A novel drug–drug coamorphous system without molecular interactions: improve the physicochemical properties of tadalafil and repaglinide

Coamorphous systems of rebamipide: Selection of amino acid coformers based on protein-ligand docking, in vitro assessment and study of interactions by computational and multivariate analysis

Three coamorphous systems of Rebamipide (REB) with the amino acids namely, Tryptophan (TRP), Phenylalanine (PHE) and Arginine (ARG) are reported. A unique approach for the virtual screening of amino acid coformers is presented by employing molecular docking studies based on interactions of the drug molecule with various amino acid fragments in the drug-receptor cocrystal structure. Successful formation of stable coamorphous systems with ARG, TRP and PHE served as the proof-of-concept along with negative benchmarking standards Histidine and Aspartic acid, wherein coamorphous systems could not be obtained despite multiple trials which resulted in crystalline physical mixtures. The coamorphous systems were characterized by a halo pattern in Powder XRD and a single glass transition temperature (Tg) in modulated DSC. Physical stability assessments of the coamorphous systems showed direct correlation of Tg with the observed stability of the amorphous phase which was found in the order ARGREB > TRPREB ≥ PHEREB. To determine the specific functional groups engaged in the interactions, multivariate analysis was performed on the FTIR spectra. These interactions were further validated by DFT and QTAIM analysis, which revealed key noncovalent interactions in the three coamorphous systems. All three coamorphous systems showed excellent release profiles of the API as demonstrated by the f2 and DE parameters in the order ARGREB ≥ TRPREB > PHEREB ≥ amorphous drug, far exceeding that of the crystalline drug. The interplay of multivariate analysis and QTAIM can be useful in estimating the interactions within the coamorphous systems which can further contribute to stability and physicochemical properties of the systems.

Pharmaceutical cocrystals: a rising star in drug delivery applications

Pharmaceutical cocrystals, owing to their manifold applications, are acting as bridge between drug discovery and pharmaceutical product development. The ability to scale up pharmaceutical cocrystals through continuous manufacturing approaches offers superior and economic pharmaceutical products. Moreover, cocrystals can be an aid for the nanoparticulate systems to solve the issues related to scale-up and cost. Cocrystals grabbed attention of academic researchers and pharmaceutical scientist due to their potential to target various diseases like cancer. The present review is mainly focussed on the diverse and comprehensive applications of pharmaceutical cocrystals in drug delivery including solubility and dissolution enhancement, improvement of bioavailability of drug, mechanical and flow properties of active pharmaceutical ingredients, controlled/sustained release and colour tuning of API. Besides, phytochemical based cocrystals, multi-drug cocrystals and cocrystals for tumour therapy have been discussed in this review. Additionally, recent progress pertinent to pharmaceutical cocrystals is also included, which may provide future directions to manufacturing and scale-up of cocrystals.

Recent advances in dual-drug co-amorphous systems

Poor solubility of drugs and therapeutic candidates poses a significant challenge in drug research and development. Biopharmaceutical class II drugs exhibit limited absorption because of their weak solubility and high permeability. Co-amorphous systems (CAMs) have been studied widely as a way to improve the solubility of drugs. This review summarizes recent advancements in dual-drug CAMs, including improvements in formulation, manufacturing, and solid-state characterization, and highlights the importance of enhancing solubility and stability. It emphasizes the potential synergistic effects of two drugs in CAMs and explores formulation strategies and challenges related to maintaining the amorphous state. Case studies demonstrate the successful application of CAMs in combination therapies that offer improved therapeutic efficacy.

Drug-drug co-amorphous systems: An emerging formulation strategy for poorly water-soluble drugs

Overcoming the poor water solubility of small-molecule drugs is a major challenge in the development of clinical pharmaceuticals. Amorphization of crystalline drugs is a highly effective strategy to improve their aqueous solubility. However, amorphous drugs are thermodynamically unstable and likely to crystallize during manufacturing and storage. Recently, drug-drug co-amorphous systems have emerged as a novel strategy to not only enable enhanced dissolution and physical stability of the individual drugs within the system but also to provide a strategy for combination therapy of the same or different clinical indications. This review serves to highlight advances in the methods used to manufacture and characterize drug-drug co-amorphous systems, summarize drug-drug co-amorphous applications reported in recent decades, and provide an outlook on future possibilities and perspectives.

Molecular complexes of drug combinations: A review of cocrystals, salts, coamorphous systems and amorphous solid dispersions

As the advancements in the medical technology and healthcare develop through the years, combinational therapy has evolved to be an important treatment modality in many disease settings, including cancer, cardiovascular disease and infectious diseases. In an effort to alleviate "pill burden" and improve patient compliance, fixed dose combinations (FDCs) have been developed to be used as effective therapeutics. Among all FDCs, the category of drug-drug molecular complexes has been proven an efficient methodology in designing and treating diseases, with many drugs being approved. Among all drug-drug molecular complexes, drug-drug cocrystals, salts, coamorphous systems and solid dispersions have been successfully developed and many have been approved by the FDA. In this review, we dwell deeply into the molecular mechanisms behind the different types of drug-drug molecular complexes, including the key functional groups involved in the intermolecular interactions, the applications of each category of molecular complexes, as well as the advantages and challenges thereof. This comprehensive review provides useful insights into the practical design and manufacture of drug-drug molecular complexes and points out the future direction for the development of new advantageous combinational therapies that benefit more patients.

Recent Advances in Co-Former Screening and Formation Prediction of Multicomponent Solid Forms of Low Molecular Weight Drugs

Multicomponent solid forms of low molecular weight drugs, such as co-crystals, salts, and co-amorphous systems, are a result of the combination of an active pharmaceutical ingredient (API) with a pharmaceutically acceptable co-former. These solid forms can enhance the physicochemical and pharmacokinetic properties of APIs, making them increasingly interesting and important in recent decades. Nevertheless, predicting the formation of API multicomponent solid forms in the early stages of formulation development can be challenging, as it often requires significant time and resources. To address this, empirical and computational methods have been developed to help screen for potential co-formers more efficiently and accurately, thus reducing the number of laboratory experiments needed. This review provides a comprehensive overview of current screening and prediction methods for the formation of API multicomponent solid forms, covering both crystalline states (co-crystals and salts) and amorphous forms (co-amorphous). Furthermore, it discusses recent advances and emerging trends in prediction methods, with a particular focus on artificial intelligence.

Diversity of Solid Forms Promoted by Ball Milling: Characterization and Intrinsic Dissolution Studies of Pioglitazone Hydrochloride and Fluvastatin Sodium Drug-Drug Systems

Coamorphous salt in a 1:1 ratio prepared by ball milling from Fluvastatin sodium (FLV) and Pioglitazone hydrochloride (PGZ·HCl) can be selectively formed by neat grinding (NG). Furthermore, the salt-cocrystal continuum was preferably formed by employing liquid-assisted grinding (LAG) using ethanol (EtOH). Attempts to prepare the coamorphous salt starting from the salt-cocrystal continuum by NG were unsuccessful. Interestingly, through ball milling by NG or LAG, a great diversity of solid forms (PGZ·HCl-FLV 1:1) could be accessed: NG and hexane (coamorphous); ethyl acetate (physical mixture); EtOH (salt-cocrystal continuum); and water (which presents two T_g, indicating immiscibility of the components). An exploration was performed at different drug-to-drug ratios by NG. By differential scanning calorimetry (DSC), the presence of two endothermic events was observed in this screening: incongruous melting point (solidus) and excess of one of the components (liquidus), except in the 1:1 solid form. From these results, eutectic behavior was observed. Through the construction of a binary phase diagram, it was determined that the 1:1 molar ratio gives rise to the formation of the most stable coamorphous composition. Dissolution profile studies of these solid forms were carried out, specifically on pure FLV and the solid forms of PGZ⋅HCl-FLV (1:2; 1:4; and 1:6), together with the coamorphous 1:1 salt. By itself, pure FLV presented the highest K_int (13.6270 ± 0.8127 mg/cm²⋅min). On the other hand, the coamorphous 1:1 showed a very low K_int (0.0220 ± 0.0014 mg/cm²·min), indicating very fast recrystallization by the FLV, which avoids observing a sudden release of this drug in the solution. This same behavior was observed in the eutectic composition 1:2. In the other solid forms, the value of K_int increases along with the %w of FLV. From the mechanochemical point of view, ball milling by NG or LAG became an important synthetic tool since it allows obtaining a great variety of solid forms to explore the solid-state reactivity of the drug-drug solid-form PGZ HCl-FLV.

Introduction to Pharmaceutical Co-amorphous Systems Using a Green Co-milling Technique

The concept of co-amorphous systems is introduced in an integrated laboratory experiment, designed for advanced chemistry students, using solvent-free, environmentally friendly mechanochemistry. The dual-drug naproxen-cimetidine co-amorphous system (NPX-CIM) is investigated as an example of the emergent field of medicinal mechanochemistry. Students are trained in solid-state characterization techniques including X-ray powder diffraction, Fourier-transform infrared spectroscopy, and thermal analysis by differential scanning calorimetry. This lab experiment also provides an opportunity to discuss the relevance of different solid forms of pharmaceutics, emphasizing particular properties of disordered materials. This experiment can easily fit the curriculum of any Chemistry or Pharmacy master level degree in courses dealing with instrumental analysis, solid state chemistry, or green chemistry, for classes of 6 to 18 students, in a 5-h lab session. Suggestions to adapt it to the use of a single characterization technique are provided.

Ball-Milling Preparation of the Drug-Drug Solid Form of Pioglitazone-Rosuvastatin at Different Molar Ratios: Characterization and Intrinsic Dissolution Rates Evaluation

Ball-milling using neat grinding (NG) or liquid-assisted grinding (LAG) by varying the polarity of the solvents allowed access to various drug-drug solid forms of pioglitazone hydrochloride (PGZ·HCl) and rosuvastatin calcium (RSV). Using NG, the coamorphous form was formed from the reaction of pioglitazone hydrochloride (PGZ·HCl) and rosuvastatin calcium (RSV) in a 2:1 molar ratio. The formation of the expected coamorphous salt could not be corroborated by FT-IR, but DSC data showed that it was indeed a single-phase amorphous mixture. By varying the molar ratios of the reactants, either keeping PGZ·HCl constant and varying RSV or vice versa, another coamorphous form was obtained when a 1:1 molar ratio was employed. In the case of the other outcomes, it was observed that they were a mixture of solid forms coexisting simultaneously with the coamorphous forms (1:1 or 2:1) together with the drug that was in excess. When RSV was in excess, it was in an amorphous form. In the case of PGZ·HCl, it was found in a semicrystalline form. The intrinsic dissolution rates (IDRs) of the solid forms of PGZ·HCl-RSV in stoichiometric ratios (1:1, 2:1, 1:4, 6:1, and 1:10) were evaluated. Interestingly, a synchronized release of both drugs in the dissolution medium was observed. In the case of the release of RSV, there were no improvements in the dissolution profiles, because the acidic media caused the formation of degradation products, limiting any probable modification in the dissolution processes. However, the coamorphous 2:1 form exhibited an improvement of 1.03 times with respect to pure PGZ·HCl. It is proposed that the modification of the dissolution process of the coamorphous 2:1 form was limited by changes in the pH of the media as RSV consumes protons from the media due to degradation processes.

Mechanistic Study on Transformation of Coamorphous Baicalein-Nicotinamide to Its Cocrystal Form

Recently, coamorphization and cocrystal technologies are of particular interest in the pharmaceutical industry due to their ability to improve the solubility/dissolution and bioavailability of poorly water-soluble drugs, while the coamorphous system often tends to convert into the stable crystalline form usually crystalline physical mixture of each component during formulation preparation or storage. In this paper, BCS II drug baicalein (BAI) along with nicotinamide (NIC) were prepared into a single homogeneous coamorphous system with a single transition temperature at 42.5 °C. Interestingly, instead of the physical mixture of crystalline BAI and NIC, coamorphous BAI-NIC would transform to its cocrystal form under stress of temperature and humidity. The transformation rate under isothermal condition was temperature-dependent, since the crystallinity of the cocrystal enhanced as the temperature increased. Further mechanic studies showed the activation energy for the transformation under non-isothermal condition was calculated to be 184.52 kJ/mol. Additionally, water vapor sorption tests with further solid characterizations indicated the transformation was faster under higher humidity condition due to the faster nucleation process of cocrystal BAI-NIC. This research not only discovered the mechanism of transformation from coamorphous BAI-NIC to cocrystal form, but also provided an unusual method for cocrystal preparation from its coamorphous form.

Application of Box-Behnken Design in the Preparation, Optimization, and In-Vivo Pharmacokinetic Evaluation of Oral Tadalafil-Loaded Niosomal Film

Benign prostatic hyperplasia (BPH) affects about 90% of men whose ages are over 65. Tadalafil, a selective PDE-5 inhibitor, was approved by FDA for BPH, however, its poor aqueous solubility and bioavailability are considered major drawbacks. This work intended to develop and evaluate oral fast dissolving film containing tadalafil-loaded niosomes for those who cannot receive the oral dosage form. Niosomes were statistically optimized by Box-Behnken experimental design and loaded into a polymeric oral film. Niosomes were assessed for their vesicular size, uniformity, and zeta potential. The thickness, content uniformity, folding endurance, tensile strength, disintegration time, and surface morphology were evaluated for the prepared polymeric film. The optimized niosomes revealed high entrapment efficiency (99.78 ± 2.132%) and the film was smooth with good flexibility and convenient thickness (110 ± 10 µm). A fast release of tadalafil was achieved within 5 min significantly faster than the niosomes-free drug film. The in-vivo bioavailability in rats established that the optimized niosomal film enhanced tadalafil systemic absorption, with higher peak concentration (Cmax = 0.63 ± 0.03 µg/mL), shorter Tmax value (0.66-fold), and relative bioavailability of 118.4% compared to the marketed tablet. These results propose that the oral film of tadalafil-loaded niosomes is a suitable therapeutic application that can be passed with ease to geriatric patients who suffer from BPH.

Amorphous and Co-Amorphous Olanzapine Stability in Formulations Intended for Wet Granulation and Pelletization

The preparation of amorphous and co-amorphous systems (CAMs) effectively addresses the solubility and bioavailability issues of poorly water-soluble chemical entities. However, stress conditions imposed during common pharmaceutical processing (e.g., tableting) may cause the recrystallization of the systems, warranting close stability monitoring throughout production. This work aimed at assessing the water and heat stability of amorphous olanzapine (OLZ) and OLZ-CAMs when subject to wet granulation and pelletization. Starting materials and products were characterized using calorimetry, diffractometry and spectroscopy, and their performance behavior was evaluated by dissolution testing. The results indicated that amorphous OLZ was reconverted back to a crystalline state after exposure to water and heat; conversely, OLZ-CAMs stabilized with saccharin (SAC), a sulfonic acid, did not show any significant loss of the amorphous content, confirming the higher stability of OLZ in the CAM. Besides resistance under the processing conditions of the dosage forms considered, OLZ-CAMs presented a higher solubility and dissolution rate than the respective crystalline counterpart. Furthermore, in situ co-amorphization of OLZ and SAC during granule production with high fractions of water unveils the possibility of reducing production steps and associated costs.

Levofloxacin Cocrystal/Salt with Phthalimide and Caffeic Acid as Promising Solid-State Approach to Improve Antimicrobial Efficiency

To overcome the issue of multidrug resistant (MDR) microbes, the exploration of ways to improve the antimicrobial efficiency of existing antibiotics is one of the promising approaches. In search of synthons with higher efficiency, in current investigations, cocrystal and amorphous salt of levofloxacin hemihydrate (LEV) were developed with phthalimide (PTH) and caffeic acid (CFA). New materials were characterized with the help of FT-IR, Raman spectroscopy, powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Shifting, attenuation, appearance/disappearance and broadening of bands were observed in the FT-IR and Raman spectra of the materials as evidence of the required product. The PXRD diffraction pattern observed for LEV-PTH indicated cocrystal while halo diffractogram of LEV-CFA revealed amorphous nature. DSC/TG analysis confirmed the hydrated nature of the cocrystal/salt. The dissolution rate and antimicrobial activity against selected strains, K.pneumonia, E. coli and S. typhi of parent drug and the new material were compared. The zone of inhibition (ZI) observed for 5 µg LEV-PTH was 30.4 + 0.36 (K. pneumonia), 26.33 + 0.35 (E. coli) and 30.03 + 0.25 mm (S. typhi) while LEV-CFA salt (5 µg) against the same strains inhibited 33.96 ± 0.25, 31.66 ± 0.35 and 27.93 ± 0.40 mm, respectively. These novel formulations enhance the dissolution rate as well as antibacterial efficiency and are expected to be potent against MDR bacterial strains.

Optimization of Methionine in Inhalable High-dose Spray-dried Amorphous Composite Particles using Response Surface Method, Infrared and Low frequency Raman Spectroscopy

The influence of amino acids, other than leucine, in improving aerosolization of inhalable powders has not been widely explored. This detailed study focused on the use of methionine, another promising endogenous amino acid, in high dose spray-dried co-amorphous powders by investigating the influence of methionine proportion (0 - 20% ^w/_w), and feed concentration (0.2 - 0.8% ^w/_v) on aerosolization of kanamycin, a model drug, using a design of experiment approach. Low frequency Raman spectroscopy was used to assess the stability of the powders stored at 25 °C/53% relative humidity over 28 days. An increase in concentration of methionine was associated with an increase in fine particle fraction (FPF), with the highest FPF of 84% being achieved at 20% ^w/_w and 0.2% ^w/_v feed concentration. With an increase in feed concentration, both yield and particle size increased for all formulations; the FPF did not change except for kanamycin only formulation in which it decreased. During storage at high humidity, similar aerosolization stabilities were offered by different proportions of methionine although methionine crystallized out in all formulations. Furthermore, the crystallization was accompanied by surface enrichment of methionine on the particles. This study suggests that there is a direct relationship between methionine content and aerosolization for kanamycin-methionine amorphous matrices but feed concentration has little effect. In addition, methionine proportion has no effect on physical stability of such matrices at high humidity.

Preparation of Titanium Oxide-Based Nanoparticles Modified with D-(+)-Mannose and Investigation of their Properties As A Potential Drug Carrier

Titanium oxide nanoparticles modified with D-(+)-mannose were obtained. In the process of their formation, they were conjugated with an active substance (tadalafil). The physicochemical properties of the obtained products were assessed, and the size and electrokinetic potential were determined using a dynamic light scattering technique. X-ray diffractometry was applied in order to define the crystalline properties, and Fourier-transform infrared spectroscopy was used to confirm the formation of the desired products. It was possible to obtain TiO2 coated with D-(+)-mannose. The average size of nanoparticles was between 230 and 268 nm. The release of the active substance from the product over a time period of three hours was assessed against the reference material, which was not modified by D-(+)-mannose. The results indicate that covering titanium oxide nanoparticles with the modifying substance favours a slower rate of release for the active substance, which is the desired effect from a pharmacological point of view. The releasing of active substance from modified products was even 68% slower than that from the reference product. These modified titanium oxides are promising materials that may have found an application as drug carriers.

Graphic Abstract

Recent solubility and dissolution enhancement techniques for repaglinide a BCS class II drug: a review

Repaglinide is an oral blood-glucose-lowering drug used to manage type-2 diabetes mellitus by lowering post-prandial glucose by stimulating insulin secretion from pancreatic beta cells.

According to the biopharmaceutical classification system, repaglinide falls under the class II category. For such drugs, limited solubility and poor dissolution rate are the major hurdles to overcome by formulation scientists, as they hinder drug absorption and lead to inadequate therapeutic effects.

Therefore, this review aims to discuss in depth the various approaches investigated in the past five years to improve the solubility and dissolution of orally administered repaglinide: namely, solid dispersion, co-amorphous technology, cyclodextrin complexation, phospholipid complexes and polymeric micelles, nanocrystals, nanosuspensions and nanofibers.

Pulmonary Drug Delivery of Antimicrobials and Anticancer Drugs Using Solid Dispersions

It is well established that currently available inhaled drug formulations are associated with extremely low lung deposition. Currently available technologies alleviate this low deposition problem via mixing the drug with inert larger particles, such as lactose monohydrate. Those inert particles are retained in the inhalation device or impacted in the throat and swallowed, allowing the smaller drug particles to continue their journey towards the lungs. While this seems like a practical approach, in some formulations, the ratio between the carrier to drug particles can be as much as 30 to 1. This limitation becomes more critical when treating lung conditions that inherently require large doses of the drug, such as antibiotics and antivirals that treat lung infections and anticancer drugs. The focus of this review article is to review the recent advancements in carrier free technologies that are based on coamorphous solid dispersions and cocrystals that can improve flow properties, and help with delivering larger doses of the drug to the lungs.

Drug-Rich Phases Induced by Amorphous Solid Dispersion: Arbitrary or Intentional Goal in Oral Drug Delivery?

Among many methods to mitigate the solubility limitations of drug compounds, amorphous solid dispersion (ASD) is considered to be one of the most promising strategies to enhance the dissolution and bioavailability of poorly water-soluble drugs. The enhancement of ASD in the oral absorption of drugs has been mainly attributed to the high apparent drug solubility during the dissolution. In the last decade, with the implementations of new knowledge and advanced analytical techniques, a drug-rich transient metastable phase was frequently highlighted within the supersaturation stage of the ASD dissolution. The extended drug absorption and bioavailability enhancement may be attributed to the metastability of such drug-rich phases. In this paper, we have reviewed (i) the possible theory behind the formation and stabilization of such metastable drug-rich phases, with a focus on non-classical nucleation; (ii) the additional benefits of the ASD-induced drug-rich phases for bioavailability enhancements. It is envisaged that a greater understanding of the non-classical nucleation theory and its application on the ASD design might accelerate the drug product development process in the future.

Considerations for the selection of co-formers in the preparation of co-amorphous formulations

Co-amorphous drug delivery systems are evolving as a credible alternative to amorphous solid dispersions technology. In Co-amorphous systems (CAMs), a drug is stabilized in amorphous form using small molecular weight compounds called as co-formers. A wide variety of small molecular weight co-formers have been leveraged in the preparation of CAMs. The stability and supersaturation potential of prepared co-amorphous phases largely depend on the type of co-former employed in the CAMs. However, the rationality behind the co-former selection in co-amorphous systems is poorly understood and scarcely compiled in the literature. There are various facets to the rational selection of co-former for CAMs. In this context, the present review compiles various factors affecting the co-former selection. The factors have been broadly classified under Thermodynamic, Kinetic and Pharmacokinetic-Pharmacologically relevant parameters. In particular, the importance of Glass transition, Miscibility, Liquid-Liquid phase separation (LLPS), Crystallization inhibition has been deliberated in detail.

Insights into co-amorphous systems in therapeutic drug delivery

Co-amorphous (CAM) systems are promising drug-delivery systems in the arena of therapeutic drug delivery, addressing the poor aqueous solubility of drugs by enhancing solubility and thereby improving the oral bioavailability and therapeutic effect of the drug. A CAM system is a single-phase homogeneous blend of two or more low molecular weight molecules that can be drug–drug or drug–co-former, stabilized via intermolecular interactions, adding the benefit of thermodynamic stability. This review covers the fundamentals of CAM systems and recent advances in formulation development. In particular, we strive to address the theoretical, molecular, technical and biopharmaceutical aspects, advantages over polymeric amorphous solid dispersions, mechanisms of stabilization of amorphous forms, insights into unexplored in silico tools in excipient selection and regulatory viewpoints.

Sinomenine-phenolic acid coamorphous drug systems: Solubilization, sustained release, and improved physical stability

Sinomenine (SIN), isolated from Caulis sinomenii, is a benzyltetrahydroisoquinoline-type alkaloid with potent anti-inflammatory and analgesic effects. SIN-HCl has been used in the forms of tablets or enteric-coated tablets in the treatment of rheumatoid arthritis in China for years, while its short half-life leads to attenuated therapeutic effects and serious side effects. In the current study, three phenolic acids, including salicylic acid (SAA), 2,3-dihydroxybenzoic acid (23DHB), and 2,4-dihydroxybenzoic acid (24DHB), were firstly employed as coamorphous coformers to prepare three binary SIN-phenolic acid coamorphous systems. These new coamorphous systems were characterized by powder X-ray diffraction (PXRD), modulated temperature differential scanning calorimetry (mDSC), and Fourier transform infrared spectroscopy (FTIR). The formation of SIN-phenolic acid coamorphous systems are supported by the absence of diffraction peaks in their PXRD spectra, as well as the single T_gs of three samples (i.e., SIN-SAA, SIN-23DHB, and SIN-24DHB) at 109.5 °C, 124.9 °C, and 135.3 °C. Importantly, the salt formation between SIN and phenolic acids was observed in FTIR. In three coamorphous systems, coamorphous SIN-24DHB shows superior physicochemical stability under both low humidity and accelerated storage conditions. They were also more soluble than crystalline SIN, while were released slower than the commercial SIN-HCl in dissolution experiments. Therefore, our study suggests that phenolic acids may be used as a new type of coformers in the preparation of coamorphous systems for active pharmaceutical ingredients.

Effects of the Glass-Forming Ability and Annealing Conditions on Cocrystallization Behaviors via Rapid Solvent Removal: A Case Study of Voriconazole

The kinetic entrapment of molecules in an amorphous phase is a common obstacle to cocrystal screening using rapid solvent removal, especially for drugs with a moderate or high glass-forming ability (GFA). The aim of this study was to elucidate the effects of the coformer's GFA and annealing conditions on the nature of amorphous phase transformation to the cocrystal counterpart. Attempts were made to cocrystallize voriconazole (VRC) with four structural analogues, namely fumaric acid (FUM), tartaric acid (TAR), malic acid (MAL), and maleic acid (MAE). The overall GFA of VRC binary systems increased with decreasing glass transition temperatures (Tgs) of these diacids, which appeared as a critical parameter for predicting the cocrystallization propensity such that a high-Tg coformer is more desirable. A new 1:1 VRC-TAR cocrystal was successfully produced via a supercooled-mediated re-cocrystallization process, and characterized by PXRD, DSC, and FTIR. The cocrystal purity against the annealing temperature displayed a bell-shaped curve, with a threshold at 40 °C. The isothermal phase purity improved with annealing and adhered to the Kolmogorov-Johnson-Mehl-Avrami kinetics. The superior dissolution behavior of the VRC-TAR cocrystal could minimize VRC precipitation upon gastric emptying. This study offers a simple but useful guide for efficient cocrystal screening based on the Tg of structurally similar coformers, annealing temperature, and time.

Development of spray-dried amorphous solid dispersions of tadalafil using glycyrrhizin for enhanced dissolution and aphrodisiac activity in male rats

Tadalafil (TDL) is a phosphodiesterase-5 inhibitor (PDE5I), indicated for erectile dysfunction (ED). However, TDL exhibits poor aqueous solubility and dissolution rate, which may limit its application. This study aims to prepare amorphous solid dispersion (ASD) by spray-drying, using glycyrrhizin-a natural drug carrier. Particle and physicochemical characterizations were performed by particle size, polydispersity index measurement, yield, drug content estimation, Fourier Transformed Infrared (FTIR) spectroscopy, Differential scanning calorimetry (DSC), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and dissolution study. In order to evaluate the aphrodisiac activity of the prepared ASD, sexual behavior study was performed in male rats. It is further considered for the stability study. Our results revealed that TDL-GLZ spray-dried dispersion was a successful drug-carrier binary mixture. XRD and SEM showed that ASD of TDL with GLZ presented in the amorphous state and dented-spherical shape, unlike the drug indicating crystalline and spiked shaped. The optimized ASD3 formulation with particle size (1.92 µm), PDI (0.32), yield (97.78%) and drug content (85.00%) showed 4.07 folds' increase in dissolution rate compared to pure TDL. The results obtained from the in vivo study exhibit significantly improved aphrodisiac activity with ASD3. The stability study revealed that the prepared ASD3 did not show any remarkable changes in the dissolution and drug content for 1 month storage at room temperature.