Combination therapy with nirmatrelvir and molnupiravir improves the survival of SARS-CoV-2 infected mice

As the SARS-CoV-2 pandemic remains uncontrolled owing to the continuous emergence of variants of concern, there is an immediate need to implement the most effective antiviral treatment strategies, especially for risk groups. Here, we evaluated the therapeutic potency of nirmatrelvir, remdesivir and molnupiravir, and their combinations in SARS-CoV-2 infected K18-hACE2 transgenic mice. Systemic treatment of mice with each drug (20 mg/kg) resulted in slightly enhanced antiviral efficacy and yielded an increased life expectancy of only about 20-40% survival. However, combination therapy with nirmatrelvir (20 mg/kg) and molnupiravir (20 mg/kg) in lethally infected mice showed profound inhibition of SARS-CoV-2 replication in both the lung and brain and synergistically improved survival rates up to 80% compared to those with nirmatrelvir (36%, P < 0.001) and molnupiravir (43%, P < 0.001) administered alone. This combination therapy effectively reduced clinical severity score, virus-induced tissue damage, and viral distribution compared to those in animals treated with these monotherapies. Furthermore, all these assessments associated with this combination were also significantly higher than that of mice receiving remdesivir monotherapy (P < 0.001) and the nirmatrelvir (20 mg/kg) and remdesivir (20 mg/kg) combination (P < 0.001), underscored the clinical significance of this combination. By contrast, the nirmatrelvir and remdesivir combination showed less antiviral efficacy, with lower survival compared to nirmatrelvir monotherapy due to the insufficient plasma exposure of the remdesivir, demonstrating the inefficient therapeutic effect of this combination in the mouse model. The combination therapy with nirmatrelvir and molnupiravir contributes to alleviated morbidity and mortality, which can serve as a basis for the design of clinical studies of this combination in the treatment of COVID-19 patients.

Cutaneous Tuberculosis and Nontuberculous Mycobacterial Infections at a National Specialized Hospital in China

To identify the microorganism distribution clinical characteristics and management of cutaneous Mycobacterium tuberculosis and nontuberculous mycobacterial infectious diseases in the past 10 years we collected and analyzed the patient records of all cutaneous M. tuberculosis and nontuberculous mycobacterial infection cases diagnosed by culture and/or PCR from 2008 to 2017 in the Hospital of Dermatology Chinese Academy of Medical Sciences. Among 203 cases including 89 M. tuberculosis infections and 114 nontuberculous mycobacterial infections M. tuberculosis was the most common species in all patients and M. marinum predominated among the nontuberculous mycobacterial followed by M. abscessus. Cases of cutaneous mycobacterial infection especially nontuberculous mycobacterial infection increased in the past 10 years and infection with rapidly growing mycobacteria significantly increased in the last 5 years in this national hospital in Southeast China. Injuries were common causative factors. Approximately 91.3% of patients responded well to longstanding antibiotic therapy.

Molecular surveillance of antimicrobial resistance and transmission pattern of Mycobacterium leprae in Chinese leprosy patients

Reports on antimicrobial resistance (AMR) of Mycobacterium leprae, relationship with bacteriological index (BI), and transmission in China are limited. We investigated the emergence of AMR mutations, the relationship between BI and AMR in complete, moderate and lack of BI decline cases, and molecular epidemiological features of AMR cases by enrolling 290 leprosy cases from four endemic provinces. Seven (2.41%), one (0.34%), five (1.72%), one (0.34%), and one (0.34%) strains had single mutations in folP1, rpoC, gyrA, gyrB, and 23S rRNA, respectively. Double mutations in folP1 and gyrA, rpoB and gyrA, and gyrA and 23S rRNA were observed in one (0.34%) strain each. Mutated strains occurred in three out of 81 (95% CI-0.005-0.079, p = 0.083) cases with complete BI decline, in seven out of 103 (95% CI 0.018-0.117, p = 0.008) cases with moderate BI decline, and in four out of 34 (95% CI 0.003-0.231, p = 0.044) cases with lack of BI decline. Most of these mutated strains were geographically separated and diverged genotypically. AMR mutations may not be the main cause of the lack of BI decline. The low transmission of AMR strains at the county level indicates an ongoing transmission at close contact levels.

Genotyping of Mycobacterium leprae for understanding the distribution and transmission of leprosy in endemic provinces of China

OBJECTIVES

Understanding the nature of Mycobacterium leprae transmission is vital to implement better control strategies for leprosy elimination. The present study expands the knowledge of county-level strain diversity, distribution, and transmission patterns of leprosy in endemic provinces of China.

METHODS

We genetically characterized 290 clinical isolates of M. leprae from four endemic provinces using variable number tandem repeats (VNTR) and single nucleotide polymorphisms (SNPs). Attained genetic profiles and cluster consequences were contrasted with geographical and migration features of leprosy at county levels.

RESULTS

Considering the allelic variability of 17 VNTR loci by the discriminatory index, (GTA)9, (AT)17, (AT)15, (TA)18, (TTC)21, and (TA)10 are reported to be more highly polymorphic than other loci. The VNTR profile generated the low-density clustering pattern in the counties of Sichuan and Yunnan, whereas clusters have been observed from the isolates from Huayuan (N = 6), Yongding (N = 3), Zixing (N = 3), Chenxi (N = 2) and Zhongfang (N = 2) counties of Hunan, and Zhijin (N = 3), Anlong (N = 2), Zhenning (N = 2), and Xixiu (N = 2) counties of Guizhou. In some clusters, people's social relations have been observed between villages. From the 290 clinical isolates, the most predominantly reported SNP was 3K (278, 95.8%), followed by SNP 1D (10, 3.4%), which are typically observed to be predominant in China. We also detected the novel SNP 3J (2, 0.8%), which has not yet been reported in China.

CONCLUSION

The clustering pattern of M. leprae indicates the transmission of leprosy still persists at county levels, suggesting that there is a need to implement better approaches for tracing the close contacts of leprosy patients.

Utility of Multi-target Nested PCR and ELISPOT Assays for the Detection of Paucibacillary Leprosy: A Possible Conclusion of Clinical Laboratory Misdiagnosis

The diagnosis of paucibacillary (PB) leprosy often possesses a diagnostic challenge, especially for pure neuritic and lesser skin lesions with the zero bacillary load, requiring a sensitive and accurate diagnostic tool. We have included 300 clinically diagnosed new leprosy cases (comprising 98 PB cases) and analyzed the sensitivity and specificity of PB leprosy cases by nested PCR with folP, gyrA, rpoB, RLEP, and 16SrRNA and Enzyme-linked Immunospot Assay test (ELISPOT) with MMPII, NDO-BSA, and LID-1 antigens by detecting interferon gamma (IFN-γ) release. The overall positivity rates of genes tested in 300 clinical specimens were identified as 55% of 16SrRNA, 59% of RLEP, 59.3% of folP, 57.3% of rpoB, 61% of gyrA while 90% of nested folP, 92.6% of nested rpoB, and 95% of nested gyrA, and 285 (95%) of at least one gene positive cases. For PB specimens, 95% PCR positivity was achieved by three tested genes in nested PCR. The data obtained from ELISPOT for three antigens were analyzed for IFN-γ expression with 600 subjects. Among 98 PB leprosy cases, the sensitivity of MMP II, LID-1, and NDO-BSA was 90%, 87%, and 83%, respectively, and the specificity was 90%, 91%, and 86%, respectively. The total number of cases positive for at least one antigen was 90 (91.8%) in PB, which is significantly higher than that in multibacillary (MB) leprosy (56.7%). The combination of multi-targets nested PCR and ELISPOT assay provides a specific tool to early clinical laboratory diagnosis of PB leprosy cases. The two assays are complementary to each other and beneficial for screening PB patients.

Influenza Treatment: Limitations of Antiviral Therapy and Advantages of Drug Combination Therapy

Influenza infection is serious and debilitating for humans and animals. The influenza virus undergoes incessant mutation, segment recombination, and genome reassortment. As a result, new epidemics and pandemics are expected to emerge, making the elimination challenging of the disease. Antiviral therapy has been used for the treatment of influenza since the development of amantadine in the 1960s; however, its use is hampered by the emergence of novel strains and the development of drug resistance. Thus, combinational therapy with two or more antivirals or immunomodulators with different modes of action is the optimal strategy for the effective treatment of influenza infection. In this review, we describe current options for combination therapy, their performance, and constraints imposed by resistance, calling attention to the advantages of combination therapy against severe influenza infections. We also discuss the challenges of influenza therapy and the limitations of approved antiviral drugs.

Landscape of the genome and host cell response of Mycobacterium shigaense reveals pathogenic features

A systems approach was used to explore the genome and transcriptome of Mycobacterium shigaense, a new opportunistic pathogen isolated from a patient with a skin infection, and the host response transcriptome was assessed using a macrophage infection model. The M. shigaense genome comprises 5,207,883 bp, with 67.2% G+C content and 5098 predicted coding genes. Evolutionarily, the bacterium belongs to a cluster in the phylogenetic tree along with three target opportunistic pathogenic strains, namely, M. avium, M. triplex and M. simiae. Potential virulence genes are indeed expressed by M. shigaense under culture conditions. Phenotypically, M. shigaense had similar infection and replication capacities in a macrophage model as the opportunistic species compared to M. tuberculosis. M. shigaense activated NF-κB, TNF, cytokines and chemokines in the host innate immune-related signaling pathways and elicited an early response shared with pathogenic bacilli except M. tuberculosis. M. shigaense upregulated specific host response genes such as TLR7, CCL4 and CXCL5. We performed an integrated and comparative analysis of M. shigaense. Multigroup comparison indicated certain differences with typical pathogenic bacilli in terms of gene features and the macrophage response.

Evaluating Z-FA-FMK, a host cathepsin L protease inhibitor, as a potent and broad-spectrum antiviral therapy against SARS-CoV-2 and related coronaviruses

Even though the World Health Organization announced the end of the COVID-19 pandemic as a global public health emergency on May 5, 2023, SARS-CoV-2 continues to pose a significant health threat worldwide, resulting in substantial numbers of infections and fatalities. This study investigated the antiviral potential of Z-FA-FMK (FMK), a novel host cathepsin L protease inhibitor, against SARS-CoV-2 infection using both in vitro and in vivo models. In vitro assessments of FMK against a diverse set of SARS-CoV-2 strains, including the Wuhan-like strain and nine variants, demonstrated potent inhibition with EC₅₀ values ranging from 0.55 to 2.41 μM, showcasing similar or superior efficacy compared to FDA-approved antivirals nirmatrelvir (NTV) and molnupiravir (MPV). In vivo experiments using orally administered FMK (25 mg/kg) in SARS-CoV-2-infected K18 hACE2 transgenic mice revealed improved survival rates of 60% and accelerated recovery compared to NTV and MPV treatments. Additionally, FMK displayed a longer half-life (17.26 ± 8.89 h) than NTV and MPV in the mouse model. Due to its host-targeting mechanism, FMK offers potential advantages such as reduced drug resistance and broad-spectrum antiviral activity against multiple coronaviruses. These findings indicate that FMK may serve as a promising candidate for further clinical evaluation in the fight against SARS-CoV-2.

SARS-CoV-2 drug resistance and therapeutic approaches

In light of the transition of COVID-19 from a pandemic to an endemic phase, there is still a dire need to address challenges associated with drug resistance, particularly among immunocompromised and high-risk populations. This review explores the current state of research on SARS-CoV-2 drug resistance and underscores the ongoing need for effective therapeutic strategies. It critically evaluates existing knowledge on resistance mechanisms and therapeutic options, aiming to consolidate information and highlight areas for future research. By examining the complex interactions between the virus and its host, the review advocates for a multifaceted approach, including combination therapies, targeted drug development, and continuous surveillance of viral mutations. It also emphasizes the impact of evolving viral variants on antiviral efficacy and suggests adaptive treatment protocols. This review aims to enhance our understanding of SARS-CoV-2 drug resistance and contribute to more effective management of COVID-19 through a discussion of promising strategies such as drug repurposing and combination therapies.

Intact Mycobacterium leprae Isolated from Placenta of a Pregnant Woman, China

Whether Mycobacterium leprae transmits from placenta to fetus remains unknown. We describe the case of a pregnant woman with untreated histoid leproma. Although her newborn was healthy, laboratory examination revealed intact M. leprae present in the placenta, suggesting that the placental barrier might prevent vertical dissemination of M. leprae.

Mammalian adaptation risk in HPAI H5N8: a comprehensive model bridging experimental data with mathematical insights

Understanding the mammalian pathogenesis and interspecies transmission of HPAI H5N8 virus hinges on mapping its adaptive markers. We used deep sequencing to track these markers over five passages in murine lung tissue. Subsequently, we evaluated the growth, selection, and RNA load of eight recombinant viruses with mammalian adaptive markers. By leveraging an integrated non-linear regression model, we quantitatively determined the influence of these markers on growth, adaptation, and RNA expression in mammalian hosts. Furthermore, our findings revealed that the interplay of these markers can lead to synergistic, additive, or antagonistic effects when combined. The elucidation distance method then transformed these results into distinct values, facilitating the derivation of a risk score for each marker. In vivo tests affirmed the accuracy of scores. As more mutations were incorporated, the overall risk score of virus heightened, and the optimal interplay between markers became essential for risk augmentation. Our study provides a robust model to assess risk from adaptive markers of HPAI H5N8, guiding strategies against future influenza threats.

Quantum leap in medical mentorship: exploring ChatGPT's transition from textbooks to terabytes

ChatGPT, an advanced AI language model, presents a transformative opportunity in several fields including the medical education. This article examines the integration of ChatGPT into healthcare learning environments, exploring its potential to revolutionize knowledge acquisition, personalize education, support curriculum development, and enhance clinical reasoning. The AI's ability to swiftly access and synthesize medical information across various specialties offers significant value to students and professionals alike. It provides rapid answers to queries on medical theories, treatment guidelines, and diagnostic methods, potentially accelerating the learning curve. The paper emphasizes the necessity of verifying ChatGPT's outputs against authoritative medical sources. A key advantage highlighted is the AI's capacity to tailor learning experiences by assessing individual needs, accommodating diverse learning styles, and offering personalized feedback. The article also considers ChatGPT's role in shaping curricula and assessment techniques, suggesting that educators may need to adapt their methods to incorporate AI-driven learning tools. Additionally, it explores how ChatGPT could bolster clinical problem-solving through AI-powered simulations, fostering critical thinking and diagnostic acumen among students. While recognizing ChatGPT's transformative potential in medical education, the article stresses the importance of thoughtful implementation, continuous validation, and the establishment of protocols to ensure its responsible and effective application in healthcare education settings.

Assessing the ChatGPT aptitude: A competent and effective Dermatology doctor?

Background

The efficacy and adeptness of ChatGPT 3.5 and ChatGPT 4.0 in the precise diagnosis and management of conditions like atopic dermatitis and Autoimmune blistering skin diseases (AIBD) remain to be elucidated. So this study examined the accuracy and effectiveness of the ChatGPT responses related to understanding, therapies, and specific cases of these two conditions.

Method

Firstly, the responses provided by ChatGPTs to a set of 50 questionnaires underwent evaluation by five distinct dermatologists, with complete adjudication of the third-party reviewer. The comparative analysis included the evaluative efficacy of both ChatGPT3.5 and ChatGPT4.0 against the diagnostic abilities exhibited by three distinct cohorts of qualified clinical professionals. And then, an examination was conducted to assess the diagnostic proficiency of ChatGPT3.5 and ChatGPT4.0 in the context of diagnosing specific instances of skin blistering autoimmune diseases.

Results

In assessing the proficiency of ChatGPTs in generating responses related to fundamental knowledge about AD it is noteworthy that both versions of ChatGPTs, despite their lack of specialized training on medical databases, exhibited a commendable capacity to yield solutions that exhibited a substantial degree of concurrence with evidence-based medical information. Accordingly we observed that the performance of ChatGPT-4.0 beyond that of the ChatGPT-3.5. However, it it crucial to emphasize that ChatGPT-4.0 did not show the ability to offer answers surpassing those provided by associate senior, and senior medical professionals. In the assessment designed to determine the proficiency of ChatGPTs in recognizing particular type of AIBD, it is evident that both ChatGPT-4 and ChatGPT-3.5 demonstrated inadequacy in providing responses that are both precise and accurate for each individual occurrence of this skin condition.

Conclusion

Both ChatGPT-3.5 and ChatGPT-4.0 satisfactory for addressing fundamental inquiries related to atopic dermatitis, however they prove insufficient for diagnosing AIBD. The progress of ChatGPT in achieving utility within the professional medical domain remains a considerable journey ahead.

Unveiling research trends in the prognosis of osteosarcoma: A bibliometric analysis from 2000 to 2022

Background

Osteosarcoma (OSA) is the most prevalent form of malignant bone tumor in children and adolescents, producing osteoid and immature bone. Numerous high quality studies have been published in the OSA field, however, no bibliometric study related to this area has been reported thus far. Therefore, the present study retrieved the published data from 2000 to 2022 to reveal the dynamics, development trends, hotspots and future directions of the OSA.

Methods

Publications regard to osteogenic sarcoma and prognosis were searched in the core collection on Web of Science database. The retrieved publications were analyzed by publication years, journals, categories, countries, citations, institutions, authors, keywords and clusters using the two widely available bibliometric visualization tools, VOS viewer (Version 1.6.16), Citespace (Version 6.2. R1).

Results

A total of 6260 publications related to the current topic were retrieved and analyzed, revealing exponential increase in the number of publications with an improvement in the citations on the OSA over time, in which China and the USA are the most productive nations. Shanghai Jiao Tong University, University of Texas System and Harvard University are prolific institutions, having highest collaboration network. Oncology Letters and Journal of Clinical Oncology are the most productive and the most cited journals respectively. The Wang Y is a prominent author and articles published by Bacci G had the highest number of citations indicating their significant impact in the field. According to keywords analysis, osteosarcoma, expression and metastasis were the most apparent keywords whereas the current research hotspots are biomarker, tumor microenvironment, immunotherapy and DNA methylation.

Conclusion

Our findings offer valuable information for researchers to understand the current research status and the necessity of future research to mitigate the mortality of the OS patients.

Molecular epidemiological characteristics of Mycobacterium leprae in highly endemic areas of China during the COVID-19 epidemic

Objectives

The present study analyzed the impact of the COVID-19 pandemic on the prevalence and incidence of new leprosy cases, as well as the diversity, distribution, and temporal transmission of Mycobacterium leprae strains at the county level in leprae-endemic provinces in Southwest China.

Methods

A total of 219 new leprosy cases during two periods, 2018-2019 and 2020-2021, were compared. We genetically characterized 83 clinical isolates of M. leprae in Guizhou using variable number tandem repeats (VNTRs) and single nucleotide polymorphisms (SNPs). The obtained genetic profiles and cluster consequences of M. leprae were compared between the two periods.

Results

There was an 18.97% decrease in the number of counties and districts reporting cases. Considering the initial months (January-March) of virus emergence, the number of new cases in 2021 increased by 167% compared to 2020. The number of patients with a delay of >12 months before COVID-19 (63.56%) was significantly higher than that during COVID-19 (48.51%). Eighty-one clinical isolates (97.60%) were positive for all 17 VNTR types, whereas two (2.40%) clinical isolates were positive for 16 VNTR types. The (GTA)9, (TA)18, (TTC)21 and (TA)10 loci showed higher polymorphism than the other loci. The VNTR profile of these clinical isolates generated five clusters, among which the counties where the patients were located were adjacent or relatively close to each other. SNP typing revealed that all clinical isolates possessed the single SNP3K.

Conclusion

COVID-19 may have a negative/imbalanced impact on the prevention and control measures of leprosy, which could be a considerable fact for official health departments. Isolates formed clusters among counties in Guizhou, indicating that the transmission chain remained during the epidemic and was less influenced by COVID-19 preventative policies.

Comparative Evaluation of Candida Species-Specific T-Cell Immune Response in Human Peripheral Blood Mononuclear Cells

Non-albicans Candida (NAC) species are increasingly recognized as significant contributors to candidemia infections; however, relatively less is known about the immune responses induced by these species. In this study, we compared the cytokine production ability of human peripheral blood mononuclear cells (PBMCs) upon stimulation with different Candida species (Candida spp.). We measured secreted cytokines using ELISA and checked the functional profiles of T-cell responses using multicolor flow cytometry. Although there was a differential expression of cytokines against Candida spp., significant difference were observed in the levels of IFN-γ, TNF-α, IL-10, IL-12p40, and IL-23 (p < 0.05) between Candida spp. A significant difference was observed between C. albicans and C. glabrata (p = 0.026) in the levels of TNF-α. C. glabrata showed significant differences compared to C. albicans, C. parapsilosis, and C. krusei in the levels of IL-10 (p values of 0.02, 0.04, and 0.01, respectively). Despite the percentages of CD4+ and CD8+ expressing Th1, Th2, and Th17 cytokines being higher in stimulated PBMCs, none of the Candida spp. showed significant differences. The levels of secreted IL-17A and IL-23 were consistently lower in Candida spp. regardless of the stimulus used. Here, we showed the differential regulation of Th1, Th2, and Th17 during Candida spp. stimulation of the immune system ex vivo. Additionally, our findings suggest that C. albicans elicits an IFN-γ response, whereas C. glabrata promotes IL-10 cellular responses, but this warrants additional studies to conclude this association. This investigation holds the potential to advance our comprehension of the distinct immune responses induced by Candida spp., with probable implications in designing antifungal immunotherapeutics.

Assessing the prognosis mortality in patients with cutaneous verrucous carcinoma using Lasso-cox regression model: a retrospective study

Elucidating risk factors and prognostic indicators for cutaneous verrucous carcinoma (CVC) is crucial for rapid medical intervention. This study examined CVC incidence risk and prognostic factors, emphasizing sex disparities. Utilizing SEER Database records, we analyzed patients diagnosed with primary CVC from 2004 to 2015. Multivariate logistic regression identified risk factors for the incidence model, while multivariate Cox regression developed the mortality prognosis model. Lasso regression and lasso Cox models determined key factors for respective models. Restricted cubic spline (RCS) models measured age-related risk associated with CVC presence and survival. The study included 1,125 CVC patients (668 males, 59.4%; 457 females, 40.6%) at the time of diagnosis. Lasso regression identified independent risk factors including age, sex, race, marital status, AJCC Stage, Combined Summary Stage, radiation, surgery, tumor size, chemotherapy, and regional lymph node involvement. The Age, sex, marital status, AJCC stage, combined summary stage, and surgery were independently associated with overall survival (OS) and statistically significant. Kaplan-Meier analysis revealed significantly shorter OS in female CVC patients compared to males (P < 0.05). The RCS model demonstrated a U-shaped pattern, indicating a significant nonlinear relationship between age and CVC incidence. The current study uncovered sex-related variations in incident risk and mortality prognostic factors, prediction of complications among CVC patients, offering valued insights for healthcare professionals in clinical assessments and interventions.

A comprehensive prognostic analysis of cause-specific mortality in patients with ovarian serous cystadenocarcinoma using a competing-risks model: a case study of the SEER database

OBJECTIVE

This retrospective study employed a competing-risks analysis utilizing the Surveillance, Epidemiology, and End Results (SEER) database to identify precise prognostic factors associated with ovarian serous cystadenocarcinoma (OSCC) in patients.

PATIENTS AND METHODS

Patients with OSCC during 2004-2015 were identified in the SEER database, and their clinicopathological, demographic, and survival data were examined. Univariate analysis using Gray's test and the cumulative incidence function was used to evaluate the prognoses of events of interest. The multivariate analysis involved several models, including the Cox proportional hazards, Fine-Gray, and cause-specific (CS) hazard function models, to estimate the hazard functions of competing risks. Hazard ratios were analyzed to identify the reliability of the prognostic factors.

RESULTS

Among the 10,400 individuals diagnosed with OSCC, 5,713 died from the illness, and 1,125 died from other causes. The cumulative incidence rate of events of interest was found to be significant for ethnicity, age at diagnosis, histological grade, American Joint Committee on Cancer (AJCC) stage, chemotherapy and surgery status, tumor size, marital status, and local lymph node metastases (p<0.05). The multivariate analysis revealed that ethnicity, histological grade, surgery and chemotherapy status, age at diagnosis, AJCC stage, marital status, and distant metastases were independent prognostic factors in the Cox model (p<0.05). Finally, the Fine-Gray and CS models demonstrated that ethnicity, histological grade, surgery and chemotherapy status, age at diagnosis, AJCC stage, tumor size, marital status, and combination summary stage were all identified as independent prognostic factors (p<0.05).

CONCLUSIONS

This study determined the risk factors for OSCC using a competing risk analysis model established by the SEER database. The findings can help clinicians understand OSCC better and provide more accurate medical support to affected patients.

Evaluation of the Antiviral Efficacy of Subcutaneous Nafamostat Formulated with Glycyrrhizic Acid against SARS-CoV-2 in a Murine Model

The ongoing COVID-19 pandemic highlights the urgent need for effective antiviral agents and vaccines. Drug repositioning, which involves modifying existing drugs, offers a promising approach for expediting the development of novel therapeutics. In this study, we developed a new drug, MDB-MDB-601a-NM, by modifying the existing drug nafamostat (NM) with the incorporation of glycyrrhizic acid (GA). We assessed the pharmacokinetic profiles of MDB-601a-NM and nafamostat in Sprague-Dawley rats, revealing rapid clearance of nafamostat and sustained drug concentration of MDB-601a-NM after subcutaneous administration. Single-dose toxicity studies showed potential toxicity and persistent swelling at the injection site with high-dose administration of MDB-601a-NM. Furthermore, we evaluated the efficacy of MDB-601a-NM in protecting against SARS-CoV-2 infection using the K18 hACE-2 transgenic mouse model. Mice treated with 60 mg/kg and 100 mg/kg of MDB-601a-NM exhibited improved protectivity in terms of weight loss and survival rates compared to the nafamostat-treated group. Histopathological analysis revealed dose-dependent improvements in histopathological changes and enhanced inhibitory efficacy in MDB-601a-NM-treated groups. Notably, no viral replication was detected in the brain tissue when mice were treated with 60 mg/kg and 100 mg/kg of MDB-601a-NM. Our developed MDB-601a-NM, a modified Nafamostat with glycyrrhizic acid, shows improved protectivity against SARS-CoV-2 infection. Its sustained drug concentration after subcutaneous administration and dose-dependent improvements makes it a promising therapeutic option.