contained NDP and AMCP at a ratio of 1:4 and polysorbate at a concentration of 0.1%, 0.3%, or 0.6%. Differential scanning calorimetry and powder X-ray diffraction were used to examine the solid solutions. No peak representing crystalline NDP was observed in any solid solution samples, suggesting that the drug was molecularly dispersed in AMCP. The NDP dissolution from NDP powder and solid solution without PS were 16.82% and 58.19%, respectively. The highest dissolution of NDP of approximately 95.25% was noted at 120 min for the formulation containing 0.6% PS20. Linear correlations were observed between the surface free energy and percentages of dissolved NDP (R² = 0.7115–0.9315). Cellular uptake across Caco-2 was selected to determine the drug permeability. The percentages of cellular uptake from the NDP powder, solid solution without and with PS20 were 0.25%, 3.60%, and 7.27%, respectively.

Molecular Insights into Warfarin Sodium 2-Propanol Solvate Solid Form Changes and Disproportionation Using a Low Volume Two-Stage Dissolution Approach

The current research work focuses on understanding the reported discrepancies and our observations in the dissolution profiles of warfarin sodium tablets and potential patient-based failure modes during oral warfarin therapy. It was hypothesized that freely soluble crystalline warfarin sodium (WAR_C) at first transforms into noncrystalline warfarin sodium (WAR_NC) under stress conditions. The WAR_C → WAR_NC conversion facilitates the rapid formation of the poorly soluble unionized form, which could lead to dissolution failures and potential poor in vivo performance. Depressed warfarin concentrations locally in the gastrointestinal tract (GIT) may in turn lead to inadequate absorption and thereby affect bioavailability. A low volume two-stage dissolution method was developed to mimic in vivo GIT conditions. Warfarin sodium tablets exposed to room temperature and 75% relative humidity for 1 week showed approximately 23% decrease in drug release. The decline in drug release supports the hypothesis that WAR_NC is converted to the unionized form faster than WAR_C does under the same conditions. Solid state characterization (powder X-ray diffractometry and differential scanning calorimetry) data demonstrated the disproportionation of warfarin sodium to unionized warfarin after solubility and dissolution studies. The findings support the hypothesis and a possible failure mode of warfarin sodium tablets. This work is a second case study from our laboratory on narrow therapeutic index drug products in which the instability of the solid state of the drug substance is potentially responsible for observed clinical failures.

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.