Published papers

Introduction: This study aims to evaluate treatment outcomes in Kampo outpatients using electronic questionnaires by accumulating multi-institutional data. It also aims to improve algorithms for predicting traditional pattern diagnosis and create algorithms for prescribed formulas and subjective symptom changes. Methods: This multi-center observational study involves adult patients visiting Kampo outpatient clinics in Japan. Data will be collected from patient electronic questionnaires, physicians' entries into an Electronic Data Capture system (Kampo/Western diagnoses and prescriptions), and medical records including medical history, concomitant medications, and routine blood/urine test results. The primary outcome is the change in Visual Analogue Scale (VAS) scores for the chief complaint. Secondary outcomes involve developing predictive models for VAS changes, pattern diagnosis, and formula prescription. Statistical analyses will be performed using R-software. Missing data will generally be handled by excluding cases lacking essential items. Outliers will be addressed through sensitivity analyses performed both with and without exclusion. Anticipated Results: The study will yield predictive algorithms for pattern diagnosis, formula selection, and subjective symptom changes. Performance metrics such as accuracy, precision, sensitivity, specificity, and F-measure will be reported for the models. Conclusion: This study aims to contribute to the appropriate use of Kampo medicine by developing clinical support systems through the creation and improvement of predictive algorithms. The findings are expected to enable efficient and safe healthcare delivery in clinical settings. Trial Registration: The study is registered with the University hospital Medical Information Network (UMIN-CTR). Registration No.: UMIN000042048.

Purpose: Although flomoxef (FMOX) has attracted substantial attention as an antibiotic against extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-producing E. coli), the pharmacokinetics/pharmacodynamics (PK/PD) characteristics of FMOX against ESBL-producing E. coli is unclear. The aim of this study was to determine the PK/PD index of FMOX against ESBL-producing E. coli. Methods: In vitro time-kill curve studies and in vivo PK/PD experiments were carried out. Results: Time–kill curves exhibited a unique bactericidal activity: time-dependent activity at low concentrations and concentration-dependent activity at high concentrations. In neutropenic murine thigh infection experiments, the antibacterial activity of FMOX correlated with the time that the free drug concentration remaining above the minimum inhibitory concentration (MIC) (fT>MIC) and the ratio of the area under the free drug concentration–time curve for a 24 h period to the MIC (fAUC24/MIC). However, the burden of ESBL producing E. coli significantly reduced when the time intervals for administration were shorter among three dosage regimens with same magnitude of fAUC24/MIC, indicating that fT>MIC is significant PK/PD index. The target value of fT>MIC for 1 log10 kill reduction was 35.1%. Conclusions: fT>MIC is the most significant PK/PD index of FMOX against ESBL-producing E. coli and its target value is ≥ 40%.

Purpose: Cefmetazole (CMZ) has received attention as a pharmaceutical intervention for extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) infections. This study aimed to investigate the pharmacokinetics/pharmacodynamics (PK/PD) characteristics of CMZ against ESBL-EC. Methods: The susceptibility and time-killing activity of CMZ against clinically isolated ESBL-EC (EC9 and EC19) were determined in vitro. The optimal PK/PD index and its target value were calculated based on the results of a PK study in healthy mice and PD study in neutropenic murine thigh infection model mice. Results: The minimum inhibitory concentrations (MICs) of CMZ against EC9 and EC19 were 2.0 and 1.0 µg/mL, respectively. Time–kill studies showed that colony-forming units decreased in a time-dependent manner at CMZ concentrations in the range of 4–64 × MIC. In in vivo PK/PD studies, the antibacterial effect of CMZ showed the better correlation with the time that the free drug concentration remaining above the MIC (fT>MIC), with the target values for a static effect and 1 log10 kill reduction calculated as 57.6% and 69.6%, respectively. Conclusion: CMZ possesses time-dependent bactericidal activities against ESBL-EC and is required to achieve “fT>MIC” ≥ 69.6% for the treatment of ESBL-EC infections.

Reports on the therapeutic drug monitoring (TDM) of second- and third-generation epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) in non-small cell lung cancer patients are limited and are required to improve the safety of EGFR-TKI therapy. Some EGFR-TKIs have active metabolites with similar or higher potency compared with the parent compounds; thus, monitoring the parent compound as well as its active metabolites is essential for truly effective TDM. In this study, we developed and validated a method that simultaneously quantifies second- and third-generation EGFR-TKIs (afatinib, dacomitinib, and osimertinib) and the active metabolites of osimertinib, AZ5104 and AZ7550, in the human serum using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The clinical application of the method was also evaluated. The analytes were extracted from a 100 μL serum sample using a simple protein precipitation method and analyzed using LC-MS/MS. Excellent linearity of calibration curves was observed at ranges of 2.5–125.0 ng/mL for afatinib, 2.5–125.0 ng/mL for dacomitinib, 4.0–800.0 ng/mL for osimertinib, 1.0–125.0 ng/mL for AZ5104, and 2.5–125.0 ng/mL for AZ7550. The precision and accuracy were below 14.9% and within ± 14.9% of the nominal concentrations, respectively. The mean recovery was higher than 94.7% and the coefficient of variation (CV) was lower than 8.3%. The mean internal-standard normalized matrix factors ranged from 94.6 to 111.9%, and the CVs were lower than 9.7%. This analytical method met the acceptance criteria of the U.S. Food and Drug Administration guidelines. The method was also successfully applied to the analysis of 45 clinical samples; it supports the efficient and valuable analysis for TDM investigations of EGFR-TKIs.

Background: Olaparib-induced anemia is a frequently occurring complication in patients with advanced ovarian cancer, fallopian tube cancer, or primary peritoneal cancer and is associated with a marked deterioration in patients’ health-related quality of life. This study aimed to clarify patient-specific risk factors for severe anemia in patients with advanced ovarian or breast cancer receiving olaparib monotherapy in a real-world setting. Methods: This multicenter, retrospective, observational study enrolled consecutively presenting patients with advanced ovarian or breast cancer who received olaparib monotherapy as maintenance or palliative treatment between April 2018 and December 2020 at three participating medical institutions in Japan. The primary endpoint was patient-associated risk factors underlying the onset of grade ≥3 anemia from olaparib treatment initiation to 90 days after treatment. Receiver operating characteristic curves were constructed and univariable and multivariable logistic regression analyses were performed to evaluate the association between patient-associated risk factors and grade ≥3 anemia. Results: Of 113 patients evaluated in this study, 32.7% (n = 37) had grade ≥3 anemia. Multivariable logistic regression analysis revealed that low baseline red blood cell (RBC) count (<3.3 × 106 cells/μL), low baseline hematocrit level (<35%), low baseline hemoglobin level (<11.6 g/dL), and breast cancer susceptibility (BRCA1/2) mutation were significantly associated with the onset of grade ≥3 anemia (adjusted odds ratio [OR], 3.39; 95% confidence interval [CI], 1.28–9.62; P = 0.017, adjusted OR, 3.63; 95% CI, 1.28–11.64; P = 0.021, adjusted OR, 3.89; 95% CI, 1.39–12.21; P = 0.014, and adjusted OR, 4.09; 95% CI, 1.55–11.67; P = 0.006, respectively). Conclusions: Our findings suggest that low baseline RBC count, low baseline hematocrit level, and low baseline hemoglobin level might be the patient-associated risk factors for severe anemia induced by olaparib monotherapy. Additionally, BRCA1/2 mutation was suggested to be a patient-related risk factor for anemia regardless of severity. Therefore, applying these patient-associated risk factors would help classify and screen patients at risk of severe anemia.

Pancreatic cancer is associated with a poor prognosis; thus, there is an urgent need to develop new and effective treatments. Ingenol mebutate (IM), which is isolated from the latex of Euphorbia peplus, was recently shown to be effective against pancreatic cancer cell lines; however, its mechanism of action has not been fully elucidated. In this study, we focused on the less drug-sensitive pancreatic cancer cell line Panc-1 and compared IM to commercially available anticancer drugs using cell survival assays. In addition, we aimed to identify novel biomolecules that may be involved in the mechanism of action of IM using RNA sequencing, western blotting, and inhibition assays. The IC50 values after 72 h of exposure to IM and SN-38, drugs to which the Panc-1 cells are most sensitive among the tested anticancer agents, were 43.1 ± 16.8 nM and 165 ± 37 nM, respectively. IM showed a cytostatic effect equal to or greater than that of the clinically used pancreatic cancer therapeutic drugs. RNA sequencing and protein expression analysis revealed that expression of stimulator of interferon genes (STING) increased at low IM concentration, whereas cell viability decreased. Co-exposure of IM and STING inhibitor, H-151, to Panc-1 or MIA PaCa-2 cell lines canceled the growth-inhibitory effects of IM alone. In conclusion, IM may have an efficacy comparable to that of existing pancreatic cancer therapeutic agents on the less drug-sensitive Panc-1 cell line and the immune-related molecule STING plays a role in the mechanism of action of IM.

Background: Potential novel strategies for adverse event (AE) management of osimertinib therapy, including therapeutic drug monitoring and the use of biomarkers, have not yet been fully investigated. This study aimed to evaluate (1) the relationship between exposure to osimertinib, especially its active metabolites (AZ5104 and AZ7550), and AEs, and (2) the relationship between germline polymorphisms and AEs. Methods: We conducted a prospective, longitudinal observational study of 53 patients with advanced non-small cell lung cancer receiving osimertinib therapy from February 2019 to April 2022. A population pharmacokinetic model was developed to estimate the area under the serum concentration–time curve from 0 to 24 h (AUC0–24) of osimertinib and its metabolites. Germline polymorphisms were analyzed using TaqMan® SNP genotyping and CycleavePCR® assays. Results: There was a significant association between the AUC0–24 of AZ7550 and grade ≥ 2 paronychia (p = 0.043) or anorexia (p = 0.011) and between that of osimertinib or AZ5104 and grade ≥ 2 diarrhea (p = 0.026 and p = 0.049, respectively). Furthermore, the AUC0–24 of AZ5104 was significantly associated with any grade ≥ 2 AEs (p = 0.046). EGFR rs2293348 and rs4947492 were associated with severe AEs (p = 0.019 and p = 0.050, respectively), and ABCG2 rs2231137 and ABCB1 rs1128503 were associated with grade ≥ 2 AEs (p = 0.008 and p = 0.038, respectively). Conclusion: Higher exposures to osimertinib, AZ5104, and AZ7550 and polymorphisms in EGFR, ABCG2, and ABCB1 were related to higher severity of AEs; therefore, monitoring these may be beneficial for osimertinib AE management.

Purpose: Cefditoren, the active form of cefditoren pivoxil, is an oral cephalosporin antimicrobial drug. Although cefditoren exhibits high antimicrobial activity against Streptococcus pneumoniae, its pharmacokinetics/pharmacodynamics (PK/PD) characteristics remain unknown. This study aimed to determine its PK/PD parameter with target values for cefditoren against S. pneumoniae in S. pneumoniae lung-infected mice and to simulate MIC range of S. pneumoniae that can be expected to be treated at approved cefditoren doses in human using population pharmacokinetic (PPK) data from patients. Methods: Susceptibility testing and time-kill assays against S. pneumoniae ATCC® 49619 were performed for in vitro PD evaluation. Based on the results of a PK study in healthy mice and PD studies in S. pneumoniae lung-infected mice, optimal PK/PD parameters were determined using the correlation curve between the PK/PD parameters and lung bacterial count changes. The target value was calculated to achieve a 2 log10 reduction in the lung bacterial counts. Results: In vitro PD evaluation showed that cefditoren had a potent antimicrobial effect against S. pneumoniae in a time-dependent manner at concentrations above the MIC. In PK/PD analyses, both fAUC24/MIC and fCmax/MIC were well correlated with bactericidal efficacy, achieving 2 log10-kill with fAUC24/MIC ≥ 63 and fCmax/MIC ≥ 16. Conclusions: Cefditoren pivoxil has good therapeutic efficacy against acute pneumonia caused by S. pneumoniae with a MIC ≤ 0.031–0.063 mg/L at approved doses in adults and children.

Two representative Kampo formulas, keishibukuryogan and tokishakuyakusan, are frequently prescribed for patients with dysmenorrhea. We previously constructed a model that could predict which of these 2 formulas was most suitable, which is based on 4 subjective symptoms and 3 objective signs. To evaluate the prognosis of patients with dysmenorrhea using the established prediction model and assess the treatment outcomes between those treated in accordance with the prediction model and those who received various other treatments. In this retrospective, observational study, we included patients with menstrual pain who visited the Kampo Clinic at the Keio University Hospital for the first time between October 2014 and December 2020. These patients were monitored over a 90-day follow-up period. Participants were categorized into 2 groups: model-accordance and various-options. The progression of visual analogue scale (VAS) values was evaluated by determining the slopes from regression analysis between these 2 groups, with changes corroborated by the medical records. The study comprised 57 patients: 37 in the model-accordance group and 20 in the various-options group. Notably, the various-options group reported a significantly higher number of subjective symptoms (P = .03). The VAS value showed a decline, as indicated by the negative slope value of the regression line, across both groups - irrespective of their classification. There were no significant differences in the occurrence of adverse events between the 2 groups. The prognosis of patients with dysmenorrhea and the incidence of adverse events remained consistent, regardless of whether the treatment approach was in accordance with the prediction model or varied. Further studies are warranted to assess the prognosis when Kampo formulas are chosen based on the prediction model in the various-options population.

Study Objective: Establish methods for measuring cefmetazole (CMZ) concentrations conduct a pharmacokinetic/pharmacodynamic (PK/PD) analysis using unbound CMZ concentrations for extended-spectrum β-lactamase producing enterobacterales (ESBL-E) and investigate optimal dosing regimens for not undergoing hemodialysis (non-HD) and undergoing hemodialysis (HD) patients. Design: Prospective observational study. Patients: Included patients treated with CMZ who provided written informed consent and were admitted to the Tokyo Bay Urayasu Ichikawa Medical Center between August 2021 and July 2022. Measurements: Total and Unbound CMZ concentration was measured by high-performance liquid chromatography (HPLC) with solid-phase extraction and ultrafiltration. Setting: Determining the CMZ dosing regimen involved modified creatinine clearance (CLCR) with measured body weight (BW) using the Cockcroft–Gault equation. For non-HD patients, blood samples were collected during at least three points. For patients undergoing HD, 1 g was administered via intravenous infusion, or rapid intravenous injection after HD, or 30 min before the end of HD. Blood samples were collected before HD (pre-HD), and 1 and 3 h after starting HD and post-HD. All blood samples were collected at steady-state. Patient information was collected from electronic medical records. An unbound PK model was constructed for the non-HD patients. A nomogram was constructed using Monte Carlo simulations with a 90% probability of target attainment at 70% free time above the minimum inhibitory concentration (MIC). For the HD patients, a nomogram was used to determine the optimal dosing regimen for each HD schedule. Main Results: CMZ measurement methods were established. A model analysis of unbound PK in 37 non-HD patients incorporated creatinine clearance (CLCR) using the Cockcroft–Gault equation, albumin (ALB) for clearance and body weight (BW) for the volume of distribution. In Monte Carlo simulations, nomograms corresponding to the MIC (known and unknown) were generated for each covariate. Using the nomogram, non-HD patients with an ESBL-E MIC of 8 mg/L, a BW of 60 kg, an ALB of 25 g/L, and a CLCR of 60 mL/min required administration of 2 g every 6 h (1- and 3-h infusions). Unbound PK model parameters were calculated for 7 HD patients, and the optimal dosing regimens following PK/PD were determined for each HD schedule. In HD patients, the regimen after and during HD was established using a treatment that was effective up to an ESBL-E MIC of 4 mg/L. Conclusions: The nomogram for CMZ regimens established by PK/PD analysis of measured CMZ concentrations enables optimal CMZ dosing for ESBL-E-infected patients.

Background: Proton pump inhibitors (PPIs) reduce the bioavailability of several anticancer drugs. The impact of PPIs co-Administered with cyclin-dependent kinase 4 and 6 inhibitors is controversial. We aimed to clarify whether the concomitant use of PPIs impacts palbociclib and abemaciclib effectiveness in breast cancer treatment. Patients and Methods: This multicenter, retrospective, observational study, conducted across 4 medical institutions in Japan, consecutively included patients with endocrine-resistant metastatic breast cancer, receiving palbociclib or abemaciclib between December 2017 and August 2022. Propensity score-matched analyses were performed. Treatment efficacy and safety with and without PPIs were compared. Progression-free survival and overall survival were estimated using the Kaplan-Meier method and compared using a log-rank test. A Cox proportional hazards model was used to estimate the hazard ratio. Results: The study included 240 patients. After 1:1 matching, 112 patients were treated with and without PPIs. The median progression-free survival period was 1.2 years in the PPI group and 1.3 years in the non-PPI group (hazard ratio, 1.19; 95% CI, 0.70-2.02). The median overall survival period was 3.6 years in the PPI group, whereas it was not reached in the non-PPI group (hazard ratio, 1.23; 95% CI, 0.61-2.47). Consistent results were obtained for subgroups receiving palbociclib (n=177) and abemaciclib (n=63) without propensity score matching. Adverse event incidence and severity were similar in both groups. Conclusion: The effectiveness of cyclin-dependent kinase 4/6 inhibitors is unlikely to be affected by concomitant PPI use. Future prospective pharmacokinetic studies are warranted.

Purpose: Hypertension (HT), dyslipidemia (DL), and diabetes mellitus (DM) are major risk factors for cardiovascular diseases. Despite the wide availability of medications to reduce this risk, poor adherence to medications remains an issue. The aim of this study is to evaluate medication adherence of prevalent users in these disease medications (HT, DL, DM) using claims data. Factors associated with non-adherence were also examined. Methods: Of 7538 participants of the Tsuruoka Metabolomics Cohort Study, 3693 (HT: 2702, DL: 2112, DM: 661) were identified as prevalent users of these disease medications. Information on lifestyle was collected through a questionnaire. Adherence was assessed by a proportion of days covered (PDC) and participants with PDC ≥0.8 were defined as adherent. Predictors of non-adherence were determined by performing multivariable logistic regression. Results: Medication adherence differed by treatment status. Among those without comorbidities, those with HT-only showed the highest adherence (90.2%), followed by those with DM-only (81.2%) and those with DL-only (80.8%). Factors associated with non-adherence in each medication group were skipping breakfast and poor understanding of medications among those with HT medications, females, having comorbidities, having a history of heart disease, and drinking habit among those with DL medications, and good sleep quality and skipping breakfast among those with DM medications. Conclusion: While participants showed high medication adherence, differences were observed across medication groups. The identified predictors of non-adherence could help target those in need of adherence support.

In this study, we developed and validated the Clinical Student Version of the Japanese Interprofessional Competency Self-Assessment Scale (C-JASSIC) for healthcare students in their clinical practice phase. Data obtained from 331 students (medical, 98; nursing, 99; pharmacy, 134) during orientation for interprofessional education (pre-IPE) and from 319 students (medical, 94; nursing, 93; pharmacy, 132) within a week following IPE (post-IPE) were analyzed. Exploratory pre-IPE and Confirmatory post-IPE factor analyses revealed a consistent 6-factor structure aligning with the Japanese Interprofessional Competency domains. The scale exhibited strong internal consistency, with Cronbach’s α values exceeding 0.8 for all factors both pre- and post-IPE. Scores for overall competency and individual domains increased post-IPE in 234 matched cases. A notable significant pre vs post difference concerned “Understanding of Others,” indicating enhanced interprofessional comprehension after clinical practice. There was a weak but significant positive correlation between IPE satisfaction and difference in pre- and post-IPE scores. However, no significant differences were observed among medical, nursing, and pharmacy students. Despite its strengths, such as its competency-based design and cultural relevance to Japan, a limitation of the study may be potential self-reporting bias. Nonetheless, C-JASSIC represents a valuable tool for seamless competency evaluations from student to professional stages, with implications for broader Asian contexts.

This study aimed to clarify the optimal value for the unbound cefmetazole concentration to remain above the minimum inhibitory concentration (MIC) (fT≥MIC) for efficacy of de-escalation to cefmetazole in patients with bacteremic urinary tract infection by extended-spectrum β-lactamase-producing Escherichia coli. This double-center retrospective observational study was conducted at Tokyo Bay Urayasu Ichikawa Medical Center and Keio University Hospital from January 2012 to October 2022. Efficacy was determined via clinical evaluation (mortality rate, recurrence rate, vital changes) and bacteriological evaluation, and the optimal fT≥MIC was calculated via receiver operating characteristic curve analysis. As a result, the number of patients evaluated were 40 (35 and 5 in the treatment success and treatment failure groups, respectively). Univariate analysis showed that fT≥MIC, recurrence rate, and MIC for cefmetazole against bacteria were significantly different for the two groups (p<0.05). Receiver operating characteristic curve analysis showed that the optimal fT≥MIC indicating efficacy was 57% (area under the curve: 0.94, 95% confidence interval: 0.86–1.00, p=0.002). All patients with fT≥MIC ≥ 57% had successful treatment, whereas the frequency of treatment failure was high among those with fT≥MIC <57%. The optimal fT≥MIC for the clinical efficacy of de-escalation to cefmetazole in patients with bacteremic urinary tract infection by extended-spectrum β-lactamase-producing E. coli was fT≥MIC ≥ 57%. This finding would be useful for optimal dosing of cefmetazole.

Inhibiting body fat accumulation is important for the prevention of obesity. In Japan, three Kampo medicines are commonly used to treat obesity: bofutsushosan, boiogito, and daisaikoto. To compare the influences of these Kampo medicines on the intestinal microbiota, it is necessary to conduct a simultaneous investigation using the same mouse model under the same experimental conditions. C57BL/6J mice were divided into five groups: normal chow (NC), high-fat diet (HFD), HFD + 3% bofutsushosan extract (BTS), HFD + 3% boiogito extract (BOT), and HFD + 3% daisaikoto extract (DST). Epididymal white adipose tissue (WAT) weight, mesenteric WAT weight, serum triglyceride levels, and serum total cholesterol levels were measured. Additionally, total bacteria, alpha diversity, beta diversity, and bacterial composition in stool samples were measured. Body weight and epididymal WAT weight gain were significantly inhibited in the BTS-treated group and DST-treated group, but not in the BOT-treated group, compared with the HFD control group. Additionally, serum total cholesterol levels were significantly lower in the DST-treated group than in the HFD group. Specific intestinal bacteria, Clostridium sensu stricto 1, Erysipelatoclostridium, Roseburia, and the Lachnospiraceae NK4A136 group, were significantly changed in the Kampo-treated groups compared with the HFD group, and each of them was correlated with body weight gain, body fat rate, epididymal WAT weight, or mesenteric WAT weight. Our simultaneous investigation of BTS, BOT, and DST under the same conditions clearly demonstrated different changes in the intestinal microbiota and different effects on fat accumulation as well as their association among the three Kampo medicines.

Patient risk factors related to coagulopathy and bleeding when using cefmetazole (CMZ) have not yet been identified, and no models exist to predict side effects during CMZ treatment. Moreover, reports that examine which patients should be careful when using CMZ to ensure safety are lacking. Our objective was to understand risk factors for elevated international normalized ratio (INR) in patients using CMZ and to develop a predictive model for INR elevation using a risk score to enable safe administration of CMZ. This multicenter, retrospective, and observational study was conducted in Tokyo Bay Urayasu Ichikawa Medical Center and Keio University Hospital using data from patients being treated with CMZ. Patients were classified into INR-elevated or non-INR-elevated groups. Univariate and multivariate analyses were performed to calculate the adjusted odds ratios (aOR) and 95% confidence intervals (CI). The actual probability of an elevated INR and probability of an elevated INR predicted by the regression β coefficients were calculated and classified into four categories according to the risk score. Binomial logistic regression analysis revealed that liver disorder (aOR, 5.65; 95% CI, 1.69–18.91; risk scores, 2), nutritional risk (aOR, 6.32; 95% CI, 3.14–12.74; risk scores, 2), no-diabetes mellitus (aOR, 4.53; 95% CI, 1.34–15.26; risk scores, 2), and warfarin use (aOR, 98.44; 95% CI, 7.05–1375.50; risk scores, 5) were significantly associated with INR elevation. The predicted incidence probabilities of INR elevation were<5% (low risk), 5–<30% (medium risk), 30–<90% (high risk), and ≥ 90% (very high risk). The model validity showed a good fit (AUC, 0.79; 95% CI, 0.73–0.85, P<0.001). We identified risk factors that contribute to INR elevation and constructed a model to predict INR elevation using the risk score. Using this predictive model enables the appropriate use of CMZ in a safe manner.

A 0.04% mitomycin C (MMC) ophthalmic solution is not commercially available and is prepared in hospitals as required. The physical properties and stability of the MMC ophthalmic solution have not been clarified because of a lack of data. This study aimed to assess the stability of the MMC ophthalmic solution under various storage conditions. The MMC ophthalmic solution was prepared by dissolving 2 mg of MMC in 5 mL of saline solution. Each batch of ophthalmic solution was stored under three conditions [cold/shaded light, room temperature/shaded light, and room temperature/scattered light (approximately 4000 lx)], and MMC concentration was determined using high-performance liquid chromatography on days 0, 1, 3, 5, 7, 14, and 21. The expiry date was calculated based on the results of the degradation analysis. pH measurements and bacterial culture tests were conducted for each storage condition. The MMC concentrations on day 21 under cold/shaded light, room temperature/shaded light, and room temperature/scattered light were 340, 287, and 227 µg/mL, respectively. MMC concentrations decreased over time, and the decrease was highest when the samples were stored at room temperature and exposed to light, and lowest under cold conditions and protected from light. The pH of MMC solutions was 5.8 after preparation, which increased to 6.9 with time under all storage conditions. Culture tests did not detect any bacteria under any storage conditions. The MMC ophthalmic solution was most stable under cold/shaded conditions, and our study clarifies its expiry date for clinical use.