Cocrystals of Hydrochlorothiazide: Solubility and Diffusion/Permeability Enhancements through Drug-Coformer Interactions

Optimizing Drug Development: Harnessing the Sustainability of Pharmaceutical Cocrystals

Environmental impacts of the industrial revolution necessitate adoption of sustainable practices in all areas of development. The pharmaceutical industry faces increasing pressure to minimize its ecological footprint due to its significant contribution to environmental pollution. Over the past two decades, pharmaceutical cocrystals have received immense popularity due to their ability to optimize the critical attributes of active pharmaceutical ingredients and presented an avenue to bring improved drug products to the market. This review explores the potential of pharmaceutical cocrystals as an ecofriendly alternative to traditional solid forms, offering a sustainable approach to drug development. From reducing the number of required doses to improving the stability of actives, from eliminating synthetic operations to using pharmaceutically approved chemicals, from the use of continuous and solvent-free manufacturing methods to leveraging published data on the safety and toxicology, the cocrystallization approach contributes to sustainability of drug development. The latest trends suggest a promising role of pharmaceutical cocrystals in bringing novel and improved medicines to the market, which has been further fuelled by the recent guidance from the major regulatory agencies.

Flexible molecular crystals for optoelectronic applications

The cornerstones of the advancement of flexible optoelectronics are the design, preparation, and utilization of novel materials with favorable mechanical and advanced optoelectronic properties. Molecular crystalline materials have emerged as a class of underexplored yet promising materials due to the reduced grain boundaries and defects anticipated to provide enhanced photoelectric characteristics. An inherent drawback that has precluded wider implementation of molecular crystals thus far, however, has been their brittleness, which renders them incapable of ensuring mechanical compliance required for even simple elastic or plastic deformation of the device. It is perplexing that despite a plethora of reports that have in the meantime become available underpinning the flexibility of molecular crystals, the "discovery" of elastically or plastically deformable crystals remains limited to cases of serendipitous and laborious trial-and-error approaches, a situation that calls for a systematic and thorough assessment of these properties and their correlation with the structure. This review provides a comprehensive and concise overview of the current understanding of the origins of crystal flexibility, the working mechanisms of deformations such as plastic and elastic bending behaviors, and insights into the examples of flexible molecular crystals, specifically concerning photoelectronic changes that occur in deformed crystals. We hope this summary will provide a reference for future experimental and computational efforts with flexible molecular crystals aimed towards improving their mechanical behavior and optoelectronic properties, ultimately intending to advance the flexible optoelectronic technology.

A Novel Cocrystal of Daidzein with Piperazine to Optimize the Solubility, Permeability and Bioavailability of Daidzein

It is well known that daidzein has various significant medicinal values and health benefits, such as anti-oxidant, anti-inflammatory, anti-cancer, anti-diabetic, cholesterol lowering, neuroprotective, cardioprotective and so on. To our disappointment, poor solubility, low permeability and inferior bioavailability seriously limit its clinical application and market development. To optimize the solubility, permeability and bioavailability of daidzein, the cocrystal of daidzein and piperazine was prepared through a scientific and reasonable design, which was thoroughly characterized by single-crystal X-ray diffraction, powder X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. Combining single-crystal X-ray diffraction analysis with theoretical calculation, detailed structural information on the cocrystal was clarified and validated. In addition, a series of evaluations on the pharmacogenetic properties of the cocrystal were investigated. The results indicated that the cocrystal of daidzein and piperazine possessed the favorable stability, increased solubility, improved permeability and optimized bioavailability of daidzein. Compared with the parent drug, the formation of cocrystal, respectively, resulted in 3.9-, 3.1-, 4.9- and 60.8-fold enhancement in the solubility in four different media, 4.8-fold elevation in the permeability and 3.2-fold in the bioavailability of daidzein. Targeting the pharmaceutical defects of daidzein, the surprising elevation in the solubility, permeability and bioavailability of daidzein was realized by a clever cocrystal strategy, which not only devoted assistance to the market development and clinical application of daidzein but also paved a new path to address the drug-forming defects of insoluble drugs.

Tuning Caco-2 permeability by cocrystallization: Insights from molecular dynamics simulation

Emerging evidence suggests that intestinal permeability can be potentially enhanced through cocrystallization. However, a mechanism for this effect remains to be established. In this study, we first demonstrate the enhancement in intestinal permeability, evaluated by the Caco-2 cell permeability assay, of acetazolamide (ACZ) in the presence of a conformer, p-aminobenzoic acid (PABA), delivered in the form of a 1:1 cocrystal. The binding strength of ACZ and PABA with the Pgp efflux transporter, either alone or as a mixture, was calculated using molecular dynamics simulation. Results show that PABA weakens the binding of ACZ with Pgp, which leads to a lower efflux ratio and elevated permeability of ACZ. This work provides molecular-level insights into a potentially effective strategy to improve the intestinal permeability of drugs. If the same cocrystal also exhibits higher solubility, oral bioavailability of BCS IV drugs can likely be improved by forming a cocrystal with a Pgp inhibitor.

Polarization Amplification in Dynamic Nuclear Polarization Magic-Angle Spinning Solid-State Nuclear Magnetic Resonance by Solubilizing Traditional Ionic Salts

Dynamic nuclear polarization can improve the sensitivity of magic-angle spinning solid-state NMR experiments by 1-2 orders of magnitude. In aqueous media, experiments are usually performed using the so-called DNP juice, a glycerol-d8/D2O/H2O mixture (60/30/10, v/v/v) that can form a homogeneous glass at cryogenic temperatures. This acts as a cryoprotectant and prevents phase separation of the paramagnetic polarizing agents (PAs) that are added to the mixture to provide the source of electron spin polarization required for DNP. Here, we show that relatively high 1H DNP enhancements (∼60) can also be obtained in water without glycerol (or other glass forming agents) simply by dissolving high concentrations of electrolytes (such as NaCl or LiCl), which perturb the otherwise unavoidable ice crystallization observed upon cooling, thereby reducing PA phase separation and restoring DNP efficiency.

Study on Sulfamethoxazole-Piperazine Salt: A Mechanistic Insight into Simultaneous Improvement of Physicochemical Properties

Multidrug salts represent more than one drug in a crystal lattice and thus could be used to deliver multiple drugs in a single dose. It showcases unique physicochemical properties in comparison to individual components, which could lead to improved efficacy and therapeutic synergism. This study presents the preparation and scale-up of sulfamethoxazole-piperazine salt, which has been thoroughly characterized by X-ray diffraction and thermal and spectroscopic analyses. A detailed mechanistic study investigates the impact of piperazine on the microenvironmental pH of the salt and its effect on the speciation profile, solubility, dissolution, and diffusion profile. Also, the improvement in the physicochemical properties of sulfamethoxazole due to the formation of salt was explored with lattice energy contributions. A greater ionization of sulfamethoxazole (due to pH changes contributed by piperazine) and lesser lattice energy of sulfamethoxazole-piperazine contributed to improved solubility, dissolution, and permeability. Moreover, the prepared salt addresses the stability issues of piperazine and exhibits good stability behavior under accelerated stability conditions. Due to the improvement of physicochemical properties, the sulfamethoxazole-piperazine salt demonstrates better pharmacokinetic parameters in comparison to sulfamethoxazole and provides a strong suggestion for the reduction of dose. The following study suggests that multidrug salts can concurrently enhance the physicochemical properties of drugs and present themselves as improved fixed-dose combinations.

A computational-based approach to fabricate Ceritinib co-amorphous system using a novel co-former Rutin for bioavailability enhancement

In this study, we used molecular simulations to design Ceritinib (CRT) co-amorphous materials (CAMs) with concurrent improvement in solubility and bioavailability. Computational modeling enabled us to select the co-former by estimating the binding energy and intermolecular interactions. Rutin (RTH) was selected as a co-former for CRT CAMs using the solvent evaporation method to anticipate simultaneous improvement of solubility and bioavailability. The solid state characterization using DSC, XRPD, FT-IR, and a significant shift in Gordon Taylor experimental Tg values of co-amorphous materials revealed single amorphous phase formation and intermolecular interactions between CRT and RTH. The co-amorphous materials exhibited physical stability for up to 4 months under dry conditions (40 °C). Further, co-amorphous materials maintained the supersaturation for 24 hrs and improved solubility as well as dissolution of CRT. CRT:RTH 1:1 CAMs improved the permeability of CRT by 2 fold, estimated by employing the everted gut sac method. The solubility advantage of CAMs was also reflected in pharmacokinetic parameters, with a 3.1-fold and 2-fold improvement of CRT:RTH 2:1 in CRT exposure (AUC 0-t) and plasma concentration (Cmax) compared to the physical mixture, respectively.

Polymorphs of a 1:1 salt of sulfadiazine and piperazine-relative stability, dissolution studies, pharmacokinetics and anti-meningitis efficiency

Two new salt forms of sulfadiazine (SDZ) and piperazine (PIP) were synthesized and characterized. Out of the two polymorphs (SDZ-PIP Ⅰ and SDZ-PIP II), SDZ-PIP Ⅱ is the more stable form at low temperature, room temperature and high temperature. The solution-mediated phase transformation result shows that SDZ-PIP II can transform into pure SDZ within 15 s in phosphate buffer at 37 °C, which leads to a loss in solubility advantage. The addition of 2 mg/mL PVP K30, a polymeric crystallization inhibitor, maintains the solubility advantage and permits supersaturation for a longer period of time. SDZ-PIP II showed 2.5 times the solubility of SDZ alone. The area under the curve (AUC) of SDZ-PIP II with 2 mg/mL PVP K30 was approximately 165% of that of SDZ alone. Moreover, SDZ-PIP II with PVP K30 was more effective than SDZ alone in treating meningitis. Therefore, the SDZ-PIP II salt improves the solubility, bioavailability, and anti-meningitis activity of SDZ.

Overcoming the Hydrophobic Nature of Zinc Phenylacetate Through Co-Crystallization with Isonicotinamide

Zinc phenylacetate (Zn-PA), a substitute for sodium phenylacetate as an ammonia-scavenging drug is hydrophobic, which poses problems for drug dissolution and solubility. We were able to co-crystallize the zinc phenylacetate with isonicotinamide (INAM) and produce a novel crystalline compound (Zn-PA-INAM). The single crystal of this new crystal was obtained, and its structure is reported here for the first time. Zn-PA-INAM was characterized computationally by ab initio, Hirshfeld calculations, CLP-PIXEL lattice energy calculation, and BFDH morphology analysis, and experimentally by PXRD, Sc-XRD, FTIR, DSC, and TGA analyses. Structural and vibrational analyses showed a major modification in intermolecular interaction of Zn-PA-INAM compared to Zn-PA. The dispersion-based pi-stacking in Zn-PA is replaced by coulomb-polarization effect of hydrogen bonds. As a result, Zn-PA-INAM is hydrophilic, improving the wettability and powder dissolution of the target compound in an aqueous solution. Morphology analysis revealed, unlike Zn-PA, Zn-PA-INAM has polar groups exposed on its prominent crystalline faces, reducing the hydrophobicity of the crystal. The shift in average water droplet contact angle from 128.1° (Zn-PA) to 27.1° (Zn-PA-INAM) is strong evidence of a marked decrease in hydrophobicity of the target compound. Finally, HPLC was used to obtain the dissolution profile and solubility of Zn-PA-INAM compared to Zn-PA.

A method for improving the properties of famotidine

According to crystal engineering, the pharmaceutical intermediate m-nitrobenzoic acid (MNBA), which contains a carboxylic acid group, was selected as a coformer (CCF) for drug cocrystallization with famotidine (FMT), and a new stable FMT salt cocrystal was synthesized. The salt cocrystals were characterized by scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, infrared spectroscopy, powder X-ray diffraction and X-ray single crystal diffraction. A single crystal structure of FMT-MNBA (1:1) was successfully obtained, and then the solubility and permeability of the newly synthesized salt cocrystal were studied. The results showed that, compared with free FMT, the FMT from the FMT-MNBA cocrystal showed improved permeability. This study provides a synthetic method to improve the permeability of BCS III drugs, which will contribute to the development of low-permeability drugs.

Cocrystals by Design: A Rational Coformer Selection Approach for Tackling the API Problems

Active pharmaceutical ingredients (API) with unfavorable physicochemical properties and stability present a significant challenge during their processing into final dosage forms. Cocrystallization of such APIs with suitable coformers is an efficient approach to mitigate the solubility and stability concerns. A considerable number of cocrystal-based products are currently being marketed and show an upward trend. However, to improve the API properties by cocrystallization, coformer selection plays a paramount role. Selection of suitable coformers not only improves the drug’s physicochemical properties but also improves the therapeutic effectiveness and reduces side effects. Numerous coformers have been used till date to prepare pharmaceutically acceptable cocrystals. The carboxylic acid-based coformers, such as fumaric acid, oxalic acid, succinic acid, and citric acid, are the most commonly used coformers in the currently marketed cocrystal-based products. Carboxylic acid-based coformers are capable of forming the hydrogen bond and contain smaller carbon chain with the APIs. This review summarizes the role of coformers in improving the physicochemical and pharmaceutical properties of APIs, and deeply explains the utility of afore-mentioned coformers in API cocrystal formation. The review concludes with a brief discussion on the patentability and regulatory issues related to pharmaceutical cocrystals.

Spectroscopic and quantum chemical investigations to explore the effect of intermolecular interactions in a diuretic drug: Hydrochlorothiazide

Hydrochlorothiazide (HCTZ) being a diuretic drug widely used in anti-hypertensive therapy as it lowers the blood pressure by reducing the reabsorption of electrolytes in kidney resulting an increment of urine output and lowering the blood pressure. The purpose of the present work is to study the structural, vibrational and chemical properties of HCTZ based on its monomeric, dimeric and trimeric models by utilizing computational methods and experimental techniques. Density functional theory (DFT) with functional B3LYP and 6-311++G (d, p) basis set was used for a detailed computational study. Monomeric, dimeric and trimeric models of HCTZ have been studied for a better understanding of inter- and intramolecular hydrogen bonding. FT-IR (400-3800 cm^-1) and FT-Raman (100-3600 cm^-1) spectroscopy have been utilized for the characterization of HCTZ. The shifting in wavenumber of NH₂ and OSO group were observed in dimer and trimer due to the formation of intermolecular hydrogen bonding. Quantum theory of atoms in molecules (QTAIM) along with natural bond orbital (NBO) analysis were performed to examine the nature and strength of hydrogen bonding which showed that all the interactions were medium and partially covalent in nature; transition from LP(3)O15 → σ*(H46 → N32) and LP(3)O39 → σ*(H74 → N51) were responsible for the formation of O15•••H46 and O39•••H74 H-bonds, respectively. HOMO-LUMO energies predicted the chemical reactivity and stability of the molecule and the energy gap for dimer (4.6240 eV) and trimer (4.0493 eV) was found to be lesser than the monomer (5.0888 eV) which showed that the dimer and trimer have predicted more chemical reactivity in comparison to monomer. The most electronegative electrostatic potential was observed around the OSO group and the most electropositive potential around the amide group from MEPS analysis. Global as well as local reactivity descriptors have predicted the reactivity and hence, stability of the title molecule.

Novel multi-component crystals of berberine with improved pharmaceutical properties

As an extremely popular natural product, berberine (BER) is mainly used for gastroenteritis and diarrhoea caused by bacteria. Research has also revealed the potent and extensive pharmacological properties of BER including its anti-arrhythmic, anti-tumour, anti-inflammatory and hypoglycemic activities and so on; therefore, BER is a promising drug for further development. However, its commercial form with hydrochloride exhibits poor stability and solubility, which are detrimental to its clinical therapeutic effects. For these purposes, the salt form was regulated via the reactive crystallization of 8-hydroxy-7,8-dihydroberberine (8H-HBER) with five pharmaceutically suitable organic acids including malonic acid (MA), L-tartaric acid (LTA), D-tartaric acid (DTA), DL-tartaric acid (DLTA) and citric acid (CA), resulting in the six novel solid forms 1BER-1LTA-1W, 1BER-1DTA-1W, 1BER-1DLTA and 2BER-2CA as well as two rare multi-stoichiometric solid forms 1BER-1MA and 1BER-2MA-2W. The preparation of the multi-stoichiometric products was greatly influenced by both the crystallization solvent type and the molar ratio of reactants. The structures of these multi-component solid forms were determined using single-crystal X-ray diffraction and further characterized by powder X-ray diffraction, thermal analysis and Fourier transform infrared spectroscopy. Stability experiments showed that all samples prepared had superior physical stability under high temperature and high humidity. Furthermore, dissolution experiments demonstrated that the maximum apparent solubilities (MAS) of all the products were significantly improved compared with the commercial form of BER in dilute hydrochloric solution (pH = 1.2). In particular, the MAS of 1BER-1MA in dilute hydrochloric solution is as high as 34 times that of the commercial form. In addition, it is preliminarily confirmed that the MAS of the samples prepared in pure water and dilute hydrochloric solution is primarily influenced by a combination of factors including the packing index, intermolecular interactions, affinity of the counter-ion to the solvent, the molar ratio of the drug to counter-ion in the product and the common ion effect. These novel solids are potential candidates for BER solid forms with improved oral dosage design and may prompt further development.

A Review of Coformer Utilization in Multicomponent Crystal Formation

Most recently discovered active pharmaceutical molecules and market-approved medicines are poorly soluble in water, resulting in limited drug bioavailability and therapeutic effectiveness. The application of coformers in a multicomponent crystal method is one possible strategy to modulate a drug's solubility. A multicomponent crystal is a solid phase formed when several molecules of different substances crystallize in a crystal lattice with a certain stoichiometric ratio. The goal of this review paper is to comprehensively describe the application of coformers in the formation of multicomponent crystals as solutions for pharmaceutically active ingredients with limited solubility. Owing to their benefits including improved physicochemical profile of pharmaceutically active ingredients, multicomponent crystal methods are predicted to become increasingly prevalent in the development of active drug ingredients in the future.

Preparation, characterization, and pharmacokinetics of rivaroxaban cocrystals with enhanced in vitro and in vivo properties in beagle dogs

Rivaroxaban (RIV) is a direct Factor Xa inhibitor anticoagulant, but the oral bioavailability of RIV is estimated to be only 60% due to its poor solubility. The aim of the present study was to improve the solubility and bioavailability of RIV. Five cocrystals—p-hydroxybenzoic acid (HBA), 2,4-dihydroxybenzoic acid (DBA), nicotinamide (NA), isonicotinamide (IA), and succinic acid (SA)—were used as cofomers and were successfully obtained and characterized by powder X-ray diffraction, thermal analysis, and Fourier transform infrared spectra. RIV-DBA and RIV-HBA cocrystals showed obvious improvements in solubility, dissolution (under sink conditions), and intrinsic dissolution rates versus RIV. Moreover, the dissolution of RIV-HBA, RIV-DBA, and RIV-SA cocrystals under non-sink conditions showed obvious “spring and parachute” patterns. The in vitro permeability levels in a Caco-2 cell model of RIV-DBA and RIV-IA cocrystals were significantly improved versus RIV. Pharmacokinetic studies in beagle dogs showed that RIV-DBA and RIV-HBA cocrystals had higher bioavailability than RIV. The enhancements in solubility and bioavailability indicate the potential of RIV cocrystals as a better candidate for the treatment of thrombosis versus RIV.

Novel Ascorbic Acid Co-Crystal Formulations for Improved Stability

A series of co-crystals of ascorbic acid were prepared with equimolar amounts of co-crystal formers (CCFs), including isonicotinic acid, nicotinic acid, 3,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid and m-hydroxybenzoic acid, by slow solvent evaporation and solvent-assisted grinding. The co-crystals were characterized by single-crystal X-ray diffraction spectroscopy, powder X-ray diffraction, IR spectroscopy, differential scanning calorimetry and thermogravimetric analysis. Molecular dynamics (MD) simulations further validated the interaction energy and the possible intermolecular hydrogen bonds among VC and CCFs. The co-crystals showed improved stability when exposed to different wavelengths of light, pH and temperatures compared to the free analogue, especially at higher pH (~9) and lower temperature (~4 °C).

Tunable Drug Release from Fused Deposition Modelling (FDM) 3D-Printed Tablets Fabricated Using a Novel Extrudable Polymer

Three-dimensional (3D) printing is proving to be a pivotal technology for developing personalized dosage forms with bench to bedside feasibility. Fused deposition modelling (FDM) 3D printing has emerged as the most used technique wherein molten drug-loaded polymer filaments are deposited layer-by-layer to fabricate a predefined shape and internal geometry. However, for precise FDM 3D printing, it is imperative for the filaments to have peculiar mechanical/physicochemical properties, which the majority of the FDA/GRAS approved polymers lack. In the current study, a novel water-soluble polymer, Poly(2-ethyl-tetra-oxazoline) [PETOx] has been investigated as an extrudable and printable polymer with two different types of drug molecule—dextromethorphan hydrobromide (DXM) and hydrochlorothiazide (HCTZ). Hot-stage microscopy experiments of drug:polymer (1:1 w/w) and filaments were carried out at 25−275 °C. HCTZ-loaded filament showed higher toughness of 17 ± 3.25 × 106 J/m3 compared with DXM and drug-free filament. Moisture sorption and flexural analysis was performed to understand the correlation of mechanical properties and storage humidity to printability. Varying the number of outer perimeters of each layer (shell number) was observed to affect the drug release pattern from the printlets. The DXM one-shell printlet showed >80%, whereas the DXM five-shell printlet showed >60% of the drug release within 60 min. PETOx could prove to be a high-performance and versatile 3D printable polymer.

Application of machine learning to predict the inhibitory activity of organic chemicals on thyroid stimulating hormone receptor

With the promotion of carbon neutrality, it is also important to synchronously promote the assessment and sustainable management of chemicals so as to protect public health. Humans and animals are possibly exposed to endocrine disruptors that have inhibitory effects on thyroid stimulating hormone receptor (TSHR). As such, it is important to identify chemicals that inhibit TSHR and to develop models to predict their inhibitory activity. In this study, 5952 compounds derived from a cyclic adenosine monophosphate (cAMP) analysis, a key signaling pathway in thyrocytes, were used to establish a binary classification model comparing methods that included random forest (RF), extreme gradient boosting (XGB), and logistic regression (LR). The prediction model based on RF showed the highest identification accuracy for revealing chemicals that may inhibit TSHR. For the RF model, recall was calculated at 0.89, balance accuracy was 0.85, and its receiver operating characteristic (ROC) curve-area under (AUC) was 0.92, indicating that the model had very high predictive capacity. The lowest CDocker energy (CE) and CDocker interaction energy (CIE) for chemicals and TSHR were determined and were subsequently introduced into the predictive model as descriptors. A regression model, extreme gradient boosting-Regression (XGBR), was successfully established yielding an R² = 0.65 to predict inhibitory activity for active compounds. Parameters that included dissociation characteristics, molecular structure, and binding energy were all key factors in the predictive model. We demonstrate that QSAR models are useful approaches, not only for identifying chemicals that inhibit TSHR, but for predicting inhibitory activity of active compounds.

Solid-State and Particle Size Control of Pharmaceutical Cocrystals using Atomization-Based Techniques

Poor bioavailability and aqueous solubility represent a major constraint during the development of new API molecules and can influence the impact of new medicines or halt their approval to the market. Cocrystals offer a novel and competitive advantage over other conventional methods with respect towards the substantial improvement in solubility profiles relative to the single-API crystals. Furthermore, the production of such cocrystals through atomization-based methods allow for greater control, with respect to particle size reduction, to further increase the solubility of the API. Such atomization-based methods include supercritical fluid methods, conventional spray drying and electrohydrodynamic atomization/electrospraying. The influence of process parameters such as solution flow rates, pressure and solution concentration, in controlling the solid-state and final particle size are discussed in this review with respect to atomization-based methods. For the last decade, literature has been attempting to catch-up with new regulatory rulings regarding the classification of cocrystals, due in part to data sparsity. In recent years, there has been an increase in cocrystal publications, specifically employing atomization-based methods. This review considers the benefits to employing atomization-based methods for the generation of pharmaceutical cocrystals, examines the most recent regulatory changes regarding cocrystals and provides an outlook towards the future of this field.

Investigating the Role of the Reduced Solubility of the Pirfenidone-Fumaric Acid Cocrystal in Sustaining the Release Rate from Its Tablet Dosage Form by Conducting Comparative Bioavailability Study in Healthy Human Volunteers

Pirfenidone (PFD) is the first pharmacological agent approved by the US Food and Drug Administration (FDA) in 2014 for the treatment of idiopathic pulmonary fibrosis (IPF). The recommended daily dosage of PFD in patients with IPF is very high (2403 mg/day) and must be mitigated through additives. In the present work, sustained-release (SR) formulations of the PFD-FA cocrystal of two different strengths such as 200 and 600 mg were prepared and its comparative bioavailability in healthy human volunteers was studied against the reference formulation PIRFENEX (200 mg). A single-dose pharmacokinetic study (200 mg IR vs 200 mg SR) demonstrated that the test formulation exhibited lower C_max and T_max in comparison to the reference formulation, which showed that the cocrystal behaved like an SR formulation. Further in the multiple-dose comparative bioavailability study (200 mg IR thrice daily vs 600 mg SR once daily), the test formulation was found bioequivalent to the reference formulation. In conclusion, the present study suggests that cocrystallization offers a promising strategy to reduce the solubility of PFD and opens the door for potential new dosage forms of this important pharmaceutical.

Novel dapagliflozin di-L-proline cocrystal-loaded tablet: Preparation, physicochemical characterization, and pharmacokinetics in beagle dogs and mini-pigs

Dapagliflozin base and a commercial dapagliflozin propanediol hydrate cocrystal (DPF-PDHC) were highly hygroscopic and thermally unstable. In this study, to address this limitation, we prepared a novel dapagliflozin di-L-proline cocrystal (DPF-LPC) and evaluated its physicochemical characterization compared with DPF-PDHC. After the preparation of the DPF-LPC-loaded tablet, its dissolution, stability and bioequivalence in beagle dogs and mini-pigs were assessed. DPF-LPC was well prepared with a dapagliflozin base and L-proline in a molar ratio of 1:2. Similar to DPF-PDHC, DPF-LPC was highly lipophilic and crystalline in nature. However, these two cocrystals exhibited different melting points and crystalline structures, indicating their different cocrystal forms. Moreover, DPF-LPC exhibited less hygroscopicity and lower water content than DPF-PDHC. The DPF-LPC-loaded tablet composed of DPF-LPC, Comprecel M102, lactose monohydrate, crospovidone, magnesium stearate, and Opadry (coating) at a weight ratio of 15.6:104.4:100.0:8.0:2.0:7.0, was dissolution-equivalent to the commercial tablet. Moreover, it provided lower impurities than the commercial tablet, indicating its better stability. In the two animals, there were no significant differences in the plasma concentrations, AUC, C_max, and T_max values, suggesting that they were bioequivalent. Therefore, the novel DPF-LPC-loaded tablet with excellent stability and bioequivalence may be used as a potential alternative to the commercial DPF-PDHC-loaded tablet.

Creation of Hydrochlorothiazide Pharmaceutical Cocrystals Via Hot-Melt Extrusion for Enhanced Solubility and Permeability

Crystal engineering is an emerging tool for altering the physicochemical properties of drug candidates. The objective of the current investigation was to develop cocrystals of hydrochlorothiazide (HCT) with coformers such as nicotinamide (NIC), resorcinol (RSL), and catechol (CAT) using hot-melt extrusion (HME) technology. The liquid-assisted grinding (LAG) method was used to prepare cocrystals by grinding the drug and coformer in a definite molar ratio as a reference and to check the feasibility of cocrystal formation. Cocrystals were prepared using HME and evaluated with differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffractometry, and scanning electron microscopy and compared with LAG cocrystals. Barrel temperature was the critical process parameter for producing high-quality cocrystals in HME. All cocrystals exhibited improved solubility compared to the native drug, and HCT-NIC cocrystals showed a two-fold increase in solubility. Similarly, HCT-RSL and HCT-CAT showed higher solubility profiles and improved diffusion/permeability characteristics compared to that of the pure HCT due to the drug-coformer interactions in the cocrystals. In this study, the solubility of the coformer was the key factor determining cocrystal solubilization. However, hot-melt extrusion is an alternative technology for creating pharmaceutical cocrystals and has potential for industrial scale-up.

Two anhydrous forms and one monohydrate of a cocrystal of axitinib and glutaric acid: characterization, property evaluation and phase transition study

The polymorphs and hydrates of multi-component crystals have not been studied as extensively as that of single-component crystals. In this work, one anhydrate and one monohydrate of a cocrystal involving...

Solubility and permeability enhancement of BCS class IV drug ribociclib through cocrystallization

Cocrystallization improves the solubility and permeability of BCS class IV anticancer drug ribociclib as a cocrystal with resorcinol and as a salt hydrate with vanillic acid.

Understanding Hygroscopicity of Theophylline via a Novel Cocrystal Polymorph: A Charge Density Study

The charge density distribution in a novel cocrystal (1) complex of 1,3-dimethylxanthine (theophylline) and propanedioic acid (malonic acid) has been determined. The molecules crystallize in the triclinic, centrosymmetric space group P1̅, with four independent molecules (Z = 4) in the asymmetric unit (two molecules each of theophylline and malonic acid). Theophylline has a notably high hygroscopic nature, and numerous cocrystals have shown a significant improvement in stability to humidity. A charge density study of the novel polymorph has identified interesting theoretical results correlating the stability enhancement of theophylline via cocrystallization. Topological analysis of the electron density highlighted key differences (up to 17.8) in Laplacian (∇²ρ) between the experimental (EXP) and single-point (SP) models, mainly around intermolecular-bonded carbonyls. Further investigation via molecular electrostatic potential maps reaffirmed that the charge redistribution enhanced intramolecular hydrogen bonding, predominantly for N(2') and N(2) (61.2 and 61.8 kJ mol^-1, respectively). An overall weaker lattice energy of the triclinic form (-126.1 kJ mol^-1) compared to that of the monoclinic form (-133.8 kJ mol^-1) suggests a lower energy threshold to overcome to initiate dissociation. Future work via physical testing of the novel cocrystal in both dissolution and solubility will further solidify the correlation between theoretical and experimental results.

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.