mRNA expression levels of cytochrome P450 CYP1A2, CYP3A4, and CYP3A5 in the epidermis: a focus on individual differences among Japanese individuals.

Various cytochrome P450 enzymes (CYPs) that contribute to drug metabolism are expressed in the skin. However, variation among individuals in CYP expression profiles is not well-understood.To investigate CYPs related to the metabolism of transdermal preparations in Japan, multiple skin tissue specimens of individuals of Japanese descent were prepared, and the mRNA expression levels of CYP1A2, CYP3A4, and CYP3A5 were measured. Associations between the expression patterns of these CYPs and body mass index (BMI) were also investigated.There were considerable individual differences in epidermal CYP1A2 mRNA expression levels, and CYP1A2 showed a weak positive correlation with CYP3A4 mRNA expression levels. In contrast to previous results for other organs, epidermal CYP3A4 mRNA expression levels showed a weak positive correlation with BMI.CYP3A4 in the epidermis may have been locally enhanced as a defence mechanism against xenobiotics in response to impaired barrier function. These differences in mRNA expression in the skin may affect the transdermal absorption of drugs, such as lidocaine and fentanyl, which are metabolised by multiple overlapping CYPs.Our study provides new insights into drug metabolism in the skin. These results are valuable for predicting drug effects and transdermal drug transfer rates in Japanese patients.

Sodium citrate buffer improves pazopanib solubility and absorption in gastric acid-suppressed rat model.

Pazopanib exhibits pH-dependent solubility and its absorption depends primarily on the stomach pH. Significant decrease of pazopanib absorption by coadministration with proton pump inhibitors in clinical situation need to be overcome. Thus, the purpose of this study is firstly to investigate the effect of acidic beverages and sodium citrate buffer on the solubility of pazopanib and secondly to examine the effect of sodium citrate buffer on pazopanib absorption in a rat model with esomeprazole-mediated gastric acid suppression. Pazopanib solubility decreased with increasing pH of sodium citrate buffer in vitro. Interestingly, its solubility in some acidic beverages was significantly lower than that in sodium citrate buffer of the same pH. The AUC0-24h of pazopanib administered in tap water to rats treated with esomeprazole (ESP rats) was 66 % lower than that in the control rats treated with saline. However, AUC0-24h was 4.8 times higher in ESP rats that received pazopanib with sodium citrate buffer (pH 2.3) compared to ESP rats that received pazopanib with tap water. Our results indicate that the drug-drug interactions between pazopanib and proton pump inhibitors can be overcome, at least in part, by suspending pazopanib in sodium citrate buffer.

Validation of an automated sample preparation module directly connected to LC-MS/MS (CLAM-LC-MS/MS system) and comparison with conventional immunoassays for quantitation of tacrolimus and cyclosporin A in a clinical setting.

BACKGROUND: Therapeutic drug monitoring (TDM) systems generally use either liquid chromatography/tandem mass spectrometry (LC-MS/MS) or immunoassay, though both methodologies have disadvantages. In this study, we aimed to evaluate whether a CLAM-LC-MS/MS system, which consists of a sample preparation module directly connected to LC-MS/MS, could be used for clinical TDM work for immunosuppressive drugs in whole blood, which requires a hemolytic process. For this purpose, we prospectively validated this system for clinical measurement of tacrolimus and cyclosporin A in patients' whole blood. The results were also compared with those of commercial immunoassays. METHODS: Whole blood from patients treated with tacrolimus or cyclosporin A at the Department of Nephrology and Departments of Rheumatology, Kanazawa University Hospital, from May 2018 to July 2019 was collected with informed consent, and drug concentrations were measured by CLAM-LC-MS/MS and by chemiluminescence immunoassay (CLIA) for tacrolimus and affinity column-mediated immunoassay (ACMIA) for cyclosporin A. Correlations between the CLAM-LC-MS/MS and immunoassay results were analyzed. RESULTS: Two hundred and twenty-four blood samples from 80 patients were used for tacrolimus measurement, and 76 samples from 21 patients were used for cyclosporin A. Intra- and inter-assay precision values of quality controls were less than 7%. There were significant correlations between CLAM-LC-MS/MS and the immunoassays for tacrolimus and cyclosporin A (Spearman rank correlation coefficients: 0.861, 0.941, P < 0.00001 in each case). The drug concentrations measured by CLAM-LC-MS/MS were about 20% lower than those obtained using the immunoassays. CLAM-LC-MS/MS maintenance requirements did not interfere with clinical operations. Compared to manual pretreatment, automated pretreatment by CLAM showed lower inter-assay precision values and greatly reduced the pretreatment time. CONCLUSIONS: The results obtained by CLAM-LC-MS/MS were highly correlated with those of commercial immunoassay methods. CLAM-LC-MS/MS offers advantages in clinical TDM practice, including simple, automatic pretreatment, low maintenance requirement, and avoidance of interference.

Application Site of Transdermal Scopolamine Influences Efficacy and Drug Concentration in Salivary Glands in Rats.

Transdermal scopolamine applied to the postauricular area is used to treat drooling. We investigated the duration of action of scopolamine ointment and the effect of the application site on drug efficacy and concentration in the salivary glands of rats. Scopolamine ointment was applied to the skin over the salivary glands (SSG) and back (SB). Saliva volume was measured after intraperitoneal administration of pilocarpine. Blood and salivary glands were collected after scopolamine ointment application, and scopolamine concentrations in the plasma and salivary glands were measured. Saliva volume after application in the SSG group was significantly lower at all time points than in the non-treated group, and the change in saliva volume in the SSG group was greater than that in the SB group at all time points. This suggests that applying scopolamine ointment to the SSG strongly suppresses salivary secretion. Scopolamine concentration in the salivary glands of the SSG group was significantly higher at 9 h. The change in the efficacy of scopolamine ointment depending on the application site was due to the difference in transfer to the salivary glands. Transdermal administration of scopolamine to the skin over the salivary glands may have high efficiency in treating drooling.

Association between switching prescribed drugs for lower urinary tract symptoms and independence of urination in post-stroke patients: A retrospective cohort study.

OBJECTIVES: Stroke patients frequently exhibit loss of independence of urination, and their lower urinary tract symptoms change with the phase of stroke. However, it is unclear whether switching prescribed drugs for lower urinary tract symptoms during hospitalization from acute care wards to convalescence rehabilitation wards affects patients' independence of urination at discharge. It is also unclear whether the impact of switching varies by stroke type. This retrospective cohort study aimed to examine these issues. MATERIALS AND METHODS: We analyzed 990 patients registered in the Kaga Regional Cooperation Clinical Pathway for Stroke database during 2015-2019. Prescriptions for lower urinary tract symptoms from pre-onset to convalescence rehabilitation were surveyed. Logistic regression analysis was performed to examine the association between switching drugs and independence of urination based on bladder management and voiding location at discharge. Stroke types were also examined in subgroup analyses. RESULTS: About 21 % of patients had their lower urinary tract symptoms prescriptions switched during hospitalization. Switching was positively associated with independence of bladder management (odds ratio 1.65, 95 % confidence interval 1.07 to 2.49) and voiding location (odds ratio 2.72, 95 % confidence interval 1.72 to 4.37). Similar associations were observed in different stroke types. CONCLUSIONS: Approximately 20 % of patients had their lower urinary tract symptoms medications switched upon transfer from acute to convalescence rehabilitation wards. Switching was significantly associated with improved urinary independence at discharge. Consistent results were observed across different stroke types, suggesting that switching medications contributes to urinary independence after stroke, regardless of the etiology or severity of stroke.

Oxidation of Naringenin, Apigenin, and Genistein by Human Family 1 Cytochrome P450 Enzymes and Comparison of Interaction of Apigenin with Human P450 1B1.1 and Scutellaria P450 82D.1.

Naringenin, an initial synthesized flavanone in various plant species, is further utilized for production of many biologically active flavonoids, e.g., apigenin, eriodictyol, and genistein, by various plant enzymes including cytochrome P450s (P450s or CYPs). We examined how these flavonoids are oxidized by human P450 family 1 and 2A enzymes. Naringenin was principally oxidized at the 3'-position to form eriodictyol by CYP1 enzymes more efficiently than by CYP2A enzymes, and the resulting eriodictyol was further oxidized to two penta-hydroxylated products. In contrast to plant P450 enzymes, these human P450s did not mediate the desaturation of naringenin and eriodictyol to give apigenin and luteolin, respectively. Apigenin was oxidized at the C3' and C6 positions to form luteolin and scutellarein by these P450s. CYP1B1.1 and 1B1.3 had high activities in apigenin 6-hydroxylation with a homotropic cooperative manner, as has been observed previously in chrysin 6-hydroxylation (Nagayoshi et al., Chem. Res. Toxicol. 2019, 32, 1268-1280). Molecular docking analysis suggested that CYP1B1 had two apigenin binding sites and showed similarities in substrate recognition sites to plant CYP82D.1, one of the enzymes in catalyzing apigenin and chrysin 6-hydroxylations in Scutellaria baicalensis. The present results suggest that human CYP1 enzymes and CYP2A13 in some reactions have important roles in the oxidation of naringenin, eriodictyol, apigenin, and genistein and that human CYP1B1 and Scutellaria CYP82D.1 have similarities in their SRS regions, catalyzing 6-hydroxylation of both apigenin and chrysin.

Case report: therapeutic monitoring of vancomycin in an acute liver failure patient with anuria under high-flow continuous hemodiafiltration.

BACKGROUND: High-flow continuous hemodiafiltration (HF-CHDF) combines diffusive and convective solute removal and is employed for artificial liver adjuvant therapy. However, there is no report on dosage planning of vancomycin (VCM) in patients with acute liver failure under HF-CHDF. CASE PRESENTATION: A 20-year-old woman (154 cm tall, weighing 50 kg) was transferred to the intensive care unit (ICU) with acute liver failure associated with autoimmune liver disease. On the following day, HF-CHDF was started due to elevated plasma ammonia concentration. On ICU day 8, VCM was started for suspected pneumonia and meningitis (30 mg/kg loading dose, then 20 mg/kg every 12 hrs). However, on ICU day 10, VCM blood concentration was under the limit of detection (< 3.0 µg/mL) and the patient developed anuria. The VCM dose was increased to 20 mg/kg every 6 hrs. Calculation with a one-compartment model using the HF-CHDF blood flow rate as a surrogate for VCM clearance, together with hematocrit and protein binding ratio, predicted a trough VCM blood concentration of 15 µg/mL. The observed concentration was about 12 µg/mL. The difference may represent non-HF-CHDF clearance. Finally, living donor liver transplantation was performed. CONCLUSION: We report an acute liver failure patient with anuria under HF-CHDF in whom VCM administration failed to produce an effective blood concentration, likely due to HF-CHDF-enhanced clearance. VCM dosage adjustment proved successful, and was confirmed by calculation using a one-compartment model.

Evaluation of factors affecting epidermal growth factor receptor tyrosine kinase inhibitor-induced hepatotoxicity in Japanese patients with non-small cell lung cancer: a two-center retrospective study.

BACKGROUND: Gefitinib and erlotinib, are epidermal growth factor receptor tyrosine kinase inhibitors, and are currently recommended for non-small cell lung cancer stage IV in the elderly and in patients with decreased performance status in the Japanese Lung Cancer Society Guideline, but they occasionally caused severe hepatotoxicity requiring postponement or modification of treatment. However, little is known about the risk factors for hepatotoxicity in patients receiving gefitinib and erlotinib. In this study, we investigated the factors influencing hepatotoxicity in Japanese non-small cell lung cancer (NSCLC) patients treated with gefitinib or erlotinib monotherapy. METHODS: Japanese patients with NSCLC who started gefitinib or erlotinib monotherapy from January 2005 to December 2017 at Kanazawa University Hospital or Kanazawa Medical University Hospital were included in this study. Factors affecting hepatotoxicity were retrospectively investigated by multiple logistic regression analysis. RESULTS: A total of 102 patients who received gefitinib and 95 patients who received erlotinib were included in the analysis. In the gefitinib group, a body mass index (BMI) ≥ 25 was associated with an increased risk of hepatotoxicity (OR = 4.571, 95% CI = 1.486-14.056, P = 0.008). In the erlotinib group, concomitant use of acid-suppressing medications (AS), namely proton pump inhibitors or histamine-2 receptor antagonists, was associated with a reduced risk of hepatotoxicity (OR = 0.341, 95% CI = 0.129-0.900, P = 0.030). CONCLUSIONS: BMI ≥ 25 in patients treated with gefitinib increased the risk of hepatotoxicity. In contrast, AS combination with erlotinib reduced the risk of hepatotoxicity. Thus, because different factors influence the risk of hepatotoxicity, monitoring for adverse events should take into account patient background factors and concomitant medications.

Ceftriaxone-induced encephalopathy in a patient with a solitary kidney.

Ceftriaxone (CRO) is a long-acting third-generation cephalosporin antibiotic. We present a case of CRO-induced encephalopathy in an 84-year-old male patient with a solitary right kidney, admitted with bilateral pneumonia and right pyelonephritis. Intravenous CRO (2 g, every 24 hours) was started for the infection, but tonic-clonic seizures of the left face and left upper extremity appeared on the eighth day. To examine the relationship between CRO administration and the seizures, we measured CRO concentrations in the patients' plasma/serum and cerebrospinal fluid. The CRO concentration in blood at the onset of encephalopathy was estimated to have been approximately 60 µg/ml based on a simulation curve. We also calculated the pharmacokinetic parameters after CRO administration. The patient had about one-tenth of the total body clearance and one-third of the volume of distribution compared with healthy adults, and the elimination half-life was about three times longer.

Relationship between Bowel/Bladder Function and Discharge in Older Stroke Patients in Convalescent Rehabilitation Wards: A Retrospective Cohort Study.

Objectives: : Many stroke patients experience motor and cognitive dysfunctions that make living at home challenging. We aimed to identify the factors associated with hospital discharge to home in older stroke patients in convalescent rehabilitation wards where intensive and comprehensive inpatient rehabilitation are performed following acute-phase treatment. Methods: : A retrospective cohort study was conducted among 1227 older stroke patients registered in the database of the Council of Kaga Local Stroke Network, Japan, between 2015 and 2019. Patients' basic characteristics, discharge destination, type and severity of stroke, cognitive status, and activities of daily living (ADL) including continence were evaluated. Results: : The proportion of subjects discharged to home was 62.3%. The mean hospital stay in the home discharge group was shorter than that in the non-home discharge group (111 days vs. 144.6 days, P <0.001). The following factors were associated with discharge to home: age (adjusted odds ratio [AOR]: 2.801, 95% confidence interval [CI] [1.473, 2.940]; P <0.001), sex (AOR: 1.513, 95% CI [1.112, 2.059]), stroke type (AOR: 1.426, 95% CI [1.013, 2.007]), low cognitive status (AOR: 3.750, 95% CI [2.615, 5.379]), low level of bladder control (AOR: 2.056, 95% CI [1.223, 3.454]), and low level of bowel control (AOR: 2.823, 95% CI [1.688, 4.722]). Conclusions: : Age, sex, stroke type, cognitive function, and ADL scores for bladder and bowel control were associated with discharge to home. Improving continence management regarding both voiding and defecation may be a promising care strategy to promote hospital discharge to home in older stroke patients.

Oxidation of 3'-methoxyflavone, 4'-methoxyflavone, and 3',4'-dimethoxyflavone and their derivatives having 5,7-dihydroxyl moieties by human cytochromes P450 1B1 and 2A13.

Oxidation of 3'-methoxyflavone, 4'-methoxyflavone, and 3',4'-dimethoxyflavone and their derivatives containing 5,7-dihydroxyl groups by human cytochrome P450 (P450 or CYP) 1B1 and 2A13 was determined using LC-MS/MS systems.3'-Methoxyflavone and 4'-methoxyflavone were mainly O-demethylated to form 3'-hydroxyflavone and 4'-hydroxyflavone, respectively, and then 3',4'-dihydroxyflavone at higher rates with CYP1B1 than with CYP2A13. 4'-Methoxy-5,7-dihydroxyflavone (acacetin) was found to be demethylated by CYP1B1 and 2A13 to form 4',5,7-trihydroxyflavone (apigenin) at rates of 0.098-1 and 0.42 min-1, respectively. 3'-Methoxy-5,7-dihydroxyflavone was also demethylated by both P450s, with CYP2A13 being more active.3',4'-Dimethoxyflavone was a good substrate for CYP1B1 but not for CYP2A13 and was found to be mainly O-demethylated to form 3',4'-dihydroxyflavone (at a rate of 4.2 min-1) and also several ring-oxygenated products having m/z 299 fragments. Molecular docking analysis supported the proper orientation for formation of these products by CYP1B1.Our present results showed that 3'- and 4'-methoxyflavone can be oxidised to their O-demethylated products and, to a lesser extent, to ring oxidation products by both P450s 1B1 and 2A13 and that 3',4'-dimethoxyflavone is a good substrate for CYP1B1 in forming both O-demethylated and ring-oxidation products. Introduction of a 57diOHF moiety into these methoxylated flavonoids caused decreased in oxidation by CYP1B1 and 2A13.

Association of a continuous continence self-management program with independence in voiding behavior among stroke patients: A retrospective cohort study.

AIMS: Many stroke patients cannot urinate independently due to motor and cognitive dysfunctions. This study examined whether a continuous continence self-management program during acute and convalescent phases is associated with independence in voiding behavior. METHODS: A retrospective cohort study was conducted among stroke patients registered in the Council of Kaga Local Stroke Network, Japan, from 2015 to 2019. In the intervention group (n = 941), a multidisciplinary continence care team and ward nurses provided continence care in the acute phase and shared the information with the staff in the convalescent ward. The control group (n = 579) received traditional voiding care from ward nurses. The primary and secondary outcomes were independence in voiding behavior at discharge from the convalescent ward and length of hospital stay, respectively. RESULTS: At discharge from the convalescent wards, the proportion of patients who voided at the toilet or bedside commode was higher in the intervention group than in the control group (76.3% vs. 62.4%, p < 0.001). The continuous continence self-management program was associated with independence in voiding behavior (adjusted odds ratio: 1.801, 95% confidence interval [CI]: [1.102, 2.942]; p = 0.019) and length of hospital stay (ß: -0.178, 95% CI: [-14.320, -7.607]; p < 0.001) after adjusting for other variables. CONCLUSIONS: The program was associated with increasing independent voiding behavior and shortened the length of hospital stay, suggesting the importance of promoting treatments for lower urinary tract symptoms and rehabilitation by a multidisciplinary continence care team for stroke patients.

Risk factors for interstitial lung disease induced by gemcitabine plus albumin-bound paclitaxel therapy in pancreatic ductal adenocarcinoma patients.

BACKGROUND: Gemcitabine plus nab-paclitaxel (GnP) therapy is used for unresectable pancreatic ductal adenocarcinoma, but may cause interstitial lung disease (ILD) as a serious side effect. However, the risk factors for ILD in patients receiving GnP therapy are not well established. Here, we retrospectively investigated the incidence of GnP-induced ILD in pancreatic ductal adenocarcinoma patients, and the risk factors. METHODS: We investigated the patients' background, laboratory data, previous treatment history, concomitant medications, number of doses of GnP, cumulative dosage and administration period, and occurrence of side effects. RESULTS: Of the 105 patients included in this study, ILD occurred in 10 (9.5%). Patients with ILD had a significantly higher frequency of concomitant treatment with Kampo medicines, especially goshajinkigan, which is considered to help prevent chemotherapy-induced peripheral neuropathy (CIPN) (odds ratio: 11.5, 95% confidence interval: 2.67-49.38). No significant differences were observed in other clinical characteristics. Notably, the severity of CIPN in patients who used goshajinkigan for prevention was not significantly different from that in patients who did not use goshajinkigan in this study. CONCLUSIONS: These results suggest that administration of goshajinkigan to patients receiving GnP therapy for prevention of CIPN may need to be reconsidered.

Limited Impact of Murine Placental MDR1 on Fetal Exposure of Certain Drugs Explained by Bypass Transfer Between Adjacent Syncytiotrophoblast Layers.

PURPOSE: Multidrug resistance protein 1 (MDR1) is located at the interface between two syncytiotrophoblast layers in rodent placenta, and may influence fetal drug distribution. Here, we quantitatively compare the functional impact per single MDR1 molecule of MDR1 at the placental barrier and blood-brain barrier in mice. METHODS: MDR1A and MDR1B proteins were quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Paclitaxel or digoxin was continuously administered to pregnant Mdr1a-/-/Mdr1b-/- or wild-type mice, and the drug concentrations in the maternal and fetal plasma and maternal brain were quantified by LC-MS/MS. RESULTS: MDR1A and MDR1B proteins are expressed in the membrane of mouse placental labyrinth, and total MDR1 at the placental barrier amounts to about 30% of that at the blood-brain barrier. The fetal-to-maternal plasma concentration ratio of digoxin was only marginally affected in Mdr1a-/-/Mdr1b-/- mice, while that of paclitaxel showed a several-fold increase. No such difference between the two drugs was found in the maternal brain distribution. The impact per single MDR1 molecule on the fetal distribution of digoxin was calculated to be much lower than that on the brain distribution, but this was not the case for paclitaxel. Our pharmacokinetic model indicates that the impact of placental MDR1 is inversely correlated to the ratio of permeability through gap junctions connecting the two syncytiotrophoblast layers to passive diffusion permeability. CONCLUSION: Our findings indicate that murine placental MDR1 has a minimal influence on the fetal concentration of certain substrates, such as digoxin, due to bypass transfer, probably via connexin26 gap junctions.

Roles of cytochrome P450 2A6 in the oxidation of flavone, 4'-hydroxyflavone, and 4'-, 3'-, and 2'-methoxyflavones by human liver microsomes.

Nine forms of recombinant cytochrome P450 (P450 or CYP) enzymes were used to study roles of individual P450 enzymes in the oxidation of flavone and some other flavonoids, 4'-hydroxyflavone and 4'-, 3'-, and 2'-methoxyflavones, by human liver microsomes using LC-MS/MS analysis.As has been reported previously , 4'-, 3'-, and 2'-methoxyflavones were preferentially O-demethylated by human liver P450 enzymes to form 4'-, 3'-, and 2'-hydroxylated flavones and also 3',4'-dihydroxyflavone from the former two substrates.In comparisons of product formation by oxidation of these methoxylated flavones, CYP2A6 was found to be a major enzyme catalysing flavone 4'- and 3'-hydroxylations by human liver microsomes but did not play significant roles in 2'-hydroxylation of flavone, O-demethylations of three methoxylated flavones, and the oxidation of 4'-hydroxyflavone to 3',4'-dihydroxyflavone.The effects of anti-CYP2A6 IgG and chemical P450 inhibitors suggested that different P450 enzymes, as well as CYP2A6, catalysed oxidation of these flavonoids at different positions by liver microsomes.These studies suggest that CYP2A6 catalyses flavone 4'- and 3'-hydroxylations in human liver microsomes and that other P450 enzymes have different roles in oxidizing these flavonoids.

Effect of NOS Inhibitors and Anticoagulants on Nitric Oxide Production in a Tissue-factor Induced Rat DIC Model.

BACKGROUND/AIM: We examined the mechanism of nitric oxide (NO) production in a tissue-factor (TF)-induced disseminated intravascular coagulation (DIC) model in rats, using inducible nitric oxide synthase (iNOS) inhibitor (L-NIL), endothelial nitric oxide synthase (eNOS) inhibitor (L-NAME), Factor Xa inhibitor (DX-9065a), and thrombin inhibitor argatroban. MATERIALS AND METHODS: Experimental DIC was induced by sustained infusion of 3.75 U/kg TF for 4 h via the tail vein. We then investigated the effect of these four agents on TF-induced DIC. RESULTS: Administration of L-NIL or L-NAME during induction of TF-induced DIC did not affect hemostatic markers, whereas elevated plasma levels of NO metabolites (NOX) were significantly suppressed by co-administration of L-NAME. A significant increase in eNOS-mRNA expression was observed in the TF-induced DIC model. Argatroban almost completely suppressed eNOS-mRNA expression. CONCLUSION: eNOS plays an important role in the NO production in the TF-induced DIC, and thrombin is a key stimulant of eNOS-mRNA expression in this model.

Initial Serum C-reactive Protein Level as a Predictor of Increasing Serum Vancomycin Concentration During Treatment.

BACKGROUND: Vancomycin has a narrow therapeutic window, and an increase in its serum concentration-to-dose ratio during treatment can cause renal toxicity. Therefore, this study was aimed at finding a marker to identify patients at risk of increasing serum vancomycin during treatment. METHODS: This was a retrospective cohort study of patients treated with vancomycin at Kanazawa University Hospital, Japan, from April 2012 to May 2015. Spearman correlation coefficients were calculated to determine the correlations between changes in vancomycin concentration-to-dose ratio and initial values or changes in laboratory data and other parameters. In addition, a multiple regression analysis was conducted. RESULTS: One hundred ninety-nine patients for whom 2 or more points of data on therapeutic drug monitoring (TDM) of intravenous vancomycin treatment were available and did not undergo dialysis were included in the study. Changes in vancomycin concentration-to-dose ratio were associated with C-reactive protein (CRP) and sodium (Na) levels on the initial day of TDM and with changes in white blood cell count, Na, and estimated glomerular filtration rates (eGFRs). Multiple regression analysis helped identify CRP and Na levels on the initial day of TDM and change in eGFR as independent influencing variables. CONCLUSIONS: A high serum CRP level on the initial day of TDM is an independent predictor of increasing vancomycin concentration-to-dose ratio in patients receiving intravenous vancomycin treatment, even if eGFR remains unchanged.

Liquid chromatography-tandem mass spectrometry analysis of oxidation of 2'-, 3'-, 4'- and 6-hydroxyflavanones by human cytochrome P450 enzymes.

2'-Hydroxyflavanone (2'OHFva), 3'OHFva, 4'OHFva, and 6OHFva, the major oxidative products of flavanone by human cytochrome P450 (P450, CYP) enzymes, were studied in regard to further oxidation by human CYP1A1, 1A2, 1B1.1, 1B1.3, and 2A6. The products formed were analyzed with LC-MS/MS and characterized by their positive ion fragmentations on mass spectrometry. Several di-hydroxylated flavanone (diOHFva) and di-hydroxylated flavone (diOHFvo) products, detected by analyzing parent ions at m/z 257 and 255, respectively, were found following incubation of these four hydroxylated flavanones with P450s. The m/z 257 products were produced at higher levels than the latter with four substrates examined. The structures of the m/z 257 products were characterized by LC-MS/MS product ion spectra, and the results suggest that 3'OHFva and 4'OHFva are further oxidized mainly at B-ring by P450s while 6OHFva oxidation was at A-ring. Different diOHFvo products (m/z 255) were also characterized by LC-MS/MS, and the results suggested that most of these diOHFvo products were formed through oxidation or desaturation of the diOHFva products (m/z 257) by P450s. Only when 4'OHFva (m/z 241) was used as a substrate, formation of 4'OHFvo (m/z 239) was detected, indicating that diOHFvo might also be formed through oxidation of 4'OHFvo by P450s. Finally, our results indicated that CYP1 family enzymes were more active than CYP2A6 in catalyzing the oxidation of these four hydroxylated flavanones, and these findings were supported by molecular docking studies of these chemicals with active sites of P450 enzymes.

Risk Factors for Delayed Elimination of Methotrexate in Children, Adolescents and Young Adults With Osteosarcoma.

BACKGROUND/AIM: High-dose methotrexate (HD-MTX) is pivotal chemotherapy in the treatment of patients with osteosarcoma. Blood concentrations of MTX are associated with several side effects, but there are large individual differences in the elimination of MTX. The aim of this study was to explore risk factors for delayed elimination of MTX in children, adolescents and young adults with osteosarcoma. PATIENTS AND METHODS: We conducted a retrospective study on Japanese patients with osteosarcoma who were treated with HD-MTX at Kanazawa University Hospital from April 2006 to March 2015. Risk factors for delayed elimination of methotrexate were identified by multiple logistic regression analysis. RESULTS: A total of 92 cycles of HD-MTX therapy were analyzed. Female and lower creatinine clearance (CCr) were identified as independent risk factors for delayed elimination of MTX. CONCLUSION: Knowing the factors associated with delayed elimination of MTX could lead to safer and optimized chemotherapy for patients with osteosarcoma.