TGR5-dependent hepatoprotection through the regulation of biliary epithelium barrier function.

OBJECTIVE: We explored the hypothesis that TGR5, the bile acid (BA) G-protein-coupled receptor highly expressed in biliary epithelial cells, protects the liver against BA overload through the regulation of biliary epithelium permeability. DESIGN: Experiments were performed under basal and TGR5 agonist treatment. In vitro transepithelial electric resistance (TER) and FITC-dextran diffusion were measured in different cell lines. In vivo FITC-dextran was injected in the gallbladder (GB) lumen and traced in plasma. Tight junction proteins and TGR5-induced signalling were investigated in vitro and in vivo (wild-type [WT] and TGR5-KO livers and GB). WT and TGR5-KO mice were submitted to bile duct ligation or alpha-naphtylisothiocyanate intoxication under vehicle or TGR5 agonist treatment, and liver injury was studied. RESULTS: In vitro TGR5 stimulation increased TER and reduced paracellular permeability for dextran. In vivo dextran diffusion after GB injection was increased in TGR5-knock-out (KO) as compared with WT mice and decreased on TGR5 stimulation. In TGR5-KO bile ducts and GB, junctional adhesion molecule A (JAM-A) was hypophosphorylated and selectively downregulated among TJP analysed. TGR5 stimulation induced JAM-A phosphorylation and stabilisation both in vitro and in vivo, associated with protein kinase C-ζ activation. TGR5 agonist-induced TER increase as well as JAM-A protein stabilisation was dependent on JAM-A Ser285 phosphorylation. TGR5 agonist-treated mice were protected from cholestasis-induced liver injury, and this protection was significantly impaired in JAM-A-KO mice. CONCLUSION: The BA receptor TGR5 regulates biliary epithelial barrier function in vitro and in vivo through an impact on JAM-A expression and phosphorylation, thereby protecting liver parenchyma against bile leakage.

Pharmacological activation of TGR5 promotes intestinal growth via a GLP-2-dependent pathway in mice.

Glucagon-like peptide (GLP)-1 and -2-secreting L cells have been shown to express the bile acid receptor Takeda G protein-receptor-5 (TGR5) and increase secretion upon receptor activation. Previous studies have explored GLP-1 secretion following acute TGR5 activation, but chronic activation and GLP-2 responses have not been characterized. In this study, we aimed to investigate the consequences of pharmacological TGR5 receptor activation on L cell hormone production in vivo using the specific TGR5 agonist RO5527239 and the GLP-2 receptor knockout mouse. Here, we show that 1) TGR5 receptor activation led to increased GLP-1 and GLP-2 content in the colon, which 2) was associated with an increased small intestinal weight that 3) was GLP-2 dependent. Additionally, we report that TGR5-mediated gallbladder filling occurred independently of GLP-2 signaling. In conclusion, we demonstrate that pharmacological TGR5 receptor activation stimulates L cells, triggering GLP-2-dependent intestinal adaption in mice.NEW & NOTEWORTHY Using the specific Takeda G protein-receptor-5 (TGR5) agonist RO5527239 and GLP-2 receptor knockout mice, we show that activation of TGR5 led to the increase in colonic GLP-1 and GLP-2 concomitant with a GLP-2 dependent growth response in the proximal portion of the small intestine.

Identification of a novel, non-tetrahydroquinoline variant of the cholesteryl ester transfer protein (CETP) inhibitor torcetrapib, with improved aqueous solubility.

1. Elaborate studies of cholesteryl ester transfer protein (CETP) polymorphisms and genetic deficiency in humans suggest direct links between CETP, high-density lipoprotein cholesterol (HDL-c) levels and coronary heart diseases. The hypothesis that CETP inhibition by small molecule inhibitors raises HDL-c has been validated clinically with structurally-diverse CETP inhibitors such as torcetrapib, anacetrapib, dalcetrapib and evacetrapib. 2. Despite promising phase 2 results with respect to HDL-c elevation, torcetrapib was discontinued in phase 3 trials due to increased mortality rates in the cardiovascular outcomes study. Emerging evidence for the adverse effects hints at off-target chemotype-specific cardiovascular toxicity, possibly related to the pressor effects of torcetrapib, since structurally diverse CETP inhibitors such as anacetrapib, evacetrapib and dalcetrapib are not associated with blood pressure increases in humans. Nonclinical follow-up studies showed that torcetrapib induces aldosterone biosynthesis and secretion in vivo and in vitro, an effect which is not observed with other CETP inhibitors in clinical development. 3. As part of ongoing efforts to identify novel CETP inhibitors devoid of pressor effects, strategies were implemented towards the design of compounds, which lack the 1,2,3,4-tetrahydroquinoline (THQ) scaffold present in torcetrapib. In this article, we disclose results of structure-activity relationship studies for a series of novel non-THQ CETP inhibitors, which resulted in the identification of a novel isonipecotic acid derivative 10 (also referred to as PF-04445597) with vastly improved oral pharmacokinetic properties mainly as a result of improved aqueous solubility. This feature is attractive in that, it bypasses significant investments needed to develop compatible solubilizing formulation(s) for oral drug delivery of highly lipophilic and poorly soluble compounds; attributes, which are usually associated with small molecule CETP inhibitors. PF-04445597 was also devoid of aldosterone secretion in human H295R adrenal carcinoma cells.

Characterization of a human and murine mPGES-1 inhibitor and comparison to mPGES-1 genetic deletion in mouse models of inflammation.

Microsomal prostaglandin E synthase-1 (mPGES-1) inhibition has been suggested as an alternative to cyclooxygenase (COX) inhibition in the treatment of pain and inflammation. We characterized a selective inhibitor of mPGES-1 activity (compound III) and studied its impact on the prostanoid profile in various models of inflammation. Compound III is a benzoimidazole, which has a submicromolar IC50 in both human and rat recombinant mPGES-1. In cellular assays, it reduced PGE2 production in A549 cells, mouse macrophages and blood, causing a shunt to the prostacyclin pathway in the former two systems. Lastly, we assayed compound III in the air pouch model to verify its impact on the prostanoid profile and compare it to the profile obtained in mPGES-1 k.o. mice. As opposed to mPGES-1 genetic deletion, which attenuated PGE2 production and caused a shunt to the thromboxane pathway, mPGES-1 inhibition with compound III reduced PGE2 production and tended to decrease the levels of other prostanoids.

Design, synthesis and biological evaluation of α-substituted isonipecotic acid benzothiazole analogues as potent bacterial type II topoisomerase inhibitors.

The discovery and optimisation of a new class of benzothiazole small molecules that inhibit bacterial DNA gyrase and topoisomerase IV are described. Antibacterial properties have been demonstrated by activity against DNA gyrase ATPase and potent activity against Staphylococcus aureus, Enterococcus faecalis, Streptococcus pyogenes and Haemophilus influenzae. Further refinements to the scaffold designed to enhance drug-likeness included analogues bearing an α-substituent to the carboxylic acid group, resulting in excellent solubility and favourable pharmacokinetic properties.

Initial data on the safety of metopimazine during pregnancy and the risk of major birth defects and pregnancy loss - An observational study using the EFEMERIS database.

INTRODUCTION: Metopimazine is an anti-emetic drug used to treat nausea and vomiting of pregnancy. However, no animal or clinical data are available regarding its safety in pregnant women. The aim of this study was, therefore, to assess the risk of birth defects and pregnancy loss associated with the use of metopimazine during pregnancy in a population-based cohort study. METHODS: The study focused on the EFEMERIS database including the prescription and dispensation of drugs for pregnant women in Haute-Garonne, France, between July 2004 and December 2017. This was an observational, retrospective, comparative study. Pregnancy loss and major birth defects were compared between women exposed to metopimazine during pregnancy and those with no exposure using multivariate logistic regression and Cox proportional risk models. RESULTS: Among 135,574 pregnant women, 11,402 (8.2%) were exposed to metopimazine during pregnancy, mostly in the first trimester (more than 70% of women). No association was found between major birth defects and exposure to metopimazine in the first trimester of pregnancy (ORa=[95% CI]=1.06 [0.92-1.23]). Pregnancy loss was negatively associated with metopimazine use during pregnancy (HRa [95% CI]=0.80 [0.72-0.88]), taking into account major potential confounders. Comparable rates were recorded between women exposed to metopimazine and those unexposed to the drug in terms of prematurity (6.7% vs. 6.4%), low birth weight (6.2% vs. 6.2%) and small for gestational age (1.2% vs. 1.4%). CONCLUSION: This study illustrates the wide use of metopimazine during pregnancy in France although no studies on efficacy or safety in pregnant women are available. The results of this study do not indicate any teratogenic effect or an increased risk of pregnancy loss of metopimazine.

Metopimazine is primarily metabolized by a liver amidase in humans.

Metopimazine (MPZ) is a peripherally restricted, dopamine D2 receptor antagonist used for four decades to treat acute nausea and vomiting. MPZ is currently under clinical investigation for the treatment of gastroparesis (GP). MPZ undergoes high first-pass metabolism that produces metopimazine acid (MPZA), the major circulating metabolite in humans. Despite a long history of use, the enzymes involved in the metabolism of MPZ have not been identified. Here we report a series of studies designed to identify potential MPZ metabolites in vitro, determine their clinical relevance in humans, and elucidate the enzymes responsible for their formation. The findings demonstrated that the formation of MPZA was primarily catalyzed by human liver microsomal amidase. Additionally, human liver cytosolic aldehyde oxidase (AO) catalyzes the formation of MPZA, in vitro, although to a much lesser extent. Neither cytochrome P450 enzymes nor flavin-monooxygenases (FMO) were involved in the formation MPZA, although two minor oxidative pathways were catalyzed by CYP3A4 and CYP2D6 in vitro. Analysis of plasma samples from subjects dosed 60 mg of MPZ verified that these oxidative pathways are very minor and that CYP enzyme involvement was negligible compared to microsomal amidase/hydrolase in overall MPZ metabolism in humans. The metabolism by liver amidase, an enzyme family not well defined in small molecule drug metabolism, with minimal metabolism by CYPs, differentiates this drug from current D2 antagonists used or in development for the treatment of GP.

Discovery of potent pteridine reductase inhibitors to guide antiparasite drug development.

Pteridine reductase (PTR1) is essential for salvage of pterins by parasitic trypanosomatids and is a target for the development of improved therapies. To identify inhibitors of Leishmania major and Trypanosoma cruzi PTR1, we combined a rapid-screening strategy using a folate-based library with structure-based design. Assays were carried out against folate-dependent enzymes including PTR1, dihydrofolate reductase (DHFR), and thymidylate synthase. Affinity profiling determined selectivity and specificity of a series of quinoxaline and 2,4-diaminopteridine derivatives, and nine compounds showed greater activity against parasite enzymes compared with human enzymes. Compound 6a displayed a K(i) of 100 nM toward LmPTR1, and the crystal structure of the LmPTR1:NADPH:6a ternary complex revealed a substrate-like binding mode distinct from that previously observed for similar compounds. A second round of design, synthesis, and assay produced a compound (6b) with a significantly improved K(i) (37 nM) against LmPTR1, and the structure of this complex was also determined. Biological evaluation of selected inhibitors was performed against the extracellular forms of T. cruzi and L. major, both wild-type and overexpressing PTR1 lines, as a model for PTR1-driven antifolate drug resistance and the intracellular form of T. cruzi. An additive profile was observed when PTR1 inhibitors were used in combination with known DHFR inhibitors, and a reduction in toxicity of treatment was observed with respect to administration of a DHFR inhibitor alone. The successful combination of antifolates targeting two enzymes indicates high potential for such an approach in the development of previously undescribed antiparasitic drugs.

Synthesis and inotropic evaluation of 1-substituted-N-(4,5-dihydro-1-methyl-[1,2,4]triazolo[4,3-a]quinolin-7-yl)piperidine-4-carboxamides.

A series of 1-substituted-N-(4,5-dihydro-1-methyl-[1,2,4]triazolo[4,3-a]quinolin-7-yl) piperidine-4-carboxamides has been synthesized and evaluated for positive inotropic activity by measuring left atrium stroke volume in isolated rabbit-heart preparations. Some of these derivatives exhibited favorable activity compared with the standard drug, milrinone, among which 1-(2-fluorobenzyl)-N-(4,5-dihydro-1-methyl-[1,2,4]triazolo[4,3-a]quinolin-7-yl)piperidine-4-carboxamide 6a was the most potent, increasing stroke volume by 11.92+/-0.35% (milrinone: 6.36+/-0.13%) at 1x10(-4)M.

Effect of iontophoresis and penetration enhancers on transdermal absorption of metopimazine.

BACKGROUND: Metopimazine is an antiemetic drug already used by oral and rectal administration. It would be interesting to develop a new formulation for a transdermal administration. OBJECTIVE: The objective of this study was to determine the influence of iontophoresis on the metopimazine transdermal absorption and the possible synergistic enhancement with chemical enhancers. METHODS: Transdermal transport of metopimazine was studied in vitro in a Franz cell with pig skin according to the following protocol: 1h of iontophoresis followed by 7h of passive diffusion. Different current densities were applied: 0, 0.125, 0.25 and 0.5 mA/cm(2). Chemical enhancers used as solvent dilution were ethanol, propylene glycol and isopropyl myristate. Metopimazine was assayed by HPLC. Fourier transform infrared spectroscopy was used to determinate the interaction between chemical enhancers and stratum corneum. RESULTS: The iontophoresis has increased the percutaneous absorption of metopimazine and has decreased the lag time with 3.85+/-0.90 microg/(cm(2)h) and 1.9h for 0.5 mA/cm(2) and with 0.27+/-0.20 microg/(cm(2)h) and >8h for passive diffusion. Transdermal transport has been increased with current density and with isopropyl myristate and was not modified by ethanol or propylene glycol. CONCLUSION: Results indicated that iontophoresis is an effective method for transdermal administration of metopimazine.

Modifications of the isonipecotic acid fragment of SNS-032: analogs with improved permeability and lower efflux ratio.

Modifications of the isonipecotic acid fragment of SNS-032 results in analogs which are more permeable and lower effluxed than SNS-032. The enantiomerically pure synthesis and the in vivo profile of analog 20 is described.

Simultaneous analysis of five antidepressant drugs using direct injection of biofluids in a capillary restricted-access media-liquid chromatography-tandem mass spectrometry system.

Direct analysis, with minimal sample pretreatment, of antidepressant drugs, fluoxetine, imipramine, desipramine, amitriptyline, and nortriptyline in biofluids was developed with a total run time of 8 min. The setup consists of two HPLC pumps, injection valve, capillary RAM-ADS-C18 pre-column and a capillary analytical C18 column connected by means of a six-port valve in backflush mode. Detection was performed with ESI-MS/MS and only 1 microm of sample was injected. Validation was adequately carried out using FLU-d(5) as internal standard. Calibration curves were constructed under a linear range of 1-250 ng mL(-1) in plasma, being the limit of quantification (LOQ), determined as 1 ng mL(-1), for all the analytes. With the described approach it was possible to reach a quantified mass sensitivity of 0.3 pg for each analyte (equivalent to 1.1-1.3 fmol), translating to a lower sample consumption (in the order of 10(3) less sample than using conventional methods).

Percutaneous absorption of metopimazine and effect of cyclodextrins.

Metopimazine (MPZ) is used to prevent emesis during chemotherapies. A transdermal delivery system of MPZ may present a great advantage in patients to improve compliance. Hydroxypropyl beta cyclodextrin (HPbetaCD) and partially methylated beta cyclodextrin (PMbetaCD) were tested to enhance the percutaneous absorption of MPZ through pig skin using Franz's cells. The MPZ hydrochloride flux was low with 0.176 +/- 0.054 microg/h/cm(2) and no flux was detected with a suspension of MPZ (base). The used characterization analyses demonstrated the formation of an inclusion complex with cyclodextrin and this complex improved percutaneous absorption of MPZ. Flux was increased to 0.240 +/- 0.032 microg/h/cm(2) and 0.566 +/- 0.057 mug/h/cm(2) for HPbetaCD and PMbetaCD, respectively, with a concentration of 20%. This study has shown that HPbetaCD and PMbetaCD improved the percutaneous penetration of MPZ. Cyclodextrin complexes increased MPZ bioavailability at the skin surface and PMbetaCD was also able to extract cutaneous fatty acids.

Differential pulse cathodic voltammetric determination of floctafenine and metopimazine.

A simple, rapid and sensitive voltammetric method for the determination of floctafenine (FFN) and metopimazine (MPZ) was developed. Well-defined cathodic waves were obtained for both drugs in Britton-Robinson buffer pH 9.0 using the differential-pulse mode at the hanging mercury drop electrode (HMDE). The current-concentration relationship was found to be linear over the ranges 0.4-3.6 and 0.4-2.4 microg ml(-1) for FFN and MPZ, respectively. The quantification of the two drugs in their pharmaceutical formulations was carried out using the proposed voltammetric method and compared with spectrophotometric analysis data. The mechanisms of the electrode reactions for the two drugs were proposed.

The Ascaris suum nicotinic receptor, ACR-16, as a drug target: Four novel negative allosteric modulators from virtual screening.

Soil-transmitted helminth infections in humans and livestock cause significant debility, reduced productivity and economic losses globally. There are a limited number of effective anthelmintic drugs available for treating helminths infections, and their frequent use has led to the development of resistance in many parasite species. There is an urgent need for novel therapeutic drugs for treating these parasites. We have chosen the ACR-16 nicotinic acetylcholine receptor of Ascaris suum (Asu-ACR-16), as a drug target and have developed three-dimensional models of this transmembrane protein receptor to facilitate the search for new bioactive compounds. Using the human α7 nAChR chimeras and Torpedo marmorata nAChR for homology modeling, we defined orthosteric and allosteric binding sites on the Asu-ACR-16 receptor for virtual screening. We identified four ligands that bind to sites on Asu-ACR-16 and tested their activity using electrophysiological recording from Asu-ACR-16 receptors expressed in Xenopus oocytes. The four ligands were acetylcholine inhibitors (SB-277011-A, IC50, 3.12 ± 1.29 µM; (+)-butaclamol Cl, IC50, 9.85 ± 2.37 µM; fmoc-1, IC50, 10.00 ± 1.38 µM; fmoc-2, IC50, 16.67 ± 1.95 µM) that behaved like negative allosteric modulators. Our work illustrates a structure-based in silico screening method for seeking anthelmintic hits, which can then be tested electrophysiologically for further characterization.

Randomized, double-blind comparison of ondansetron versus ondansetron plus metopimazine as antiemetic prophylaxis during platinum-based chemotherapy in patients with cancer.

PURPOSE: To investigate the antiemetic effect and tolerability of the 5-hydroxytryptamine3(5-HT3) antagonist ondansetron plus the dopamine D2 antagonist metopimazine versus ondansetron alone in patients receiving platinum-based chemotherapy. PATIENTS AND METHODS: One hundred eleven chemotherapy-naive patients who were scheduled to receive two consecutive courses of platinum-based chemotherapy were randomized between ondansetron 8 mg intravenously (IV) followed by 8 mg orally twice a day plus metopimazine 35 mg/m2 as a 24-hour continuous infusion followed by 30 mg orally four times a day for 4 days, or ondansetron plus placebo. The study used a double-blind, crossover, placebo-controlled design. RESULTS: Ninety-four patients completed the crossover. Complete response (CR; no emetic episodes) was obtained on day 1 in 77.7% of the patients who received the combination versus 50.0% of those who received ondansetron alone (P = .00002), and in 51.7% versus 31.0% on days 2 to 6 (P = .0009). The overall CR (days 1 to 6) was 48.9% versus 25.3% (P = .0002). Additionally, significantly less nausea was observed with the combination on day 1 (P = .0002), days 2 to 6 (P = .0001), and days 1 to 6 (P = .00004). Patient preference was 63.6% for the combination and 13.6% for ondansetron alone; 22.7% expressed no treatment preference (P < .0001; therapeutic gain 50.0%; 95% confidence interval [CI], 31.6% to 68.4%). Adverse reactions were mild and without significant differences between the two treatments. CONCLUSION: Metopimazine plus ondansetron was significantly superior to ondansetron alone, concerning all efficacy parameters assessed, in patients who received platinum-based chemotherapy.

Ondansetron plus metopimazine compared with ondansetron plus metopimazine plus prednisolone as antiemetic prophylaxis in patients receiving multiple cycles of moderately emetogenic chemotherapy.

PURPOSE: To compare the antiemetic efficacy and tolerability of ondansetron plus metopimazine with ondansetron plus metopimazine plus prednisolone during nine cycles of moderately emetogenic chemotherapy. PATIENTS AND METHODS: A total of 221 women with stage I or II breast cancer and no prior chemotherapy who were scheduled to receive adjuvant chemotherapy with intravenous cyclophosphamide, fluorouracil and methotrexate or cyclophosphamide, epirubicin, and fluorouracil given every 3 weeks were included in a double-blind parallel trial. Patients were randomized to 3 days of oral treatment with ondansetron plus metopimazine, or ondansetron plus metopimazine plus prednisolone. Ondansetron was administered as 8 mg bid, metopimazine as 30 mg qid, and prednisolone as 50 mg qd. RESULTS: In all, 216 patients (97.7%) were assessable for efficacy during a total of 1,462 cycles. In cycle 1, complete protection from emetic episodes/nausea day 1, days 2 through 5, and days 1 through 5 was achieved in 84.4%/51.4%, 82.6%/41.3%, and 79.8%/34.9% with ondansetron plus metopimazine and in 84.1%/57.0%, 86.8%/53.8%, and 79.4%/43.0% with ondansetron plus metopimazine plus prednisolone, respectively. In cycle 1, the three-drug combination was superior only in the treatment of nausea on days 2 through 5 (P =.0497). The cumulative emetic protection rate after nine cycles was 0.52 with ondansetron plus metopimazine and 0.75 with ondansetron plus metopimazine plus prednisolone. Side effects were generally few and mild with both treatments. Constipation was the only adverse event significantly more frequent with the three-drug combination (P =.029). CONCLUSION: Ondansetron plus metopimazine plus prednisolone is highly effective and superior to ondansetron plus metopimazine during nine cycles of moderately emetogenic chemotherapy.

Comparison of the efficacy and safety of combinations of metopimazine or ondansetron with methylprednisolone in the prevention of delayed emesis in patients receiving chemotherapy.

BACKGROUND: Delayed emesis following chemotherapy in cancer patients remains an important challenge for treatment and contributes to poor quality of life and treatment compliance. OBJECTIVES: To compare the efficacy and tolerability of associations of metopimazine and ondansetron with methylprednisolone for the prevention of delayed chemotherapy-induced nausea and emesis. METHODS: A randomised, open-label, observational, cross-over design was used to compare two treatment strategies following two consecutive sessions of chemotherapy separated by at least 1 week. Patients were randomised to treatment with sublingual metopimazine (15 mg tid) or ondansetron lyophilisate (8 mg bid) for 5 days. All patients received oral methylprednisolone (48 mg). Patients reported episodes of nausea and emesis in a diary, and completed the Functional Living Index Emesis quality of life questionnaire. Adverse events were also evaluated. RESULTS: Ninety-nine patients were included in the study, 79.5% of whom were women, with a mean age of 52.7 years. Breast cancer was the most common individual cancer and most patients were receiving combinations of cytotoxic drugs. Treatment was successful at preventing delayed emesis in 73.6% of patients during treatment with the metopimazine-methylprednisolone association and 57.5% during the ondansetron-methylprednisolone association. Analysis of discordant pairs revealed a significant benefit in favour of the methopimazine-methylprednisolone association (p = 0.006). No significant difference was observed between treatments for the overall quality of life score. The incidence of gastrointestinal disorders, particularly constipation, was significantly higher during ondansetron-methylprednisolone treatment (p = 0.0112). CONCLUSION: Methopimazine is an effective and well-tolerated alternative to setrons for the treatment of delayed nausea and emesis in patients undergoing chemotherapy.

Determination of plasma pipecolic acid by an easy and rapid liquid chromatography-tandem mass spectrometry method.

Pipecolic acid (PA) is an important biochemical marker for the diagnosis of peroxisomal disorders. PA is also a factor responsible for hepatic encephalopathy and a possible biomarker for pyridoxine-dependent seizures. We developed an easy and rapid PA quantification method, by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), requiring no derivatization and applicable to small sample volumes. Plasma (100 µl) is extracted with 500 µl acetonitrile (ACN) containing 2 µmol/l [(2)H5]-phenylalanine as internal standard, vortexed and centrifuged. The supernatant is analyzed by HPLC-MS/MS in positive-ion mode using multiple reaction monitoring scan type. HPLC column is a Luna HILIC (150×3.0mm; 3 µ 200A): Buffer A: ammonium formate 5 mmol/l; Buffer B: ACN/H20 90:10 containing ammonium formate 5 mmol/l. PA retention time is 4.86 min. Recovery was 93.8%, linearity was assessed between 0.05 and 50 µmol/l (R(2)=0.998), lower limit of detection was 0.010 µmol/l and lower limit of quantification was 0.050 µmol/l. Coefficient of variation was 3.2% intra-assay and 3.4% inter-assay, respectively. Clinical validation was obtained by comparing PA plasma values from 5 patients affected by peroxisomal disorders (mean, 23.38 µmol/l; range, 11.20-37.1 µmol/l) to 24 ages related healthy subjects (mean, 1.711 µmol/l; range, 0.517-3.580 µmol/l).