Investigation of the Storage and Stability as Well as the Dissolution Rate of Novel Ilaprazole/Xylitol Cocrystal.

Reflux esophagitis, a treatment for gastric ulcers known as Ilaprazole (Ila), is not stable during storage and handling at room temperature, requiring storage at 5 degrees Celsius. In this study, to address these issues with Ila, coformers rich in oxygen (O) and hydroxyl (OH) groups capable of forming hydrogen bonds with were selected. These coformers included Xylitol (Xyl), Meglumine (Meg), Nicotinic acid (Nic), L-Aspartic acid (Asp), and L-Glutamic acid (Glu). A 1:1 physical mixture of Ila and each coformer was prepared, and the potential for cocrystal formation was predicted using differential scanning calorimetry (DSC) screening. The results indicated the potential for cocrystal formation in the Ila/Xyl physical mixture. Subsequently, Ila and Xyl were mixed in ethyl acetate (EA) in a 1:1 ratio, and after 28 h of slurry, the formation of Ila/Xyl cocrystal was confirmed through solid-state CP/MAS 13C NMR spectrum analysis, showing intermolecular hydrogen bonding and conformational changes. Furthermore, the 1:1 ratio of Ila/Xyl cocrystal was confirmed through solution-state NMR (1H, 13C, and 2D) molecular structure analysis. To assess the stability of Ila/Xyl cocrystal at room temperature, it was stored and compared with Ila at 25 ± 2 °C and relative humidity (RH) of 65 ± 5% over three months. The results showed that the purity of Ila/Xyl cocrystal remained at 99.8% from the initial purity of 99.75% over the three months, while Ila was predicted to decrease from an initial 99.8% purity to 90% after three months. Additionally, at 25 ± 2 °C and RH 65 ± 5%, a specific impurity B in Ila/Xyl cocrystal was observed to be 0.03% over three months, whereas Ila was predicted to increase from an initial 0.032% to 2.28% after three months. To evaluate the dissolution rate of Ila/Xyl cocrystal, a formulation was prepared and compared with Ila at pH 10, with a dosage equivalent to 10 mg of Ila. The results showed that Ila/Xyl cocrystal reached 55% within 15 min and 100% within 45 min, while Ila was predicted to reach 32% at 15 min and 100% only after 60 min. However, overall, the Ila/Xyl cocrystal showed results equivalent to or exceeding the dissolution rate of Ila. Therefore, it is predicted that the Ila/Xyl cocrystal will maximize its effectiveness as a more convenient crystal structure for formulation development, allowing storage and preservation at room temperature without the need for the problematic 5 °C refrigeration during ambient conditions and storage, addressing the issues associated with Ila.

Rapid and Efficient Separation of Decursin and Decursinol Angelate from Angelica gigas Nakai using Ionic Liquid, (BMIm)BF4, Combined with Crystallization.

Ionic liquids (ILs) have gained much attention as alternative solvents to volatile organic solvents due to their attractive properties. This study aimed to develop an efficient method for the selective separation of decursin (D) and decursinol angelate (DA) from Angelica gigas Nakai (A. gigas) using ILs and crystallization. The IL 1-butyl-3-methylimidazolium tetrafluoroborate ((BMIm)BF4) was the most efficient at extracting D and DA. Parameters including solid-to-liquid ratio, time, and temperature were optimized by response surface methodology (RSM). Under optimal extraction conditions (1 g/6.5 mL solid-to-liquid ratio, 60 °C temperature, and 120 min time), the extraction yields of D and DA were 43.32 mg/g (97.06%) and 17.87 mg/g (97.12%), respectively. Moreover, drowning out crystallization using deionized water (DW) as an anti-solvent offered an excellent ability to recover D and DA from the A. gigas-(BMIm)BF4 extraction solution. The rates of recovery and the total purity of D and DA were found to be greater than 97%. Therefore, a rapid and efficient method of combining ILs with crystallization was effectively achieved for the selective separation of D and DA. This approach is assumed to be beneficial in the pharmaceutical industry for the effective obtention of D- and DA-enriched products.

Kinetics of the Solution-Mediated Polymorphic Transformation of the Novel l-Carnitine Orotate Polymorph, Form-II.

Research studies related to the polymorphs of l-Carnitine orotate (CO), a medication used for the treatment and prevention of liver diseases, are insignificant or almost nonexistent. Accordingly, in the present study, l-Carnitine orotate (CO) was prepared for investigating CO polymorphs. Here, a reactive crystallization was induced by reacting 1g of l-Carn (1 equivalent) and 0.97 g of OA (1 equivalent) in methanol (MeOH); as a result, CO form-I and CO form-II polymorphs were obtained after 1 h and 16 h of stirring, respectively. The characterization of CO polymorphs was carried out utilizing Powder X-ray diffraction (PXRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and solid-state Nuclear Magnetic Resonance Spectroscopy (solid-state CP/MAS 13C-NMR). The solution-mediated polymorphic transformation (SMPT) of CO polymorphs was investigated in MeOH at controlled temperature and fixed rotational speed. The results revealed that CO form-I is a metastable polymorph while CO form-II is a stable polymorph. From the same results, it was confirmed that CO form-I was converted to CO form-II during the polymorphic phase transformation process. Moreover, it was assessed that the increase in temperature and supersaturation level significantly promotes the rate of nucleation, as well as the rate of mass transfer of CO form-II. In addition, nucleation and mass transfer equations were employed for the quantitative determination of SMPT experimental results. Lastly, it was suggested that CO form-II was more thermodynamically stable than CO form-I and that both polymorphs belong to the monotropic system.

Co-Amorphous Screening for the Solubility Enhancement of Poorly Water-Soluble Mirabegron and Investigation of Their Intermolecular Interactions and Dissolution Behaviors.

In the present study, the screening of Mirabegron (MBR) co-amorphous was performed to produce water-soluble and thermodynamically stable MBR co-amorphous with the purpose of overcoming the water solubility problem of MBR. MBR is Biopharmaceutics Classification System (BCS) class II drug used for the treatment of an overreactive bladder. The co-amorphous screening was carried out by means of the vacuum evaporation crystallization technique in methanol solvent using three water-soluble carboxylic acids, characterized by a pKa difference greater than 3 with MBR such as fumaric acid (FA), l-pyroglutamic acid (PG), and citric acid (CA). Powder X-ray diffraction (PXRD) results suggested that all solid materials produced at MBR-FA (1 equivalent (eq.)/1 equivalent (eq.)), MBR-PG (1 eq./1 eq.), and MBR-CA (1 eq./1 eq.) conditions were amorphous state solid materials. Furthermore, by means of solution-state nuclear magnetic resonance (NMR) (¹H, 13C, and 2D) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, we could assess that MBR and carboxylic acid molecules were linked via ionic interactions to produce MBR co-amorphous. Besides, solid-state cross polarization (CP)/magic angle spinning (MAS) 13C-NMR analysis was conducted for additional assessment of MBR co-amorphous. Afterwards, dissolution tests of MBR co-amorphouses, MBR crystalline solid, and MBR amorphous were carried out for 12 h to evaluate and to compare their solubilities, dissolution rates, and phase transformation phenomenon. Here, the results suggested that MBR co-amorphouses displayed more than 57-fold higher aqueous solubility compared to MBR crystalline solid, and PXRD monitoring result suggested that MBR co-amorphouses were able to maintain their amorphous state for more than 12 h. The same results revealed that MBR amorphous exhibited increased solubility of approximatively 6.7-fold higher compared to MBR crystalline solid. However, the PXRD monitoring result suggested that MBR amorphous undergo rapid phase transformation to crystalline form in just 35 min and that within an hour all MBR amorphous are completely converted to crystalline solid. Accordingly, the increase in MBR co-amorphous' solubility was attributed to the presence of ionic interactions in MBR co-amorphous molecules. Moreover, from the differential scanning calorimetry (DSC) monitoring results, we predicted that the high glass transition temperature (Tg) of MBR co-amorphous compared to MBR amorphous was the main factor influencing the phase stability of MBR co-amorphous.

Crystal Structure Analysis of the First Discovered Stability-Enhanced Solid State of Tenofovir Disoproxil Free Base Using Single Crystal X-ray Diffraction.

Tenofovir disoproxil (TD), an anti-virus drug, is currently marketed under its most stable form, Form-I of Tenofovir disoproxil fumarate (TDF). However, studies regarding the properties of TD free base crystal as a promising drug as well as its crystal structure have not yet been reported. This assumption was made because TD free base is not directly produced in a solid form during the manufacturing process. TD free base is first obtained in an oil form, and is then synthesized into TDF crystal. In this regard, the present study was conducted to investigate both the potentiality of TD free base to be an active pharmaceutical ingredient (API) and its crystal structure. Here, TD free base solid was produced by means of drowning-out crystallization. Next, single crystal X-ray diffraction (SXD) was employed to determine the crystal structure. Powder X-ray diffraction (PXRD) and a differential scanning calorimetry (DSC) analysis were performed to evaluate the crystal's properties. Furthermore, experiments were carried out at 15%, 35%, 55%, 75%, and 95% relative humidity (RH) for 12 h using a hygroscopic tester to determine and to compare the hygroscopicity and stability of TD free base with TDF crystal. Additionally, experiments were conducted under accelerated (40 °C, RH 75%) and stress storage (60 °C, RH 75%) conditions for 30 days to investigate the changes in purity and the formation of dimer. In this work, we report that TD free base possesses lower hygroscopicity, and thus does not generate dimer impurity from hydrolysis. Primarily, this is attributed to the fact that TD free base is not an easily ionized salt but comprises neutral hydrophobic molecules. According to the structural properties, the improved hygroscopic property of the TD free base crystal was due to the decrease of crystal polarity owing to the intermolecular H-bonds present in TD free base rings. In addition, the solubility investigation study carried out in aqueous solution and at gastrointestinal pH revealed a similarity in TDF and TD free base solubility under the mentioned conditions. Accordingly, we could confirm the potentiality of TD free base as an active pharmaceutical ingredient.

Application of ionic liquid to polymorphic transformation of anti-viral/HIV drug adefovir dipivoxil.

Ionic liquids (ILs) are defined as salts with a melting point below 100 °C. ILs have received increasing attention as new alternative to organic solvents because of their unique physicochemical properties. Therefore, this study was conducted in the purpose to present the efficacy of ILs as new solvents capable to control the Polymorphic transformation phenomenon. Here, the polymorphic transformation phenomenon of adefovir dipivoxil, an efficient antiviral active pharmaceutical ingredient on human immunodeficiency virus, was investigated. The phase transformation phenomenon from the metastable polymorph, new form (NF) to the stable polymorph, Form-X in 1-allyl-3-ethylimidazolium tetrafluoroborate (AEImBF4) and 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (BDMImBF4) ILs solutions was observed utilizing the solvent-mediated phase transformation method The thermodynamic factors, AEImBF4/BDMImBF4 solvent composition ratio of 3:7-6:4 and the temperature in range of 25-100 °C, as well as the dynamic factor, the rational speed in range of 300-1000 rpm were parameters studied in this experiment. The thermodynamic and dynamic equations involving nucleation and mass transfer were applied for the quantitative analysis. The result of the present study confirmed the use of ILs as substitute solvent for volatile organic solvents, and demonstrated the efficacy of ILs as potential solvent-media to control the polymorphic transformation.

Polymorphic and kinetic investigation of adefovir dipivoxil during phase transformation.

To search polymorphs of adefovir dipivoxil (AD), the polymorphic transformation approach in solution was developed. Also, the kinetics of polymorphic transformation was investigated to effectively control polymorphs. The AD crystals were obtained by crystallization at -10°C, and then the polymorphic transformation was induced by raising temperature. The polymorphs of AD were confirmed using DSC, XRD and solubility analyses. The polymorphic fraction during transformation was monitored for kinetic investigation. Via polymorphic transformation in solution, four polymorphs of AD were found and two of them were new (NF-I, NF-II). The DSC analysis revealed that solvate form (NF-I) was changed to form-V in solid state, and then re-crystallized to NF-II at 93°C, and finally became form-I at 97°C. This serial change of polymorphs in DSC was identical to polymorphic transformation sequence in solution. The kinetic rates of polymorphic transformation described by nucleation and mass transfer theories were well matched with experimental measurement. The polymorphic transformation approach was effective to search polymorphs of which the structure was changed to the other one in the solution. The kinetic information of polymorphic transformation predicted by Volmer's nucleation model and Stokes-Einstein diffusion equation was valuable for exact control of polymorphic purity.