Artificial Neural Network Analysis of Determinants of Tacrolimus Pharmacokinetics in Liver Transplant Recipients

BACKGROUND

The efficacy and toxicity of tacrolimus are closely related to its trough blood concentrations. Identifying the influencing factors of pharmacokinetics of tacrolimus in the early postoperative period is conducive to the optimization of the individualized tacrolimus administration protocol and to help liver transplant (LT) recipients achieve the target blood concentrations.

OBJECTIVE

This study aimed to develop an artificial neural network (ANN) for predicting the blood concentration of tacrolimus soon after liver transplantation and for identifying determinants of the concentration based on Shapley additive explanation (SHAP).

METHODS

In this retrospective study, we enrolled 31 recipients who were first treated with liver transplantation from the Department of Liver Transplantation and Hepatic Surgery, the First Affiliated Hospital of Shandong First Medical University (Shandong Provincial Qianfoshan Hospital) from November 2020 to May 2021. The basic information, biochemical indexes, use of concomitant drugs, and genetic factors of organ donors and recipients were used for the ANN model inputs, and the output was the steady-state trough concentration (C0) of tacrolimus after oral administration in LT recipients. The ANN model was established to predict C0 of tacrolimus, SHAP was applied to the trained model, and the SHAP value of each input was calculated to analyze quantitatively the influencing factors for the output C0.

RESULTS

A back-propagation ANN model with 3 hidden layers was established using deep learning. The mean prediction error was 0.27 ± 0.75 ng/mL; mean absolute error, 0.60 ± 0.52 ng/mL; correlation coefficient between predicted and actual C0 values, 0.9677; and absolute prediction error of all blood concentrations obtained by the ANN model, ≤3.0 ng/mL. The results indicated that the following factors had the most significant effect on C0: age, daily drug dose, genotype at CYP3A5 polymorphism rs776746 in both recipient and donor, and concomitant use of caspofungin. The predicted C0 value of tacrolimus in LT recipients increased in a dose-dependent manner when the daily dose exceeded 3 mg, whereas it decreased with age when LT recipients were older than 48 years. The predicted C0 was higher when recipients and donors had the genotype CYP3A5*3*3 than when they had the genotype CYP3A5*1. The predicted C0 value also increased with the use of caspofungin or Wuzhi capsule.

CONCLUSION AND RELEVANCE

The established ANN model can be used to predict the C0 value of tacrolimus in LT recipients with high accuracy and good predictive ability, serving as a reference for personalized treatment in the early stage after liver transplantation.

Determination of aloesone in rat plasma by LC-MS/MS spectrometry and its application in a pharmacokinetic study

Aim: We aimed to develop a rapid and accurate LC-MS/MS method for determining the concentration of aloesone in rat plasma, and to investigate its pharmacokinetics. Methods: The rat plasma samples were extracted using acetonitrile. Chromatographic separation was achieved using a Kinetex XB-C18 column, with a mobile phase of methanol and water (containing 0.1‰ formic acid) in a gradient elution. An ESI source, operating in positive ion mode with multiple reaction monitoring, was utilized. Results & conclusion: The developed method meets all the requirements for methodological validation, and it was successfully applied in the pharmacokinetic study. It was observed that oral administration of aloesone in rats resulted in rapid absorption (time to reach Cmax: 0.083 h) but low bioavailability (12.59%).

Phenibut screening and quantification with liquid chromatography-tandem mass spectrometry and its application to driving cases

An analytical strategy for identification by an LC-MS/MS multitarget screening method and a suitable LC-MS/MS based quantification were developed for the psychotropic drug phenibut. The samples analyzed were collected during traffic control and were associated with driving under the influence of drugs. A positive sample for phenibut was identified in a single case of driving under the influence. The quantification revealed a drug concentration of 1.9 μg/mL. An interaction with blood alcohol (BAC = 0.10%) was discussed as the explanation of the way of driving and deficit manifestations observed (swaying, nystagmus, quivering of the eyelid, and reddened eyes). According to the available information, the quantified phenibut concentration could be explained by an intake of four tablets (self-reported) during the day containing 250 mg of the drug. Chromatography was performed with a Luna 5 μm C18 (2) 100 A, 150 mm × 2 mm analytical column, and a buffer system consisted of 10 mM ammonium acetate and 0.1% acetic acid (v/v) included in mobile phases marked as A (H2 O/methanol = 95/5, v/v) and B (H2 O/methanol = 3/97, v/v). An effective limit of detection (LOD = 0.002 μg/mL) could be achieved for the multitarget screening method. The quantification of phenibut was performed on a second LC-MS/MS system with LOD/LOQ values of 0.22/0.40 μg/mL. Since phenibut quantification data are rare, the presented information can be used with caution for evaluation of positive cases in the future.

Prevalence and blood concentrations of benzodiazepines and opioids in opioid-positive death investigations in Ontario, Canada, from 2017 to 2021

The aim of this study was to investigate the incidence of benzodiazepines in opioid-positive death investigations, including trends in frequency and combination of drugs, as well as demographic data and blood concentrations, where available. Additionally, naloxone concentrations in polysubstance compared to opioid-only cases were analyzed. This was a retrospective study that consisted of all post-mortem toxicology cases in Ontario, Canada, from January 01, 2017, to December 31, 2021, with an opioid finding in any analyzed autopsy specimen. There were 11,033 death investigations identified. The overall rate of benzodiazepine co-involvement was 54.5%. Males accounted for the majority of cases (71%), and the most affected age group was 30- to 39-year-olds. The most frequently detected opioid was fentanyl and the most frequently detected benzodiazepine was etizolam, which was also the most frequently observed opioid/benzodiazepine combination. Findings related to differences in concentrations of opioids when naloxone was also present were mostly non-significant, except for methadone. The rate of benzodiazepine detection with opioids grew faster than opioid detections overall, potentially due to the increasingly toxic drug supply. Detection of novel psychoactive drugs fluctuated more unpredictably than opioids and benzodiazepines associated with clinical use. These findings can help inform policy decisions by public health agencies in exploring harm reduction efforts, for example, education and drug-checking services.

Evaluation of early retinal changes in patients on long-term hydroxychloroquine using optical coherence tomography angiography

Background

Connective tissue diseases (CTD), including systemic lupus erythematosus and rheumatoid arthritis (RA), have long been treated with hydroxychloroquine (HCQ). However, prolonged HCQ use poses a risk of adverse effects, particularly retinopathy.

Objective

To detect early retinal changes assessed by optical coherence tomography angiography (OCTA) in CTD patients with long-term HCQ treatment and to explore the relationship between OCTA parameters and the concentrations of HCQ and its metabolites.

Design

A cross-sectional study conducted from March 2020 to October 2021 at the First Affiliated Hospital of Anhui Medical University.

Methods

The area and perimeter of the foveal avascular zone (FAZ), the thickness of the fovea and parafovea, and the vascular density of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) in each area of the macula were measured by OCTA in 43 CTD patients treated with HCQ for over 6 months. Meantime, blood concentrations of HCQ and its metabolites were determined by high-performance liquid chromatography-tandem mass spectrometry, and the clinical documents of all 43 involved patients were collected.

Results

There is no significant correlation between OCTA outcomes and the patient's age, disease duration, and weight-dependent dose. HCQ cumulative duration positively correlated with FAZ area and perimeter (r = 0.419, p = 0.005 and r = 0.407, p = 0.007, respectively) and negatively correlated with the foveal vessel density in DCP (r = -0.378, p = 0.012). HCQ cumulative dose had a positive correlation with FAZ area and perimeter (r = 0.445, p = 0.003 and r = 0.434, p = 0.004, respectively) and had a negative correlation with foveal vessel density in SCP and DCP (r = -0.383, p = 0.011 and r = -0.424, p = 0.005, respectively). OCTA outcomes did not correlate with HCQ and its metabolite concentrations.

Conclusion

OCTA could be used to detect microvascular changes in the macula of CTD patients with long-term HCQ therapy. It was not found the concentrations of HCQ and its metabolites were associated with retinal vascular changes.

Polypharmacy-Related Shock Symptoms and Complications Associated with Phenothiazine: A Case Report

This report describes a case of shock symptoms in a 72-year-old woman with epilepsy who had been in a state of polypharmacy, taking multiple antipsychotic drugs. After receiving a normal dose of periciazine, she exhibited impaired consciousness, hypothermia, and hypotension and was admitted to hospital. Despite poor response to vasopressors, conservative treatment led to gradual improvement. Subsequent pharmacokinetic analysis showed non-toxic blood concentrations of periciazine, suggesting that even small doses of phenothiazines could result in toxic symptoms. This case highlights the importance of monitoring for adverse reactions when prescribing multiple antipsychotic drugs, particularly in older polypharmacy patients.

Explore the Dosimetric Relationship between the Intake of Chemical Contaminants and Their Occurrence in Blood and Urine

The dosimetric relationship between the human intake dose of a chemical contaminant (an "external dose") and its concentrations in bodily fluids such as blood and urine (related to an "internal dose"), often characterized by a dose-to-concentration ratio, has critical applications in exposure science, toxicology, and risk assessment, especially in the "new approach methods" era. However, there is a lack of a mechanistic, systematic understanding of how such a dosimetric relationship depends on fundamental chemical properties, such as partition coefficients and biotransformation half-lives. Here, we investigate this issue using a well-evaluated toxicokinetic model, which links external and internal doses by quantifying the absorption and elimination of chemicals. Results are visualized in a series of chemical partitioning space plots, whereby a chemical's dose-to-concentration ratio can be approximately predicted based on its partitioning between air, water, and octanol phases. Our results indicate that when taken in equal doses, chemicals with low volatility and moderate to high hydrophobicity exhibit the highest concentrations in the blood, and chemicals undergoing significant biotransformation tend to exhibit lower concentrations in comparison to their counterparts undergoing negligible biotransformation but possessing similar partitioning properties. Chemicals with high hydrophilicity have the highest concentrations in urine. Such revealed property dependence is similar for both adults and children and for individuals with normal body weights and with obesity. Overall, insights gained from this study are important in predicting blood and urinary concentrations from exposure information and in determining the exposure rate that produces the blood or urinary concentrations observed in biomonitoring studies.

Suicide with oral midazolam: post-mortem toxicological investigations using Ostro® plate and UPLC-MS/MS

A middle-aged woman was found dead with multiple empty blisters of midazolam (DORMICUM®), equivalent to 450mg, near her body. The autopsy revealed that the cause of death was secondary to an asphyxia syndrome. Standard toxicological procedures identified midazolam only in blood, urine and gastric content. A quantitative analytical method for midazolam (MDZ) and 1-hydroxy-midazolam (1-OH-MDZ) was validated using protein precipitation, a phospholipid removal Ostro® plates and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). MDZ and 1-OH-MDZ were quantified in peripheral blood at 910 ng/mL and 534 ng/mL, respectively, and superior to 2000 ng/mL in urine. Reported to the body weight, the dose, which was lethal, was estimated to 6.7 mg/kg. The usual dose used in intensive care unit is 0.03-0.3 mg/kg. MDZ intoxication outside of hospital are rare given the restricted availably of this drug in France. Nevertheless, MDZ under oral form remains available in several countries. Toxic MDZ blood concentrations are described after intravenous administration for anesthesia and are not suited for oral intoxication. Based on the autopsy findings, police investigation and toxicology results, the cause of death was determined to be a self-inflicted oral MDZ acute intoxication, which is the first to be documented to the best of our knowledge. This fatal intoxication provides analytical data that could support subsequent toxicological result interpretation in similar forensic cases.

Delayed elimination in humans after ingestion of colchicine: Two fatal cases of colchicine poisoning

Colchicine has been widely used in the treatment of acute gout over the years, but it has a narrow therapeutic index, and overdose can be life threatening. A method using ultra-high-performance liquid chromatography-tandem mass spectrometry system was applied in two fatal cases of colchicine poisoning in this study to the determination of colchicine in blood. In case 1, a 19-year-old man suffered from depression and ingested 160 colchicine tablets (each 0.5 mg). The concentration of colchicine in his blood samples showed a fluctuating trend and kept above the therapeutic steady-state concentration for 5 days. In case 2, a 70-year-old female patient with a history of gout and chronic colchicine intake ingested five times the usual dose of colchicine (5 mg) and died after 12 days of medical care, with 5 ng/mL of colchicine in her blood sample. Our findings suggest that the delayed elimination and accumulation in humans after colchicine overdose could keep the concentration of colchicine maintaining above the therapeutic steady-state concentration for many days before dying, probably along with a fluctuating trend.

Gene polymorphisms affect postoperative imatinib plasma levels and edema in adults with gastrointestinal stromal tumor

Aim: To assess the role of genetic polymorphisms in postoperative imatinib concentrations and edema in patients with gastrointestinal stromal tumor. Methods: The relationships between genetic polymorphisms, imatinib concentrations and edema were explored. Results: Carriers of the rs683369 G-allele and rs2231142 T-allele had significantly higher imatinib concentrations. Grade ≥2 periorbital edemas were related to the carriership of two C-alleles in rs2072454 with an adjusted odds ratio of 2.85, two T-alleles in rs1867351 with an adjusted odds ratio of 3.42 and two A-alleles in rs11636419 with an adjusted odds ratio of 3.15. Conclusion: rs683369 and rs2231142 affect the metabolism of imatinib; rs2072454, rs1867351 and rs11636419 are related to grade ≥2 periorbital edemas.

Correlation between blood concentration of roxadustat and clinical efficacy in patients with anemia of chronic kidney disease

Roxadustat has been associated with the efficacy and safety in patients with chronic kidney disease-related anemia. However, the relationship between roxadustat blood concentration and clinical efficacy is lacking. To explore of the correlation between clinical efficacy and blood concentration of roxadustat in patients with renal anemia of chronic kidney diseases, so as to provide reference for rational clinical drug use. A total of 46 patients were selected with a diagnosis of renal anemia who were prescribed roxadustat at the department of nephrology of the First Hospital of Hebei Medical University from December 2019 to March 2020. The roxadustat blood concentration was determined at 12 weeks of treatment, according to the cumulative response rate, patients were divided into the response group and the nonresponse group, and the relationship between roxadustat blood concentration and treatment effect was analyzed. We also explored the correlation between various factors and the blood concentration. The patients in the response group had higher roxadustat blood concentrations than the nonresponse group (P < .05), and there was no correlation between blood concentration and clinical characteristics such as age, gender, and dosage (P > .05). The blood concentration of roxadustat was correlated with clinical efficacy. The higher the blood concentration, the better the clinical efficacy, meaning it might be a predictor of efficacy.

The Impact of Early Optimization of Infliximab Blood Concentrations >1 μg/mL on Therapeutic Effectiveness in Rheumatoid Arthritis

BACKGROUND

Infliximab is a human-murine chimeric monoclonal IgG antibody against tumor necrosis factor that is used in combination with methotrexate for the treatment of moderate to severe rheumatoid arthritis (RA). The trough concentration of serum infliximab required to control disease activity in RA is ≥1 μg/mL, and we investigated whether this trough concentration can predict the effectiveness of RA treatment.

METHODS

We retrospectively analyzed the cases of 76 patients with RA. The REMICHECK Q® (REMIQ) is a kit that can check for serum infliximab concentrations. Infliximab concentrations >1 μg/mL at 14 weeks after an initial infliximab induction is considered REMIQ-positive, otherwise considered REMIQ-negative. Here, we determined the retention rates and investigated the clinical and serologic features of REMIQ-positive and REMIQ-negative patients.

RESULTS

At 14 weeks, significantly more of the REMIQ-positive patients (n = 46) were responders compared to the non-responders (n = 30). The retention rate at 54 weeks was also significantly higher in the REMIQ-positive group versus the negative group. After 14 weeks, more patients in the REMIQ-negative group were considered inadequate responders, and their infliximab doses were escalated. At baseline, the REMIQ-positive group had significantly lower C-reactive protein (CRP) levels compared to the negative group. Cox regression analysis with multiple variables showed that the positivity of REMIQ (hazard ratio [HR] 2.10 and 95% confidence interval [CI]: 1.55-5.71) at baseline was associated with the achievement of low disease activity. The positivities of rheumatoid factor and anti-CCP antibody at baseline were associated with the achievement of remission with infliximab treatment (HR 0.44, 95% CI: 0.09-0.82 and HR 0.35, 95% CI: 0.04-0.48, respectively).

CONCLUSIONS

The results of this study suggest that the control of RA disease activity may be facilitated by using the REMIQ kit at 14 weeks to check whether it is necessary to increase a patient's infliximab dose to ensure a therapeutic blood concentration that will help the patient achieve low disease activity.

Analysis of the correlation between clinical efficacy and blood concentration of olanzapine in schizophrenia patients

To analyze the relationship between olanzapine blood concentration and clinical efficacy in schizophrenia patients, which has been expected to provide a scientific reference basis for improving the treatment effect of olanzapine in schizophrenia patients. Four hundred eighty-six psychiatric inpatients were randomly selected from October 31, 2019, to October 31, 2020, and all enrolled patients were given olanzapine treatment, and the treatment effect of schizophrenia patients was assessed according to the Positive and Negative Symptom Scale subtraction rate, and divided into treatment effective and ineffective groups at 1, 2, and 3 weeks of treatment, respectively. The olanzapine blood concentration in the body was monitored at 1, 2, and 3 weeks of treatment, and the relationship between olanzapine blood concentration and treatment effect at different time points was analyzed. Patients in the ineffective group had lower olanzapine blood concentrations than the effective group in treatment 1, 2, and 3 weeks and lower Positive and Negative Symptom Scale score reduction rates than the effective group (P < .05); the differences in other baseline information between the groups were not statistically significant (P > .05). Logistic regression analysis showed that olanzapine blood concentration at different times of treatment was related to the treatment effect (odds ratio > 1, P < .05); the results of the bivariate Spearman linear correlation test showed that olanzapine blood concentration at different times of treatment was positively related to the treatment effect of schizophrenia patients (R > 0, P < .05). In schizophrenia patients treated with olanzapine, the higher the olanzapine blood concentration in patients, the better the clinical treatment effect. Accordingly, the clinical can develop individualized medication regimens based on the results of blood concentration testing in the body under the premise of ensuring safety, aiming to ensure maximum efficacy.

Application of Teeth in Toxicological Analysis of Decomposed Cadavers Using a Carbamazepine-Administered Rat Model

In a regular autopsy, blood and organs are used to quantify drug and toxicant concentrations; however, specimens such as blood cannot be collected from highly decomposed corpses, making the quantification of drug and toxicants impossible. This study aimed to estimate the blood carbamazepine (CBZ) concentration from teeth, a part of the human body that is best preserved after death. We sampled teeth and blood of rats administered CBZ. The correlation between the tooth and serum CBZ concentrations was analyzed. Rats were euthanized after CBZ administration and kept at 22 °C for 0 to 15 days before sampling the teeth and measuring the CBZ concentration. Undecalcified, fresh, frozen sections of rat teeth were prepared, and CBZ localization was evaluated. CBZ concentrations in both teeth and cardiac blood peaked at 60 min after administration and increased in a dose-dependent manner. CBZ concentration in teeth did not substantially change after death, with high CBZ distribution being observed in the pulp cavity. The tooth and serum CBZ concentrations were highly correlated, suggesting that the measurement of toxicant concentration in sampled teeth would allow for the estimation of blood toxicant concentration in highly decomposed corpses.

The Effects of Vonoprazan Fumarate on the Tacrolimus Blood Concentration in Liver Transplant Recipients

BACKGROUND/AIM

The proton pump inhibitors were reported to affect the blood concentration of tacrolimus. Vonoprazan fumarate is a new acid suppressant with potent acid inhibitory effects. There have been no reports concerning the effect of vonoprazan on the tacrolimus blood concentration in liver transplant (LT) recipients.

PATIENTS AND METHODS

Eighteen living donor liver transplantation (LDLT) recipients who switched from proton pump inhibitors (PPIs) to vonoprazan between 2016 to 2018 were enrolled in this retrospective study. We investigated blood levels of tacrolimus, and liver and renal function before and after the change from PPIs to vonoprazan.

RESULTS

The median C ₀ /D of tacrolimus before conversion, 3 months after conversion, and 6 months after conversion were 2.33, 1.53, and 1.89, respectively, and there was no significant difference. Conversion from another PPI to vonoprazan was not associated with a worsening liver function. The estimated glomerular filtration rate was significantly worse after conversion.

CONCLUSION

Vonoprazan can be safely administered to LT recipients receiving tacrolimus during the stable period.

Biodistribution of Insulin Following Massive Insulin Subcutaneous Injection

A man in his 30s injected insulin several times into his abdomen and was found dead several hours later. Micropathological findings showed alveolar injury with hemorrhaging and cerebral parietal lobe nerve cell edema. Biochemical examinations showed that the blood insulin level was high, significantly so at the insulin injection sites. The blood glucose and C-peptide levels were low. The insulin level in the kidneys was low. In forensic medicine, a postmortem diagnosis of insulin subcutaneous injection is often difficult. When insulin injection is suspected, particularly high insulin levels can be expected at the insulin injection site, rather than in the blood.

The equilibrated blood sevoflurane concentrations show a rapid decrease after switching from ventilation for the human lung to cardiopulmonary bypass

Volatile anesthetics (VAs) protect myocardial cells during cardiovascular surgeries, including cardiopulmonary bypass (CPB). In CPB, blood is gradually transferred from the body to a CPB unit until the target cardiac index is achieved, following which human lung (HL) ventilation is stopped. This pilot study aimed to evaluate changes in the blood sevoflurane concentrations 5 min after the start of CPB when its delivery to the oxygenator began after HL ventilation with sevoflurane was completed. Six patients were recruited and participated in this study. For each patient, the equilibrated blood sample, collected 20 min after starting the delivery of 1.7% sevoflurane (HL group), and another blood sample, collected 5 min after starting the CPB, were analyzed using gas chromatography equipped with a flame ionization detector. The mean (± standard deviation) sevoflurane concentrations in the HL and 5 min after starting CPB groups were 58.6 ± 4.7 and 14.5 ± 5.0 μg/ml, respectively (P < 0.01). In conclusion, the equilibrated blood sevoflurane concentrations showed a rapid decrease when switching from sevoflurane ventilation for the HL to CPB unless it was introduced to the oxygenator until completion of the switch.

Blood Concentrations and Dietary Intake of Cd among the General Population in South Korea

This study aimed to identify the time trends of blood Cd concentrations and their correlation with the Cd-B and the intakes of food groups as an influencing factor for Cd exposure among the general population in South Korea. During seven Korea National Health and Nutrition Examination Surveys from 2005 to 2017, a total of 9578 individuals (4317 men and 5261 women) participated in a 24 h recall test for a dietary survey and a blood-metal survey using physical examinations performed in the same survey year. The blood Cd concentration was observed to decrease significantly (p < 0.05) from 1.51 µg/L in 2005 to 0.76 µg/L in 2017. In terms of the food groups, grains and cereals, potatoes and starch, and fruits were significantly correlated with the corresponding Cd concentrations and also showed decreased intakes. For Koreans, the observed decrease in blood Cd concentrations was probably caused by a decrease in the intake of food groups of plant origin.

Methodologies for the Determination of Blood Alpha1 Antitrypsin Levels: A Systematic Review

Background: The study of hematic concentrations of alpha1 antitrypsin (AAT) is currently one step in the diagnosis of AAT deficiency. To try to clarify the relevance of the laboratory techniques, we carried out a systematic review of the literature. Methods: Studies evaluating the quantification of AAT in peripheral blood were searched in PubMed in July 2021. The selection criteria included (1) any type of study design that included a quantification of AAT in peripheral blood; (2) studies written in English or Spanish; (3) studies evaluating human beings; and (4) studies involving adults. Results: Out of 207 studies, the most frequently used techniques were nephelometry (43.9%), followed by ELISA (19.8%) and turbidimetry (13.5%). Altogether, 182 (87.9%) cases expressed their results in units of gram, while 16 (7.7%) articles expressed them in units of mole. Only 2.9% articles referred to the standard used, 43.5% articles indicated the commercial kit used, and 36.2% indicated the analyzer used. Conclusions: The technical aspects of these determinations are not always reported in the literature. Journals should be attentive to these technical requirements and ensure that they are included in the works in which AAT is determined in order to ensure a correct interpretation of the study findings.

PBK Model-Based Prediction of Intestinal Microbial and Host Metabolism of Zearalenone and Consequences for its Estrogenicity

Scope

The aim of the present study is to develop physiologically‐based kinetic (PBK) models for rat and human that include intestinal microbial and hepatic metabolism of zearalenone (ZEN) in order to predict systemic concentrations of ZEN and to obtain insight in the contribution of metabolism by the intestinal microbiota to the overall metabolism of ZEN.

Methods and Results

In vitro derived kinetic parameters, apparent maximum velocities (V_max) and Michaelis–Menten constants (K_m) for liver and intestinal microbial metabolism of ZEN are included in the PBK models. The models include a sub‐model for the metabolite, α‐zearalenol (α‐ZEL), a metabolite known to be 60‐times more potent as an estrogen than ZEN. Integrating intestinal microbial ZEN metabolism into the PBK models revealed that hepatic metabolism drives the formation of α‐ZEL. Furthermore, the models predicted that at the tolerable daily intake (TDI) of 0.25 µg kg⁻¹ bw the internal concentration of ZEN and α‐ZEL are three‐orders of magnitude below concentrations reported to induce estrogenicity in vitro.

Conclusion

It is concluded that combining kinetic data on liver and intestinal microbial metabolism in a PBK model facilitates a holistic view on the role of the intestinal microbiota in the overall metabolism of the foodborne xenobiotic ZEN and its bioactivation to α‐ZEL.

Vitamin D and the Risk of Non-Melanoma Skin Cancer: A Systematic Literature Review and Meta-Analysis on Behalf of the Italian Melanoma Intergroup

Simple Summary

Vitamin D has been extensively studied in relation to cancer risk at several body sites, but its relationship with non-melanoma skin cancer (NMSC), the most frequent malignancy in humans, is still unclear. Here, we performed a systematic literature search and meta-analysis of published studies and did not find convincing evidence that a causal association exists between vitamin D intake (from foods and supplements), vitamin D blood concentration, or polymorphisms of the genes coding for the vitamin D receptor and binding protein, and NMSC risk.

Abstract

We aimed to provide a comprehensive overview of the link between vitamin D and non-melanoma skin cancer (NMSC). For this purpose, we conducted a systematic literature review (updated to 3 February 2021) and meta-analysis of the studies reporting on the association between vitamin D intake (from diet and supplements) and blood concentration, polymorphisms of the vitamin D receptor (VDR) and vitamin D binding protein (VDBP) genes, and the risk of NMSC. Random effects meta-analysis models were fitted to merge study-specific risk estimates into summary relative risk (SRR) and corresponding 95% confidence intervals (CI). Twenty-four studies altogether were included. There was a suggestive association between increasing serum/plasma vitamin D concentration and NMSC risk (SRR for highest vs. lowest concentration 1.67, 95%CI 0.61–4.56), although with large heterogeneity across studies (I² = 91%). NMSC risk was associated with highest vitamin D intake in observational studies but not in clinical trials. Finally, there was no significant association between any polymorphism of the VDR and VDBP genes and NMSC risk. In conclusion, no strong relationship between vitamin D metabolism and NMSC risk appears to exist according to our systematic review and meta-analysis, although some findings are worthy of further investigation.

The influence of edema on the bisoprolol blood concentration after bisoprolol dermal patch application: A case-control study

BACKGROUND

Beta-blocking is important for critically ill patients. Although some patients are required to continue taking beta-blockers after they no longer need critical care, some of these patients have impaired swallowing abilities. Bisoprolol dermal patches have recently been introduced and appear to be a good alternative to oral bisoprolol tablets. However, it is still unclear whether the pharmacodynamics of such patches are affected by edema in patients who have experienced critical care. This study aimed to clarify the effects of systemic edema on beta-blocker absorption from dermal patches in critically ill patients.

METHOD

Patients who exhibited tachycardia and impaired swallowing function after critical care were included in this study. They were assigned to either the edema group (n = 6) or no edema group (n = 6) depending on the presence/absence of edema in the lower extremities. A bisoprolol dermal patch was pasted onto each subject, and the blood bisoprolol concentration was checked at 8 timepoints over the next 24 hours. The area under the serum concentration time curve, maximum concentration observed (Cmax), and time of maximum concentration observed were also examined.

RESULT

The mean blood bisoprolol concentrations of the 2 groups were not significantly different at 2, 4, 6, 8, 10, 12, 16, or 24 hours after the patch application. The area under the serum concentration time curve and maximum concentration observed were not different between the groups. The mean heart rates of the 2 groups were not significantly different at 6, 12, or 24 hours after the patch application (Student t test, P = .0588, P = .1080, and P = .2322, respectively).

CONCLUSION

In this study, the blood concentration of bisoprolol and its heart rate-reducing effects after bisoprolol dermal patch application might not be affected by systemic edema in the lower extremities.

Central Nervous System Migration of Astaxanthin and Adonixanthin Following Their Oral Administration in Cynomolgus Monkeys

Astaxanthin, which has been shown to have significant antioxidant activity, is rapidly spreading as a health functioning ingredient in the health food and cosmetics sectors worldwide. It is well known that astaxanthin acts on the brain; however, there is little evidence of brain translocation due to the difficulty in identifying astaxanthin in tissues. Therefore, in this study, we investigated the concentrations of astaxanthin and adonixanthin, the latter being a biosynthetic intermediate from β-carotene to astaxanthin, in the brain after oral administration in primates. Cynomolgus monkeys were orally administered astaxanthin or adonixanthin at a dose of 50 mg/kg for 10 d, through a disposable catheter inserted into the stomach via the nasal passage. Following euthanization, the monkeys' brains and various other organs were collected. The carotenoid content in serum and individual organs was analyzed by high-performance liquid chromatography. Adonixanthin was found to accumulate at a higher concentration than astaxanthin in monkey brain tissues. Also, both astaxanthin and adonixanthin were found to be distributed in the heart, spleen, liver, and kidneys. These findings indicate that astaxanthin and adonixanthin can enter the central nervous system of primates following their oral administration. This provides important evidence for the activity of astaxanthin and adonixanthin on the central nervous system.

Disposition Kinetics of Amitraz in Lactating Does

Amitraz, a member of the formamidine pesticide family, commonly used for ectoparasite control, is applied as a dip or low-pressure hand spray to cattle and swine, and the neck collar on dogs. Data on amitraz were generated mainly on laboratory animals, hens, dogs, and baboons. The data on the toxicity and disposition of amitraz in animals and its residues in the milk are inadequate. Therefore, the present study was intended to analyze the disposition kinetics of amitraz and its pattern of elimination in the milk of lactating does after a single dermal application at a concentration of 0.25%. Blood at predetermined time intervals and milk twice daily were collected for eight days post application. The drug concentration was assayed by high-performance liquid chromatography (HPLC). Amitraz was detected in whole blood as early as 0.5 h, which attained a peak concentration at 12 ± 5 h, followed by a steady decline; however, detection persisted until 168 h. Amitraz was present in the blood at its 50% C_max even after 48 h, and was still detectable after 7 days. The disposition after a single dermal application was best described non-compartmentally. The mean terminal half-life (t_1/2), mean residence time (MRT), and area under the curve (AUC_0–t) were 111 ± 31 h, 168 ± 39 h, and 539 ± 211 µg/mL/h, respectively. The apparent volume of distribution (Vd_area) was 92 ± 36 mL/g with an observed clearance (Cl) of 0.57 ± 0.33 mL/kg/h. Thus, the drug was well absorbed, widely distributed and slowly eliminated from the animal body. Amitraz achieved milk concentration approximating 0.2 per cent of the total dose after a single exposure and the steady-state elimination of amitraz in milk above the recommended maximum residue limit (MRL) of 0.01 mg/kg can act as a source of public health concern when applied on lactating animals.

Concomitant Use of High-dose Methotrexate and Glycyrrhizin Affects Pharmacokinetics of Methotrexate, Resulting in Hepatic Toxicity

BACKGROUND/AIM

High-dose methotrexate is a therapy for acute leukemia, malignant lymphoma, and osteosarcoma. Glycyrrhizin has been used to treat hepatic dysfunction caused by high-dose methotrexate. However, few studies have investigated the interaction between glycyrrhizin and high-dose methotrexate.

MATERIALS AND METHODS

Male Wistar rats were treated with high-dose methotrexate (500 or 1,000 mg/kg) alone, or with co-administration of 100 mg/kg glycyrrhizin. Plasma concentrations of methotrexate, alanine aminotransferase, aspartate aminotransferase, and total bilirubin were measured.

RESULTS

At both methotrexate doses, the blood concentration of methotrexate was significantly increased and total clearance was significantly reduced using co-administration of glycyrrhizin compared with methotrexate alone, which led to increased levels of hepatic enzymes. These results suggest that glycyrrhizin significantly increases the plasma level and delays the clearance of methotrexate, resulting in hepatic toxicity.

CONCLUSION

The concomitant use of methotrexate and glycyrrhizin should be considered with caution.

Influence of Pyrexia on Pharmacokinetics of Azithromycin and Its Interaction With Tolfenamic Acid in Goats

Azithromycin is a macrolide antimicrobial agent of the azalide group with a broad spectrum of activity against gram-negative and gram-positive bacterial organisms. Tolfenamic acid is a non-steroidal anti-inflammatory drug of the fenamate group, which is used extensively in humans and animals due to its anti-inflammatory, analgesic, and antipyretic properties. There is dearth of literature on any type of drug interaction between azithromycin and tolfenamic acid in any species, including human beings and alteration of its pharmacokinetics by fever. Therefore, the objective of this study was to investigate the alteration of disposition kinetics of azithromycin alone and in the presence of tolfenamic acid in Malabari goats by fever, following an intravenous administration at a dose rate of 20 mg/kg body weight. Blood samples collected from both afebrile and febrile goats at predetermined time intervals after the administration of azithromycin alone and then in combination with tolfenamic acid (2 mg/kg, intravenously), respectively, were analyzed using high-performance liquid chromatography. Non-compartmental analysis was used to determine the peak blood concentration (C max), time-to-peak plasma concentration (T max), half-life (t 1/2λz ), area under the curve (AUC 0-t, AUC 0-inf), area under the first moment curve (AUMC 0-inf), mean residence time (MRT0-inf), apparent volume of distribution at steady state (V ss), and the total body clearance of drug from the blood (Cl). In febrile animals, significant differences were noted in the values of C max, Cl, and V ss. Thus, azithromycin disappears into an additional compartment in febrile goats, which may be due to its extended cellular penetration into the inflammatory cells, resulting in anti-inflammatory activity. Tolfenamic acid significantly altered the pharmacokinetics of azithromycin in both normal and febrile animals. Tolfenamic acid, being a better anti-inflammatory agent, suppresses the inflammatory mediators, reducing the possibility of increased utilization of azithromycin in febrile condition.

Tacrolimus 0.03% ointment treatment in exfoliative cheilitis: A randomised controlled clinical trial and monitoring blood concentration

BACKGROUND

Tacrolimus has been used to treat various inflammatory skin diseases, but its safety for topical application on the oral mucosa is unknown. Exfoliative cheilitis (EC) is a chronic inflammatory disorder of the lips characterised by repeated scaling; it is difficult to manage. The aim of this study was to assess the efficacy and safety of tacrolimus 0.03% ointment as a topical treatment in patients with EC.

METHODS

In this randomised controlled clinical trial, 40 patients with EC were randomly assigned to receive either tacrolimus 0.03% ointment (experimental group, n = 20) or triamcinolone acetonide 0.1% cream (control group, n = 20) treatment for a 3-week period. Medication was administered in 3, 2 and 1 daily doses during the first, second and third weeks, respectively. The patients with complete healing were followed up for 3 months. The clinical outcomes were measured, including the scores regarding signs (scale, dryness, rhagades and swelling) and symptoms (rough, dry, pain, pruritus and burning sensation) at every visit. Blood concentrations of tacrolimus were assessed.

RESULTS

After the 3-week treatment, healing rates of scale in the experimental and control groups were 65% and 10%, respectively (P = .018). Improvement in all signs and two symptoms (rough, pruritus) was much greater in the experimental group (P < .05). The 3-month recurrence rate was higher in the control group (P = .029). Tacrolimus blood concentrations were in the safe range (< 5 ng/mL).

CONCLUSION

Topical tacrolimus 0.03% ointment has good short-term efficacy and safety for treating EC.

Area under the blood concentration-time curve (AUC) of ethylbenzene concentration in rats: relationship to inhalation and oral administration route-dose

For human risk assessment of toxic chemicals, especially volatile organic compounds (VOCs), the Ministry of the Environment, Government of Japan, has called for the interconversion of inhalation-dose and oral-dose data, two common exposure routes. To address this issue, the present study investigated the time-course changes of ethylbenzene (EB) concentrations in the blood of rats during and after 6-hr inhalation exposure to EB (25, 50, 100, and 200 ppm) and after oral administration of EB by a single oral gavage (25, 50, 100, and 200 mg/kg) of EB. The Area Under the blood concentration-time Curve (AUC) at each blood collection time point (0, 30, 60, 120, 180, 360, 420, 540, and 1440 min, after starting exposure) was determined. The inhalation dose of 25 ppm corresponded closely to the oral administration of 25 mg/kg・bw (r value of 0.859), and the inhalation dose of 200 ppm correlated with the oral administration of 100 mg/kg・bw (r value of 0.948). These results suggest that this comparison using the AUC data at each blood collection time point is valuable for understanding the route- and dose-effects of EB. This study will improve risk assessment of human exposure to EB and other VOCs.

Marked decrease of tacrolimus blood concentration caused by compound Chinese herbal granules in a patient with refractory nephrotic syndrome

WHAT IS KNOWN AND OBJECTIVE

The blood concentration of tacrolimus can be affected by co-administrated drugs. The objective is to draw more attention to herb-drug interactions in China, where herbal medicines are commonly used.

CASE DESCRIPTION

The blood concentration of tacrolimus in a girl with refractory nephrotic syndrome decreased nearly a half despite no change in dose. Nebulizer therapy, cyclophosphamide and a compound Chinese herbal medicine were the only additional treatments than usual.

WHAT IS NEW AND CONCLUSION

The most possible cause of the decrease in tacrolimus concentration was the administration of Radix Astragali among compound Chinese herbal medicine granules.

The Effect of Different Doses of Zearalenone in Feed on the Bioavailability of Zearalenone and Alpha-Zearalenol, and the Concentrations of Estradiol and Testosterone in the Peripheral Blood of Pre-Pubertal Gilts

The objective of this study was to determine the effect of long-term (48 days), per os administration of specific zearalenone (ZEN) doses (20 and 40 μg ZEN/kg BW in experimental groups EI and EII, which were equivalent to 200% and 400% of the upper range limit of the no-observed-adverse-effect-level (NOAEL), respectively) on the bioavailability of ZEN and the rate of changes in estradiol and testosterone concentrations in the peripheral blood of pre-pubertal gilts. ZEN and α-ZEL levels were similar until day 28. After day 28, α-ZEL concentrations increased significantly in group EI, whereas a significant rise in ZEN levels was noted in group EII. The presence of estradiol in peripheral blood plasma was not observed until day 20 of the experiment. Spontaneous secretion of estradiol was minimal, and it was determined at very low levels of up to 10 pg/mL in EI and EII groups. Testosterone concentrations ranged from 4 to 9 ng/mL in all groups. A decrease in the concentrations of both analyzed hormones was reported in the last stage of the experiment. The results of the experiment indicate that: (i) The bioavailability of ZEN in peripheral blood has low diagnostic value, (ii) exposure to low doses of ZEN induces minor changes in the concentrations of the analyzed hormones, which could lead to situational supraphysiological hormone levels and changes in endogenous hormonal balance.

[Vitamin status of adult population of the Russian Federation: 1987-2017]

In a review in order to characterize the dynamics of vitamin status for the period from 1987 to the present, the results of 16 surveys (conducted in 2015-2017) of the sufficiency with vitamins C, A, E, B2 and B6 of adult men and women of working age (about 1200 people) living in different regions of the Russian Federation, were compared with the frequency of vitamin insufficiency among the population in the previous period. The statistically significant improvement in the population's supply with vitamin C in the previous decade continued in 2015-2017. The deficit of this vitamin practically ceased to occur. Reduced blood serum levels of vitamin A were rare (except for patients with tuberculosis, the indigenous inhabitants of an inaccessible village beyond the Arctic region, and pregnant women, especially in the third trimester). In comparison with the previous period, a fairly rare occurrence of vitamin E deficiency persisted. Vitamin B2 deficiency was still detected in a significant number of subjects (25-75th percentile was at the level of 30-50%) and was encountered approximately at the same frequency as in the previous period. The lack of B vitamins in the adult population was still much more common than the deficiency of vitamins A, E and C. The incidence of the combined deficiency of three or more vitamins (including, in addition to vitamins C, A, E, B2 and β-carotene, vitamins D, В6, В12, folates) currently ranged from 5 to 39%. In this same range was the frequency of observation of persons sufficiently supplied with all studied vitamins. To improve the vitamin supply of the population, the urgent need for legislative consolidation and/or adoption of normative acts regulating compulsory enrichment of food products of mass consumption (bread and milk) with vitamins D and B group has arisen.

Study on the relationship between age and the concentrations of heavy metal elements in human bone

Background

Excessive amounts of heavy metals such as cadmium, chromium, cobalt, lead, thallium, and manganese are extremely harmful to the human body. These elements can accumulate in bone and impact bone metabolism. In this study, we investigated the relationship between age and the concentrations of these elements in human bone and blood.

Methods

Bone and blood samples were obtained from both older and younger patients. The concentrations of the elements under investigation were measured by inductively coupled plasma mass spectrometry (ICP-MS), and the specific concentrations in the bone and blood were then calculated.

Results

The results showed that with increasing age, the concentrations of chromium, cobalt, and thallium in bone decreased significantly, while the concentration of cadmium in bone markedly increased. However, there was no clear correlation between age and the concentrations of these heavy metals in blood. Notably, there was a close correlation between the concentration of cobalt in bone and the presence of osteopenia.

Conclusions

Senescence of the human body is accompanied by the shifting of cobalt, chromium, and thallium from the bone to the outer- bone. However, the concentration of cadmium in bone increases with age. These changes are very likely to be related to the equilibrium of bone metabolism in senescent individuals. In addition, only cobalt was shown to be significantly related to osteopenia.

Effect of One-Lung Ventilation on Blood Sevoflurane and Desflurane Concentrations

OBJECTIVE

To determine the blood sevoflurane and desflurane concentrations during one-lung ventilation (OLV).

DESIGN

Randomized, single-blind study.

SETTING

Single university hospital.

PARTICIPANTS

The study comprised 24 patients, 35 to 70 years old who were scheduled for either a major abdominal surgery or thoracotomy.

INTERVENTIONS

The patients were divided into the following 4 groups: sevoflurane two-lung ventilation (TLV), sevoflurane OLV, desflurane TLV, and desflurane OLV. Vaporizers were set at 1.5% sevoflurane or 6% desflurane.

MEASUREMENTS AND MAIN RESULTS

In the TLV groups, blood samples were taken in 10-minute intervals starting 40 minutes after the start of TLV (T₁-T₉) for blood gas analysis and gas chromatography. In the OLV groups, the first sample was collected at 40 minutes of TLV (T₁), and other samples were collected in 10-minute intervals from the start of OLV (T₂-T₉). Saturation of peripheral oxygen (SpO₂), hemodynamic variables, and inspired and end-tidal volatiles were recorded. The fraction uptake of the volatile agents (F) was calculated for each patient at the same time points. The mean arterial sevoflurane concentration in the sevoflurane OLV group at T₁ decreased from 40.7 ± 4.4 to 30.2 ± 2.5 µg/mL at T₃ (p = 0.014, 26% decrease). In the OLV desflurane group, the mean arterial desflurane concentration at T₁ declined from 224.6 ± 44.8 to 159.8 ± 32 µg/mL at T₃ (p=0.018, 29% decrease). However, the reduction of sevoflurane concentration compared with that of desflurane at T₃ was not statistically significant (p = 0.31). In addition, the fraction uptake of the volatile agents values significantly increased at the start of OLV (p = 0.001).

CONCLUSION

An OLV procedure causes a decrease in the both arterial and venous blood concentrations of sevoflurane and desflurane. This reduction is believed to be due to ventilation-perfusion mismatch.

Reflectance spectroscopy: to shed new light on the capillary refill test

To use Bioengineering methodology is used to achieve, at five anatomical sites, a detailed, quantitative assessment of the return of blood content to the blanched area, during the Capillary Refill (CR) test. An observational, non-randomized, experimental study on 23 healthy subjects (14 females) was performed in our climate controlled skin physiology laboratory. Our main outcome measures were based on the chronological assessment and quantification of red blood cell concentration (RBC) after the release of blanching pressure in the CR test, using Tissue Viability Imaging (TiVi), a digital photographic technique based on polarisation spectroscopy. TiVi enabled collection of detailed data on skin RBC concentration during the CR test. The results were shown as curves with skin blood concentration (TiVi-value) on the y-axis and the time on the x-axis. Quantitative CR responses showed site and temperature variability. We also suggest possible objective endpoint values from the capillary refill curve. Detailed data on skin RBC concentration during the CR test is easily obtained and allows objective determination of end points not possible to achieve by naked eye assessment. These findings have the potential to place the utility of the CR test in a clinical setting in a new light. Picture: Regular photograph and TiVi Image showing CR test and corresponding graph for the CR response.

Biological monitoring of dermal and air exposure to cobalt at a Swedish hard metal production plant: does dermal exposure contribute to uptake?

BACKGROUND

Occupational exposure to cobalt is well established in hard metal manufacture. Cobalt is known to cause contact allergy, asthma, hard metal lung disease, and lung cancer. The relationship between skin exposure and uptake determined in blood has not been extensively investigated.

OBJECTIVE

To examine whether skin and inhalable air exposure to cobalt contributes to uptake, determined as cobalt in blood, in a hard metal manufacturing factory.

METHODS

The amount of cobalt on the skin found with an acid wash technique, the air concentrations of inhalable cobalt and cobalt blood concentrations were determined and correlated in exposed workers.

RESULTS

We found a significant rank correlation for cobalt concentrations on the skin, in inhalable air, and in blood (0.376-0.498). Multiple linear regression showed significant regression coefficients for cobalt skin exposure and blood (B = 0.01, p < 0.05) and for inhalable cobalt in air and blood (B = 49.1, p < 0.001). According to our model based on data from the regression analyses, a twofold increase in skin exposure levels at different air concentrations caused a 3-14% increase in blood levels.

CONCLUSIONS

Our data suggest that skin exposure to cobalt in the hard metal industry could affect the total uptake at the same order of magnitude as air exposure.

[Correlation of blood concentration of tacrolimus with serum cystatin C in renal transplant recipients and effect of tacrolimus on glucose and lipid metabolism]

OBJECTIVE

To investigate the correlation between blood concentrations of tacrolimus (FK506) and cystatin C (Cys C) and the effect of FK506 on glycolipid metabolism in renal transplant recipients.

METHODS

A total of 325 patients receiving renal transplantation between August, 2014 and September, 2015 in Nanfang Hospital were divided into 4 groups according to the postoperative time (1 month group, 1-3 months group, 4-6 months group, and 7-12 months group). FK506 blood trough concentration was measured at the time of postoperative follow-up, and creatinine (Scr) and Cys C levels were also detected. Results Plasma FK506 concentration decreased with age in the recipients and showed a positive correlation with Cys C (r=0.985, P=0.015) but no obvious correlation with Scr (r=0.259, P=0.741). FK506 had no effect on blood glucose (5.53-5.59 mmol<L) or blood lipids (TG 1.47-1.55 mmol<L, TC 5.04-5.17 mmol<L, LDL-C 3.00-3.07 mmol<L, and VLDL 0.73-0.76 mmol<L) in patients 1-6 months after renal transplantation.

CONCLUSION

FK506 does not affect the level of glycolipid metabolism in patients after renal transplantation. Cys C is positively related to blood concentration of FK506 in the renal transplantation recipients. The rational use of FK506 can improve the effectiveness and safety of the treatment in the recipients.

Genetic Variations Associated with Vitamin A Status and Vitamin A Bioavailability

Blood concentration of vitamin A (VA), which is present as different molecules, i.e., mainly retinol and provitamin A carotenoids, plus retinyl esters in the postprandial period after a VA-containing meal, is affected by numerous factors: dietary VA intake, VA absorption efficiency, efficiency of provitamin A carotenoid conversion to VA, VA tissue uptake, etc. Most of these factors are in turn modulated by genetic variations in genes encoding proteins involved in VA metabolism. Genome-wide association studies (GWAS) and candidate gene association studies have identified single nucleotide polymorphisms (SNPs) associated with blood concentrations of retinol and β-carotene, as well as with β-carotene bioavailability. These genetic variations likely explain, at least in part, interindividual variability in VA status and in VA bioavailability. However, much work remains to be done to identify all of the SNPs involved in VA status and bioavailability and to assess the possible involvement of other kinds of genetic variations, e.g., copy number variants and insertions/deletions, in these phenotypes. Yet, the potential usefulness of this area of research is exciting regarding the proposition of more personalized dietary recommendations in VA, particularly in populations at risk of VA deficiency.

Pharmacology of Chloroquine and Hydroxychloroquine

The 4-aminoquinolines are weak bases that are completely absorbed from the gastrointestinal tract, sequestered in peripheral tissues, metabolized in the liver to pharmacologically active by-products, and excreted via the kidneys and the feces. The parent drugs and metabolites are excreted with a half-life of elimination of approximately 40 days. However, slow release from sequestered stores of the drugs means that after discontinuation, they continue to be released into the plasma for years. Correct dosing is based on the ideal body weight of the patient, which depends on height. The 4AQs diminish autoimmunity without compromising immunity to infections.

Estimation of minimum whole-blood tacrolimus concentration for therapeutic drug monitoring with plasma prednisolone concentration: A retrospective cohort study in Japanese kidney transplant recipients

BACKGROUND

In immunosuppressive therapy administered after organ transplantation, therapeutic drug monitoring (TDM) of tacrolimus must be performed frequently because of the large variation in its pharmacokinetic properties and a progressive decrease in dose requirements. An indicator for estimating the target minimum whole-blood tacrolimus concentration (Cmin TAC) would be useful to minimize the number of blood samplings required for tacrolimus TDM.

OBJECTIVES

The primary objective of this study was to investigate whether plasma prednisolone concentration, postoperative days (POD) and AUC 0 to 9 hours before transplantation (AUC0-9int) are useful indicators of tacrolimus TDM. The secondary objective was to determine the usefulness of blood tacrolimus concentration as an indicator of the development of nontraumatic, glucocorticoid-induced necrosis of the femoral head, an adverse event that has been associated with the use of prednisolone in vivo.

METHODS

This open-label, nonrandomized, retrospective study was conducted at the Department of Transplantation and Regenerative Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan. Data from 43 male and 22 female patients (mean age, 38 years [range, 9-64 years]) who received a living-related kidney transplant from 2001 to 2004 were included. Multiple blood samplings were performed to determine AUC0-9int, AUC 0 to 9 hours after drug administration and after transplantation (AUC0-9), Cmin TAC, Cmax, and Tmax after transplantation. The correlations between each parameter were determined. The correlation between POD and the changes in tacrolimus bioavailability was investigated using the indicator, defined as the tacrolimus dose required to maintain the target (10-15 ng/mL) Cmin TAC (dose/C10-15). Correlations between dose/C10-15 and AUC0-9int (3 AUC0-9int groups, defined as follows: low, medium, and high [<93, ≧93-≤152, and ≧152 ng·h/mL, respectively]) were determined. Correlations between mean Cmin values of prednisolone at a dose of 40 mg on PODs 4 to 11 (Cmin PSL40) and Cmin TAC, or AUC0-9int were determined. A subanalysis was used to determine the relationship between dose/C10-15 and the prevalence of nontraumatic, glucocorticoid-induced necrosis of the femoral head.

RESULTS

Cmin TAC was found to be significantly correlated with AUC0-9int (r=0.554; P<0.001) and Cmin PSL40 (r=0.336; P<0.001). In the low-AUC0-9int group, dose/C10-15 was higher than that of the other groups (P<0.001). AUC0-9int was significantly correlated with Cmin PSL40 (r=0.445; P<0.001)). Dose/C10-15 in the patient group that had necrosis of the femoral head was lower than that of the group without necrosis (n=6; P<0.01).

CONCLUSIONS

The results of this small, retrospective study suggest that Cmin PSL40, AUC0-9int, and POD were significant predictors of Cmin TAC. These parameters were found to be a useful indicator of tacrolimus TDM in these Japanese transplant recipients. Our results also suggest that dose/C10-15 and AUC0-9int might be useful indicators for estimating the risk for nontraumatic, steroid-induced necrosis of the femoral head. (Curr Ther Res Clin Exp. 2006;67: 103-117) Copyright © 2006 Excerpta Medica, Inc.

Inhalation exposure to 1,2-dichloropropane: Distribution of blood and tissue concentrations of 1,2-dichloropropane in rats during and after exposure

The present investigation was undertaken to determine the distribution and accumulation of 1,2-dichloropropane (DCP) in the blood, lung, liver, kidney, and abdominal fat of rats during and after inhalation exposure. Male rats were exposed to 80 or 500 ppm (v/v) DCP vapor for 360 min and the concentrations of DCP in the blood and tissues during the inhalation exposure period and after the end of the exposure period were measured. DCP accumulation in the abdominal fat was much greater than that in the blood and other tissues. Eighteen hours after the end of inhalation exposure, DCP could still be detected in the abdominal fat in the 80-ppm group, and in the blood, liver, kidney, and abdominal fat in the 500-ppm group. Our results are valuable data pertaining to the pharmacokinetics of DCP and to human health risk assessment of exposure to DCP vapor by inhalation.

Simultaneous determination of methanol, acetaldehyde, acetone, and ethanol in human blood by gas chromatography with flame ionization detection

BACKGROUND

Methanol, acetaldehyde, acetone, and ethanol, which are commonly used as biomarkers of several diseases, in acute intoxications, and forensic settings, can be detected and quantified in biological fluids. Gas chromatography (GC)-mass spectrometry techniques are complex, require highly trained personnel and expensive materials. Gas chromatographic determinations of ethanol, methanol, and acetone have been reported in one study with suboptimal accuracy. Our objective was to improve the assessment of these compounds in human blood using GC with flame ionization detection.

METHODS

An amount of 50 µl of blood was diluted with 300 µl of sterile water, 40 µl of 10% sodium tungstate, and 20 µl of 1% sulphuric acid. After centrifugation, 1 µl of the supernatant was injected into the gas chromatograph. We used a dimethylpolysiloxane capillary column of 30 m × 0.25 mm × 0.25 µm.

RESULTS

We observed linear correlations from 7.5 to 240 mg/l for methanol, acetaldehyde, and acetone and from 75 to 2400 mg/l for ethanol. Precision at concentrations 15, 60, and 120 mg/l for methanol, acetaldehyde, and acetone and 150, 600, and 1200 mg/ml for ethanol were 0.8-6.9%. Ranges of accuracy were 94.7-98.9% for methanol, 91.2-97.4% for acetaldehyde, 96.1-98.7% for acetone, and 105.5-111.6% for ethanol. Limits of detection were 0.80 mg/l for methanol, 0.61 mg/l for acetaldehyde, 0.58 mg/l for acetone, and 0.53 mg/l for ethanol.

CONCLUSION

This method is suitable for routine clinical and forensic practices.

Pharmacokinetics of Ethanol - Issues of Forensic Importance

A reliable method for the quantitative analysis of ethanol in microvolumes (50-100 μL) of blood became available in 1922, making it possible to investigate the absorption, distribution, metabolism, and excretion (ADME) of ethanol in healthy volunteers. The basic principles of ethanol pharmacokinetics were established in the 1930s, including the notion of zero-order elimination kinetics from blood and distribution of the absorbed dose into the total body water. The hepatic enzyme alcohol dehydrogenase (ADH) is primarily responsible for the oxidative metabolism of ethanol. This enzyme was purified and characterized in the early 1950s and shown to have a low Michaelis constant (km), being about ~0.1 g/L. Liver ADH is therefore saturated with substrate after the first couple of drinks and for all practical purposes the concentration-time (C-T) profiles of ethanol are a good approximation to zero-order kinetics. However, because of dose-dependent saturation kinetics, the entire postabsorptive declining part of the blood-alcohol concentration (BAC) curve looks more like a hockey stick rather than a straight line. A faster rate of ethanol elimination from blood in habituated individuals (alcoholics) is explained by participation of a high km microsomal enzyme (CYP2E1), which is inducible after a period of chronic heavy drinking. Owing to the combined influences of genetic and environmental factors, one expects a roughly threefold difference in elimination rates of ethanol from blood (0.1-0.3 g/L/h) between individuals. The volume of distribution (Vd) of ethanol, which depends on a person's age, gender, and proportion of fat to lean body mass, shows a twofold variation between individuals (0.4-0.8 L/kg). This forensic science review traces the development of forensic pharmacokinetics of ethanol from a historical perspective, followed by a discussion of important issues related to the disposition and fate of ethanol in the body, including (a) quantitative evaluation of blood-alcohol curves and the factors influencing the peak concentration in blood (Cmax) and the time of its occurrence (tmax), (b) biological variations in the ADME of ethanol, including the apparent volume of distribution (Vd or rho), the disappearance rate from blood (β or k0), and the disposal rate by the entire body in 1 h (B60), and (c) questions about ADME of ethanol often arising during the prosecuting of accused drunken drivers.