Effect of tongue-palate contact mode on food transport during mastication.

The physiological mechanisms underlying Stage II transport (STII), during which comminuted solid food is transported from the oral cavity into the meso-pharynx for aggregation into a pre-swallow bolus, have yet to be clarified. The purpose of the present study was to investigate relationships between tongue-palate contact during mastication and incidence of STII by synchronised analysis of tongue pressure production on a hard palate and video-endoscopic (VE) images during mastication. Tongue pressure at 5 measuring points with an ultra-thin sensor sheet attached to the hard palate and trans-nasal VE images while masticating corned beef was recorded for 12 healthy subjects. All recordings were divided into 2 groups: mastication with STII and without STII. Tongue pressure duration was longer at the anterior-median part in the group with STII than in the group without STII. Integrated values of tongue pressure were greater at the anterior-median parts and posterior circumferential part in the group with STII. Integrated values of tongue pressure per second were greater in late-stage mastication than in early-stage mastication in the group with STII. These results suggest that the tongue-palate contacting at the anterior-median and post-circumferential parts of the hard palate is related with the incidence of STII.

A two centre observational study of simultaneous pulse oximetry and arterial oxygen saturation recordings in intensive care unit patients.

The influence of variables that might affect the accuracy of pulse oximetry (SpO2) recordings in critically ill patients is not well established. We sought to describe the relationship between paired SpO2/SaO2 (oxygen saturation via arterial blood gas analysis) in adult intensive care unit (ICU) patients and to describe the diagnostic performance of SpO2 in detecting low SaO2 and PaO2. A paired SpO2/SaO2 measurement was obtained from 404 adults in ICU. Measurements were used to calculate bias, precision, and limits of agreement. Associations between bias and variables including vasopressor and inotrope use, capillary refill time, hand temperature, pulse pressure, body temperature, oximeter model, and skin colour were estimated. There was no overall statistically significant bias in paired SpO2/SaO2 measurements; observed limits of agreement were +/-4.4%. However, body temperature, oximeter model, and skin colour, were statistically significantly associated with the degree of bias. SpO2 <89% had a sensitivity of 3/7 (42.9%; 95% confidence intervals, CI, 9.9% to 81.6%) and a specificity of 344/384 (89.6%; 95% CI 86.1% to 92.5%) for detecting SaO2 <89%. The absence of statistically significant bias in paired SpO2/SaO2 in adult ICU patients provides support for the use of pulse oximetry to titrate oxygen therapy. However, SpO2 recordings alone should be used cautiously when SaO2 recordings of 4.4% higher or lower than the observed SpO2 would be of concern. A range of variables relevant to the critically ill had little or no effect on bias.

Comparison of electrochemiluminescence immunoassay and latex agglutination turbidimetric immunoassay for evaluation of everolimus blood concentrations in renal transplant patients.

WHAT IS KNOWN AND OBJECTIVE: For analysis of blood concentrations of everolimus, many hospital laboratories use either latex agglutination turbidimetric immunoassay (LTIA) or electrochemiluminescence immunoassay (ECLIA). However, no studies have compared both immunoassay methods under the same conditions. Accordingly, in this study, we compared everolimus blood concentrations obtained by LTIA and ECLIA in renal transplant patients. METHODS: Blood samples (n = 230) from 60 renal transplant patients (19 female and 41 male) were evaluated using both immunoassays. Subsequently, we switched the assay for detection of everolimus blood concentrations from LTIA to ECLIA as a clinical application. Three quality control (QC) samples for LTIA were analysed using ECLIA, and 3 QC samples for ECLIA were analysed using LTIA. RESULTS: The Deming regression of ECLIA versus LTIA generated the following parameters: slope, 1.0067 and intercept, 1.7489 ng/mL, in the analysis of 230 samples. Bland-Altman analysis showed an average positive bias of 1.73 ng/mL between ECLIA and LTIA. When the clinical apparatus was switched from LTIA to ECLIA, the average everolimus blood concentration assayed by LTIA before switching was 3.57 ng/mL, whereas that by ECLIA after switching in the same patients taking the same daily dose (mean: 1.43 mg/day) was 5.85 ng/mL. The QCs assayed using LTIA were lower by an average of 67.3% (range: 55.8%-79.5%) for ECLIA, and in the same 230 samples from patients, the everolimus blood concentrations assayed by LTIA were lower by an average of 67.4% (range: 37.1%-114.5%) of ECLIA. WHAT IS NEW AND CONCLUSION: Analysis of everolimus concentrations by immunoassays with high precision and accuracy is required to ensure long-term survival of transplant recipients. Although the concentrations of QCs and calibrators of everolimus in LTIA were previously corrected to 70% concentration because of cross-reactivity with everolimus metabolites, these adjustments may need to be reviewed.

The effect of bolus volume on laryngeal closure and UES opening in swallowing: Kinematic analysis using 320-row area detector CT study.

This study investigated the effects of three different volumes of honey-thick liquid on the temporal characteristics of swallowing. Twenty-six healthy subjects (15 males, 11 females) underwent 320-row area detector CT scan while swallowing 3, 10 and 20 mL of honey-thick liquid barium. Three-dimensional images were created at 10 images/s. Kinematic events involving six structures (velopharynx, hyoid bone, epiglottis, laryngeal vestibule (LV), true vocal cords (TVC), upper esophageal sphincter (UES)) and timing of bolus movement were timed using frame by frame analysis. The overall sequence of events did not differ across three volumes; however, increasing bolus volume significantly changed the onset and termination of events. The bolus head reached to pharynx and esophagus earlier and the duration of bolus passing through UES was significantly longer in 10 and 20 mL compared to 3 mL (P < .05). Consequently, the onset of UES opening was significantly earlier with increased volume (P < .05). LV and TVC closure occurred later in 20 mL compared to 3 mL (P < .05). These changes in motion of pharynx and larynx appeared to promote swallow safety by preventing aspiration, suggesting that anatomical structure movements adapt in response to bolus volume. Our findings also suggest that the pharyngeal swallow behaviours may be modified by afferents in the oral cavity. The three-dimensional visualization and quantitative measurements provided by 320-ADCT provide essential benchmarks for understanding swallowing, both normal and abnormal.

Anatomy of the larynx and pharynx: effects of age, gender and height revealed by multidetector computed tomography.

Although oropharyngeal and laryngeal structures are essential for swallowing, the three-dimensional (3D) anatomy is not well understood, due in part to limitations of available measuring techniques. This study uses 3D images acquired by 320-row area detector computed tomography ('320-ADCT'), to measure the pharynx and larynx and to investigate the effects of age, gender and height. Fifty-four healthy volunteers (30 male, 24 female, 23-77 years) underwent one single-phase volume scan (0.35 s) with 320-ADCT during resting tidal breathing. Six measurements of the pharynx and two of larynx were performed. Bivariate statistical methods were used to analyse the effects of gender, age and height on these measurements. Length and volume were significantly larger for men than for women for every measurement (P < 0.05) and increased with height (P < 0.05). Multiple regression analysis was performed to understand the interactions of gender, height and age. Gender, height and age each had significant effects on certain values. The volume of the larynx and hypopharynx was significantly affected by height and age. The length of pharynx was associated with gender and age. Length of the vocal folds and distance from the valleculae to the vocal folds were significantly affected by gender (P < 0.05). These results suggest that age, gender and height have independent and interacting effects on the morphology of the pharynx and larynx. Three-dimensional imaging and morphometrics using 320-ADCT are powerful tools for efficiently and reliably observing and measuring the pharynx and larynx.

Monitoring of methylergometrine in human breast milk by solid-phase extraction and high-performance liquid chromatography with fluorimetric detection.

A high-performance liquid chromatographic assay has been developed for the detection and quantification of the conventional postnatal uterotonic drug, methylergometrine, in human breast milk using a C-18 reversed-phase column by isocratic elution. The analytical method consisted of sample clean-up by solid-phase extraction, and the fluorescence detection required only 8.5 min per sample for separation and quantitation. This assay gave intra- and inter-assay coefficients of variation of less than 7.9% and 7.7%, respectively, and the detection limit was approximately 50 pg/ml. This method was applied for drug level monitoring in the breast milk of patients given methylergometrine.

Impact of polyplex micelles installed with cyclic RGD peptide as ligand on gene delivery to vascular lesions.

Gene therapy is expected to open a new strategy for the treatment of refractory vascular diseases, so the development of appropriate gene vectors for vascular lesions is needed. To realize this requirement with a non-viral approach, cyclo(RGDfK) peptide (cRGD) was introduced to block copolymer, poly(ethylene glycol)-block-polycation carrying ethylenediamine units (PEG-PAsp(DET)). cRGD recognizes α(v)ß(3) and α(v)ß(5) integrins, which are abundantly expressed in vascular lesions. cRGD-conjugated PEG-PAsp(DET) (cRGD-PEG-PAsp(DET)) formed polyplex micelles through complexation with plasmid DNA (pDNA) and the cRGD-PEG-PAsp(DET) micelles achieved significantly more efficient gene expression and cellular uptake as compared with PEG-PAsp(DET) micelles in endothelial cells and vascular smooth muscle cells. Intracellular tracking of pDNA showed that cRGD-PEG-PAsp(DET) micelles were internalized via caveolae-mediated endocytosis, which is associated with a pathway avoiding lysosomal degradation and that, PEG-PAsp(DET) micelles were transported to acidic endosomes and lysosomes via clathrin-mediated endocytosis. Further, in vivo evaluation in rat carotid artery with a neointimal lesion revealed that cRGD-PEG-PAsp(DET) micelles realized sustained gene expression, whereas PEG-PAsp(DET) micelles facilitated rapid, but transient gene expression. These findings suggest that introduction of cRGD to polyplex micelles might create novel and useful functions for gene transfer and contribute to the establishment of efficient gene therapy for vascular diseases.

Long-term results of endovascular treatment for splenic artery aneurysms.

AIM: The aim of this paper was to evaluate our single-center experience of the management of splenic artery aneurysm (SAA), with particular attention to the long-term results of endovascular treatment. METHODS: Thirty-eight patients with the diagnosis of SAA at the Tokyo University Hospital during the past 23 years were retrospectively reviewed. Interventions were considered for patients with SAA>2 cm in diameter. Nine patients were treated by transcatheter embolization (TE), and 8 by open surgical repair (SR). Twenty-one patients were observed (OB). TE was performed with microcoils placed distal and proximal to the aneurysm in the afferent artery to isolate the aneurysm. RESULTS: In the TE group, the primary technical success rate was 100%. No 30-day mortality or any catheter-related complication was observed. The median length of hospital stay after TE, excluding one patient who required further surgery, was shorter than that after SR (8 versus 16 days, P=0.001). During follow-up (median =45 months), no patient died and no recurrence of SAA was observed. In the SR group, all aneurysms were repaired successfully without any severe complication, and no aneurysm-related death occurred during follow-up (median =57 months). In the OB group, no aneurysm rupture or increase in aneurysm size was observed during follow-up (median =35 months). CONCLUSION: TE provided good early and long-term results, comparable to those obtained with conventional SR. In addition, TE had several advantages associated with its minimal invasiveness. TE by the isolation technique could be the first-line strategy for all SAA requiring treatment.

Pharmacogenetic determinants for interindividual difference of tacrolimus pharmacokinetics 1 year after renal transplantation.

WHAT IS KNOWN AND OBJECTIVE: Tacrolimus, a widely used immunosuppressive agent in organ transplantation, has a narrow therapeutic window. It has been suggested that its interaction with lansoprazole could be dependent on polymorphisms of CYP3A5 and CYP2C19. The objective of this study was to investigate how, 1 year after renal transplantation, CYP3A5 and CYP2C19 polymorphisms, biochemical parameters and coadministration with lansoprazole, influenced tacrolimus pharmacokinetics. METHODS: The pharmacokinetics of tacrolimus was studied 1 year after renal transplantation, in 75 recipients who were all receiving continuation treatment with 12-hourly oral tacrolimus, and 30 mg lansoprazole daily (Group 1; n = 20) or, 10 mg rabeprazole daily or no proton pump inhibitor (Group 2; n = 55). RESULTS: There were no significant differences in the dose-adjusted area under the plasma concentration-time curve (AUC(0-12)) and maximum plasma concentration (C(max)) of tacrolimus between CYP2C19 genotype groups, but there were significant differences between CYP3A5 genotypes groups (*1/*1 + *1/*3 vs. *3/*3 = 45·2 ± 20·0 vs. 71·0 ± 34·1 ng·h/mL/mg, P < 0·0001 and 6·3 ± 2·6 vs. 9·3 ± 7·0 ng/mL/mg, P = 0·0017, respectively) and between co-administration with and without lansoprazole (74·5 ± 34·0 vs. 52·4 ± 27·4 ng·h/mL/mg, P = 0·0054 and 10·9 ± 8·8 vs. 6·7 ± 3·0 ng/mL/mg, P = 0·0024, respectively). In a multiple regression analysis, the dose-adjusted AUC(0-12) and C(max) of tacrolimus were associated with CYP3A5*3/*3 and co-administration with lansoprazole. WHAT IS NEW AND CONCLUSION: CYP2C19 does not seem to contribute to the interaction between tacrolimus and lansoprazole. The long-term combination of tacrolimus and lansoprazole requires careful monitoring of patients with the CYP3A5*3/*3 genotype.

A simple, sensitive high-performance liquid chromatography -ultraviolet method for the quantification of concentration and steady-state pharmacokinetics of itraconazole and hydroxyitraconazole.

BACKGROUND: A steady-state trough plasma itraconazole concentration greater than 500 ng/mL is a therapeutic target for itraconazole. A simple, rapid and sensitive high-performance liquid chromatography-based method was developed for quantitation of itraconazole and hydroxyitraconazole in human plasma. METHODS: Itraconazole and hydroxyitraconazole were separated using a mobile phase of 0.5% KH2PO4 (pH 6.0)-acetonitrile (30:70, v/v) on a CAPCELLPAK C18 MGII column at a flow rate of 0.5 mL/min and ultraviolet absorbance at 260 nm. RESULTS: The analysis required 200 microL of plasma and involved a rapid, simple solid-phase extraction with an Oasis HLB cartridge, which resulted in recoveries of 87-92% for itraconazole and 91-94% for hydroxyitraconazole. The lower limit of quantification for itraconazole and hydroxyitraconazole was 5 ng/mL each. Intra- and interday coefficients of variation for itraconazole and hydroxyitraconazole were less than 11.3% and 12.2%, respectively, and accuracies were within 11.7% and 4.5% over the linear range, respectively. Although the steady-state plasma concentrations of itraconazole and hydroxyitraconazole ranged from 506 to 2482 ng/mL and from 766 to 2444 ng/mL, respectively, after a two-day loading dose of 400 mg/day intravenous itraconazole followed by the administration of 200 mg/day itraconazole oral solution, calibration curves of itraconazole and hydroxyitraconazole showed positive linearity in a concentration range of 5-2500 and 50-2500 ng/mL, respectively. CONCLUSIONS: Our results indicate that this method is applicable for the monitoring of plasma levels of itraconazole and hydroxyitraconazole in a clinical setting. Furthermore, the regimen presented here might also be effective in preventing infection, but further studies with large sample sizes are necessary to investigate this avenue.

Current status of the medical expenses for the treatment of arteriosclerosis obliterans in Japan.

AIM: We aimed to determine the current status of the medical expenses for the treatment of arteriosclerosis obliterans (ASO) and evaluate the cost effectiveness of the medical practices employed in ASO treatment in Japan. METHODS: We performed a prospective observational study using 140 ASO patients. The cost of the medical practices comprised the costs of outpatient treatment, pharmacological agents, and hospitalization. To compare the average monthly costs, the patients were divided into preintervention, postintervention, or conservative-therapy groups. To compare the total costs and effectiveness of each treatment, the patients who had first visited our division during the study period were classified into surgery, endovascular-revascularization (EVR), or conservative-therapy groups. The adverse reactions of the 4 most popular agents for ASO were investigated, and bleeding events were assessed specifically. RESULTS: The average monthly costs for outpatient treatment and pharmacological agents were yen 168,002 in conservative cases, yen 149,871 in preoperation cases, and yen 128,527 in postoperation cases. The mean total costs were yen 5,407,950 in conservative cases, yen 7,375,290 in surgical cases, and yen 2,631,650 in EVR cases. The average change of the gauge in clinical status was 0.57 in conservative cases, 2.13 in surgical cases, and 2.25 in EVR cases. Warfarin induced more bleeding complications than the other agents. CONCLUSION: The costs of pharmacological agents represented much of the medical costs in any treatment groups.

Inter-individual difference determinant of prednisolone pharmacokinetics for Japanese renal transplant recipients in the maintenance stage.

The objective of this study was to elucidate the effects of CYP3A5, ABCB1, NR1I2 and NR3C1 BclI gene polymorphisms on prednisolone exposure for 65 Japanese renal transplant recipients in the maintenance stage one year after transplantation. Prednisolone dosage ranged from 2.5 to 15.0 mg day(-1) based on individual immunosuppressive states. The dose-adjusted area under the plasma concentration-time curve (AUC(0-24)) and the maximal plasma concentration (C(max)) of prednisolone in recipients with the BclI G allele were significantly higher than in those with the CC genotype (p = 0.029 and 0.021, respectively), but there were no significant differences in the half-life and T(max) of prednisolone between the two groups. None of the CYP3A5, ABCB1 or NR1I2 allele variants had any significant influence on the dose-adjusted AUC(0-24) of prednisolone. The NR3C1 BclI polymorphism was important in the inter-individual variability of prednisolone pharmacokinetics. The transactivation of the CYP3A4 promoter by prednisolone via the glucocorticoid receptor might be especially responsive for intestinal CYP3A4.

Clinical evaluation after a notification policy of linezolid use: a case series of 22 patients.

Linezolid exhibits a broad spectrum of activity against Gram-positive cocci, including Methicillin-resistant Staphylococcus aureus (mRSA) and vancomycin-resistant enterococci (VRe). However, recent studies have already reported the emergence of linezolid-resistant mRSA or VRe. the purpose of this study is to evaluate not only the efficacy of linezolid for the treatment of nosocomial mRSA infections but also the effect of a notification policy of linezolid use. the charts of inpatients who had been treated with linezolid were reviewed for clinical outcome. After introduction of the notification policy of linezolid use, the clinical success rate was 73.3%, and the rate of appropriate linezolid use was 80%, whereas the success rate was 14.2% and the appropriate use rate was 14.3% before the policy. in conclusion, appropriate use controlled by a notification policy of antibiotics use is essential for prevention of the emergence and spread of linezolid-resistant bacteria, and for proper demonstration of its antibacterial ability.

Influence of carboxylesterase 2 genetic polymorphisms on mycophenolic acid pharmacokinetics in Japanese renal transplant recipients.

Mycophenolic acid (MPA), converted from the prodrug mycophenolate mofetil (MMF), is generated by intestinal and hepatic esterases. The role of carboxylesterase (CES) in MMF hydrolysis was examined in vitro using human liver microsomes. V(max) and K(m) values of MMF hydrolysis in pooled human liver microsomes were 1368 +/- 44 nmol min(-1) mg(-1) protein and 1030 +/- 65 microM, respectively. Hydrolytic activity was inhibited by the CES inhibitors phenylmethylsulfonylfluoride, bis-p-nitorophenylphosphate and diisopropylfluorophosphate, with IC(50) values of 77.1, 3.59 and 0.0312 microM, respectively. Eighty Japanese renal transplant recipients that received repeated-doses of MMF, tacrolimus and prednisolone,were evaluated for MPA pharmacokinetics 28 days after transplantation to investigate the relationship between MPA pharmacokinetics and CES2 genetic polymorphisms. No significant differences in MPA pharmacokinetics were observed between CES2 A4595G, C8721T orA-1548G genotype groups. CES2 allelic variants also did not appear to affect plasma MPA concentrations between individuals. In conclusion, the study demonstrated that while CES1 and/or CES2 are involved in the hydrolysis of MMF to MPA, CES2 allelic variants appeared to make only a minor contribution to inter-personal differences in MPA pharmacokinetics.

Effect of telmisartan, valsartan and candesartan on mycophenolate mofetil pharmacokinetics in Japanese renal transplant recipients.

OBJECTIVE: The aim of this study was to elucidate the effect of the peroxisome proliferator-activated receptor-gamma (PPAR-gamma) activating angiotensin receptor blocker (ARB) telmisartan and the non-PPAR-gamma activating ARB valsartan and candesartan on mycophenolic acid (MPA) pharmacokinetics in renal transplant recipients. METHODS: Recipients (n = 10 each group) were randomly given either 40 mg of telmisartan, 80 mg of valsartan or 8 mg of candesartan cilexetil for at least 6 months, and no ARB. Blood was sampled a year after transplantation. RESULTS: Dose-adjusted maximum and trough plasma concentration of MPA co-administered with telmisartan were the lowest in all groups. The mean dose-adjusted area under the concentration curve from 0 to 12 h (AUC(0-12)) and AUC(0-6) of MPA co-administered with telmisartan were significantly lower than that without ARB (98 vs. 138 ng x h/mL/mg, P = 0.0353 and 63 vs. 96 ng x h/mL/mg, P = 0.0305). Coadministration of valsartan and candesartan did not alter MPA pharmacokinetics. The AUC ratio of MPA glucuronide (MPAG)/MPA co-administered with telmisartan was higher than that without ARBs, but not significantly (14.2 vs. 9.1). The mean maximum and minimum plasma concentrations of telmisartan (40 mg) after oral administration were 84 and 15 ng/mL, respectively, and that of valsartan (80 mg) 2220 and 441 ng/mL, respectively. Plasma concentrations of candesartan in most transplant patients were not observed 19 h after oral administration of candesartan cilexeil (8 mg). CONCLUSIONS: The degree of drug interaction between MPA and telmisartan was significantly greater than that between MPA and valsartan or candesartan. Uridine diphosphate-glucuronosyltransferase (UGT) 1A9 has been identified as a PPAR-gamma target gene. UGT induction by telmisartan might stimulate MPA glucuronidation. A combination of telmisartan and mycophenolate mofetil might require periodic monitoring of MPA.

No pharmacokinetic interactions between mycophenolic acid and tacrolimus in renal transplant recipients.

OBJECTIVE: The aim of this study was to investigate drug interactions between mycophenolic acid (MPA), the active metabolite of mycophenolate mofetil (MMF) and tacrolimus, as well as the impact of CYP3A5 and UGT2B7 genetic polymorphisms on these drug interactions in 71 Japanese renal transplant recipients. METHODS: Recipients received combination immunosuppressive therapy consisting of tacrolimus and MMF. On day 28 after transplantation, the concentrations of MPA and tacrolimus were measured by high-performance liquid chromatography and microparticle enzyme immunoassay respectively. RESULTS: Acute rejection was over twice more common in recipients with a total area under the observed plasma concentration-time curve (AUC(0-12)) of MPA <70 microg x h/mL than in those with higher values AUC(0-12) values (17% vs. 7%). Using this cut-off AUC value, sensitivity was 70.6% and specificity 55.6% for acute rejection (AR). There was no change in AUC(0-12), maximum plasma concentration, trough plasma concentration, or oral clearance of tacrolimus with variation in dosage or AUC of MPA. There were also no significant differences in the MPA pharmacokinetic parameters among three tacrolimus C(0) groups: 5 < or = C(0) < 10, 10 < or = C(0) < 15 and 15 < or =C(0) < 20 ng/mL. Furthermore, there were no significant differences in MPA pharmacokinetic parameters between the UGT2B7*1/*1 and *1/*2 genotype groups having the CYP3A5*1 allele or the CYP3A5*3/*3 genotype. CONCLUSION: Therapeutic dosages of MMF, do not significantly influence tacrolimus pharmacokinetics, and vice versa. Consequently, MPA and tacrolimus can be safely combined; however, it is necessary to monitor the plasma concentrations of each immunosuppressive agent to minimize acute rejection.

Influence of ABCB1 C3435T polymorphism on the pharmacokinetics of lansoprazole and gastroesophageal symptoms in Japanese renal transplant recipients classified as CYP2C19 extensive metabolizers and treated with tacrolimus.

OBJECTIVE: Lansoprazole and tacrolimus are substrates of ATP binding cassette (ABC) transporters such as P-glycoprotein (ABCBI/multidrug resistance 1) and cytochrome P450 (CYP). The purpose of this study was to investigate the implication of the ABCB1 C3435Tpolymorphism on the pharmacokinetics of (R)-lansoprazole, the major enantiomer, in CYP2C19 extensive metabolizers (EMs) and on gastroesophageal symptoms in renal transplant recipients receiving tacrolimus. MATERIALS: 24 recipients who were CYP2C19 EMs were studied. METHODS: Oral administration of 30 mg lansoprazole was started 2 days before transplantation. On Day 2 before and Day 28 after transplantation, the plasma concentrations of (R)-lansoprazole and tacrolimus were measured. RESULTS: Pretransplantation, there were no significant differences in the pharmacokinetic parameters of (R)-lansoprazole between the 3 ABCBI C3435T genotypes. However, after renal transplantation, the peak plasma concentration (Cma ) and area under the plasma concentration-time curve (AUCO-24) of (R)-lansoprazole in patients with the ABCB1 C3435T C allele significantly increased, but not in patients with the TT genotype. These pharmacokinetic variations in (R)-lansoprazole did not influence the AUC of tacrolimus. There were no significant differences in the frequency of gastroesophageal symptoms among the three ABCB] C3435Tgenotypes. CONCLUSIONS: (R)-lansoprazole concentrations significantly increased in CYP2C19 extensive metabolizers with the ABCB1 C3435T C allele, but not TT genotype, after renal transplantation. However, the clinical relevance of this observation may be minor because these pharmacogenetic changes were not associated with the occurrence of gastroesophageal complications.

Intestinal CYP3A4 is not involved in the enantioselective disposition of lansoprazole.

The contribution of (S)-lansoprazole to CYP3A4-catalysed sulfoxidation is greater than that of (R)-lansoprazole. The aim was to investigate the effect of grapefruit juice on the enantioselective disposition of lansoprazole among three CYP2C19 genotype groups. Eighteen healthy subjects, consisting of six each of homozygous extensive metabolizers (homEMs), heterozygous extensive metabolizers (hetEMs) and poor metabolizers (PMs), ingested a single oral dose of 60 mg racemic lansoprazole after taking either 200 ml grapefruit juice or water. There was no effect of grapefruit juice on the mean maximum plasma concentrations (C(max)) or the elimination half-life for each lansoprazole enantiomer in all three CYP2C19 genotype groups. Similarly, the pharmacokinetic parameters of lansoprazole sulfone remained unaltered by grapefruit juice in all three groups. The CYP3A4-mediated first-pass sulfoxidation of (R)- and (S)-lansoprazole were not influenced by grapefruit juice. In addition, stereoselectivity of the intestinal CYP3A4-catalysed sulfoxidation of (R)- and (S)-lansoprazole was not observed.

Comparison of enantioselective disposition of rabeprazole versus lansoprazole in renal-transplant recipients who are CYP2C19 extensive metabolizers.

The purpose of this study was to investigate the comparative pharmacokinetics of rabeprazole and lansoprazole enantiomers in renal-transplant recipients on tacrolimus who were CYP2C19 extensive metabolizers. Sixteen Japanese patients were randomly assigned after renal transplantation to receive repeated doses of one of the following two regimens for 28 days; tacrolimus, mycophenolate mofetil and prednisolone together with either 20mg of racemic rabeprazole (n=8) or 30 mg of racemic lansoprazole (n=8). The mean Cmax and AUC0-24 of (R)-lansoprazole compared to (S)-lansoprazole in renal transplant recipients were 12-fold (954+/-522 vs. 167+/-137 ngml(-1), respectively) and 6.9-fold (4787+/-3454 vs. 451+/-354 nghml(-1), respectively) greater, and its elimination half-life was 2.1-fold (2.3+/-1.0 vs. 1.2+/-0.6h, respectively) longer. In contrast, although the elimination half-life of (R)-rabeprazole was significantly longer than that of the (S)-enantiomer (2.1+/-0.5 vs. 1.3+/-0.9h, respectively; P<0.05), there was no difference in Cmax between the (R)- and (S)-enantiomer (186+/-40 vs. 200+/-92 ngml(-1), respectively). In conclusion, in renal-transplant recipients who are CYP2C19 extensive metabolizers, there is less stereoselective difference in the pharmacokinetic disposition between the (R)- and (S)-enantiomers of rabeprazole than those of lansoprazole.