A review of the physiological effects of microgravity and innovative formulation for space travelers

During the space travel mission, astronauts' physiological and psychological behavior will alter, and they will start consuming terrestrial drug products. However, factors such as microgravity, radiation exposure, temperature, humidity, strong vibrations, space debris, and other issues encountered, the drug product undergo instability This instability combined with physiological changes will affect the shelf life and diminish the pharmacokinetic and pharmacodynamic profile of the drug product. Consequently, the physicochemical changes will produce a toxic degradation product and a lesser potency dosage form which may result in reduced or no therapeutic action, so the astronaut consumes an additional dose to remain healthy. On long-duration missions like Mars, the drug product cannot be replaced, and the astronaut may relay on the available medications. Sometimes, radiation-induced impurities in the drug product will cause severe problems for the astronaut. So, this review article highlights the current state of various space-related factors affecting the drug product and provides a comprehensive summary of the physiological changes which primarly focus on absorption, distribution, metabolism, and excretion (ADME). Along with that, we insist some of the strategies like novel formulations, space medicine manufacturing from plants, and 3D printed medicine for astronauts in longer-duration missions. Such developments are anticipated to significantly contribute to new developments with applications in both human space exploration and on terrestrial healthcare.

Charge balanced aggregation: A universal approach to aqueous organic nanocrystals

Organic nanocrystals, particularly those composed of conjugated molecules, hold immense potential for various applications. However, their practical utility is often hindered by the challenge of achieving stable aqueous dispersions, which are essential for biological compatibility and effective delivery. This study introduces a novel and versatile strategy for preparing stable aqueous organic nanocrystals using a modified reprecipitation method. We demonstrate the broad applicability of this approach by successfully preparing a diverse library of nanocrystals from 27 conjugated molecules. Our findings reveal a charge-balanced aggregation mechanism for nanocrystal formation, highlighting the crucial role of surface charge in controlling particle size and stability. Based on this mechanism, we establish a comprehensive molecular combination strategy that directly links molecular properties to colloidal behaviour, enabling the straightforward prediction and preparation of stable aqueous dispersions without the need for excipients. This strategy provides a practical workflow for tailoring the functionality of these nanocrystals for a wide range of applications. To illustrate their therapeutic potential, we demonstrate the enhanced efficacy of these nanocrystals in treating acute ulcerative colitis, myocardial ischemia/reperfusion injury, and cancer in mouse models. This work paves the way for developing next-generation nanomaterials with tailored functionalities for diverse biomedical applications.

Highly Soluble Dacarbazine Multicomponent Crystals Less Prone to Photodegradation

Dacarbazine (DTIC) is a widely prescribed oncolytic agent to treat advanced malignant melanomas. Nevertheless, the drug is known for exhibiting low and pH-dependent solubility, in addition to being photosensitive. These features imply the formation of the inactive photodegradation product 2-azahypoxanthine (2-AZA) during pharmaceutical manufacturing and even drug administration. We have focused on developing novel DTIC salt/cocrystal forms with enhanced solubility and dissolution behaviors to overcome or minimize this undesirable biopharmaceutical profile. By cocrystallization techniques, two salts, two cocrystals, and one salt-cocrystal have been successfully prepared through reactions with aliphatic carboxylic acids. A detailed structural study of these new multicomponent crystals was conducted using X-ray diffraction (SCXRD, PXRD), spectroscopic (FT-IR and 1H NMR), and thermal (TG and DSC) analyses. Most DTIC crystal forms reported display substantial enhancements in solubility (up to 19-fold), with faster intrinsic dissolution rates (from 1.3 to 22-fold), contributing positively to reducing the photodegradation of DTIC in solution. These findings reinforce the potential of these new solid forms to enhance the limited DTIC biopharmaceutical profile.

Repurposing of Antifungal Drug Flucytosine/Flucytosine Cocrystals for Anticancer Activity against Prostate Cancer Targeting Apoptosis and Inflammatory Signaling Pathways

This study aimed to repurpose the antifungal drug flucytosine (FCN) for anticancer activity together with cocrystals of nutraceutical coformers sinapic acid (SNP) and syringic acid (SYA). The cocrystal screening experiments with SNP resulted in three cocrystal hydrate forms in which two are polymorphs, namely, FCN-SNP F-I and FCN-SNP F-II, and the third one with different stoichiometry in the asymmetric unit (1:2:1 ratio of FCN:SNP:H2O, FCN-SNP F-III). Cocrystallization with SYA resulted in two hydrated cocrystal polymorphs, namely, FCN-SYA F-I and FCN-SYA F-II. All the cocrystal polymorphs were obtained concomitantly during the slow evaporation method, and one of the polymorphs of each system was produced in bulk by the slurry method. The interaction energy and lattice energies of all cocrystal polymorphs were established using solid-state DFT calculations, and the outcomes correlated with the experimental results. Further, the in vitro cytotoxic activity of the cocrystals was determined against DU145 prostate cancer and the results showed that the FCN-based cocrystals (FCN-SNP F-III and FCN-SYA F-I) have excellent growth inhibitory activity at lower concentrations compared with parent FCN molecules. The prepared cocrystals induce apoptosis by generating oxidative stress and causing nuclear damage in prostate cancer cells. The Western blot analysis also depicted that the cocrystals downregulate the inflammatory markers such as NLRP3 and caspase-1 and upregulate the intrinsic apoptosis signaling pathway marker proteins, such as Bax, p53, and caspase-3. These findings suggest that the antifungal drug FCN can be repurposed for anticancer activity.

Efficient Screening of Pharmaceutical Cocrystals by Microspacing In-Air Sublimation

Cocrystal screening and single-crystal growth remain the primary obstacles in the development of pharmaceutical cocrystals. Here, we present a new approach for cocrystal screening, microspacing in-air sublimation (MAS), to obtain new cocrystals and grow high-quality single crystals of cocrystals within tens of minutes. The method possesses the advantages of strong designable ability of devices, user-friendly control, and compatibility with materials, especially for the thermolabile molecules. A novel drug-drug cocrystal of favipiravir (FPV) with salicylamide (SAA) was first discovered by this method, which shows improved physiochemical properties. Furthermore, this method proved effective in cultivating single crystals of FPV-isonicotinamide (FPV-INIA), FPV-urea, FPV-nicotinamide (FPV-NIA), and FPV-tromethamine (FPV-Tro) cocrystals, and the structures of these cocrystals were determined for the first time. By adjusting the growth temperature and growth distance precisely, we also achieved single crystals of 10 different paracetamol (PCA) cocrystals and piracetam (PIR) cocrystals, which underscores the versatility and efficiency of this method in pharmaceutical cocrystal screening.

The curious case of proton migration under pressure in the malonic acid and 4,4'-bipyridine cocrystal

In the search for new active pharmaceutical ingredients, the precise control of the chemistry of cocrystals becomes essential. One crucial step within this chemistry is proton migration between cocrystal coformers to form a salt, usually anticipated by the empirical ΔpKa rule. Due to the effective role it plays in modifying intermolecular distances and interactions, pressure adds a new dimension to the ΔpKa rule. Still, this variable has been scarcely applied to induce proton-transfer reactions within these systems. In our study, high-pressure X-ray diffraction and Raman spectroscopy experiments, supported by DFT calculations, reveal modifications to the protonation states of the 4,4'-bipyridine (BIPY) and malonic acid (MA) cocrystal (BIPYMA) that allow the conversion of the cocrystal phase into ionic salt polymorphs. On compression, neutral BIPYMA and monoprotonated (BIPYH+MA-) species coexist up to 3.1 GPa, where a phase transition to a structure of P21/c symmetry occurs, induced by a double proton-transfer reaction forming BIPYH22+MA2-. The low-pressure C2/c phase is recovered at 2.4 GPa on decompression, leading to a 0.7 GPa hysteresis pressure range. This is one of a few studies on proton transfer in multicomponent crystals that shows how susceptible the interconversion between differently charged species is to even slight pressure changes, and how the proton transfer can be a triggering factor leading to changes in the crystal symmetry. These new data, coupled with information from previous reports on proton-transfer reactions between coformers, extend the applicability of the ΔpKa rule incorporating the pressure required to induce salt formation.

Improving the physicochemical and pharmacokinetic properties of olaparib through cocrystallization strategy

Olaparib (OLA) is the first PARP inhibitor worldwide used for the treatment of ovarian cancer. However, the oral absorption of OLA is extremely limited by its poor solubility. Herein, pharmaceutical cocrystallization strategy was employed to optimize the physicochemical and pharmacokinetic properties. Four cocrystals of OLA with oxalic acid (OLA-OA), malonic acid (OLA-MA), fumaric acid (OLA-FA) and maleic acid (OLA-MLA) were successfully discovered and characterized. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the formation of cocrystals rather than salts, and the possible hydrogen bonding patterns were analyzed through molecular surface electrostatic potential calculations. The in vitro and in vivo evaluations indicate that all of the cocrystals demonstrate significantly improved dissolution performance, oral absorption and tabletability compared to pure OLA. Among them, OLA-FA exhibit sufficient stability and the most increased Cmax and AUC0-24h values that were 11.6 and 6.1 times of free OLA, respectively, which has great potential to be developed into the improved solid preparations of OLA.

Accelerated Wound Healing with a Diminutive Scar through Cocrystal Engineered Curcumin

Pharmaceutical cocrystals ( Regulatory Classification of Pharmaceutical Co-Crystals Guidance for Industry; Food and Drug Administration, 2018) are crystalline solids produced through supramolecular chemistry to modulate the physicochemical properties of active pharmaceutical ingredients (APIs). Despite their extensive development in interdisciplinary sciences, this is a pioneering study on the efficacy of pharmaceutical cocrystals in wound healing and scar reducing. Curcumin-pyrogallol cocrystal (CUR-PYR) was accordingly cherry-picked since its superior physicochemical properties adequately compensate for limitative drawbacks of curcumin (CUR). CUR-PYR has been synthesized by a liquid-assisted grinding (LAG) method and characterized via FT-IR, DSC, and PXRD analyses. In vitro antibacterial study indicated that CUR-PYR cocrystal, CUR+PYR physical mixture (PM), and PYR are more effective against both Gram-negative (Pseudomonas aeruginosa and Escherichia coli) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria in comparison with CUR. In vitro results also demonstrated that the viability of HDF and NIH-3T3 cells treated with CUR-PYR were improved more than those received CUR which is attributed to the effect of PYR in the form of cocrystal. The wound healing process has been monitored through a 15 day in vivo experiment on 75 male rats stratified into six groups: five groups treated by CUR-PYR+Vaseline (CUR-PYR.ung), CUR+PYR+Vaseline (CUR+PYR.ung), CUR+Vaseline (CUR.ung), PYR+Vaseline (PYR.ung), and Vaseline (VAS) ointments and a negative control group of 0.9% sodium chloride solution (NS). It was revealed that the wounds under CUR-PYR.ung treatment closed by day 12 postsurgery, while the wounds in other groups failed to reach the complete closure end point until the end of the experiment. Surprisingly, a diminutive scar (3.89 ± 0.97% of initial wound size) was observed in the CUR-PYR.ung treated wounds by day 15 after injury, followed by corresponding values for PYR.ung (12.08 ± 2.75%), CUR+PYR.ung (13.89 ± 5.02%), CUR.ung (16.24 ± 6.39%), VAS (18.97 ± 6.89%), and NS (20.33 ± 5.77%). Besides, investigating histopathological parameters including inflammation, granulation tissue, re-epithelialization, and collagen deposition signified outstandingly higher ability of CUR-PYR cocrystal in wound healing than either of its two constituents separately or their simple PM. It was concluded that desired solubility of the prepared cocrystal was essentially responsible for accelerating wound closure and promoting tissue regeneration which yielded minimal scarring. This prototype research suggests a promising application of pharmaceutical cocrystals for the purpose of wound healing.

Control of Dissolution and Supersaturation/Precipitation of Poorly Water-Soluble Drugs from Cocrystals Based on Solubility Products: A Case Study with a Ketoconazole Cocrystal

This study demonstrates in vitro and in vivo control of cocrystal dissolution with drug supersaturation/precipitation based on the solubility product of a cocrystal. As a cocrystal model, KTZ-4ABA (ketoconazole, KTZ, a poorly water-soluble drug cocrystal, with 4-aminobenzoic acid, 4ABA, a coformer) was used. The presence of 4ABA in the dissolution media dramatically reduced the dissolution rate of KTZ-4ABA and regulated the supersaturation/precipitation of KTZ, supported by the solubility product of KTZ-4ABA. In the in vitro dissolution study, the combined solid form of KTZ-4ABA and a ten-fold amount of 4ABA significantly lowered the degree of KTZ supersaturation without precipitation and further cocrystal dissolution. To confirm cocrystal dissolution control in the gastrointestinal tract with the same composition as the in vitro study, an in vivo oral administration study with rats was conducted. When KTZ was coadministered to rats in the cocrystal form, an excess of 4ABA coadministered with KTZ-4ABA in the solid form reduced the maximum plasma KTZ concentration (Cmax), prolonged the time to reach the Cmax, but did not influence the area under the plasma concentration-time curve. These results demonstrate that both in vitro and in vivo cocrystal dissolution can be regulated by adding an appropriate amount of coformer based on the solubility product, which can be one of the promising strategies for the oral use of cocrystal formulations.

Influence of Co-amorphization on the Physical Stability and Dissolution Performance of an Anthelmintic Drug Flubendazole

In this work, the co-amorphization approach was applied to flubendazole (FluBZ), resulting in the formation of two novel solid forms of FluBZ with l-phenylalanine (Phe) and l-tryptophan (Trp). A variety of physicochemical techniques have been used to describe new systems, including powder X-ray diffraction, thermal methods, infrared spectroscopy, and scanning electron microscopy. Co-amorphization has been shown to suppress crystallization tendency and considerably increase the shelf-life storage of amorphous flubendazole solid across a wide range of relative humidities. The dissolution behavior of the amorphous forms in biorelevant media at pH = 1.6, pH = 6.5, and 37 °C has been studied in terms of C_max (maximum FluBZ concentration), T_max (time to attain peak drug concentration), and AUC (concentration area under the curve during dissolution). At pH = 6.5, a continuous supersaturation and the highest AUC value of all examined systems were observed for the FluBZ-Phe (1:1) system. The phase solubility diagrams revealed that the reason for the better dissolution performance of FluBZ-Phe (1:1) at pH = 6.5 is a complexation between the components in a solution. This work highlights the applicability of co-amorphous systems in improving the physical stability and dissolution performance of drug compounds with poor biopharmaceutical characteristics.

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.

Mechanosynthesis of magnolol multicomponent crystalline solids for improved natural antibiotics and customizable release profiles

Antibiotic is one of the most important discoveries in human and animal medicine. However, the inefficient use of antibiotics has caused widespread and persistent contamination of ecosystems, setting off microbial resistance storms. Magnolol is a botanical antibiotic, but poor physicochemical properties result in low bioavailability. Increasing solubility of magnolol can help to reduce the doses of medications to patients, minimize bothersome side effects. In this work, three novel multicomponent crystalline solids were synthesized from magnolol and isomeric coformers by mechanochemistry. It was found that the multicomponent crystalline solids achieved the customizable release profile of magnolol by manipulating the substituent positions of the isomers and complexation. Antibacterial activity test showed that bioactivity on two bacteria was considerably improved by designed MGN multicomponent crystals. In addition, the coformers controlled the dissolution behavior and further stabilized the improvement according to the variable statistical analysis. In conclusion, the properties of antibiotic multicomponent solids can be manipulated through the coformers. This provides an effective strategy for managing the release of drugs to meet individual biological differences and diverse therapeutic needs.

Co-Crystallization Approach to Enhance the Stability of Moisture-Sensitive Drugs

Stability is an essential quality attribute of any pharmaceutical formulation. Poor stability can change the color and physical appearance of a drug, directly impacting the patient's perception. Unstable drug products may also face loss of active pharmaceutical ingredients (APIs) and degradation, making the medicine ineffective and toxic. Moisture content is known to be the leading cause of the degradation of nearly 50% of medicinal products, leading to impurities in solid dose formulations. The polarity of the atoms in an API and the surface chemistry of API particles majorly influence the affinity towards water molecules. Moisture induces chemical reactions, including free water that has also been identified as an important factor in determining drug product stability. Among the various approaches, crystal engineering and specifically co-crystals, have a proven ability to increase the stability of moisture-sensitive APIs. Other approaches, such as changing the salt form, can lead to solubility issues, thus making the co-crystal approach more suited to enhancing hygroscopic stability. There are many reported studies where co-crystals have exhibited reduced hygroscopicity compared to pure API, thereby improving the product's stability. In this review, the authors focus on recent updates and trends in these studies related to improving the hygroscopic stability of compounds, discuss the reasons behind the enhanced stability, and briefly discuss the screening of co-formers for moisture-sensitive drugs.

Modulation of Solid-State Chemical Stability of Gabapentin by Pyridinecarboxylic Acid

PURPOSE

Gabapentin (GBP) is an anticonvulsant drug with poor chemical stability that is particularly sensitive to heat and mechanical stress, which can lead to intramolecular lactamization. The purpose of this study was to enhance the chemical stability of GBP by cocrystallization with organic acids.

METHOD

Two novel multicomponent crystals, GBP-2,6-pyridinedicarboxylic acid salt (GBP-2,6PDA salt) and GBP-2,5-pyridinedicarboxylic acid cocrystal (GBP-2,5PDA cocrystal) were synthesized and characterized by various solid-state analytical techniques. The degradation behavior of GBP, GBP-2,6PDA salt and GBP-2,5PDA cocrystals were evaluated under thermal and mechanical stresses.

RESULT

Under thermal and mechanical stresses, GBP-2,5PDA cocrystals were found to undergo severer degradation than GBP-2,6PDA salt and neat GBP. GBP-2,6PDA salt exhibited superior chemical stability compared to the others. Furthermore, the crystal structure revealed that the order of atomic distance between the carboxyl group (C7) and amino group (N12) of GBP is as follows: GBP-2,5PDA cocrystal < GBP < GBP-2,6PDA salt, which is consistent with the chemical stability of GBP in different solid forms. Therefore, we believe that the distance between C7 and N12, the reaction active sites leading to dehydrative condensation of GBP, is a key factor determining the chemical stability of GBP in the solid state.

CONCLUSIONS

These results provide a potential method to improve the chemical stability of GBP during the manufacturing process and storage.

Food-inspired innovations to improve the stability of active pharmaceutical ingredients

Food-processing and pharmaceutical industries share a lot of stability issues against the same physical, chemical, and microbiological phenomena. They also share some solutions to improve the stability as the use of preservatives and packaging. Ecological concerns lead to the development of tremendous innovations in food. Some of these innovations could also be beneficial in the pharmaceutical domain. The objective of this review is to evaluate the potential application of these findings in the pharmaceutical field and the main limits in terms of toxicity, environmental, economic and regulatory issues. The principal factors influencing the shelf-life were highlighted through the description of the stability studies usually performed in the pharmaceutical industry (according to European guidelines). To counter those factors, different solutions are currently available as preservatives and specific packaging. They were described and debated with an overview of recent food innovations in each field. The limits of the current solutions in the pharmaceutical field and the innovation in the food field have inspired a critical pharmaceutical outlook. The active and intelligent packaging for active pharmaceutical ingredients of the future is imagined.