Enhanced dissolution and stability of adefovir dipivoxil by cocrystal formation

Comparison of mechanochemical methods in the synthesis of binaphthol-benzoquinone based cocrystals

Mechanochemical methods either under neat or liquid assisted conditions have proven to be successful in making cocrystals. In this paper we compare the outcome of cocrystallization using two different mechanochemical methods, ball milling (BM) and resonant acoustic mixing (RAM), with solution crystallization. Racemic binaphthol and benzoquinone based binary and ternary cocrystals were investigated by BM and RAM. Both mechanochemical methods were successful in making the binary and ternary cocrystals that have been observed in solid state and solution. It is shown that the type of mechanochemical force imparted to the sample is very different between BM and RAM and this in turn leads to different cocrystallization outcomes. Thus, different mechanochemical methods should not be treated as the same and care must be taken when choosing a mechanochemical method for a particular application.

Drug-Coformer Loaded-Mesoporous Silica Nanoparticles: A Review of the Preparation, Characterization, and Mechanism of Drug Release

Drug-coformer systems, such as coamorphous and cocrystal, are gaining recognition as highly effective strategies for enhancing the stability, solubility, and dissolution of drugs. These systems depend on the interactions between drug and coformer to prevent the conversion of amorphous drugs into the crystalline form and improve the solubility. Furthermore, mesoporous silica (MPS) is also a promising carrier commonly used for stabilization, leading to solubility improvement of poorly water-soluble drugs. The surface interaction of drug-MPS and the nanoconfinement effect prevent amorphous drugs from crystallizing. A novel method has been developed recently, which entails the loading of drug-coformer into MPS to improve the solubility, dissolution, and physical stability of the amorphous drug. This method uses the synergistic effects of drug-coformer interactions and the nanoconfinement effect within MPS. Several studies have reported successful incorporation of drug-coformer into MPS, indicating the potential for significant improvement in dissolution characteristics and physical stability of the drug. Therefore, this study aimed to discuss the preparation and characterization of drug-coformer within MPS, particularly the interaction in the nanoconfinement, as well as the impact on drug release and physical stability.

PREPARATION AND SOLID-STATE CHARACTERIZATION OF KETOPROFEN-SUCCINIC ACID-SACCHARIN CO-CRYSTAL WITH IMPROVED SOLUBILITY

Objective: This study aimed to improve the solubility of Ketoprofen, a non-steroidal anti-inflammatory drug (NSAID) that belongs to the Biopharmaceutical Classification System (BCS) Class II, through co-crystallization using succinic acid and saccharin coformers in a 1:1:1 and 2:1:1 molar ratio. Methods: The slurry method was utilized to prepare the ketoprofen co-crystals, which were then subjected to various physical-chemical characterization techniques such as melting point determination, dissolution studies, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Results: The results showed that the 1:1:1 molar ratio of ketoprofen-succinic acid-saccharin co-crystal (Formula 1) exhibited higher solubility than the solubility standard of Ketoprofen and the 2:1:1 molar ratio of the co-crystal (Formula 2). The dissolution profile (Q30) of Formula 1, Formula 2, and standard Ketoprofen were 96.73±1.77, 93.09±1.16, and 70.22±4.72, respectively. These findings suggest that co-crystallization with succinic acid and saccharin conformers using the slurry method can significantly enhance the solubility of Ketoprofen. Conclusion: The 1:1:1 molar ratio of ketoprofen-succinic acid-saccharin co-crystal (Formula 1) was the most effective formulation among the tested samples, demonstrating the highest solubility. This research may provide valuable insights for developing novel drug formulations with improved bioavailability and therapeutic efficacy.

Norfloxacin Cocrystals: Mechanochemical Synthesis and Scale-up Viability Through Solubility Studies

Cocrystals are recognized as one of the most efficient approaches to improve aqueous solubility of Biopharmaceutical Classification System, BCS, classes II and IV drugs. Cocrystal discovery and the establishment of experimental conditions suitable for scale-up purposes are some of the main challenges in cocrystal investigation. In this work, the investigation of mechanochemical synthesis of norfloxacin cocrystals with picolinic and isonicotinic acids is performed, leading to the discovery of two new cocrystals of this important BCS class IV antibiotic, which were characterized through thermal, spectral and diffractometric analysis. Norfloxacin apparent aqueous solubility using the cocrystals is also presented, with higher values being obtained for all the investigated systems when compared to the pure drug. Norfloxacin has 3 polymorphs and several solvents/hydrates, which represents a challenge for obtaining pure cocrystal forms from solvent crystallization. This challenge was successfully overcome in this work, as experimental conditions to obtain the pure cocrystals (the new ones and also norfloxacin-nicotinic acid and norfloxacin-saccharin) were established using Crystal16 equipment. This is a crucial step to envisage future scale-up procedures and therefore a valuable information for the pharmaceutical industry.

Cocrystallization of 5-fluorouracil with gallic acid: A novel 5-fluorouracil cocrystal displaying synergistic anti-tumor activity both in oral and intraperitoneal injection administration

Gallic acid (GA) is a naturally occurring polyphenolic compound exhibiting anti-tumor activity. To clarify the capability of GA in optimizing the in vitro/in vivo properties of the first line anti-tumor drug 5-fluorouracil (5-FU) and achieve synergistically enhanced anti-tumor activity, a novel cocrystal hydrate of 5-FU-GA-H₂O was successfully screened and characterized based on various spectroscopic and experimental analysis including Fourier transform infrared spectroscopy (FT-IR), Raman spectra (Raman), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetric (TG) and scanning electric microscope (SEM) techniques. The results suggested the existence of hydrogen bonding interactions between C=O group of 5-FU and O-H group of GA. Although the dissolution rate and solubility of 5-FU-GA-H₂O cocrystal were slowed and lowered compared with that of 5-FU, respectively, the membrane permeability was enhanced for cocrystal compared with that of intact 5-FU and physical mixture (PM) of 5-FU and GA. For the cocrystal, the cumulative amount per unit area of permeated 5-FU in the first 10 h was 2.56 and 9.97 times of that of pure 5-FU and PM, respectively, in the case that transmembrane behavior of 5-FU depended on the type of solution from which the powder was dissolved. Meanwhile, improvement on oral bioavailability by co-crystallization was observed; AUC_0-t of cocrystal was 2.78-fold higher than that of 5-FU. Furthermore, the cocrystal displayed a superior cytotoxic activity on 4T1 mouse breast cancer cells compared with pure 5-FU and even the PM. It was confirmed that the cocrystal solution induced higher autophagic flux than those of 5-FU and PM in 4T1 cell, suggesting that autophagy rather than apoptosis mainly mediated cell death. The obvious difference of tumor inhibition activity between PM and cocrystal in intraperitoneal injection administration indicated that some of the interactions formed in the solid cocrystal could retain in solution in some way. Benefiting from synergistic cytotoxicity, drug efficacy in vivo was enhanced through injection administration of solution from which cocrystal was dissolved.

A SWOT analysis of nano co-crystals in drug delivery: present outlook and future perspectives

The formulation of poorly soluble drugs is an intractable challenge in the field of drug design, development and delivery. This is particularly problematic for molecules that exhibit poor solubility in both organic and aqueous media. Usually, this is difficult to resolve using conventional formulation strategies and has resulted in many potential drug candidates not progressing beyond early stage development. Furthermore, some drug candidates are abandoned due to toxicity or have an undesirable biopharmaceutical profile. In many instances drug candidates do not exhibit desirable processing characteristics to be manufactured at scale. Nanocrystals and co-crystals, are progressive approaches in crystal engineering that can solve some of these limitations. While these techniques are relatively facile, they also require optimisation. Combining crystallography with nanoscience can yield nano co-crystals that feature the benefits of both fields, resulting in additive or synergistic effects to drug discovery and development. Nano co-crystals as drug delivery systems can potentially improve drug bioavailability and reduce the side-effects and pill burden of many drug candidates that require chronic dosing as part of treatment regimens. In addition, nano co-crystals are carrier-free colloidal drug delivery systems with particle sizes ranging between 100 and 1000 nm comprising a drug molecule, a co-former and a viable drug delivery strategy for poorly soluble drugs. They are simple to prepare and have broad applicability. In this article, the strengths, weaknesses, opportunities and threats to the use of nano co-crystals are reviewed and a concise incursion into the salient aspects of nano co-crystals is undertaken.

Mitigating Drug Stability Challenges Through Cocrystallization

Drug stability plays a significant role in the pharmaceutical industry from early-phase drug discovery to product registration as well as the entire life cycle of a product. Various formulation approaches have been employed to overcome drug stability issues. These approaches are sometimes time-consuming which ultimately affect the timeline of the product launch and may further require formulation optimization steps, affecting the overall cost. Pharmaceutical cocrystal is a well-established route to fine tune the biopharmaceutical properties of drugs without covalent modification. This article highlights the role of cocrystallization in mitigating the stability issues of challenging drug molecules. Representative case studies wherein the drug stability issue is addressed through pharmaceutical cocrystals have been discussed briefly and are summarized in tabular form. The emphasis has been made on the structural information of cocrystals and understanding the mechanism that improves the stability of the parent drug through cocrystallization. Besides, a guided strategy has been proposed to modulate the stability of drug molecules through cocrystallization approach. Finally, the stability concern of fixed-dose or drug combinations and the challenges associated with cocrystals are also touched.

Recent Advances in Pharmaceutical Cocrystals: A Focused Review of Flavonoid Cocrystals

Cocrystallization is currently an attractive technique for tailoring the physicochemical properties of active pharmaceutical ingredients (APIs). Flavonoids are a large class of natural products with a wide range of beneficial properties, including anticancer, anti-inflammatory, antiviral and antioxidant properties, which makes them extensively studied. In order to improve the properties of flavonoids, such as solubility and bioavailability, the formation of cocrystals may be a feasible strategy. This review discusses in detail the possible hydrogen bond sites in the structure of APIs and the hydrogen bonding networks in the cocrystal structures, which will be beneficial for the targeted synthesis of flavonoid cocrystals. In addition, some successful studies that favorably alter the physicochemical properties of APIs through cocrystallization with coformers are also highlighted here. In addition to improving the solubility and bioavailability of flavonoids in most cases, flavonoid cocrystals may also alter their other properties, such as anti-inflammatory activity and photoluminescence properties.

In Situ Co-Amorphization of Olanzapine in the Matrix and on the Coat of Pellets

In situ amorphization is a promising approach, considered in the present work, to enhance the solubility and dissolution rate of olanzapine, while minimizing the exposure of the amorphous material to the stress conditions applied during conventional processing. The production of pellets by extrusion/spheronization and the coating of inert beads were investigated as novel methods to promote the co-amorphization of olanzapine, a poorly water-soluble drug, and saccharin. Samples were characterized using differential scanning calorimetry, X-ray powder diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy, and dissolution and stability testing. The co-amorphous produced were compared with crystalline olanzapine, or physical mixture of olanzapine and saccharin. Results suggested that the addition of water to mixtures containing olanzapine and saccharin during the production of pellets, and the coating of inert beads, induced the in situ co-amorphization of these substances. The coating of inert beads enhanced the solubility and dissolution rate of olanzapine, especially when compared to pellets coated with the crystalline drug, but also with pellets containing the co-amorphous entity in the matrix of beads. Nine months stability tests (23 °C/60% RH) confirmed the preservation of the solid-state properties of the co-amorphous form on/in pellets. Overall, results highlighted the feasibility and benefits of in situ co-amorphization, either when the drug was entrapped in the pellets matrix, or preferentially applied directly on the surface of pellets.

Development of Biocompatible Ciprofloxacin-Gold Nanoparticle Coated Sutures for Surgical Site Infections

Surgical site infections (SSIs) are mainly observed after surgeries that use biomaterials. The aim of this present work was to develop ciprofloxacin hydrochloride (CPH)-loaded gold nanoparticles. These ciprofloxacin-gold nanoparticles were coated onto a sterile surgical suture using an adsorption technique, followed by rigidization via ionotropic crosslinking using sodium alginate. Furthermore, UV-visible spectroscopy, infrared spectroscopy, and scanning electron microscopy were used to characterize the samples. The particle size of the nanoparticles was 126.2 ± 13.35 nm with a polydispersity index of 0.134 ± 0.03, indicating nanosize formation with a monodispersed system. As per the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines, stability studies were performed for 30 days under the following conditions: 2-8 °C, 25 ± 2 °C/60 ± 5% RH, and 40 ± 2 °C/75 ± 5% RH. For both Gram-negative and Gram-positive bacteria, the drug-coupled nanoparticle-laden sutures showed a twofold higher zone of inhibition compared with plain drug-coated sutures. In vitro drug release studies showed a prolonged release of up to 180 h. Hemolysis and histopathology studies displayed these sutures' acceptable biocompatibility with the healing of tissue in Albino Swiss mice. The results depict that the use of antibiotic-coated sutures for preventing surgical site infection for a long duration could be a viable clinical option.

Improved Pharmaceutical Properties of Ritonavir through Co-crystallization Approach with Liquid Assisted Grinding Method

Ritonavir is a BCS class II antiretroviral agent which shows poor aqueous solubility and low oral bioavailability. The cocrystallization approach was selected to overcome these problems and to improve the physicochemical and mechanical properties of Ritonavir. The novel pharmaceutical Ritonavir-L-tyrosine cocrystals (RTC at a molar ratio of 1:1) were synthesized using the liquid assisted grinding (LAG) method. The possibility of molecular interactions between drug and coformer were studied using Gold software version 5.2. The newly formed crystalline solid phase was characterized through Differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), Fourier transform-infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), and Solid-State Nuclear magnetic resonance (SSNMR). The improved pharmaceutical properties were confirmed by solubility, dissolution, and powder compaction study. The prepared cocrystals exhibited an 11.24-fold increase in solubility and a 3.73-fold increase in % of drug release at 1 h compared to pure drug. Tabletability and compaction behaviour of the pure drug and cocrystal with added excipients assessed. The tabletability profile of cocrystals showed enhanced tabletting performance as compared to pure drug. The stability studies revealed that cocrystals were stable for at least one month when stored at 40 °C/75% RH and 25 °C/60% RH conditions. The cocrystallization approach was found to be very promising and showed an overall improved performance of Ritonavir.

Enhancing the stability of active pharmaceutical ingredients by the cocrystal strategy

Cocrystal strategies to achieve excellent physiochemical performance under different environmental stress were highlighted here. The lattice energy and the energy barrier of degradation reactions are two pillars in a stable cocrystal construction.

Effect of Coformer Selection on In Vitro and In Vivo Performance of Adefovir Dipivoxil Cocrystals

PURPOSE

This study aimed to improve the in vitro dissolution, permeability and oral bioavailability of adefovir dipivoxil (ADD) by cocrystal technology and clarify the important role of coformer selection on the cocrystal's properties.

METHODS

ADD was cocrystallized with three small molecules (i.e., paracetamol (PA), saccharin (SAC) and nicotinamide (NIC)), respectively. The obtained ADD-PA cocrystal was characterized by DSC, TGA, PXRD and FTIR. Comparative study on dissolution rates among the three ADD cocrystals were conducted in water and pH 6.8 phosphate buffer. Besides, effects of coformers on intestinal permeability of ADD were evaluated via in vitro Caco-2 cell model and in situ single-pass intestinal perfusion model in rats. Furthermore, in vivo pharmacokinetic study of ADD cocrystals was also compared.

RESULTS

Dissolution rates of ADD cocrystals were improved with the order of ADD-SAC cocrystal > ADD-PA cocrystal > ADD-NIC cocrystal. The permeability studies on Caco-2 cell model and single-pass intestinal perfusion model indicated that PA could enhance intestinal absorption of ADD by P-gp inhibition, while SAC and NIC did not. Further in vivo pharmacokinetic study showed that ADD-SAC cocrystal exhibited higher C_max (1.4-fold) and AUC_0-t (1.3-fold) of ADD than administration of ADD alone, and C_max and AUC_0-t of ADD-PA cocrystal were significantly enhanced by 2.1-fold and 2.2-fold, respectively, which was attributed to its higher dissolution and improved intestinal permeability.

CONCLUSION

Coformer selection had an important role on cocrystal's properties, and cocrystallization of ADD with a suitable coformer was an effective approach to enhance both dissolution and bioavailability of ADD.

Supramolecular self-assembly of amantadine hydrochloride with ferulic acid via dual optimization strategy establishes a precedent of synergistic antiviral drug-phenolic acid nutraceutical cocrystal

To display the capability of the phenolic acid nutraceutical ferulic acid (FLA) in optimizing the in vitro/in vivo properties of the antiviral drug amantadine hydrochloride (AMH) and achieve synergistically enhanced antiviral effects, thereby gaining some new insights into pharmaceutical cocrystals of antiviral drugs with phenolic acid nutraceuticals, a cocrystallization strategy of dual optimization was created. Based on this strategy, the first drug-phenolic acid nutraceutical cocrystal of AMH with FLA, namely AMH-FLA-H2O, was successfully assembled and completely characterized by employing single-crystal X-ray diffraction and other analytical techniques. The cocrystal was revealed to be composed of AMH, FLA, and water molecules in the ratio of 3 : 1 : 1.5, and charge-assisted hydrogen bonds containing chloride ions crucially maintained the crystal lattice together with water molecules. The in vitro/in vivo properties of the cocrystal were systematically evaluated via both theoretical and experimental methods, and the results indicate that the dissolubility of AMH is down-regulated by two-thirds in the cocrystal, resulting in its potential for sustained pharmacokinetic release and the elimination of the adverse effects of AMH. More importantly, the enhanced antiviral effects of the current cocrystal were proven against four viral strains, and the pharmaceutical synergy between AMH and FLA was realized with a combination index (CI) of less than 1. Thus, the present work provides a novel crystalline product with bright commercial prospect for the classical antiviral drug AMH and also establishes an avenue for the synergetic antiviral application of nutraceutical phenolic acids via the cocrystallization strategy of dual optimization.

Fabrication of Carbamazepine Cocrystals: Characterization, In Vitro and Comparative In Vivo Evaluation

Carbamazepine (CBZ) is an antiepileptic drug having low bioavailability due to its hydrophobic nature. In the current study, efforts are made to investigate the effect of dicarboxylic acid coformer spacer groups (aliphatic chain length) on physicochemical properties, relative humidity (RH) stability, and oral bioavailability of CBZ cocrystals. Slurry crystallization technique was employed for the preparation of CBZ cocrystals with the following coformers: adipic (AA), glutaric (GA), succinic (SA), and malonic acid (MA). Powder X-ray diffractometry and Fourier-transform infrared spectroscopy confirmed cocrystal preparation. Physicochemical properties, RH stability, and oral bioavailability of cocrystals were investigated. Among the prepared cocrystals, CBZ-GA showed maximum solubility as well as improved dissolution profile (CBZ-GA > CBZ-MA > CBZ-AA > pure CBZ > CBZ-SA) in ethanol. Maximum RH stability was shown by CBZ-AA, CBZ-SA, and CBZ-MA. In vivo studies confirmed boosted oral bioavailability of cocrystals compared to pure CBZ. Furthermore, in vivo studies depicted the oral bioavailability order of cocrystals as CBZ-GA > CBZ-MA > Tegral® > CBZ-AA > CBZ-SA > pure CBZ. Thus, pharmaceutical scientists can effectively employ cocrystallization technique for tuning physicochemical properties of hydrophobic drugs to achieve the desired oral bioavailability. Overall, results reflect no consistent effect of spacer group on physicochemical properties, RH stability, and oral bioavailability of cocrystals.

Taming the dynamics in a pharmaceutical by cocrystallization: investigating the impact of the coformer by solid-state NMR

The anti-HIV pharmaceutical efavirenz is highly dynamic in its crystalline state, and we show that these dynamics can be tamed through the introduction of a coformer.

Investigation of the Structure and Dynamics of Antiviral Drug Adefovir Dipivoxil by Site-Specific Spin-Lattice Relaxation Time Measurements and Chemical Shift Anisotropy Tensor Measurements

Adefovir is regarded as a potential antiviral agent. However, it cannot be considered as a valuable drug candidate due to its high polarity that limits its permeability across the human intestinal mucosa. When the ribose phosphate group of adefovir is replaced by the isopolar phosphonomethyl ether functionality, it neutralizes the negative charge of the drug. This makes the drug lipid-soluble and potent to diffuse across the cell membrane. The prodrug adefovir dipivoxil is regarded as a potent antiviral drug against hepatitis B virus (HBV), human immunodeficiency virus (HIV), Rauscher murine leukemia virus (R-MuLV), murine cytomegalovirus (MCMV), herpes simplex virus (HSV), simian immunodeficiency virus (SIV), and feline immunodeficiency virus (FIV). The correlation between the structure and the dynamics of adefovir dipivoxil is determined by measuring the principal components of chemical shift anisotropy (CSA) tensor, site-specific spin-lattice relaxation time, and molecular correlation time at crystallographically different carbon nuclei sites. The CSA parameters, spin-lattice relaxation time, and molecular correlation time of phosphorous nucleus of the organophosphate group of adefovir dipivoxil molecule are also determined. The spin-lattice relaxation time of carbon nuclei varies from 1 to 107 s. The range of molecular correlation time also varies from 10-4 to 10-8 s. These remarkable diversities of motional dynamics of the molecules imply that there exist various motional degrees of freedom within this valuable drug and these motional degrees of freedom are independent of each other, which may be the reason for the biological activities exhibited by the drug. The correlation between structure and dynamics of such an important antiviral drug adefovir dipivoxil can be visualized by these types of extensive spectroscopic measurements, which will enlighten the path of inventing advanced medicine in the pharmaceutical industry, and it will also illuminate the understanding of the structure-activity relationships of antiviral drug.

Quality by Design Optimization of Cold Sonochemical Synthesis of Zidovudine-Lamivudine Nanosuspensions

Lamivudine (3TC) and zidovudine (AZT) are antiviral agents used to manage HIV/AIDS infection. The compounds require frequent dosing, exhibit unpredictable bioavailability and a side effect profile that includes hepato- and haema-toxicity. A novel pseudo one-solvent bottom-up approach and Design of Experiments using sodium dodecyl sulphate (SDS) and α-tocopheryl polyethylene glycol succinate 1000 (TPGS 1000) to electrosterically stablize the nano co-crystals was used to develop, produce and optimize 3TC and AZT nano co-crystals. Equimolar solutions of 3TC in surfactant dissolved in de-ionised water and AZT in methanol were rapidly injected into a vessel and sonicated at 4 °C. The resultant suspensions were characterized using a Zetasizer and the particle size, polydispersity index and Zeta potential determined. Optimization of the nanosuspensions was conducted using a Central Composite Design to produce nano co-crystals with specific identified and desirable Critical Quality Attributes including particle size (PS) < 1000 nm, polydispersity index (PDI) < 0.500 and Zeta potential (ZP) < −30mV. Further characterization was undertaken using Fourier Transform infrared spectroscopy, energy dispersive X-ray spectroscopy, differential scanning calorimetry, powder X-ray diffraction and transmission electron microscopy. In vitro cytotoxicity studies revealed that the optimized nano co-crystals reduced the toxicity of AZT and 3TC to HeLa cells.

A Comparative Study of the Effect of Different Stabilizers on the Critical Quality Attributes of Self-Assembling Nano Co-Crystals

Lamivudine (3TC) and zidovudine (AZT) are antiviral agents used orally to manage HIV/AIDS infection. A pseudo one-solvent bottom-up approach was used to develop and produce nano co-crystals of 3TC and AZT. Equimolar amounts of 3TC dissolved in de-ionized water and AZT in methanol were rapidly injected into a pre-cooled vessel and sonicated at 4 °C. The resultant suspensions were characterized using a Zetasizer. The particle size, polydispersity index and Zeta potential were elucidated. Further characterization was undertaken using powder X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and energy dispersive X-ray spectroscopy scanning electron microscopy. Different surfactants were assessed for their ability to stabilize the nano co-crystals and for their ability to produce nano co-crystals with specific and desirable critical quality attributes (CQA) including particle size (PS) < 1000 nm, polydispersity index (PDI) < 0.500 and Zeta potential (ZP) < -30 mV. All surfactants produced co-crystals in the nanometer range. The PDI and PS are concentration-dependent for all nano co-crystals manufactured while only ZP was within specification when sodium dodecyl sulfate was used in the process.

Exploring the novel green eutectic solvent for the synthesis of 4-hydroxy-2-methyl-N-2-pyridinyl-2H-1,2,-benzothiazine-3-carboxamide 1,1-dioxide with benzoic acid cocrystal using a co-grinding technique

In the present study, the suitability of a green eutectic solvent, a mixture of menthol and camphor for cocrystal synthesis has been investigated to improve the biopharmaceutical properties of poorly water-soluble drugs.

Solid-State Quantification of Cocrystals in Pharmaceutical Tablets Using Transmission Low-Frequency Raman Spectroscopy

To enable the continuous production of cocrystal-containing pharmaceutical tablets, guaranteeing the cocrystal content of the final pharmaceutical tablets in the solid state is critical. This study demonstrates the quantification of caffeine-glutaric acid cocrystals in model tablets using transmission low-frequency Raman spectroscopy. Although distinguishing between cocrystals and raw materials using conventional Raman spectroscopy is difficult, the use of low-frequency Raman spectroscopy enables the discrimination of cocrystals and raw materials. Low-frequency Raman spectra were analyzed by the partial least-squares method (PLS) to obtain the predicted contents in the model tablets. To evaluate the quantitative ability of this method, the root means square error of cross-validation (RMSECV) was determined by comparing the actual concentration and predicted content with a calibration curve. For cocrystal-containing tablets, the quantitative ability of the transmission mode (RMSECV = 2.06- 3.17) was 13.4-31.4% higher than that of the backscattering mode (RMSECV= 2.37- 3.91). The coexistence of raw crystalline materials did not affect the quantitative ability for cocrystals.

Desolvation behavior of indinavir sulfate ethanol and follow-up by terahertz spectroscopy

Active pharmaceutical ingredients are composed of single-component or multicomponent crystals. Multicomponent crystals include salts, co-crystals, and solvates. Indinavir sulfate is the ethanol solvate form of indinavir that is known to deliquesce through moisture absorption. However, the detailed behavior of solvent molecules in the crystal has not been investigated. In this study, we studied the desolvation mechanism of indinavir sulfate ethanol and investigated the behavior of solvent molecules in the solid from. Indinavir sulfate ethanol contained 1.7 molecules of ethanol, 0.7 of which desolvated at room temperature. They were originally two ethanol solvent molecules; one molecule of ethanol desolvated at room temperature, and the conformation of the remaining ethanol and t-butyl groups changed in conjunction with the removal of one ethanol molecule. Desolvation could hardly be detected by powder X-ray diffraction; however, it was detected using terahertz spectroscopy. Terahertz measurement of desolvation showed a high correlation with thermogravimetry data, suggesting that desolvation could be observed non-destructively using terahertz spectroscopy. We concluded that indinavir sulfate 1 ethanol deliquesced at 60% relative humidity, and it turned into an amorphous solid after drying.

Synthesis, Crystal Structure, and Solubility Analysis of a Famotidine Cocrystal

A novel cocrystal of the potent H2 receptor antagonist famotidine (FMT) was synthesized with malonic acid (MAL) to enhance its solubility. The cocrystal structure was characterized by X-ray single crystal diffraction, and the asymmetry unit contains one FMT and one MAL connected via intermolecular hydrogen bonds. The crystal structure is monoclinic with a P21/n space group and unit cell parameters a = 7.0748 (3) Å, b = 26.6502 (9) Å, c = 9.9823 (4) Å, α = 90, β = 104.2228 (12), γ = 90, V = 1824.42 (12) Å3, and Z = 4. The cocrystal had unique thermal, spectroscopic, and powder X-ray diffraction (PXRD) properties that differed from FMT. The solubility of the famotidine-malonic acid cocrystal (FMT-MAL) was 4.2-fold higher than FMT; the FAM-MAL had no change in FMT stability at high temperature, high humidity, or with illumination.

Naringenin Cocrystals Prepared by Solution Crystallization Method for Improving Bioavailability and Anti-hyperlipidemia Effects

Naringenin exerts anti-inflammatory, hypolipidemic, and hepatoprotective effects; however, it shows low oral bioavailability because of poor water solubility. In this work, cocrystals of naringenin were formed to address these issues. Using the solution crystallization method, various naringenin cocrystals were prepared with different cocrystal coformers, including naringenin-nicotinamide, naringenin-isonicotinamide, naringenin-caffeine, naringenin-betaine, and naringenin-L-proline. The formation of these cocrystals was assayed by using DSC, XRD, and FT-IR spectroscopy. The stoichiometric ratio of naringenin and the CCFs in the corresponding cocrystals was investigated by NMR. The solubility of naringenin, as well as its dissolution rate, was markedly improved by forming cocrystals. The oral bioavailability of naringenin administered as naringenin-L-proline and naringenin-betaine cocrystals was achieved significantly greater than that of pure naringenin (p < 0.05). In particular, the C_max of naringenin-L-proline and naringenin-betaine cocrystals were 2.00-fold and 3.35-fold higher, and the AUC of naringenin-L-proline and naringenin-betaine cocrystals were 2.39-fold and 4.91-fold, respectively, higher than pure naringenin in rats. With the naringenin-betaine cocrystals for oral delivery, the drug distribution in the liver was significantly increased compared to pure naringenin. Accordingly, the naringenin-betaine cocrystals showed improved anti-hyperlipidemia effects on the C57 BL/6J PNPLA3 I148M transgenic mouse hyperlipidemia model. Collectively, cocrystal formation is a promising way to increase the bioavailability of naringenin for treating hyperlipidemia.

Preparation and Characterization of Novel Pharmaceutical Co-Crystals: Ticagrelor with Nicotinamide

Two new co-crystals, Ticagrelor with Nicotinamide, have been prepared with improved solubility. Because Ticalegor has a poor solubility and dissolution rate, a novel co-crystallization method with structurally homogenous crystalline material, an active pharmaceutical ingredient (API), and co-former indefinite stoichiometric amount has been made to improve Ticagrelor’s solubility. The co-crystal of Ticagrelor (TICA) with Nicotinamide (NCA) was prepared in ratio (1:1) and confirmed by FTIR, DSC, and XRD characterization. Furthermore, the single crystal structure of TICA-NCA hydrate was analyzed. The solubility of co-crystals was investigated in pH 2 acidic medium, which was a significant improvement as compared to the solubility of a free drug. The in vitro dissolution rate of co-crystal was larger than that of the commercial product.

Practical guidelines for the characterization and quality control of pure drug nanoparticles and nano-cocrystals in the pharmaceutical industry

The number of poorly soluble drug candidates is increasing, and this is also seen in the research interest towards drug nanoparticles and (nano-)cocrystals; improved solubility is the most important application of these nanosystems. In order to confirm the functionality of these nanoparticles throughout their lifecycle, repeatability of the formulation processes, functional performance of the formed systems in pre-determined way and system stability, a thorough physicochemical understanding with the aid of necessary analytical techniques is needed. Even very minor deviations in for example particle size or size deviation in nanoscale can alter the product bioavailability, and the effect is even more dramatic with the smallest particle size fractions. Also, small particle size sets special requirements for the analytical techniques. In this review most important physicochemical properties of drug nanocrystals and nano-cocrystals are presented, suitable analytical techniques, their pros and cons, are described with the extra input on practical point of view.

Selection of effective cocrystals former for dissolution rate improvement of active pharmaceutical ingredients based on lipoaffinity index

New theoretical screening procedure was proposed for appropriate selection of potential cocrystal formers possessing the ability of enhancing dissolution rates of drugs. The procedure relies on the training set comprising 102 positive and 17 negative cases of cocrystals found in the literature. Despite the fact that the only available data were of qualitative character, performed statistical analysis using binary classification allowed to formulate quantitative criterions. Among considered 3679 molecular descriptors the relative value of lipoaffinity index, expressed as the difference between values calculated for active compound and excipient, has been found as the most appropriate measure suited for discrimination of positive and negative cases. Assuming 5% precision, the applied classification criterion led to inclusion of 70% positive cases in the final prediction. Since lipoaffinity index is a molecular descriptor computed using only 2D information about a chemical structure, its estimation is straightforward and computationally inexpensive. The inclusion of an additional criterion quantifying the cocrystallization probability leads to the following conjunction criterions H_mix<-0.18 and ΔLA>3.61, allowing for identification of dissolution rate enhancers. The screening procedure was applied for finding the most promising coformers of such drugs as Iloperidone, Ritonavir, Carbamazepine and Enthenzamide.

Preparation and characterization of adefovir dipivoxil-stearic acid cocrystal with enhanced physicochemical properties

The objectives of this study were to prepare cocrystal composed of adefovir dipivoxil (AD) and stearic acid (SA) and to investigate the enhanced properties of the cocrystal. The cocrystal was prepared by antisolvent precipitation and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRPD), and differential scanning calorimetry (DSC). The enhanced properties were evaluated by dissolution testing, permeability studies, and powder rheology analysis. The AD raw material has a cuboid-like crystal and the cocrystal has a needle shape. In the FT-IR study, there were bathochromic shifts caused by the hydrogen bonding. The melting point of the cocrystal was 52.9 °C, which was lower than that of AD. The XRPD pattern also had distinct differences, supporting the formation of a new crystalline form. The cocrystal showed changes in the lattice energy and the solvation strength, which caused an enhanced dissolution. The permeability was increased due to the SA, which acts as a P-gp inhibitor. The tabletability was enhanced due to the altered crystal habit. In conclusion, cocrystal containing AD and SA was successfully prepared, presenting advantages such as enhanced solubility, tabletability, and permeability. The use of the cocrystal is a desirable approach for the improved physicochemical properties.

Development of a pharmaceutical cocrystal with solution crystallization technology: Preparation, characterization, and evaluation of myricetin-proline cocrystals

Myricetin shows low oral bioavailability (<10%) in rats due to poor aqueous solubility, although it has demonstrated various pharmacological activities such as those related to anticancer, anti-diabetes, and hepatic protection. To overcome this issue, in this study, pharmaceutical cocrystals were designed to efficiently deliver myricetin by oral administration. A 1:2 stoichiometric cocrystal of myricetin with proline was prepared successfully by solution crystallization based on the ternary phase diagram (TPD) principle, and it is presented as a new sphericity-like crystalline phase characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The formation of myricetin-proline cocrystals was a spontaneous and exothermic process, probably due to the supramolecular interactions between themselves, which were determined by Fourier transform-infrared spectroscopy (FT-IR). Consequently, the dissolution efficiency of myricetin from cocrystals was increased 7.69-fold compared with that of coarse myricetin, and the oral bioavailability of myricetin cocrystals in rats was enhanced by approximately 3.03 times compared with that of pure myricetin. The present study provides useful information for the potential application of cocrystal technology for water-insoluble drugs, especially flavonoid compounds.

Cocrystals to facilitate delivery of poorly soluble compounds beyond-rule-of-5

Besides enhancing aqueous solubilities, cocrystals have the ability to fine-tune solubility advantage over drug, supersaturation index, and bioavailability. This review presents important facts about cocrystals that set them apart from other solid-state forms of drugs, and a quantitative set of rules for the selection of additives and solution/formulation conditions that predict cocrystal solubility, supersaturation index, and transition points. Cocrystal eutectic constants are shown to be the most important cocrystal property that can be measured once a cocrystal is discovered, and simple relationships are presented that allow for prediction of cocrystal behavior as a function of pH and drug solubilizing agents. Cocrystal eutectic constant is a stability or supersatuation index that: (a) reflects how close or far from equilibrium a cocrystal is, (b) establishes transition points, and (c) provides a quantitative scale of cocrystal true solubility changes over drug. The benefit of this strategy is that a single measurement, that requires little material and time, provides a principled basis to tailor cocrystal supersaturation index by the rational selection of cocrystal formulation, dissolution, and processing conditions.

Multicomponent Crystal Systems of Known Antimalarial Drug Molecules

Potential drug molecules are often discarded due to poor physicochemical properties and pharmacokinetic profiles. As such, research into the use of multicomponent crystal systems (such as salts and co-crystals) is currently being conducted with the aim of improving the properties of the molecule, without altering the bioactivity of the drug. Although numerous studies have been performed on a wide variety of drug molecules, research with antimalarial drug molecules seems to have been neglected. With many of the current drugs becoming inactive due to resistance, there is an urgent need to find effective drugs with good pharmacokinetic profiles. The objective of this review is therefore to determine the extent to which multicomponent crystal systems have been used in antimalarial chemotherapy and whether this method provides a viable alternative to discarding potential drug candidates.

Saccharin salts of biologically active hydrazone derivatives

Crystal structures, solubility and formation thermodynamics of saccharin salts with biologically active hydrazone derivatives were investigated.

Continuous engineering of nano-cocrystals for medical and energetic applications

Cocrystals, solid mixtures of different molecules on molecular scale, are supposed to be tailor made materials with improved employability compared to their pristine individual components in domains such as medicine and explosives. In medicine, cocrystals are obtained by crystallization of active pharmaceutical ingredients with precisely chosen coformers to design medicaments that demonstrate enhanced stability, high solubility, and therefore high bioavailability and optimized drug up-take. Nanoscaling may further advance these characteristica compared to their micronsized counterparts – because of a larger surface to volume ratio of nanoparticles. In the field of energetic materials, cocrystals offer the opportunity to design smart explosives, combining high reactivity with significantly reduced sensitivity, nowadays essential for a safe manipulation and handling. Furthermore, cocrystals are used in ferroelectrics, non-linear material response and electronic organics. However, state of the art batch processes produce low volume of cocrystals of variable quality and only have produced micronsized cocrystals so far, no nano-cocrystals. Here we demonstrate the continuous preparation of pharmaceutical and energetic micro- and nano-cocrystals using the Spray Flash Evaporation process. Our laboratory scale pilot plant continuously prepared up to 8 grams per hour of Caffeine/Oxalic acid 2:1, Caffeine/Glutaric acid 1:1, TNT/CL-20 1:1 and HMX/Cl-20 1:2 nano- and submicronsized cocrystals.