The Prodrug Approach: A Successful Tool for Improving Drug Solubility

Stepping forward: T-cell redirecting bispecific antibodies in cancer therapy

T cell-redirecting bispecific antibodies are specifically designed to bind to tumor-associated antigens, thereby engaging with CD3 on the T cell receptor. This linkage between tumor cells and T cells actively triggers T cell activation and initiates targeted killing of the identified tumor cells. These antibodies have emerged as one of the most promising avenues within tumor immunotherapy. However, despite success in treating hematological malignancies, significant advancements in solid tumors have yet to be explored. In this review, we aim to address the critical challenges associated with T cell-redirecting bispecific antibodies and explore novel strategies to overcome these obstacles, with the ultimate goal of expanding the application of this therapy to include solid tumors.

Discovery of Alkyl Triphenylphosphonium Pinostrobin Derivatives as Potent Anti-Breast Cancer Agents

Pinostrobin demonstrated anticancer properties, but its hydrophobic feature led to a reduction in bioavailability. The mitochondria-targeted approach successfully synthesized eight new alkyl triphenylphosphonium pinostrobin derivatives (1-8) with good yield in this study. Seven compounds (1-3, 5-8) showed greater cytotoxic potency against the human MCF-7 breast cancer cell line than pinostrobin. Molecular docking studies were performed with two important targets in hormone-dependent anticancer strategies, estrogen receptor α (ERα) ligand binding domains, 3ERT (antagonist recognition and antiproliferative function), and 1GWR (agonist recognition and pro-proliferative function). In addition, the MD simulation study of the two most potent compounds (2 and 3) complexed with both ERα forms suggested that compounds 2 and 3 could serve as favourable antagonists. Furthermore, the in silico ADMET prediction indicated that compounds 2 and 3 could be potential drug candidates.

New conjugates based on N4-hydroxycytidine with more potent antiviral efficacy in vitro than EIDD-2801 against SARS-CoV-2 and other human coronaviruses

The spread of COVID-19 continues due to genetic variation in SARS-CoV-2. Highly mutated variants of SARS-CoV-2 have an increased transmissibility and immune evasion. Due to the emergence of various new variants of the virus, there is an urgent need to develop broadly effective specific drugs for therapeutic strategies for the prevention and treatment of COVID-19. Molnupiravir (EIDD-2801, MK-4482), is an orally bioavailable ribonucleoside analogue of β-D-N4-hydroxycytidine (NHC), has demonstrated efficacy against SARS-CoV-2 and was recently approved for COVID-19 treatment. To improve antiviral potency of NHC, we developed a panel of NHC conjugates with lipophilic vectors and ester derivatives with amino- and carboxylic-acids. Most of the synthesized compounds had comparable or higher (2-20 times) antiviral activity than EIDD-2801, against different lineages of SARS-CoV-2, MERS-CoV, seasonal coronaviruses OC43 and 229E, as well as bovine coronavirus. For further studies, we assessed the most promising compound in terms of activity, simplicity and cost of synthesis - NHC conjugate with phenylpropionic acid (SN_9). SN_9 has shown high efficacy in prophylactic, therapeutic and transmission models of COVID-19 infection in hamsters. Importantly, SN_9 profoundly inhibited virus replication in the lower respiratory tract of hamsters and transgenic mice infected with the Omicron sublineages XBB.1.9.1, XBB.1.16 and EG.5.1.1. These data indicate that SN_9 represents a promising antiviral drug candidate for COVID-19 treatment, and NHC modification strategies deserve further investigation as an approach to develop prodrugs against various coronaviruses.

Influence of Different Ratios of DSPE-PEG2k on Ester Prodrug Self-Assembly Nanoparticles for Cell Migration and Proliferation Suppression

Background

Bufalin (BFL, an active anti-tumor compound derived from toad venom) is limited in its application due to high toxicity and rapid metabolism of the cardiotonic steroid. Ester prodrug self-assembly nanoparticles have shown significant improved effects in addressing the above-mentioned issues.

Methods

An ester bond was formed between linoleic acid and bufalin to synthesize linoleic acid-bufalin prodrug (LeB). The self-assembly nanoparticles (LeB-PSNs) containing different mass ratios of DSPE-PEG2k and prodrug (6:4, 7:3, 8:2, 9:1 and 10:0) were prepared via co-precipitation method and defined as 6:4-PSNs, 7:3-PSNs, 8:2-PSNs, 9:1-PSNs and LeB-PSNs, respectively. Further, the characterization (particle size, zeta potential, surface morphology and stability) of the nanoparticles was carried out. Finally, we evaluated the impact of different ratios of DSPE-PEG2k on the hydrolysis rate, cytotoxicity, cellular uptake, cell migration and proliferation suppression potential of the prodrug nanoparticles.

Results

The linoleic acid-bufalin prodrug (LeB) was successfully synthesized. Upon the addition of DSPE-PEG2k at different weight ratios, both particle size and polydispersity index (PDI) significantly decreased, while the zeta potential increased remarkably. No significant differences in particle size, PDI and Zeta potential were observed among the 9:1, 8:2 and 7:3 PSNs. Notably, the 8:2 (w/w) DSPE-PEG2k nanoparticles exhibited superior stability, hydrolysis and cellular uptake rates, along with efficient cell cytotoxicity, cell migration and proliferation suppression.

Conclusion

These findings indicate that DSPE-PEG2k could improve the performance of BFL prodrug nanoparticles, namely enhancing stability and achieving adaptive drug release by modulating the hydrolysis rate of esterase. This study therefore provides more opportunities for the development of BFL application.

Modular Fabrication of Bioorthogonal Nanozymes for Biomedical Applications

The incorporation of transition metal catalysts (TMCs) into nanoscaffolds generates nanocatalysts that replicate key aspects of enzymatic behavior. The TMCs can access bioorthogonal chemistry unavailable to living systems. These bioorthogonal nanozymes can be employed as in situ "factories" for generating bioactive molecules where needed. The generation of effective bioorthogonal nanozymes requires co-engineering of the TMC and the nanometric scaffold. This review presents an overview of recent advances in the field of bioorthogonal nanozymes, focusing on modular design aspects of both nanomaterial and catalyst and how they synergistically work together for in situ uncaging of imaging and therapeutic agents.

Cutaneous Pharmacokinetics of Topically Applied Novel Dermatological Formulations

Novel formulations are developed for dermatological applications to address a wide range of patient needs and therapeutic challenges. By pushing the limits of pharmaceutical technology, these formulations strive to provide safer, more effective, and patient-friendly solutions for dermatological concerns, ultimately improving the overall quality of dermatological care. The article explores the different types of novel dermatological formulations, including nanocarriers, transdermal patches, microsponges, and microneedles, and the techniques involved in the cutaneous pharmacokinetics of these innovative formulations. Furthermore, the significance of knowing cutaneous pharmacokinetics and the difficulties faced during pharmacokinetic assessment have been emphasized. The article examines all the methods employed for the pharmacokinetic evaluation of novel dermatological formulations. In addition to a concise overview of earlier techniques, discussions on novel methodologies, including tape stripping, in vitro permeation testing, cutaneous microdialysis, confocal Raman microscopy, and matrix-assisted laser desorption/ionization mass spectrometry have been conducted. Emerging technologies like the use of microfluidic devices for skin absorption studies and computational models for predicting drug pharmacokinetics have also been discussed. This article serves as a valuable resource for researchers, scientists, and pharmaceutical professionals determined to enhance the development and understanding of novel dermatological drug products and the complex dynamics of cutaneous pharmacokinetics.

A Review on Carbon Nanotubes Family of Nanomaterials and Their Health Field

The use of carbon nanotubes (CNTs), which are nanometric materials, in pathogen detection, protection of environments, food safety, and in the diagnosis and treatment of diseases, as efficient drug delivery systems, is relevant for the improvement and advancement of pharmacological profiles of many molecules employed in therapeutics and in tissue bioengineering. It has contributed to the advancement of science due to the development of new tools and devices in the field of medicine. CNTs have versatile mechanical, physical, and chemical properties, in addition to their great potential for association with other materials to contribute to applications in different fields of medicine. As, for example, photothermal therapy, due to the ability to convert infrared light into heat, in tissue engineering, due to the mechanical resistance, flexibility, elasticity, and low density, in addition to many other possible applications, and as biomarkers, where the electronic and optics properties enable the transduction of their signals. This review aims to describe the state of the art and the perspectives and challenges of applying CNTs in the medical field. A systematic search was carried out in the indexes Medline, Lilacs, SciELO, and Web of Science using the descriptors "carbon nanotubes", "tissue regeneration", "electrical interface (biosensors and chemical sensors)", "photosensitizers", "photothermal", "drug delivery", "biocompatibility" and "nanotechnology", and "Prodrug design" and appropriately grouped. The literature reviewed showed great applicability, but more studies are needed regarding the biocompatibility of CNTs. The data obtained point to the need for standardized studies on the applications and interactions of these nanostructures with biological systems.

Riboflavin Crystals with Extremely High Water Solubility

New insights into the unique biochemical properties of riboflavin (Rf), also known as vitamin B2, are leading to the development of its use not only as a vitamin supplement but also as a potential anti-inflammatory, immunomodulatory, antioxidant, anticancer, and antiviral agent, where it may play a role as an inhibitor of viral proteinases. At the same time, the comparison of the pharmacoactivity of Rf with its known metabolites, namely, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), is very complicated due to its poor water solubility: 0.1-0.3 g/L versus 67 g/L for FMN and 50 g/L for FAD, which is the limiting factor for its administration in clinical practice. In this study, we report the recrystallization procedure of the type A Rf crystals into the slightly hydrophobic type B/C and a new hydrophilic crystal form that has been termed the P type. Our method of Rf crystal modification based on recrystallization from dilute alkaline solution provides an unprecedented extremely high water solubility of Rf, reaching 23.5 g/L. A comprehensive study of the physicochemical properties of type P riboflavin showed increased photodynamic therapeutic activity compared to the known types A and B/C against clinical isolates of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Salmonella typhimurium. Importantly, our work not only demonstrates a simple and inexpensive method for the synthesis of riboflavin with high solubility, which should lead to increased bioactivity, but also opens up opportunities for improving both known and new therapeutic applications of vitamin B2.

Long-term antitrypanosomal effect of quinapyramine sulphate-loaded oil-based nanosuspension in T. evansi-infected mouse model

The goal of the present work consisted of the formulation development and evaluation of quinapyramine sulphate (QS)-loaded long-acting oil-based nanosuspension for improved antitrypanosomal effect. QS was transformed into a hydrophobic ionic complex using anionic sodium cholate (Na.C). The complex was characterized by FTIR, DSC, and XRD. Oil-based nanosuspension was prepared by dispersing the QS-Na.C complex in thixotropically thickened olive oil. The nanoformulation was found to be cytocompatible (82.5 ± 5.87% cell viability at the minimum effective concentration [MEC]) in THP-1 cell lines and selectively trypanotoxic (p < 0.0001). The pharmacokinetic studies of QS-Na.C complex-loaded oily nanosuspension showed 13.54-fold, 7.09-fold, 1.78-fold, and 17.35-fold increases in t1/2, AUC0-∞, Vz/F, and MRT0-ꝏ, respectively, as compared to free QS. Moreover, a 7.08-fold reduction in plasma clearance was observed after the treatment with the optimized formulation in Wistar rats. Furthermore, treatment with QS-Na.C complex-loaded oily nanosuspension (7.5 mg/kg) in T. evansi-infected mice model showed the absence of parasitaemia for more than 75 days after the treatment during in vivo efficacy studies. The efficacy of the treatment was assessed by observation of blood smear and PCR assay for DNA amplification. To conclude, our findings suggest that the efficient delivery of QS from the developed QS-Na.C complex-loaded oily nanosuspension could be a promising treatment option for veterinary infections against trypanosomiasis.

Evaluating physiochemical properties of FDA-approved orally administered drugs

INTRODUCTION

Analyses of orally administered FDA-approved drugs from 1990 to 1993 enabled the identification of a set of physiochemical properties known as Lipinski's Rule of Five (Ro5). The original Ro5 and extended versions still remain the reference criteria for drug development programs. Since many bioactive compounds do not conform to the Ro5, we validated the relevance of and adherence to these rulesets in a contemporary cohort of FDA-approved drugs.

AREAS COVERED

The authors noted that a significant proportion of FDA-approved orally administered parent compounds from 2011 to 2022 deviate from the original Ro5 criteria (~38%) or the Ro5 with extensions (~53%). They then evaluated if a contemporary Ro5 criteria (cRo5) could be devised to better predict oral bioavailability. Furthermore, they discuss many case studies showcasing the need for and benefit of increasing the size of certain compounds and cover several evolving strategies for improving oral bioavailability.

EXPERT OPINION

Despite many revisions to the Ro5, the authors find that no single proposed physiochemical rule has universal concordance with absolute oral bioavailability. Innovations in drug delivery and formulation have dramatically expanded the range of physicochemical properties and the chemical diversity for oral administration.

Design and synthesis of bioreductive prodrugs of class I histone deacetylase inhibitors and their biological evaluation in virally transfected acute myeloid leukemia cells

Although histone deacetylase (HDAC) inhibitors show promise in treating various types of hematologic malignancies, they have some limitations, including poor pharmacokinetics and off-target side effects. Prodrug design has shown promise as an approach to improve pharmacokinetic properties and to improve target tissue specificity. In this work, several bioreductive prodrugs for class I HDACs were designed based on known selective HDAC inhibitors. The zinc-binding group of the HDAC inhibitors was masked with various nitroarylmethyl residues to make them substrates of nitroreductase (NTR). The developed prodrugs showed weak HDAC inhibitory activity compared to their parent inhibitors. The prodrugs were tested against wild-type and NTR-transfected THP1 cells. Cellular assays showed that both 2-nitroimidazole-based prodrugs 5 and 6 were best activated by the NTR and exhibited potent activity against NTR-THP1 cells. Compound 6 showed the highest cellular activity (GI50  = 77 nM) and exhibited moderate selectivity. Moreover, activation of prodrug 6 by NTR was confirmed by liquid chromatography-mass spectrometry analysis, which showed the release of the parent inhibitor after incubation with Escherichia coli NTR. Thus, compound 6 can be considered a novel prodrug selective for class I HDACs, which could be used as a good starting point for increasing selectivity and for further optimization.

Developing an adult stem cell derived microphysiological intestinal system for predicting oral prodrug bioconversion and permeability in humans

Microphysiological systems (MPS) incorporating human intestinal organoids have shown the potential to faithfully model intestinal biology with the promise to accelerate development of oral prodrugs. We hypothesized that an MPS model incorporating flow, shear stress, and vasculature could provide more reliable measures of prodrug bioconversion and permeability. Following construction of jejunal and duodenal organoid MPS derived from 3 donors, we determined the area under the concentration-time (AUC) curve for the active drug in the vascular channel and characterized the enzymology of prodrug bioconversion. Fosamprenavir underwent phosphatase mediated hydrolysis to amprenavir while dabigatran etexilate (DABE) exhibited proper CES2- and, as anticipated, not CES1-mediated de-esterification, followed by permeation of amprenavir to the vascular channel. When experiments were conducted in the presence of bio-converting enzyme inhibitors (orthovanadate for alkaline phosphatase; bis(p-nitrophenyl)phosphate for carboxylesterase), the AUC of the active drug decreased accordingly in the vascular channel. In addition to functional analysis, the MPS was characterized through imaging and proteomic analysis. Imaging revealed proper expression and localization of epithelial, endothelial, tight junction and catalytic enzyme markers. Global proteomic analysis was used to analyze the MPS model and 3 comparator sources: an organoid-based transwell model (which was also evaluated for function), Matrigel embedded organoids and finally jejunal and duodenal cadaver tissues collected from 3 donors. Hierarchical clustering analysis (HCA) and principal component analysis (PCA) of global proteomic data demonstrated that all organoid-based models exhibited strong similarity and were distinct from tissues. Intestinal organoids in the MPS model exhibited strong similarity to human tissue for key epithelial markers via HCA. Quantitative proteomic analysis showed higher expression of key prodrug converting and drug metabolizing enzymes in MPS-derived organoids compared to tissues, organoids in Matrigel, and organoids on transwells. When comparing organoids from MPS and transwells, expression of intestinal alkaline phosphatase (ALPI), carboxylesterase (CES)2, cytochrome P450 3A4 (CYP3A4) and sucrase isomaltase (SI) was 2.97-, 1.2-, 11.3-, and 27.7-fold higher for duodenum and 7.7-, 4.6-, 18.1-, and 112.2-fold higher for jejunum organoids in MPS, respectively. The MPS approach can provide a more physiological system than enzymes, organoids, and organoids on transwells for pharmacokinetic analysis of prodrugs that account for 10% of all commercial medicines.

Evaluation of dapsone and its synthetic derivative DDS‑13 in cancer in vitro

The present study highlighted the repositioning of the drug dapsone (DDS) for cancer therapy. Due to its mechanism of action, DDS has a dual effect as an antibiotic and as an anti-inflammatory/immunomodulator; however, at high doses, it has important adverse effects. The derivative DDS-13 [N,N'-(sulfonyl bis (4,1-phenylene)) dioctanamide] was synthesized through an N-acylation reaction to compare it with DDS. Its cytotoxic effects in cancer cells (DU145 and HeLa) and non-cancer cells (HDFa) were observed at concentrations ranging 0.01-100 µM and its physicochemical/pharmacokinetic properties were analyzed using the SwissADME tool. The objectives of the present study were to evaluate the anticancer activity of both DDS and DDS-13 and to identify the physicochemical and pharmacokinetic properties of DDS-13. The results showed that DDS-13 presented a cytotoxic effect in the DU145 cell line (IC50=19.06 µM), while DDS showed a cytotoxic effect on both the DU145 (IC50=11.11 µM) and HeLa (IC50=13.07 µM) cell lines. DDS-13 appears to be a good cytotoxic candidate for the treatment of prostate cancer, while DDS appears to be a good candidate for both cervical and prostate cancer. Neither candidate showed a cytotoxic effect in non-cancerous cells. The different pharmacokinetic properties of DDS-13 make it a new candidate for evaluation in preclinical models for the treatment of cancer.

Cell-Penetrating Peptides: A Powerful Tool for Targeted Drug Delivery

The cellular membrane hinders the effective delivery of therapeutics to targeted sites. Cellpenetrating peptide (CPP) is one of the best options for rapidly internalizing across the cellular membrane. CPPs have recently attracted lots of attention because of their excellent transduction efficiency and low cytotoxicity. The CPP-cargo complex is an effective and efficient method of delivering several chemotherapeutic agents used to treat various diseases. Additionally, CPP has become another strategy to overcome some of the current therapeutic agents' limitations. However, no CPP complex is approved by the US FDA because of its limitations and issues. In this review, we mainly discuss the cellpenetrating peptide as the delivery vehicle, the cellular uptake mechanism of CPPs, their design, and some strategies to synthesize the CPP complex via some linkers such as disulfide bond, oxime, etc. Here, we also discuss the recent status of CPPs in the market.

Targeted delivery of LXR-agonists to atherosclerotic lesions mediated by polydiacetylene micelles

We report the development of compact and stabilized micelles incorporating a synthetic LXR agonist prodrug for the passive targeting of atherosclerotic lesions and therapeutic intervention. In vivo studies showed that the nanohybrid micelles exhibited favorable pharmacokinetics/biodistribution and were able to upregulate, to some extent, LXR target genes with no alteration of lipid metabolism.

Comparative Evaluation of Particle Size Reduction, Salt Formation, and Amorphous Formulation on the Biopharmaceutical Performance of a Weak Base Drug Candidate

Various approaches have been developed to enhance the solubility or dissolution rate for the delivery of poorly water-soluble molecules. In this work, guided by an in silico solubility sensitivity analysis for oral absorption, a comparative assessment of the biopharmaceutical performance of a jet-milled free base, a tosylate salt, and a 50:50 (w/w) amorphous solid dispersion (ASD) with hydroxypropyl methylcellulose acetate succinate (HPMCAS) of a weak base drug candidate, GDC-3280, was conducted. Successful particle size reduction without amorphization or form change was confirmed for the jet-milled free base. The potential of solubility enhancement and desupersaturation risk were identified for tosylate salt and ASD formulation by measurements of tosylate salt solubility product constant (Ksp) and amorphous solubility of GDC-3280. In vitro dissolution testing demonstrated dissolution rate improvement for the jet-milled free base when compared with the unmilled free base and confirmed solubility enhancement followed by desupersaturation for GDC-3280 tosylate salt and ASD formulation. A crystallization inhibitor, hydroxypropyl methylcellulose (HPMC), was found to slow down the desupersaturation of tosylate salt solution, providing general insights for the development of pharmaceutical salts with disproportionation risks. Finally, a pharmacokinetic study in dogs showed that the in vivo exposure increased by 1.7- to 2-fold for the tosylate salt and ASD formulation compared with the jet-milled free base, consistent with the in silico solubility sensitivity analysis for the fraction of drug absorbed. Overall, this work provides insights into the evaluation of multiple formulation approaches for enhancing the biopharmaceutical performance of poorly water-soluble drugs.

Glycosidase-targeting small molecules for biological and therapeutic applications

Glycosidases are ubiquitous enzymes that catalyze the hydrolysis of glycosidic linkages in oligosaccharides and glycoconjugates. These enzymes play a vital role in a wide variety of biological events, such as digestion of nutritional carbohydrates, lysosomal catabolism of glycoconjugates, and posttranslational modifications of glycoproteins. Abnormal glycosidase activities are associated with a variety of diseases, particularly cancer and lysosomal storage disorders. Owing to the physiological and pathological significance of glycosidases, the development of small molecules that target these enzymes is an active area in glycoscience and medicinal chemistry. Research efforts carried out thus far have led to the discovery of numerous glycosidase-targeting small molecules that have been utilized to elucidate biological processes as well as to develop effective chemotherapeutic agents. In this review, we describe the results of research studies reported since 2018, giving particular emphasis to the use of fluorescent probes for detection and imaging of glycosidases, activity-based probes for covalent labelling of these enzymes, glycosidase inhibitors, and glycosidase-activatable prodrugs.

Development of Masitinib Derivatives with Enhanced Mpro Ligand Efficiency and Reduced Cytotoxicity

Recently, a high-throughput screen of 1900 clinically used drugs identified masitinib, an orally bioavailable tyrosine kinase inhibitor, as a potential treatment for COVID-19. Masitinib acts as a broad-spectrum inhibitor for human coronaviruses, including SARS-CoV-2 and several of its variants. In this work, we rely on atomistic molecular dynamics simulations with advanced sampling methods to develop a deeper understanding of masitinib's mechanism of Mpro inhibition. To improve the inhibitory efficiency and to increase the ligand selectivity for the viral target, we determined the minimal portion of the molecule (fragment) that is responsible for most of the interactions that arise within the masitinib-Mpro complex. We found that masitinib forms highly stable and specific H-bond interactions with Mpro through its pyridine and aminothiazole rings. Importantly, the interaction with His163 is a key anchoring point of the inhibitor, and its perturbation leads to ligand unbinding within nanoseconds. Based on these observations, a small library of rationally designed masitinib derivatives (M1-M5) was proposed. Our results show increased inhibitory efficiency and highly reduced cytotoxicity for the M3 and M4 derivatives compared to masitinib.

Current screening, design, and delivery approaches to address low permeability of chemically synthesized modalities in drug discovery and early clinical development

A drug's permeability across biological membranes is a key property associated with the successful development of an orally absorbed drug candidate. Although a variety of methods are available for predicting and assessing permeability, some are more preferred than others at specific stages of drug discovery and development across the pharmaceutical industry. Permeability measurements may be interpreted differently depending on the chosen method. Herein, we present a refreshed perspective on the screening approaches and philosophy in permeability evaluation, from early drug discovery to early clinical development. Additionally, we review and discuss chemical design and drug delivery technologies that can be leveraged to overcome permeability challenges, which are increasingly being used with emerging modalities.

Bioorthogonal activation of prodrugs, for the potential treatment of breast cancer, using the Staudinger reaction

Selective prodrug activation at a tumor site is crucial to maximise the efficiency of chemotherapy approaches and minimise side effects due to off-site activation. In this paper, a new prodrug activation strategy is reported based on the bioorthogonal Staudinger reaction. The feasibility of this prodrug activation strategy was initially demonstrated using 9-azido sialic acid 4 as a trigger and two novel triphenylphosphine-modified N-mustard-PRO 10 and doxorubicin-PRO 12 prodrugs in an HPLC-monitored release study. Then, the azide reporter group was introduced on cancer cells' surfaces through metabolic glycoengineering of sialic acid-rich surface glycans using azide-modified monosaccharides (9-azido sialic acid 4, tetra-O-acetylated-9-azido sialic acid 5 and tetra-O-acetyl azidomannosamine). Next, the N-mustard-PRO 10 and doxorubicin-PRO 12 prodrugs were employed in vitro with the bioengineered cells, and activation of the prodrugs, which allowed selective release of the cytotoxic moiety at the tumour cell, was assessed. Release of the parent drugs from the prodrugs was shown to be dependent on the level of metabolic labelling, where tetra-O-acetyl azidomannosamine allowed the highest level of azide reporter generation in tumor cells and led to full recovery of the parent cytotoxic drug's potency. The selectivity of azide expression on breast cancer MCF-7 cells versus normal fibroblast L929 cells was also probed, with the 9-azido sialic acid and tetra-O-acetylated-9-azido sialic acid showing ∼17-fold higher azide expression on the former. Taken together, these data demonstrate the feasibility of the Staudinger reaction for selective activation of prodrugs targeted to the MCF-7 breast cancer cells.

Investigating the Effect of Basic Amino Acids and Glucosamine on the Solubility of Ibuprofen and Piroxicam

Purpose

Poor aqueous solubility hampers the development of several compounds as pharmacological agents. Hence, preparing novel formulations with augmented absorption is a challenge in pharmaceutical industries. In this paper, we have examined the effect of basic amino acids including arginine (ARG), lysine (LYS), and glucosamine (GlucN) on the solubility of ibuprofen (IBU) and piroxicam (PXM) as drugs with limited solubility. We have also studied the effect of the dissolution media with the pH values 1.2 to 7.4.

Methods

The saturation shake-flask method was used for solubility studies in the presence of amino acids. Briefly, buffer solutions containing different concentrations of amino acids were prepared. Then, an excess amount of each drug with these buffers was shaken to reach equilibrium. After 48 hours, the upper phase was separated, and solubility was calculated by reading their UV-Vis absorbance.

Results

The results illustrated that amino acids increased solubility of both drugs with different ratios, which were pH and concentration-dependent. Solubility improved as the amount of amino acids went up, and this upward pattern was more robust with ARG than LYS. The presence of GlucN in citrate buffer significantly enhanced IBU solubility. The solubility of PXM in accompany of GlucN in water did not change significantly while in citrate buffer solubility enhanced specially at pH 6.

Conclusion

Overall, GlucN in citrate buffer and ARG in phosphate buffer could be introduced as the most suitable media for IBU and PXM solubility improvement, respectively.

Optimization of Drug-Linker to Enable Long-term Storage of Antibody-Drug Conjugate for Subcutaneous Dosing

To facilitate subcutaneous dosing, biotherapeutics need to exhibit properties that enable high-concentration formulation and long-term stability in the formulation buffer. For antibody-drug conjugates (ADCs), the introduction of drug-linkers can lead to increased hydrophobicity and higher levels of aggregation, which are both detrimental to the properties required for subcutaneous dosing. Herein we show how the physicochemical properties of ADCs could be controlled through the drug-linker chemistry in combination with prodrug chemistry of the payload, and how optimization of these combinations could afford ADCs with significantly improved solution stability. Key to achieving this optimization is the use of an accelerated stress test performed in a minimal formulation buffer.

X-ray-responsive prodrugs and polymeric nanocarriers for multimodal cancer therapy

Radiotherapy as one of the most important cancer treatment modalities has been widely used in the therapy of various cancers. The clinically used radiation (e.g. X-ray) for radiotherapy has the advantages of precise spatiotemporal controllability and deep tissue penetration. However, traditional radiotherapy is frequently limited by the high side effects and tumor hypoxia. The combination of radiotherapy and other cancer treatment modalities may overcome the disadvantages of radiotherapy and improve the final therapeutic efficacy. In recent years, X-ray-activable prodrugs and polymeric nanocarriers have been extensively explored to introduce other treatment modalities in the precise position during radiotherapy, which can reduce the side toxicity of the drugs and improve the combination therapeutic efficacy. In this review, we focus on recent advances in X-ray-activable prodrugs and polymeric nanocarriers to boost X-ray-based multimodal synergistic therapy with reduced toxicity. The design strategies of prodrugs and polymeric nanocarriers are highlighted. Finally, challenges and outlooks of X-ray-activable prodrugs and polymeric nanocarriers are discussed.

Alkaline phosphatase (ALP) activatable small molecule-based prodrugs for cancer theranostics

Highly water-soluble small molecule-based prodrugs (5-FUPD and SAHAPD) are formulated. They comprise a phosphate group to lock the active drug payload (5-fluorouracil and SAHA) along with a turn-on fluorophore consisting of a glutathione (GSH) depletory feature. Installation of the phosphate group along with purification of final product has been accomplished in an operationally facile manner. Activation of the prodrugs is facilitated by alkaline phosphatase (ALP)-mediated hydrolysis of the phosphate group followed by 1,8-elimination. The prodrugs were found to be highly effective against ALP flared human cervical cancer (HeLa) and liver cancer (HepG2) cell lines. Most notably, they were found to be innocuous to normal liver cells (WRL-68).

Application of Sucrose Acetate Isobutyrate in Development of Co-Amorphous Formulations of Tacrolimus for Bioavailability Enhancement

The focus of the present work was to develop co-amorphous dispersion (CAD) formulations of tacrolimus (TAC) using sucrose acetate isobutyrate as a carrier, evaluate by in vitro and in vivo methods and compare its performance with hydroxypropyl methylcellulose (HPMC) based amorphous solid dispersion (ASD) formulation. CAD and ASD formulations were prepared by solvent evaporation method followed by characterization by Fourier transformed infrared spectroscopy, X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), dissolution, stability, and pharmacokinetics. XRPD and DSC indicated amorphous phase transformation of the drug in the CAD and ASD formulations, and dissolved more than 85% of the drug in 90 min. No drug crystallization was observed in the thermogram and diffractogram of the formulations after storage at 25 °C/60% RH and 40 °C/75% RH. No significant change in the dissolution profile was observed after and before storage. SAIB-based CAD and HPMC-based ASD formulations were bioequivalent as they met 90% confidence of 90-11.1% for C_max and AUC. The CAD and ASD formulations exhibited C_max and AUC 1.7-1.8 and 1.5-1.8 folds of tablet formulations containing the drug's crystalline phase. In conclusion, the stability, dissolution, and pharmacokinetic performance of SAIB-based CAD and HPMC-based ASD formulations were similar, and thus clinical performance would be similar.

Advancement in Solubilization Approaches: A Step towards Bioavailability Enhancement of Poorly Soluble Drugs

A drug's aqueous solubility is defined as the ability to dissolve in a particular solvent, and it is currently a major hurdle in bringing new drug molecules to the market. According to some estimates, up to 40% of commercialized products and 70-90% of drug candidates in the development stage are poorly soluble, which results in low bioavailability, diminished therapeutic effects, and dosage escalation. Because of this, solubility must be taken into consideration when developing and fabricating pharmaceutical products. To date, a number of approaches have been investigated to address the problem of poor solubility. This review article attempts to summarize several conventional methods utilized to increase the solubility of poorly soluble drugs. These methods include the principles of physical and chemical approaches such as particle size reduction, solid dispersion, supercritical fluid technology, cryogenic technology, inclusion complex formation techniques, and floating granules. It includes structural modification (i.e., prodrug, salt formation, co-crystallization, use of co-solvents, hydrotrophy, polymorphs, amorphous solid dispersions, and pH variation). Various nanotechnological approaches such as liposomes, nanoparticles, dendrimers, micelles, metal organic frameworks, nanogels, nanoemulsions, nanosuspension, carbon nanotubes, and so forth have also been widely investigated for solubility enhancement. All these approaches have brought forward the enhancement of the bioavailability of orally administered drugs by improving the solubility of poorly water-soluble drugs. However, the solubility issues have not been completely resolved, owing to several challenges associated with current approaches, such as reproducibility in large scale production. Considering that there is no universal approach for solving solubility issues, more research is needed to simplify the existing technologies, which could increase the number of commercially available products employing these techniques.

Design, Synthesis, and Evaluation of Carbonate-Linked Halogenated Phenazine-Quinone Prodrugs with Improved Water-Solubility and Potent Antibacterial Profiles

Pathogenic bacteria have devastating impacts on human health as a result of acquired antibiotic resistance and innate tolerance. Every class of our current antibiotic arsenal was initially discovered as growth-inhibiting agents that target actively replicating (individual, free-floating) planktonic bacteria. Bacteria are notorious for utilizing a diversity of resistance mechanisms to overcome the action of conventional antibiotic therapies and forming surface-attached biofilm communities enriched in (non-replicating) persister cells. To address problems associated with pathogenic bacteria, our group is developing halogenated phenazine (HP) molecules that demonstrate potent antibacterial and biofilm-eradicating activities through a unique iron starvation mode of action. In this study, we designed, synthesized, and investigated a focused collection of carbonate-linked HP prodrugs bearing a quinone trigger to target the reductive cytoplasm of bacteria for bioactivation and subsequent HP release. The quinone moiety also contains a polyethylene glycol group, which dramatically enhances the water-solubility properties of the HP-quinone prodrugs reported herein. We found carbonate-linked HP-quinone prodrugs 11, 21-23 to demonstrate good linker stability, rapid release of the active HP warhead following dithiothreitol (reductive) treatment, and potent antibacterial activities against methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis, and Enterococcus faecalis. In addition, HP-quinone prodrug 21 induced rapid iron starvation in MRSA and S. epidermidis biofilms, illustrating prodrug action within these surface-attached communities. Overall, we are highly encouraged by these findings and believe that HP prodrugs have the potential to address antibiotic resistant and tolerant bacterial infections.

Peptide cargo administration: current state and applications

Effective delivery of drug molecules to the target site is a challenging task. In the last decade, several innovations in the drug delivery system (DDS) have tremendously improved the therapeutic efficacy of drug molecules. Among various DDS, cell-penetrating peptides (CPPs) based DDS have gathered notable attention owing to their safety, efficacy, selectivity, specificity, and ease of synthesis. CPPs are emerging as an efficient and effective pharmaceutical nanocarriers-based platforms for successful management of various important human health disorders. Failure of several current chemotherapeutic strategies is attributed to low solubility, reduced bioavailability, and off-target delivery of several anti-cancer drugs. Similarly, development of therapeutics for vision-threatening disorders is challenged by the anatomical as well as physiological complexity of the eye. Such therapeutic challenges in cancer and ocular disease management can be overcome by developing cell-penetrating peptide (CPP) based peptide drug conjugates (PDCs). CPPs can be used to deliver various types of cargo molecules including nucleic acids, small molecules, and peptides/proteinaceous agents. In this review, we have briefly introduced CPPs and the linker strategies employed for the development of PDCs. Furthermore, recent studies employing CPP-based PDCs for cancer and ocular disease management have been discussed in detail highlighting their significance over conventional DDS. Later sections of the review are focused on the current status of clinical trials and future implications of CPP-based PDCs in vaccine development. KEY POINTS: • Cell-penetrating peptides (CPPs) can deliver a variety of cargo macromolecules via covalent and non-covalent conjugation. • CPP-based peptide drug conjugates (PDCs) can overcome drawbacks of conventional drug delivery methods such as biocompatibility, solubility, stability, and specificity. • Various PDCs are in clinical trial phase for cancer and ocular therapeutics.

Structure modification: a successful tool for prodrug design

Prodrug strategy is critical for innovative drug development. Structural modification is the most straightforward and effective method to develop prodrugs. Improving drug defects and optimizing the physical and chemical properties of a drug, such as lipophilicity and water solubility, changing the way of administration can be achieved through specific structural modification. Designing prodrugs by linking microenvironment-responsive groups to the prototype drugs is of great help in enhancing drug targeting. In the meantime, making connections between prodrugs and suitable drug delivery systems could realize drug loading increases, greater stability, bioavailability and drug release control. In this paper, lipidic, water-soluble, pH-responsive, redox-sensitive and enzyme-activatable prodrugs are reviewed on the basis of structural modification.

Maleic Acid as a Co-Former for Pharmaceutically Active GABA Derivatives: Mechanochemistry or Solvent Crystallization?

In this study, we compare the mechanochemical and classical solvent crystallization methods for forming maleates of GABA and its pharmaceutically active derivatives: Pregabalin, Gabapentin, Phenibut, and Baclofen. Common characterization techniques, like powder and single crystal X-ray diffraction, IR-spectroscopy, differential scanning calorimetry, thermogravimetric analysis and ¹H-NMR spectroscopy, are used for the evaluation of structural and physicochemical properties. Our work shows that maleate formation is possible with all investigated target compounds. Large increases in solubility can be achieved, especially for Pregabalin, where up to twentyfold higher solubility in its maleate compared to the pure form can be reached. We furthermore compare the mechanochemical and solvent crystallization regarding quickness, reliability of phase production, and overall product quality. A synthetic route is shown to have an impact on certain properties such as melting point or solubility of the same obtained products, e.g., for Gabapentin and Pregabalin, or lead to the formation of hydrates vs. anhydrous forms. For the GABA and Baclofen maleates, the method of crystallization is not important, and similarly, good results can be obtained by either route. In contrast, Phenibut maleate cannot be obtained pure and single-phase by either method. Our work aims to elucidate promising candidates for the multicomponent crystal formation of blockbuster GABA pharmaceuticals and highlight the usefulness of mechanochemical production routes.

Potential Anti-SARS-CoV-2 Prodrugs Activated by Phosphorylation and Their Role in the Aged Population

The COVID-19 pandemic has flared across every part of the globe and affected populations from different age groups differently. People aged from 40 to 80 years or older are at an increased risk of morbidity and mortality due to COVID-19. Therefore, there is an urgent requirement to develop therapeutics to decrease the risk of the disease in the aged population. Over the last few years, several prodrugs have demonstrated significant anti-SARS-CoV-2 effects in in vitro assays, animal models, and medical practice. Prodrugs are used to enhance drug delivery by improving pharmacokinetic parameters, decreasing toxicity, and attaining site specificity. This article discusses recently explored prodrugs such as remdesivir, molnupiravir, favipiravir, and 2-deoxy-D-glucose (2-DG) and their implications in the aged population, as well as investigating recent clinical trials.

Guaiazulene and related compounds: A review of current perspective on biomedical applications

BACKGROUND

Thousands of people worldwide pass away yearly due to neurological disorders, cardiovascular illnesses, cancer, metabolic disorders, and microbial infections. Additionally, a sizable population has also been impacted by hepatotoxicity, ulcers, gastroesophageal reflux disease, and breast fissure. These ailments are likewise steadily increasing along with the increase in life expectancy. Finding innovative therapies to cure and consequently lessen the impact of these ailments is, therefore, a global concern.

METHODS AND MATERIALS

All provided literature on Guaiazulene (GA) and its related compounds were searched using various electronic databases such as PubMed, Google Scholar, Web of Science, Elsevier, Springer, ACS, CNKI, and books via the keywords Guaiazulene, Matricaria chamomilla, GA-related compounds, and Guaiazulene analogous.

RESULTS

The FDA has approved the bicyclic sesquiterpene GA, commonly referred to as azulon or 1,4-dimethyl-7-isopropylazulene, as a component in cosmetic colorants. The pleiotropic health advantages of GA and related substances, especially their antioxidant and anti-inflammatory effects, attracted a lot of research. Numerous studies have found that GA can help to manage various conditions, including bacterial infections, tumors, immunomodulation, expectorants, diuretics, diaphoresis, ulcers, dermatitis, proliferation, and gastritis. These conditions all involve lipid peroxidation and inflammatory response. In this review, we have covered the biomedical applications of GA. Moreover, we also emphasize the therapeutic potential of guaiazulene derivatives in pre-clinical and clinical settings, along with their underlying mechanism(s).

CONCLUSION

GA and its related compounds exhibit therapeutic potential in several diseases. Still, it is necessary to investigate their potential in animal models for various other ailments and establish their safety profile. They might be a good candidate to advance to clinical trials.

Molnupiravir: A Versatile Prodrug against SARS-CoV-2 Variants

The nucleoside analog β-D-N4-hydroxycytidine is the active metabolite of the prodrug molnupiravir and is accepted as an efficient drug against COVID-19. Molnupiravir targets the RNA-dependent RNA polymerase (RdRp) enzyme, which is responsible for replicating the viral genome during the replication process of certain types of viruses. It works by disrupting the normal function of the RdRp enzyme, causing it to make mistakes during the replication of the viral genome. These mistakes can prevent the viral RNA from being transcribed, converted into a complementary DNA template, translated, or converted into a functional protein. By disrupting these crucial steps in the viral replication process, molnupiravir can effectively inhibit the replication of the virus and reduce its ability to cause disease. This review article sheds light on the impact of molnupiravir and its metabolite on SARS-CoV-2 variants of concern, such as delta, omicron, and hybrid/recombinant variants. The detailed mechanism and molecular interactions using molecular docking and dynamics have also been covered. The safety and tolerability of molnupiravir in patients with comorbidities have also been emphasized.

Advances in Oral Drug Delivery Systems: Challenges and Opportunities

The oral route is the most preferred route for systemic and local drug delivery. However, the oral drug delivery system faces the harsh physiological and physicochemical environment of the gastrointestinal tract, which limits the bioavailability and targeted design of oral drug delivery system. Innovative pharmaceutical approaches including nanoparticulate formulations, biomimetic drug formulations, and microfabricated devices have been explored to optimize drug targeting and bioavailability. In this review, the anatomical factors, biochemical factors, and physiology factors that influence delivering drug via oral route are discussed and recent advance in conventional and novel oral drug delivery approaches for improving drug bioavailability and targeting ability are highlighted. We also address the challenges and opportunities of oral drug delivery systems in future.

Metabolism Pathways of Major Therapeutics for Treating Monkeypox Mono- and Co-infection with Human Immunodeficient Virus or SARS-CoV-2

Monkeypox is a zoonotic viral disease and remains endemic in tropical regions of Central and West Africa. Since May of 2022, cases of monkeypox have soared and spread worldwide. Confirmed cases have shown no travel history to the endemic regions as seen in the past. The World Health Organization declared monkeypox a global public health emergency in July 2022, and the United States government followed suit one month later. The current outbreak, in contrast to traditional epidemics, has high coinfection rates, particularly with HIV (human immunodeficiency virus), and to a lesser extent with SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), the pathogen of COVID-19. No drugs have been approved specifically for monkeypox. However, there are therapeutic agents authorized to treat monkeypox under the Investigational New Drug protocol, including brincidofovir, cidofovir, and tecovirimat. In contrast to limited options for monkeypox treatment, there are available drugs specifically for HIV or SARS-CoV-2 infection. Interestingly, these HIV and COVID-19 medicines share metabolism pathways with those authorized to treat monkeypox, particularly of hydrolysis, phosphorylation, and active membrane transport. This review discusses how these pathways shared by these medicines should be considered to gain therapeutic synergy and maximize safety for treating monkeypox coinfections.

Flavonoid-Conjugated Gadolinium Complexes as Anti-Inflammatory Theranostic Agents

In this study, we designed, synthesized, and evaluated gadolinium compounds conjugated with flavonoids as potential theranostic agents for the treatment of inflammation. These novel theranostic agents combine a molecular imaging agent and one of three flavonoids (galangin, chrysin, and 7-hydroxyflavone) as anti-inflammatory drugs as a single integrated platform. Using these agents, MR imaging showed contrast enhancement (>10 in CNR) at inflamed sites in an animal inflammation model, and subsequent MR imaging used to monitor the therapeutic efficacy of these integrated agents revealed changes in inflamed regions. The anti-inflammatory effects of these agents were demonstrated both in vitro and in vivo. Furthermore, the antioxidant efficacy of the agents was evaluated by measuring their reactive oxygen species scavenging properties. For example, Gd-galangin at 30 μM showed a three-fold higher ROS scavenging of DPPH. Taken together, our findings provide convincing evidence to indicate that flavonoid-conjugated gadolinium compounds can be used as potentially efficient theranostic agents for the treatment of inflammation.

Dual-Drug Nanosystem: Etoposide Prodrug and Cisplatin Coloaded Nanostructured Lipid Carriers for Lung Cancer Therapy

Purpose

Cisplatin (CDDP) and etoposide (Etp) are recommended first-line therapy for lung cancer. Nanostructured lipid carriers (NLCs) are engineered to deliver drugs for lung cancer treatment. In the present study, NLCs were applied to coload an Etp prodrug (EtpP) and CDDP.

Methods

The Etp prodrug was synthesized by linking the phenolic hydroxyl group of Etp with polyethylene glycol (PEG). EtpP and CDDP coencapsulated NLCs (EtpP-CDDP NLCs) were prepared using film ultrasound. Cytotoxicity of drugs and drug-containing NLCs was assessed by evaluating cell viability using MTT assays. In vivo antitumor efficiency of EtpP-CDDP NLCs was evaluated on lung cancer-bearing xenografts.

Results

EtpP-CDDP NLCs showed a uniformly spherical morphology with a size of 176.8±4.9 nm and -potential of -31.9±3.2 mV. Cellular uptake efficiency of EtpP-CDDP NLCs was 57.4%±3.9% on A549/DDP cells. EtpP-CDDP NLCs exhibited more sustained plasma retention, the highest drug distribution in tumors, and the highest tumor-inhibition rates in lung tumor-bearing mice.

Conclusion

EtpP-CDDP NLCs improved tumor-cell uptake, cytotoxicity, and tumor-inhibition efficiency, and could be used as a promising drug-delivery system for lung cancer combination therapy.

Discovery of a novel water-soluble, rapid-release triptolide prodrug with improved drug-like properties and high efficacy in human acute myeloid leukemia

In this work, a series of water-soluble triptolide prodrugs were synthesized, and their triptolide release rate, pharmacokinetic characteristics and anti-tumor effect were measured. We found that inserting glycolic acid as a linker between triptolide and the cyclic amino acid accelerated the release of triptolide from prodrugs into the plasma while preserving its safety. Among them, prodrug TP-P1 was significantly better than Minnelide (the only water-soluble triptolide prodrug in clinical trials) in terms of release rate in plasma and synthetic yield. In mouse models of human acute myeloid leukemia (AML), TP-P1 was effective in reducing xenograft tumors at dose levels as low as 25 μg/kg, and eliminating tumors at dose 100 μg/kg. Furthermore, TP-P1 could significantly enhance the efficacy of FLT3 inhibitors in the treatment of AML. These experimental results showed the potential of TP-P1 as water-soluble prodrugs of triptolide.

Fast-Fed Variability: Insights into Drug Delivery, Molecular Manifestations, and Regulatory Aspects

Among various drug administration routes, oral drug delivery is preferred and is considered patient-friendly; hence, most of the marketed drugs are available as conventional tablets or capsules. In such cases, the administration of drugs with or without food has tremendous importance on the bioavailability of the drugs. The presence of food may increase (positive effect) or decrease (negative effect) the bioavailability of the drug. Such a positive or negative effect is undesirable since it makes dosage estimation difficult in several diseases. This may lead to an increased propensity for adverse effects of drugs when a positive food effect is perceived. However, a negative food effect may lead to therapeutic insufficiency for patients suffering from life-threatening disorders. This review emphasizes the causes of food effects, formulation strategies to overcome the fast-fed variability, and the regulatory aspects of drugs with food effects, which may open new avenues for researchers to design products that may help to eliminate fast-fed variability.

MOG analogues to explore the MCT2 pharmacophore, α-ketoglutarate biology and cellular effects of N-oxalylglycine

α-ketoglutarate (αKG) is a central metabolic node with a broad influence on cellular physiology. The αKG analogue N-oxalylglycine (NOG) and its membrane-permeable pro-drug derivative dimethyl-oxalylglycine (DMOG) have been extensively used as tools to study prolyl hydroxylases (PHDs) and other αKG-dependent processes. In cell culture media, DMOG is rapidly converted to MOG, which enters cells through monocarboxylate transporter MCT2, leading to intracellular NOG concentrations that are sufficiently high to inhibit glutaminolysis enzymes and cause cytotoxicity. Therefore, the degree of (D)MOG instability together with MCT2 expression levels determine the intracellular targets NOG engages with and, ultimately, its effects on cell viability. Here we designed and characterised a series of MOG analogues with the aims of improving compound stability and exploring the functional requirements for interaction with MCT2, a relatively understudied member of the SLC16 family. We report MOG analogues that maintain ability to enter cells via MCT2, and identify compounds that do not inhibit glutaminolysis or cause cytotoxicity but can still inhibit PHDs. We use these analogues to show that, under our experimental conditions, glutaminolysis-induced activation of mTORC1 can be uncoupled from PHD activity. Therefore, these new compounds can help deconvolute cellular effects that result from the polypharmacological action of NOG.

Anticancer Drugs: Recent Strategies to Improve Stability Profile, Pharmacokinetic and Pharmacodynamic Properties

In past decades, anticancer research has led to remarkable results despite many of the approved drugs still being characterized by high systemic toxicity mainly due to the lack of tumor selectivity and present pharmacokinetic drawbacks, including low water solubility, that negatively affect the drug circulation time and bioavailability. The stability studies, performed in mild conditions during their development or under stressing exposure to high temperature, hydrolytic medium or light source, have demonstrated the sensitivity of anticancer drugs to many parameters. For this reason, the formation of degradation products is assessed both in pharmaceutical formulations and in the environment as hospital waste. To date, numerous formulations have been developed for achieving tissue-specific drug targeting and reducing toxic side effects, as well as for improving drug stability. The development of prodrugs represents a promising strategy in targeted cancer therapy for improving the selectivity, efficacy and stability of active compounds. Recent studies show that the incorporation of anticancer drugs into vesicular systems, such as polymeric micelles or cyclodextrins, or the use of nanocarriers containing chemotherapeutics that conjugate to monoclonal antibodies can improve solubility, pharmacokinetics, cellular absorption and stability. In this study, we summarize the latest advances in knowledge regarding the development of effective highly stable anticancer drugs formulated as stable prodrugs or entrapped in nanosystems.

Development of Sesamol Carbamate-L-Phenylalanine Prodrug Targeting L-Type Amino Acid Transporter1 (LAT1) as a Potential Antiproliferative Agent against Melanoma

Sesamol is a compound reported to have anti-melanogenesis and anti-melanoma actions. Sesamol, however, has low intracellular drug concentration and fast excretion, which can limit its benefits in the clinic. To overcome this drawback and increase intracellular delivery of sesamol into the target melanoma, research has focused on L-type amino acid transporter 1 (LAT1)-mediated prodrug delivery into melanoma cells. The sesamol prodrug was designed by conjugating sesamol with L-phenylalanine at the para position with a carbamate bond. LAT1 targeting was evaluated vis-à-vis a competitive [¹⁴C]-leucine uptake inhibition. The sesamol prodrug has a higher [¹⁴C]-leucine uptake inhibition than sesamol in human LAT1-transfected HEK293 cells. Moreover, the sesamol prodrug was taken up by LAT1-mediated transport into SK-MEL-2 cells more effectively than sesamol. The sesamol prodrug underwent complete hydrolysis, releasing the active sesamol at 72 h, which significantly exerted its cytotoxicity (IC₅₀ of 29.3 µM) against SK-MEL-cells more than sesamol alone. Taken together, the strategy for LAT1-mediated prodrug delivery has utility for the selective uptake of sesamol, thereby increasing its intracellular concentration and antiproliferation activity, targeting melanoma SK-MEL-2 cells that overexpress the LAT1 protein. The sesamol prodrug thus warrants further evaluation in an in vivo model.

Structural Modification in Anesthetic Drug Development for Prodrugs and Soft Drugs

Among the advancements in drug structural modifications, the increased focus on drug metabolic and pharmacokinetic properties in the anesthetic drug design process has led to significant developments. Drug metabolism also plays a key role in optimizing the pharmacokinetics, pharmacodynamics, and safety of drug molecules. Thus, in the field of anesthesiology, the applications of pharmacokinetic strategies are discussed in the context of sedatives, analgesics, and muscle relaxants. In this review, we summarize two approaches for structural optimization to develop anesthetic drugs, by designing prodrugs and soft drugs. Drugs that both failed and succeeded during the developmental stage are highlighted to illustrate how drug metabolism and pharmacokinetic optimization strategies may help improve their physical and chemical properties.

Analogues of Pyrimidine Nucleosides as Mycobacteria Growth Inhibitors

Tuberculosis (TB) is the oldest human infection disease. Mortality from TB significantly decreased in the 20th century, because of vaccination and the widespread use of antibiotics. However, about a third of the world’s population is currently infected with Mycobacterium tuberculosis (Mtb) and the death rate from TB is about 1.4–2 million people per year. In the second half of the 20th century, new extensively multidrug-resistant strains of Mtb were identified, which are steadily increasing among TB patients. Therefore, there is an urgent need to develop new anti-TB drugs, which remains one of the priorities of pharmacology and medicinal chemistry. The antimycobacterial activity of nucleoside derivatives and analogues was revealed not so long ago, and a lot of studies on their antibacterial properties have been published. Despite the fact that there are no clinically used drugs based on nucleoside analogues, some progress has been made in this area. This review summarizes current research in the field of the design and study of inhibitors of mycobacteria, primarily Mtb.