Insights into stereoselective ring formation in canonical strigolactone: Identification of a dirigent domain-containing enzyme catalyzing orobanchol synthesis.

Strigolactones (SLs) are plant apocarotenoids with diverse roles and structures. Canonical SLs, widespread and characterized by structural variations in their tricyclic lactone (ABC-ring), are classified into two types based on C-ring configurations. The steric C-ring configuration emerges during the BC-ring closure, downstream of the biosynthetic intermediate, carlactonoic acid (CLA). Most plants produce either type of canonical SLs stereoselectively, e.g., tomato (Solanum lycopersicum) yields orobanchol with an α-oriented C-ring. The mechanisms driving SL structural diversification are partially understood, with limited insight into functional implications. Furthermore, the exact molecular mechanism for the stereoselective BC-ring closure reaction is yet to be known. We identified an enzyme, the stereoselective BC-ring-forming factor (SRF), from the dirigent protein (DIR) family, specifically the DIR-f subfamily, whose biochemical function had not been characterized, making it a key enzyme in stereoselective canonical SL biosynthesis with the α-oriented C-ring. We first confirm the precise catalytic function of the tomato cytochrome P450 SlCYP722C, previously shown to be involved in orobanchol biosynthesis [T. Wakabayashi et al., Sci. Adv. 5, eaax9067 (2019)], to convert CLA to 18-oxocarlactonoic acid. We then show that SRF catalyzes the stereoselective BC-ring closure reaction of 18-oxocarlactonoic acid, forming orobanchol. Our methodology combines experimental and computational techniques, including SRF structure prediction and conducting molecular dynamics simulations, suggesting a catalytic mechanism based on the conrotatory 4π-electrocyclic reaction for the stereoselective BC-ring formation in orobanchol. This study sheds light on the molecular basis of how plants produce SLs with specific stereochemistry in a controlled manner.

Assessment of Blood Prostaglandin E2 Metabolite Levels among Infants Born Preterm with Patent Ductus Arteriosus: A Prospective Study.

OBJECTIVE: To assess the role of prostaglandin E2 by measuring blood prostaglandin E2 metabolite (PGEM) concentrations in preterm infants with patent ductus arteriosus (PDA). STUDY DESIGN: A prospective observational study of preterm infants born before 32 weeks of gestational age (GA) was performed in a single tertiary hospital in Japan. Blood samples were collected to measure serum concentrations of PGEM, ibuprofen (IBU), and cytokines. Multiple regression analyses assessed associations between blood PGEM levels and perinatal factors, development of hemodynamically significant PDA (hsPDA), and IBU treatment response of hsPDA. RESULTS: Seventy-nine infants (median GA 28 weeks) were enrolled in this study. Forty-seven received IBU for hsPDA treatment 1 d after birth in median. PDA closure occurred in 25 infants after a single IBU treatment. Serum PGEM concentrations were associated with histologic chorioamnionitis (P < .01), but not with GA, respiratory distress syndrome, or serum IL-6 concentrations. Serum PGEM concentrations decreased after initial IBU treatment; however, they were not associated with hsPDA development (P = .39). IBU concentrations correlated with IBU treatment response (aOR 1.29, P < .01). However, pre-IBU serum PGEM levels and PGEM reduction ratio did not (P = .13, .15, respectively). CONCLUSIONS: Serum PGEM concentrations in preterm infants were associated with maternal histologic chorioamnionitis, but not hsPDA development. IBU treatment response was associated with higher blood IBU concentrations, but not PGEM concentrations.

Pharmacokinetic study of erlotinib in a pregnant woman with advanced non-small cell lung cancer and observation of the effects on the child growth.

AIMS: The aim of the study is to report the clinical and pharmacological observations from a pregnant patient treated with erlotinib in the second and third trimesters of pregnancy. METHODS: Maternal and neonatal blood levels and safety of erlotinib and its metabolites were evaluated. Child development was monitored for 6 years. RESULTS: A 31-year-old woman with stage IV lung adenocarcinoma with EGFR exon19 deletion began treatment with erlotinib 150 mg/day at 17 weeks of gestation. Although foetal growth retardation and oligohydramnios were observed at several times during the pregnancy, treatment was continued due to the severity of the maternal presentation, with ongoing foetal monitoring. The foetus seemed to tolerate and recover well without specific interventions. A healthy baby boy was delivered at 37 weeks gestation. The child grew and developed without any obvious issues. At last follow-up, at age 6 years, he was attending school at a grade appropriate for his age without health or developmental problems. Blood levels of erlotinib were 397-856 ng/mL at 18-37 weeks of gestation and 1190 ng/mL at 8 weeks postpartum. The blood concentration ratios of OSI-413-to-erlotinib ranged from 0.167 to 0.253 at 18-37 weeks of gestation, excluding 24 weeks, and 0.131 at 8 weeks postpartum. The maternal-to-foetal transfer rate of erlotinib, OSI-420 and OSI-413 were 24.5, 34.8 and 20.3%, respectively. CONCLUSION: Erlotinib use during the second and third trimester of pregnancy did not seem to cause any untoward effects on the developing foetus, or any long-lasting effects that could be detected during 6 years of follow-up of the child.

External Validation of a Limited Sampling Strategy for the Estimation of Mycophenolic Acid Exposure Between Different Assay Methods: PETINIA and HPLC Methods.

INTRODUCTION: A limited sampling strategy (LSS) for estimating the area under the plasma concentration-time curve (AUC0-12) of the immunosuppressant mycophenolic acid (MPA) is used for therapeutic drug monitoring (TDM) in clinical practice. Our study delves into the applicability of the MPA AUC0-12 LSS, originally developed using particle-enhanced turbidimetric inhibition immunoassay (PETINIA) measurements, to those obtained via high-performance liquid chromatography with ultraviolet detection (HPLC-UV). METHODS: We developed an LSS for estimating MPA AUC0-12 based on PETINIA measurements in 32 adult kidney transplant patients who were receiving mycophenolate mofetil. Validation of this strategy was conducted in an additional 14 adult kidney transplant patients (validation sets) through measurements obtained by both PETINIA and HPLC-UV. Predictive performance was assessed using mean absolute error (MAE), root mean squared error (RMSE), and "good guess" defined as predicted AUC within observed AUC ± 15%. RESULTS: The three time point equation (0, 2, and 6 h) emerged as optimal for estimating MPA AUC0-12, balancing predictive performance and usefulness in clinical settings. In validation sets, the coefficient of determination for observed versus predicted AUC0-12 was consistent between PETINIA (0.978) and HPLC-UV (0.958) measurements. Comparable MAE, RMSE, and "good guess" outcomes were observed for PETINIA (6.4%, 8.1%, and 85.7%, respectively) and HPLC-UV (7.6%, 9.4%, and 85.7%, respectively) measurements. CONCLUSION: Our findings support the application of the MPA AUC0-12 LSS, originally developed using PETINIA measurements, to those obtained via HPLC-UV.

Impact of Hepatitis B Surface and Core Antibody Levels on Hepatitis B Virus Reactivation.

Hepatitis B virus reactivation (HBV-R) is a serious complication that can occur in patients with resolved HBV infection during cancer chemotherapy. We examined the levels of HBV surface antibody (HBsAb) and HBV core antibody (HBcAb) to assess the incidence of HBV-R in cancer patients including hematopoietic stem cell transplantation (HSCT) and rituximab administration. This retrospective cohort study included 590 patients with resolved HBV infection. The incidence of HBV-R was evaluated 761.5 (range, 90-3898) days after the inititiation of chemotherapy. Of the patients, 13 (2.2%) developed HBV-R after the start of chemotherapy. All 13 patients exhibited lower HBsAb (<100 mIU/mL) levels at baseline. A higher level of HBcAb (≥100 cut off index (C.O.I.)) was a possible risk factor for HBV-R as well as HSCT and rituximab administration. The simultaneous presence of HBsAb <100 mIU/mL and HBcAb ≥100 C.O.I. increased the risk of HBV-R by 18.5%. Patients treated with rituximab were at a higher risk of HBV-R (18.4%) despite having HBcAb <100 C.O.I. Our results suggest that assessment of HBsAb and HBcAb levels prior to the chemotherapy is important for identifying patients at high risk of HBV-R, especially in solid cancers without HSCT and rituximab administration.

Stereospecific reduction of 2'S-configured strigolactones by cowpea OPR3 enzymes.

Strigolactones (SLs), plant-derived apocarotenoids, serve dual roles as phytohormones and rhizosphere signaling molecules. While exogenous administration of SLs to plants aids in studying their functions, the metabolic destiny of these administered SLs remains poorly elucidated. Our previous research demonstrated that among synthetic SL GR24 stereoisomers administered to cowpea (Vigna unguiculata), 2'-epi-GR24 undergoes selective reduction at the C-3',4' double bond in its D-ring. In this investigation, we isolated proteins from cowpea roots based on SL reducing activity and identified 12-oxophytodienoate reductase 3 homologs (VuOPR3s) as contributors to this reduction. Enzymatic assays conducted with recombinant proteins revealed that VuOPR3s exhibited a preference for reducing activity toward 2'S-configured SLs, including 2'-epi-GR24. This specificity for 2'S-configured SLs was congruent with that observed for orobanchol produced by cowpea and its stereoisomers. These findings suggest that exogenously administered SLs undergo enzymatic stereoselective reduction, underscoring the importance of considering stereospecificity when interpreting data obtained from SL usage.

An analytical method using salting-out assisted liquid-liquid extraction to quantify ceftriaxone from micro volumes of human serum.

Ceftriaxone (CTRX) is a commonly used cephalosporin antibiotic. It is suggested that monitoring plasma/serum concentrations is helpful for its safe use. This study aimed to develop and validate an analytical method for measuring CTRX concentrations in human serum according to International Conference on Harmonization guideline M10. Ten microliters of serum sample was purified using a salting-out assisted liquid-liquid extraction procedure with magnesium sulfate. The upper layer was then diluted threefold and analyzed using a liquid chromatography-tandem mass spectrometry-based method with a total run time of 12 min. The linear calibration curve was obtained over the concentration range 5-500 µg/ml. The within-run accuracy varied from 0.2 to 6.5%, and the precision was ≤8.0%. The between-run accuracy and precision ranged from 0.7% to 5.6% and ≤6.4%, respectively. Significant carryover was resolved by injecting four blanks after high-concentration CTRX samples. The recovery rates from spiked serum at low and high concentrations were 44.4 and 43.4%, respectively. Other factors, including selectivity, matrix effects, stability, dilution integrity and reinjection reproducibility also met the acceptance criteria. Serum concentrations in 14 samples obtained from two participants receiving 2 g/day of CTRX were successfully determined using this method.

Factors associated with mortality in patients with extremity necrotizing soft-tissue infections: a single academic center experience.

PURPOSE: Necrotizing soft-tissue infection (NSTI) is a surgical emergency associated with high mortality. This study primarily aimed to identify the factors associated with in-hospital mortality due to NSTI in the extremities at a single institution. Secondarily, we aimed to clarify the effectiveness of the optimal combination of hyperbaric oxygen therapy (HBOT) and surgery for NSTI treatment. STUDY DESIGN: Retrospective observational study. METHODS: This study included all patients newly diagnosed with NSTI in the extremity from 2003 to 2021 in our hospital. Factors associated with mortality, including patient's characteristics, duration from onset to hospitalization, NSTI type, and clinical data at the initial visit; acute disseminated intravascular coagulation (DIC), laboratory risk indicator for necrotizing fasciitis score, and sequential organ failure assessment score; treatment, initial surgery, surgery times, amputation, HBOT, combined surgery with HBOT, and clinical outcomes; amputation rate, mortality rate, and hospitalization duration were examined. RESULTS: A total of 37 cases were treated for NSTIs. The median age was 64 years (range: 22-86). Five cases (13.5%) died during hospitalization. Ten patients were diagnosed with DIC at the initial visit, of whom four died. HBOT combined with surgery was performed in 23 cases, and 16 cases underwent multiple surgeries. Factors associated with mortality included DIC (p = 0.015, 95% confidence interval [CI]: 0.015-0.633) and multiple surgeries combined with HBOT (p = 0.028, 95% CI: 1.302-95.418). CONCLUSION: This study demonstrates that DIC at the initial visit is associated with mortality in extremity NSTI. Additionally, HBOT might improve prognosis when combined with multiple surgeries.

A simple HPLC assay for determining eltrombopag concentration in human serum.

Eltrombopag, a thrombopoietin receptor agonist, is used for the treatment of idiopathic thrombocytopenic purpura (ITP) and aplastic anemia. We developed a HPLC assay for the determination of serum eltrombopag concentration in ITP patients. An aliquot of a serum sample spiked with diclofenac as the internal standard (IS) was treated with acetonitrile to precipitate the proteins. Eltrombopag and the IS were separated on an octadecylsilyl silica-gel column using a mobile phase consisting of 10 mM 1-pentanesulfonic acid sodium salt, acetonitrile, and acetic acid. The detection wavelength was set at 265 nm. The calibration curve was linear at the concentration range of 0.15-12.5 µg/mL for eltrombopag (r = 0.9987). The recoveries of eltrombopag from the serum samples were greater than 95.9% with coefficients of variation (CVs) being less than 2.8%. The CVs for the intra-day and inter-day assays were 1.9-11.8% and 1.0-11.8%, respectively. This assay method could be used for therapeutic drug monitoring of eltrombopag in ITP patients.

High-Performance Liquid Chromatography for Therapeutic Drug Monitoring of Serum Lenvatinib.

BACKGROUND: Therapeutic drug monitoring (TDM) and dose adjustment of lenvatinib may be beneficial in the treatment of radioiodine-refractory thyroid cancer, by maximizing antitumor effects and minimizing adverse drug reactions. The aim of this study was, therefore, to develop and validate a high-performance liquid chromatography method using an ultraviolet detection system for routine serum lenvatinib detection in patients with thyroid cancer. METHODS: Serum specimens, spiked with an internal standard, were treated by a solid-phase extraction through an octadecylsilyl silica cartridge. Lenvatinib and internal standard were concomitantly separated from serum using a conventional octadecylsilyl silica column through isocratic elution, using a mobile phase consisting of 0.02 mol/L sodium phosphate (pH 6.7) and acetonitrile (50/50, vol/vol) at a flow rate of 1.0 mL/min. The detection wavelength was set at 244 nm. Serum samples from 5 patients were used for clinical validation of the method. RESULTS: The calibration curve for lenvatinib was linear (Pearson correlation coefficient, r = 0.9998) over the concentration range of 6.25-400 ng/mL, with a lower limit of quantification of 6.25 ng/mL. Extraction recoveries for lenvatinib were 97% or more, with coefficients of variation less than 2.2%. The coefficients of variation for intraday and interday assays were less than 4.7% and 6.0%, respectively. CONCLUSIONS: This sensitive high-performance liquid chromatography method can be used for lenvatinib therapeutic drug monitoring when liquid chromatography-tandem mass spectrometry facilities are unavailable.

Utilizing physiologically based pharmacokinetic modeling to predict theoretically conceivable extreme elevation of serum flecainide concentration in an anuric hemodialysis patient with cirrhosis.

PURPOSE: Higher drug concentrations in complex clinical scenarios in which multiple factors such as drug-drug interactions (DDIs) and comorbidities are simultaneously present are not necessarily rationalized in prospective clinical studies. Physiologically based pharmacokinetic (PBPK) modeling and simulation of the anti-arrhythmic drug flecainide, as an example, were utilized to quantitatively rationalize the higher flecainide concentration in a complex clinical case involving end-stage renal disease (ESRD), cirrhosis, and the co-administration of mexiletine, a CYP1A2 inhibitor. METHODS: The developed flecainide PBPK model was used to evaluate the DDI effect (as measured by AUC ratio before and after inhibition) of mexiletine and the combined disease effects of ESRD and cirrhosis on flecainide exposure. RESULTS: The predicted DDI effect of mexiletine was negligible or weak in anuric hemodialysis with cirrhosis population (mean [5th/95th percentiles], 1.23 [0.97-1.67]), although it was negligible in healthy volunteers (1.03 [1.02-1.05]). The predicted flecainide concentrations after multiple flecainide doses (50 mg BID) in the anuric hemodialysis with cirrhosis population were comparable with the observed value (3602 ng/mL), which fell between the predicted concentrations in the absence and presence of mexiletine (3043 [718-8499] and 5914 [880-20,624] ng/mL, respectively). CONCLUSIONS: The PBPK simulation proposed a likely explanation that the observed higher flecainide concentration could be attributed to the combined effects of ESRD, cirrhosis, and a potential DDI with mexiletine. This approach provides quantitative insight into theoretically conceivable extremes in drug exposure occurring in complex clinical situations even if uncommon.

Involvement of Renal Efflux Transporter MATE1 in Renal Excretion of Flecainide.

Flecainide, an anti-arrhythmic drug, undergoes renal excretion through active renal tubular secretion in addition to passive glomerular filtration. The contribution of renal uptake and efflux transporters in active renal tubular secretion of flecainide remains unclear except that flecainide is a substrate of human multidrug resistance protein 1 (MDR1). To elucidate renal efflux and uptake transporters involved with active renal tubular secretion of flecainide, we conducted in vitro interaction studies of flecainide using organic cation transporter 2 (OCT2), multidrug and toxin extrusion (MATE) 1, and MATE2-K. Uptake transporter inhibition assays using hOCT2-Chinese hamster ovary (CHO), hMATE1-CHO, and hMATE2-K-Madin Darby canine kidney strain II (MDCKII) cells revealed that flecainide (2.5 µM) inhibited hMATE1-mediated transport by 40% with an IC50 value of 6.7 µM; however, it showed no or weak inhibitory effects on hOCT2- and hMATE2-K-mediated transport. For investigating flecainide as a substrate of hMATE1, the accumulation of flecainide in hMATE1-CHO was compared with that in control cells. Uptake transporter substrate assay revealed that flecainide (1 µM) showed 1.11-fold accumulation though the hMATE1-related active transport was significantly decreased in the presence of quinidine (42.0 ± 23.9 vs. 11.8 ± 4.1 pmol/mg in transfected cells; p < 0.05). These results suggest that flecainide is a weak substrate of hMATE1, which is involved in the renal tubular secretion of cationic drugs, and hMATE1 may be less important in the pharmacokinetic drug-drug interaction for renal excretion of flecainide. However, in vivo drug-drug interaction studies of flecainide with substrates of hMATE1 may be needed because flecainide has the potential to inhibit hMATE1.

Effects of Proton Pump Inhibitor Coadministration on the Plasma Concentration of Erlotinib in Patients With Non-Small Cell Lung Cancer.

BACKGROUND: Erlotinib is used for treating non-small cell lung cancer (NSCLC). Intestinal absorption of erlotinib is impaired under gastric pH elevation; therefore, coadministration of gastric acid suppressants may provide lower blood concentration of erlotinib. We investigated the effects of erlotinib coadministration with proton pump inhibitors (PPIs) and histamine H2 receptor blockers (H2RBs) on the plasma concentration of erlotinib and erlotinib-induced adverse reaction in patients with NSCLC. METHODS: Forty-two patients receiving erlotinib therapy for NSCLC were recruited for this study. Association of adverse reactions (rash and diarrhea) with plasma concentration of erlotinib was examined. Plasma concentration-to-dose (C/D) ratios and oral clearance (CL/F), which was estimated by population pharmacokinetic analysis of plasma concentrations of erlotinib, were compared among 3 patient groups: without coadministration of gastric acid suppressants (control group), with coadministration of PPI (PPI group), and coadministration of H2RB (H2RB group). RESULTS: Patients with grade ≥2 rash had higher plasma concentrations of erlotinib compared with those with grade ≤1 [1.02 (0.43-2.60) versus 0.67 (0.10-1.85) mcg/mL, P < 0.01]. The C/D ratios of erlotinib in the PPI and H2RB groups were lower than that in the control group [0.39 (0.08-0.76) and 0.48 (0.33-0.81) versus 0.51 (0.28-1.28) mcg·mL·mg·kg], where statistical significance was observed between PPI and control groups (P < 0.05). The population pharmacokinetic estimated oral CL/F in the PPI and H2RB groups were higher than that in the control group [5.55 (3.36-14.52) and 4.82 (2.08-6.32) versus 3.95 (2.01-10.44) L/h], where statistical significance was observed between PPI and control groups (P < 0.05). CONCLUSIONS: Plasma concentrations of erlotinib in patients under coadministration of gastric acid suppressants were lower than those without gastric acid suppressants through drug interaction, suppressing the intestinal absorption of erlotinib. The magnitude of this drug interaction was more pronounced in the coadministration of PPI compared with H2RB.

Optimal sampling time and clinical implication of the SCN5A promoter haplotype in propafenone therapeutic drug monitoring.

PURPOSE: The clinical usefulness of therapeutic drug monitoring (TDM) of propafenone, a sodium channel blocker, has been unclear due to the lack of information regarding optimal blood sampling time and therapeutic concentration range. Antiarrhythmic effects of sodium channel blockers are affected by the activity of the cardiac sodium channel (SCN5A). We investigated the optimal sampling time and the clinical implication of the SCN5A promoter haplotype in propafenone TDM. METHODS: We evaluated serum concentrations of propafenone, the SCN5A promoter haplotype, and antiarrhythmic efficacy in 55 patients with supraventricular tachy-arrhythmias. Blood samples obtained 1.5-6 and 10-24 h after the last dose were categorized as peak and trough samples, respectively. RESULTS: The peak propafenone concentration was significantly higher in effectively treated patients than that in patients showing insufficient response (337 ± 213 vs. 177 ± 93 ng/mL, P = 0.005), but the trough propafenone concentration was not significantly different between the two groups (68 ± 48 vs. 42 ± 36 ng/mL). Clinically relevant propafenone efficacy was achieved significantly more often in SCN5A haplotype B carriers than in wild-type haplotype A homozygotes (90 vs. 60%, P < 0.05). Among the haplotype A homozygotes, peak propafenone concentration was higher in effectively treated patients than that in patients showing insufficient response (299 ± 177 vs. 177 ± 93 ng/mL, P = 0.061). CONCLUSION: The present study found that antiarrhythmic efficacy of propafenone was associated with peak propafenone concentration rather than trough concentration and was affected by the SCN5A promoter haplotype.

Simultaneous determination of serum propafenone and its metabolites using high-performance liquid chromatography.

Propafenone, a class Ic antiarrhythmic agent, is metabolized to 5-hydroxypropafeone (5-OHP) and N-depropylpropafenone (NDPP). Simultaneous determination of serum propafenone and its metabolites was performed using HPLC equipped with a conventional octadecylsilyl silica column and ultraviolet detector. The wavelength was set at 250 nm. Propafenone and its metabolites in the serum were extracted using diethyl ether. The mobile phase solution, comprising 1-pentanesulfonic acid sodium salt (0.1 m), acetonitrile and acetic acid (280:185:2.5, v/v/v), was pumped at a flow rate of 1 mL/min. The recoveries of propafenone, 5-OHP and NDPP were greater than 85, 82 and 60%, respectively, with the coefficients of variation (CVs) less than 5.4, 1.9 and 2.9%, respectively. The calibration curves were linear for a concentration range of 12.5-1500 ng/mL for propafenone and 2-500 ng/mL for 5-OHP and NDPP (r > 0.999). CVs in the intraday assays were 1.0-3.8% for propafenone, 0.6-2.0% for 5-OHP and 0.6-1.7% for NDPP. CVs in interday assays were 1.3-7.7% for propafenone, 1.1-6.5% for 5-OHP and 5.4-8.0% for NDPP. The present HPLC method can be used to assess the disposition of propafenone and its metabolites for pharmacokinetic studies and therapeutic drug monitoring of propafenone.

Assessment of indomethacin oral spray for the treatment of oropharyngeal mucositis-induced pain during anticancer therapy.

PURPOSE: The efficacy and safety of indomethacin (IM) oral spray (OS) as a pain control therapy for oropharyngeal mucositis due to anticancer chemo- and radiotherapy were assessed in patients with head and neck carcinomas and haematological tumours. METHOD: We observed 35 patients (male/female, 20/15; 53 ± 17 years) with oropharyngeal mucositis who were treated with IM-OS preparation for pain relief at University of Tsukuba Hospital, Japan. Analgesic effects were assessed using the six-grade face scale for pain in 28 patients at the start of IM oral spray treatment. Systemic exposure was assessed by determining urinary excretions of IM in seven patients. RESULTS: Pain relief was achieved in 26 (93%) patients at 25 (5-60) min after applying the IM-OS preparation (15.6 ± 3.4 µg/kg) and analgesic effects were maintained for 120 (10-360) min. The pain was significantly decreased after using the spray (3.6 ± 0.7 vs. 2.4 ± 0.9, p < 0.01). Moreover, urinary IM excretion rates after applying the IM spray preparation were 1.8 ± 0.8% of the IM oral spray dose (130.5 ± 77.7 µg/kg/day), which was markedly lower than that following oral administration of IM (60%). No adverse events were observed following application of the spray. CONCLUSIONS: The present IM spray is an effective and safe preparation for pain relief and can be used as an alternative therapeutic option for oropharyngeal mucositis in cancer patients.

ß1-Adrenergic receptor Arg389Gly polymorphism affects the antiarrhythmic efficacy of flecainide in patients with coadministration of ß-blockers.

OBJECTIVE: ß1-Adrenergic receptor (ß1-AR) stimulation modulates the antiarrhythmic activities of sodium channel blockers. The ß1-AR Gly389 variant shows a marked decrease in agonist-stimulated cyclic AMP production compared with that of the wild-type Arg389 in vitro. We investigated whether the Arg389Gly polymorphism affects the efficacy of flecainide, a typical sodium channel blocker, in patients with or without coadministration of ß-blockers. METHODS: The effects of the ß1-AR Arg389Gly polymorphism on the antiarrhythmic efficacy of flecainide were compared between with and without coadministered ß-blockers in 159 patients with supraventricular tachyarrhythmia. The antiarrhythmic efficacy of flecainide was assessed for at least 2 months by evaluating symptomatology, 12-lead ECGs, and Holter monitoring results. RESULTS: Genetic differences in the antiarrhythmic efficacy of flecainide were observed in patients with coadministration of ß-blockers. Tachyarrhythmia was well controlled in 60% of Arg389-homozygotes, 30% of Gly389-heterozygotes, and 0% of Gly389-homozygotes (P=0.001). In contrast, no difference in the antiarrhythmic efficacy was observed among the three genotypes in the patients without coadministration of ß-blockers (64, 70, and 60%, respectively). Heart rate in tachyarrhythmia in patients treated with flecainide was significantly higher in Gly389 carriers than in Arg389-homozygotes (P=0.013). CONCLUSION: The Gly389 polymorphism decreased the antiarrhythmic efficacy of flecainide when coadministered with ß-blockers. The results indicate that the Arg389Gly polymorphism may play an important role in predicting the efficacy of flecainide in patients with coadministration of ß-blockers.

A Simple High-Performance Liquid Chromatography for Determining Lapatinib and Erlotinib in Human Plasma.

BACKGROUND: Lapatinib and erlotinib are used for cancer treatment, showing large interindividual variability. Therapeutic drug monitoring may be useful for assessing the clinical outcomes and adverse events. A simple high-performance liquid chromatography UV method was developed for the determination of lapatinib and erlotinib in human plasma. METHODS: An aliquot of plasma sample spiked with internal standard was treated with acetonitrile to precipitate the proteins. Lapatinib and erlotinib were separated on an octadecylsilyl silica gel column using a mobile phase consisting of acetonitrile, methanol, water, and trifluoroacetic acid (26:26:48:0.1) pumped at a flow rate of 1.0 mL/min. The detection wavelength was set at 316 nm. RESULTS: The calibration curves for lapatinib and erlotinib were linear (r = 0.9999) in the range of 0.125-8.00 mcg/mL. The extraction recoveries for both lapatinib and erlotinib at the plasma concentration of 0.125-8.00 mcg/mL were higher than 89.9% with coefficients of variation less than 3.5%. The coefficients of variation for intraday and interday assays of lapatinib and erlotinib were less than 5.1% and 6.1%, respectively. CONCLUSIONS: The present method can be used for blood concentration monitoring for lapatinib or erlotinib in exactly the same conditions.