A longitudinal study of Candida bloodstream infections in a Japanese university hospital: species distribution, drug susceptibility, clinical features, and mortality predictors.

We aimed to detect possible changes in Candida species distribution over time and to know the antifungal susceptibility profile of isolates obtained from patients with bloodstream infection (BSI) due to this pathogen. Risk factors associated with 30-day mortality were also assessed. We conducted a retrospective cohort study of patients diagnosed with Candida BSI at a Japanese university hospital from 2013 to 2021. The change in the distribution pattern of the Candida spp. isolated was examined by considering three successive sub-periods of 3 years each. Risk factors for 30-day mortality were determined using Cox regression analysis. In the entire study period, Candida albicans was the most frequent species (46.7%), followed by Candida glabrata (21.5%) and Candida parapsilosis (18.7%). There was no change in Candida species distribution comparing the three sub-periods analyzed. All isolates were susceptible to micafungin, and most were susceptible to fluconazole, except for C. glabrata. No isolates were resistant to amphotericin B or voriconazole. The overall 30-day mortality was 40.2%. Univariate analysis revealed an association between 30-day mortality and central venous catheter (CVC) removal at any time, high Pitt bacteremia score (PBS), and high Charlson comorbidity index (CCI). Multivariate Cox analysis found that high PBS was the only independent predictor of 30-day mortality; subsequent multivariate Cox regression demonstrated that early CVC removal significantly reduced 30-day mortality. Candida species distribution and antifungal susceptibility profile in our hospital remained similar from 2013 to 2021. Early CVC removal may improve candidemia outcomes.

Disproportionality Analysis of Safety Signals for a Wide Variety of Opioid-Related Adverse Events in Elderly Patients Using the Japanese Adverse Drug Event Report (JADER) Database.

Opioids are widely used for the treatment of moderate/severe pain in cancer and noncancer patients. In this study, we searched for safety signals for a wide variety of opioid-related adverse events (AEs) in elderly patients by disproportionality analysis using the Japanese Adverse Drug Event Report (JADER) database. Data from the JADER database from April 2004 to May 2018 were obtained from the Pharmaceuticals and Medical Devices Agency website. Safety signal detection of opioid-related AEs in elderly patients was defined using the relative elderly reporting odds ratio (ROR). Among the analyzed AEs, opioid-induced neurotoxicity (OIN) was assessed based on the time to onset using the Weibull shape parameter. The following safety signals were detected in elderly patients: respiratory depression, somnolence, hallucinations, akathisia and OIN. Fentanyl, tramadol, oxycodone and morphine exhibited a large relative elderly ROR for OIN. The median time to onset of OIN of transdermal fentanyl, oral tramadol, oral oxycodone and oral morphine was 13.5, 6, 9, and 6 d, respectively. These opioids were classified as early failure types using the Weibull distribution. Our results showed that elderly patients who are administered opioids should be closely monitored for AEs, such as respiratory depression, OIN and akathisia.

Identification of target small molecule tyrosine kinase inhibitors that need monitoring and clinical application of protocol for early detection of cancer therapeutics-related cardiac dysfunction using signal detection: An investigation of real world data.

PURPOSE: In order to detect cancer therapeutics-related cardiac dysfunction (CTRCD) early, we identified which drugs were to be monitored using signal detection and the package insert, and created and applied a protocol to address this. METHODS: Adverse event data recorded in the Japanese Adverse Drug Event Report (JADER) database between April 2004 and January 2018 were used. Among small molecule tyrosine kinase inhibitors that are not described in the serious side-effects section of the package insert despite signal detection, tyrosine kinase inhibitors with severe side-effects in the background of cases reported by JADER database were selected to be monitored in clinical practice. We applied our findings clinically by creating a protocol to detect CTRCD early. All cases at Tosei General Hospital where the target tyrosine kinase inhibitors were administered from when they were first released in November 2019 were included. We compared the results from before and after we began the protocol to clarify its effects. RESULTS: We found that CTRCD was not described in the serious side-effect section of the package inserts for Bosutinib, Alectinib, and Osimertinib even though CTRCD signals were detected for them. Therefore, it is possible that we may have previously overlooked CTRCD. When we applied our protocol using Osimertinib as the target drug, we were able to detect CTRCD early in 5/21 (24%) patients. CONCLUSIONS: It was clarified that the drug identification method used in this study for early detection of adverse events leads to early detection of adverse events when applied clinically.

Influence of UGT1A1 polymorphism on etoposide plus platinum-induced neutropenia in Japanese patients with small-cell lung cancer.

BACKGROUND: The association between UGT1A1 polymorphism and etoposide-induced toxicities is still not clear. The aim of this study was to assess the association between uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene polymorphism and severe hematologic toxicities in Japanese patients receiving etoposide plus platinum chemotherapy for small-cell lung cancer. METHODS: This retrospective analysis included patients with small-cell lung cancer who had received their first-line chemotherapy with etoposide plus cisplatin or carboplatin, between October 2008 and April 2018, at the University of Fukui Hospital. The relationship between UGT1A1 polymorphisms and first-cycle neutropenia as well as thrombocytopenia was evaluated. RESULTS: A total of 55 patients were enrolled. The incidence of grade 4 neutropenia during the first cycle of etoposide-based chemotherapy was higher in patients with homozygous (hmz) polymorphisms for UGT1A1*28 and *6 (*28/*28, *6/*6, and *6/*28) than in patients with wild-type (wt) (*1/*1) and heterozygous (htz) (*1/*28 and *1/*6) polymorphisms (88% vs 43% P = 0.03). The incidence of febrile neutropenia and grade 4 thrombocytopenia, however, was not significantly different. Multivariate analysis suggested that grade 4 neutropenia associated significantly with an hmz UGT1A1 genotype [odds ratio (OR) 11.3; P = 0.04] and administration of granulocyte colony-stimulating factor (G-CSF) before the neutrophil counts dropped to < 500 cells/µL (OR; P = 0.01). CONCLUSIONS: UGT1A1*28 and UGT1A1*6 mutations might be regarded as predictors for etoposide-induced grade 4 neutropenia.

Application of hospital preparations for cancer treatment, and an approach toward their commercialization.

In Japan, pharmacists who are in consultation with doctors independently prepare medications in an attempt to meet the needs of patients in the hospital. In particular, the need for hospital preparations to treat cancer is high and diverse. However, unlike gov]ernment-approved medications, independently and individually prepared hospital preparations raise concerns about their effectiveness, safety, economic efficiency, quality control, etc. One way to address these concerns is to commercialize these preparations and to understand the difference between necessity and demand from various points of view. We have conducted nation-wide utilization surveys and evaluated the literature on hospital preparations. On the basis of the findings of this survey, we have concluded that pharmaceutical companies and the government need to implement the commercialization of hospital preparations in clinical practice. In this report, we discuss the significance of commercialization of hospital preparations, concerns regarding pharmaceutical preparations, and our recent efforts on cancer treatment. We hope to continuously contribute to society and to medical care by improving individualized care and by commercializing medications needed in clinical practice.

Pharmacoethnicity of docetaxel-induced severe neutropenia: integrated analysis of published phase II and III trials.

BACKGROUND: Ethnic differences in drug susceptibility and toxicity are a major concern, not only in drug development but also in the clinical setting. We review the toxicity profiles of docetaxel according to dose and ethnicity. METHODS: We analyzed phase II and III clinical trials that included a once-every-3-weeks single-agent docetaxel arm. Logistic regression analysis was applied to identify the significant variables affecting the reported incidence of docetaxel-induced severe neutropenia. RESULTS: Multivariate logistic regression analysis identified studies conducted in Asia [odds ratio (OR) 19.0; 95% confidence interval (95% CI) 3.64-99.0] and docetaxel dose (OR 1.08; 95% CI 1.03-1.13) as independent variables for the incidence of grade 3/4 neutropenia. CONCLUSIONS: There is a significant difference in the incidence of docetaxel-induced severe neutropenia between Asian and non-Asian clinical studies. Physicians and pharmacists should consider ethnic diversity in docetaxel toxicity when interpreting the results of clinical trials.

[Risk factors and subjective symptoms of drug-induced leucopenia].

The present study investigated risk factors and subjective symptoms associated with drug-induced leucopenia. We selected 248 patients with drug-induced leucopenia from the Case Reports of Adverse Drug Reactions and Poisoning Information System (CARPIS) database of over 47000 case reports of adverse drug reactions and assigned them to a case group. We also randomly selected 743 cases of adverse drug reactions not associated with leucopenia as a control group. A comparison of patient characteristic data between the two groups using logistic-regression analysis revealed that female sex, autoimmune disease and renal damage were background risk factors for drug-induced leucopenia. In addition, thiamazole, ritodrine, propylthiouracil, ticlopidine, allopurinol, minocycline and captopril administration significantly increased the risk of drug-induced leucopenia. A significant association was also found for fever, chills and pharyngeal abnormalities. Based on these findings, we developed two estimated regression equations to help prevent drug-induced leucopenia in the community pharmacy setting.

Visualization of Kinase Inhibition-Related Adverse Events Using the Japanese Adverse Drug Event Report Database.

INTRODUCTION: Small molecule tyrosine kinase inhibitors (TKIs) inhibit not only the target kinase but also various kinases as off-target inhibitors not mentioned in the package insert. However, there are no reports that comprehensively examine the relationship between adverse events and kinase affinity. OBJECTIVE: In this study, we combined basic data and clinical data to visualize the relationship between kinase affinity and adverse events, which will be useful for the management of adverse events in clinical practice. METHODS: We targeted TKIs that have been used domestically and for which the dissociation constant was obtained as reported by Davis et al. Adverse event data recorded in the Japanese Adverse Drug Event Report (JADER) database provided by the Pharmaceuticals and Medical Devices Agency between April 2004 and January 2018 were used. We calculated the reporting rates of the Standardized MedDRA Queries (SMQ) for the adverse events of interest and visualized the correlation coefficients with kinase affinity. We used the adverse events associated with VEGFR2 and EGFR to assess their validity. RESULTS: We found a correlation among known kinase-related adverse events, suggesting that the methodology may be used as a signal detection method to generate hypotheses for clinical and basic research. CONCLUSION: Our comprehensive analysis of the kinase affinity of TKIs in this study, which was based on basic TKI kinase affinity data and the clinical data of the reporting rates, suggested that our comprehensive analysis method is useful for generating hypotheses about possible causal relationships between pharmacological effects and adverse events.

Population pharmacokinetic model development and exposure-response analysis of vincristine in patients with malignant lymphoma.

PURPOSE: Vincristine (VCR) is a key drug for treating various malignancies. However, few data are available on the pharmacokinetics of VCR, especially in adult patients. The objective of this study was to clarify the population pharmacokinetics and exposure-response relationships of VCR in adult malignant lymphoma patients. METHODS: Blood samples were collected from patients who were administered R-CHOP-like regimens, and the VCR plasma concentration was determined using liquid chromatography-mass spectrometry. Using NONMEM software, population pharmacokinetic parameters were estimated, and covariates were evaluated. The relationships between the individual parameters and adverse events or therapeutic effects were also investigated. RESULTS: Plasma concentrations were measured in 30 patients. In the final population pharmacokinetics model, body surface area and age were incorporated into clearance as significant covariates. The inter-individual variations in clearance and volume of distribution in the central and third compartments were 17.0, 26.6, and 66.3%, respectively, and the residual variability in the plasma concentration was 23.8%. Although the variability observed in the volume of distribution was large, good predictability was obtained in the individual estimation. The severity of anemia and peripheral neuropathy was correlated with clearance and peak concentration, respectively (adjusted P = 0.040 and 0.024, respectively). In diffuse large B cell lymphoma patients, those with higher area under the curve and dose experienced longer progression-free survival (P = 0.023 and 0.013, respectively). CONCLUSION: The population pharmacokinetics of VCR were evaluated in adult malignant lymphoma patients. VCR pharmacokinetic data could explain in part the adverse events and prognosis of these patients.

Association of methicillin resistance with mortality of hospital-acquired Staphylococcus aureus bacteremia.

OBJECTIVE: Methicillin-resistant (MR) Staphylococcus aureus bacteremia (SAB) is associated with higher mortality rates than methicillin-susceptible (MS) SAB. This study assessed potential predictors of mortality and evaluated the association of methicillin resistance with mortality in patients with SAB. METHODS: We conducted a retrospective cohort study in patients with hospital-acquired SAB, from 2009 to 2018. Clinical features of patients with MR-SAB were compared with those of patients with MS-SAB and predictors of 30-day mortality were determined using Cox regression analysis. RESULTS: Among 162 patients, 56.8% had MR-SAB. Overall 30-day mortality was 19.1%; MR-SAB had higher mortality (25.0%) than MS-SAB (11.4%). Univariate analysis highlighted long-term hospitalization, prior antibiotics use, and delayed initiation of appropriate antibiotics as risk factors. Cox regression analysis showed that respiratory tract source, Pitt bacteremia score, Charlson comorbidity index, and appropriate antibiotic therapy within 24 hours were independently and significantly associated with 30-day mortality outcome. CONCLUSIONS: Methicillin resistance was not an independent risk factor for mortality in patients with SAB. Early, appropriate antibiotic treatment is an important prognostic factor.

[The Effectiveness of Counseling Using Preventative Informational Sheets with Climate and Environmental Data from Insurance Pharmacies in Preventing Worsened Asthma Symptoms].

We investigated the possibility that having pharmacists give asthma patients informational sheets on climate and environmental changes at insurance pharmacies during patient counseling might prevent the worsening of asthma symptoms. Patients with hyperlipidemia were comparative subjects. We created informational sheets about climate and environmental changes and their influence on asthma. During patient counseling, pharmacists gave them to all asthma patients who visited insurance pharmacies over a period of 2 months, between November and December 2017. Based on previous studies, we called days which showed certain climate or environmental changes as compared to the previous day "change days". We compared the number of visiting patients on change days after preventative information was provided (between January and March 2018) with the number before information was provided (between January and March 2017). In addition, we compared those numbers with the number of patients who visited the target pharmacies between January and March 2016 in order to examine the influence of yearly climate change. The same procedure was used with hyperlipidemic patients. The number of visiting asthma patients after information was provided significantly decreased (5.1±2.1, p=0.03) compared with the number before information was provided, between January and March 2017 (6.1±2.8). The number of aforementioned visits compared to those between January and March 2016 also significantly decreased (p=0.01). Our results suggest that preventative information about climate and environmental changes provided by pharmacists during patient counseling might influence the number of asthma patient visits and prevent the exacerbation of their symptoms.

Quality of Web Information About Palliative Care on Websites from the United States and Japan: Comparative Evaluation Study.

BACKGROUND: Patients and their families are able to obtain information about palliative care from websites easily nowadays. However, there are concerns on the accuracy of information on the Web and how up to date it is. OBJECTIVE: The objective of this study was to elucidate problematic points of medical information about palliative care obtained from websites, and to compare the quality of the information between Japanese and US websites. METHODS: We searched Google Japan and Google USA for websites relating to palliative care. We then evaluated the top 50 websites from each search using the DISCERN and LIDA instruments. RESULTS: We found that Japanese websites were given a lower evaluation of reliability than US websites. In 3 LIDA instrument subcategories-engagability (P<.001), currency (P=.001), and content production procedure (P<.001)-US websites scored significantly higher and had large effect sizes. CONCLUSIONS: Our results suggest that Japanese websites have problems with the frequency with which they are updated, their update procedures and policies, and the scrutiny process the evidence must undergo. Additionally, there was a weak association between search ranking and reliability, and simultaneously we found that reliability could not be assessed by search ranking alone.

Relationship between Physicochemical Properties of Medical Supplies and Serious Adverse Drug Reactions Listed in the Package Inserts.

We sought to clarify the relationship between the physicochemical properties of each medical supply and serious adverse drug reactions listed in the package inserts, by reviewing new information. We investigated 1) 1078 medicines currently available on the domestic Japanese market by using physicochemical data, such as cLogD, molecular weight (MW), and pKa and 2) the serious adverse drug reactions stated in the package inserts and the presence or absence of serious renal and liver disorders, as well as mental, extrapyramidal, and skin disorders. The renal disorders data showed: cLogD<0, adjusted odds ratio (aOR)=2.00; MW values ≥500, aOR=2.28; and pKa<7.4, aOR=1.95-2.06. The liver disorders data showed: pKa<8.4, aOR=1.83-1.95, and MW values ≥300, aOR=1.47-1.87. The mental disorders data showed: cLogD≥0, aOR=2.12, and MW values<400, aOR=2.46-2.85. The extrapyramidal disorders data showed: pKa≥6.4, aOR=4.50-11.32; cLogD≥0, aOR=4.71; and MW values<500, aOR=7.95-15.08. The skin disorders data showed: cLogD<0, aOR=1.46; MW values ≥500, aOR=1.69; and pKa<6.4, aOR=1.65 or<7.4-8.4, aOR=1.59. This information will be useful for investigating the relationships between new drugs entering the market and their potential future adverse drug reactions, and for establishing both precautionary and medical observational standards.

Signal of Miscarriage with Aripiprazole: A Disproportionality Analysis of the Japanese Adverse Drug Event Report Database.

INTRODUCTION: With recent advances in medicines, many patients with schizophrenia have become able to conceive. One common second-generation antipsychotic given to patients with schizophrenia is aripiprazole. The label information of aripiprazole in Japan states that according to one case report "there is a report of miscarriage in clinical trial". OBJECTIVE: The aim of this study was to evaluate the relationship between aripiprazole and miscarriage by conducting a disproportionality analysis of an adverse drug event report database. METHODS: We conducted a disproportionality analysis of second-generation antipsychotic exposure during pregnancy using the Japanese Adverse Drug Event Report database, which is a spontaneous reporting database in Japan. We investigated aripiprazole and other approved second-generation antipsychotics in Japan. In accordance with the previous report, we created a data set for analysis consisting of pregnancy-related reports. RESULTS: A potential signal for miscarriage was detected for aripiprazole [proportional reporting ratio: 2.39, χ 2: 13.77, reporting odds ratio (95% confidence interval): 2.76 (1.62-4.69); n = 18]. In contrast, no potential signal for miscarriage was detected for other second-generation antipsychotics. CONCLUSION: Through our analysis of the Japanese Adverse Drug Event Report database, we found a potential signal for miscarriage for aripiprazole. Safety information on the use of aripiprazole during pregnancy is very limited. Therefore, we suggest that the potential signal detected in our analysis be explored further.

[The Synergistic Effect of Problem-based Learning Combined with the Jigsaw Method in a Pharmacotherapy Course].

To promote problem-solving ability within a pharmacotherapy course, we developed new problem-based learning (PBL) and information and communication technologies (ICT) support systems, and introduced the "Jigsaw Method," an active learning method in which, similar to parts of a jigsaw puzzle, students are dependent on each other to create the full picture, to succeed. We conducted 10 PBL modules (one case per module), each lasting one week. To encourage constructive group work, information sharing, and student understanding in the individual modules, we implemented a Jigsaw Method-based wiki worksheet system in which students were to identify patient problems and check each other's work on an e-portfolio system. After completing this new curriculum, students were able to create comprehensive therapeutic care plans. A significant correlation was observed between the students' care plan evaluation scores and their module test results, suggesting that constructive group work can enhance problem-solving ability in therapeutics. These results clearly indicate the benefit of combining our new PBL-ICT support system with the Jigsaw Method.

[Methodology for Estimating the Risk of Adverse Drug Reactions in Pregnant Women: Analysis of the Japanese Adverse Drug Event Report Database].

Safety information regarding drug use during pregnancy is insufficient. The present study aimed to establish an optimal signal detection method to identify adverse drug reactions in pregnant women and to evaluate information in the Japanese Adverse Drug Event Report (JADER) database between April 2004 and November 2014. We identified reports on pregnant women using the Standardised MedDRA Queries. We calculated the proportional reporting ratio (PRR) and reporting odds ratio (ROR) of the risk factors for the two known risks of antithyroid drugs and methimazole (MMI) embryopathy, and ritodrine and fetal/infant cardiovascular events. The PRR and ROR values differed between all reports in the JADER database and those on pregnant women, affecting whether signal detection criteria were met. Therefore we considered that reports on pregnant women should be used when risks associated with pregnancy were determined using signal detection. Analyses of MMI embryopathy revealed MMI signals [PRR, 159.7; ROR, 669.9; 95% confidence interval (CI), 282.4-1588.7] but no propylthiouracil signals (PRR, 1.98; ROR, 2.0; 95%CI, 0.3-15.4). These findings were consistent with those of reported risks. Analyses of fetal/infant cardiovascular events revealed ritodrine signals (PRR, 2.1; ROR, 2.1; 95%CI, 1.4-3.3). These findings were also consistent with reported risks. Mining the JADER database was helpful for analyzing adverse drug reactions in pregnant women.

[Development and Validation of Estimate Equations for Adverse Drug Reactions Using Risk Factors and Subjective Symptoms].

The purpose of this study was to develop and validate estimate equations for preventing adverse drug reactions (ADRs). We conducted five case-control studies to identify individual risk factors and subjective symptoms associated with the following five ADRs: drug-induced ischemic heart disease; renal damage; muscle disorder; interstitial pneumonia; and leucopenia. We performed logistic regression analysis and obtained eight regression equations for each ADR. We converted these to ADR estimate equations for predicting the likelihood of ADRs. We randomly selected 50 cases with non-individual ADRs from the Case Reports of Adverse Drug Reactions and Poisoning Information System (CARPIS) database of over 65000 case reports of ADRs, and assigned these cases to a validation case group. We then calculated the predictive probability for 50 cases using the eight estimate equations for each ADR. The highest probability for each ADR was set as the probability of each ADR. If the probability was over 50%, the case was interpreted as ADR-positive. We calculated and evaluated the sensitivity, specificity, and positive likelihood ratio of this system. Sensitivity of the estimate equations for muscle disorder and interstitial pneumonia were ≥90%. Specificity and positive likelihood ratios of estimate equations for renal damage, interstitial pneumonia and leucopenia were ≥80% and ≥5, respectively. Our estimate equations thus showed high validity, and are therefore helpful for the prevention or early detection of ADRs.

Predictors of response of patients with solid tumors to granulocyte colony-stimulating factor.

BACKGROUND: Granulocyte colony-stimulating factor administration is an important component of supportive therapy in chemotherapy-induced leukopenia. Although patient response to granulocyte colony-stimulating factor administration is known to vary, the factors responsible for poor response have not been identified. OBJECTIVE: To identify the predictors of the responses of patients with solid tumors to granulocyte colony-stimulating factor. SETTING: A 600-bed university hospital offering secondary and tertiary care in Japan. METHODS: This retrospective cohort study examined the response of 181 patients with solid tumors who were administered prophylactic granulocyte colony-stimulating factor for the first time after they developed severe grade 3/4 leukopenia (white blood cell count <2,000 × 10(-9)/L) because of adjuvant or neoadjuvant chemotherapy. The granulocyte colony-stimulating factor response was defined as the length of the leukocyte recovery period, which was assessed as the period within which the normal white blood cell count (white blood cell count >3,000 × 10(-9)/L) is reached after the first dosage of granulocyte colony-stimulating factor. After classification of the patients as either poor or normal granulocyte colony-stimulating factor responders according to the confidence interval of the recovery period, their characteristics were compared. MAIN OUTCOME MEASURE: The time for recovery to normal white blood cell count was 2-7 days (90 % confidence interval), and the cutoff value for differentiating poor responders (n = 14) from normal responders (n = 167) was 8 days. Univariate analysis identified previous radiotherapy, number of chemotherapy courses, high granulocyte colony-stimulating factor dosage, and hypoalbuminemia to be significantly associated with granulocyte colony-stimulating factor response. Multivariate analysis identified undergoing four or more chemotherapy courses (odds ratio = 5.09; 95 % confidence interval, 1.14-22.71) and heart failure (odds ratio = 5.96; 95 % confidence interval, 1.09-32.57) to be significantly associated with poor granulocyte colony-stimulating factor response. CONCLUSIONS: Undergoing four or more chemotherapy courses and heart failure are independent risk factors for poor response to granulocyte colony-stimulating factor. These findings may help prevent the complications of leukopenia during chemotherapy and highlight the need to develop better strategies for preventing and treating infectious disease in patients undergoing granulocyte colony-stimulating factor administration.

Variability in teicoplanin protein binding and its prediction using serum albumin concentrations.

The impact of lower serum albumin levels on teicoplanin pharmacokinetics has not been previously determined. The authors assessed the relationship between total and free concentrations of teicoplanin in serum samples obtained from patients receiving teicoplanin therapy for Gram-positive bacterial infections. In addition, the authors determined the contribution of serum albumin concentrations to the unbound fraction of teicoplanin. One hundred ninety-eight serum samples were obtained from 65 patients undergoing routine therapeutic drug monitoring of teicoplanin. Free serum teicoplanin was separated by ultrafiltration, and total and free serum concentrations of teicoplanin were determined by a fluorescence polarization immunoassay. Regression analysis was then performed to build a prediction model for the free serum teicoplanin concentration from the total serum teicoplanin concentration and the serum albumin level using the first 132 samples. The predictive performance of this model was then tested using the next 66 samples. Free serum teicoplanin concentrations (Cf) (mug/mL) were predicted using a simple model constructed using total serum teicoplanin (Ct) (mug/mL) and albumin concentrations (ALB) (g/dL): Cf = Ct/(1 + 1.78 * ALB). This model could estimate free serum teicoplanin concentrations with a small bias and an acceptable error. The measured free level of teicoplanin will lie between 0.63 and 1.38 times the predicted concentration in 95% of cases. Serum albumin level plays a major role in the variability of the fraction unbound of teicoplanin. This model can reliably estimate free serum teicoplanin concentrations more easily than by using direct measurements.