Background: Pembrolizumab is a monoclonal antibody (mAb) approved for treating Non-Small Cell Lung Cancer (NSCLC), melanoma and lymphomas. Commercialized in single-size (100 mg/4 mL) vials, the pembrolizumab solution contains no preservative. As such, the manufacturer recommends using pembrolizumab vials only once, and thus, to rapidly dispose of any unused portion. Thus, appreciable amounts of this costly product are wasted. Objective: To evaluate the physical, chemical and microbiological stability of pembrolizumab vial leftovers stored at room temperature or at 4 °C, 7 and 14 days after first vial puncturing. Methods: Following pH assessments, submicronic aggregation and turbidity of pembrolizumab were measured by dynamic light scattering (DLS) and spectrophotometry, respectively. In addition, SE-HPLC (size-exclusion high-performance liquid chromatography), IEX-HPLC (ion exchange HPLC) and peptide mapping HPLC served to respectively evaluate aggregation and fragmentation, distribution of charge and primary structure of pembrolizumab. Incubation at 37 °C for 48 h of pembrolizumab vial leftovers on blood agar plates was used to determine their microbiological stability. Results: Physical, chemical and microbiological stability of pembrolizumab leftovers was demonstrated for at least two full weeks. Conclusions: These results argue forcefully in favor of allowing prolongation of pembrolizumab vial leftovers usage well beyond a single day.

A few years ago, ranolazine, acting mainly by blocking late sodium channels (INa-L), was approved as an add-on therapy for treating symptomatic angina. Early clinical experience with ranolazine has shown that, among its side effects, the drug causes dose-dependent reductions of both glycemia and glycated hemoglobin (A1C) in individuals affected by chronic angina and type 2 diabetes (T2D). Interestingly, it was recently shown that the antidiabetic drugs empagliflozin, canagliflozin, and dapagliflozin (all SGLT-2 inhibitors), while causing glycosuria, are also blocking INa-L, suggesting that this mechanism could also contribute to their antidiabetic action. Eleclazine is a recently developed drug that is selective and 8 times more potent than ranolazine to block INa-L. Although it has shown disappointing results in heart failure and arrhythmia trials, the potential antidiabetic action of eleclazine as a pure INa-L blocker has never been investigated. The objective was, therefore, to test the hypothesis that eleclazine has relevant antidiabetic effects in vivo in an animal model of T2D.

Durvalumab is a monoclonal antibody approved for the treatment of lung, urothelial and biliary tract cancers. Durvalumab is supplied in vials as a solution containing no preservatives. Monographs recommend single use of durvalumab vials, and that any leftovers be discarded within 24 h. Thus, significant portions of unused product from opened vials are wasted on a daily basis, generating considerable financial losses. The objective of the present study was to assess the physicochemical and microbiological stability of durvalumab vials kept at 4 °C or room temperature, at 7 and 14 days after opening. Following pH and osmolality measurements, turbidity and submicronic aggregation of durvalumab solution were evaluated by spectrophotometry and dynamic light scattering, respectively. Moreover, steric exclusion high performance liquid chromatography (SE-HPLC), ion exchange HPLC (IEX-HPLC) and peptide mapping HPLC were used to respectively assess aggregation/fragmentation, charge distribution and primary structure of durvalumab. Microbiological stability of durvalumab was evaluated by incubation of vial leftovers on blood agar. All experiments showed physicochemical and microbiological stability of durvalumab vial leftovers for at least 14 days when aseptically handled and kept at either 4 °C or at room temperature. These results suggest the possible extension of utilization of durvalumab vial leftovers well beyond 24 h.

Maintenance of normal cardiac rhythm requires coordinated activity of ion channels and transporters that allow well-ordered propagation of electrical impulses across the myocardium. Disruptions in this orderly process provoke cardiac arrhythmias that may be lethal in some patients. Risk of common acquired arrhythmias is increased markedly when structural heart disease caused by myocardial infarction (due to fibrotic scar formation) or left ventricular dysfunction is present. Genetic polymorphisms influence structure or excitability of the myocardial substrate, which increases vulnerability or risk of arrhythmias in patients. Similarly, genetic polymorphisms of drug-metabolizing enzymes give rise to distinct subgroups within the population that affect specific drug biotransformation reactions. Nonetheless, identification of triggers involved in initiation or maintenance of cardiac arrhythmias remains a major challenge. Herein, we provide an overview of knowledge regarding physiopathology of inherited and acquired cardiac arrhythmias along with a summary of treatments (pharmacologic or non-pharmacologic) used to limit their effect on morbidity and potential mortality. Improved understanding of molecular and cellular aspects of arrhythmogenesis and more epidemiologic studies (for a more accurate portrait of incidence and prevalence) are crucial for development of novel treatments and for management of cardiac arrhythmias and their consequences in patients, as their incidence is increasing worldwide.

Abstract: Bradycardia and QTc interval prolongation on the ECG have been reported with remdesivir (Veklury), an antiviral drug recently approved for treating severely ill patients with COVID-19. The objective was to evaluate the effects of remdesivir on cardiac electrophysiology ex vivo and in vivo. Ex vivo: Langendorff retroperfusion experiments were performed on isolated hearts from male Hartley guinea pigs (n = 23, total) exposed to either remdesivir 3, 10, or 30 µmol/L to assess drug-induced prolongation of the monophasic action potential duration measured at 90% repolarization (MAPD90). In vivo: ECG recordings using wireless cardiac telemetry were performed in guinea pigs (n = 6) treated with daily i.p. doses of remdesivir 5 mg/kg on day 1 and 2.5 mg/kg on days 2–10. Ex vivo remdesivir (3, 10, and 30 µmol/L) had no statistically significant effect on MAPD90, while pacing the hearts at basic stimulation cycle lengths of 200 or 250 milliseconds, or when the hearts were not paced and beating at their intrinsic heart rate. In a second set of similar ex vivo experiments, remdesivir 10 µmol/L did not potentiate the MAPD90-prolonging effects of dofetilide 20 nmol/L (n = 4) hearts. In vivo remdesivir caused small but statistically significant prolongations of the RR and QTcF intervals at day 1 (5 mg/kg) and at day 10 (2.5 mg/kg). No ventricular arrhythmias were ever observed under the effect of remdesivir. Remdesivir causes bradycardia, and mild QTc prolongation, which nonetheless, could be of clinical relevance in many hospitalized patients with COVID-19 concomitantly treated with multiple drugs.

BACKGROUNDRemdesivir was authorized with conditions in Canada on July 27, 2020 for the treatment of severe COVID-19 in adults and youth (aged ≥ 12 years) with pneumonia requiring supplemental oxygen. In the Canadian Veklury® monograph, it is mentioned that current non-clinical and clinical data do not suggest a risk of QT prolongation, but QT prolongation has not been fully evaluated in humans. Interestingly, in a recent small series of 67 patients treated with remdesivir alone daily (200 mg Day 1, 100 mg Days 2-7); although no instance of torsades de pointes was reported, there was a mean 24.4-ms increase in the QTc, with 9% of all QTc ≥ 500 ms and 9% of all DQTc ≥ 60 ms. Our aim was therefore to further evaluate the effects of remdesivir on cardiac electrophysiology.METHODS AND RESULTS1) Ex vivo Langendorff retroperfusion experiments: Isolated hearts from male Hartley guinea pigs were either let at their natural sinus rhythm (SR) or paced at basic cycle lengths (BCL) of 250 or 200 ms. They were allowed to stabilize and were then exposed for 15 minutes to either remdesivir 3 (n=7), 10 (n=7) or 30 (n=5) µmol/L to assess drug-induced effect on monophasic action potential duration measured at 90% repolarization (MAPD90). 2) In vivo wireless cardiac telemetry experiments: Guinea pigs (n=3) implanted with radio transmitters were administered i.p. daily doses of remdesivir (5 mg/kg on Day 1 and 2.5 mg/kg on Days 2-10) and continuous ECG recordings were made. Results: See Tables.CONCLUSIONPrevious clinical studies have shown peak plasma concentrations of remdesivir in the 5-10 µmol/L range after the 200 mg Day 1 dose. In the present study, remdesivir had hardly any significant ex vivo effect on MAPD90 at clinically relevant concentrations (3-30 µmol/L). However, in vivo, the drug caused significant prolongation of the QT at Day 1 and Day 10 and of QTcF at Day 10. Interestingly, a trend toward bradycardia was observed in vivo after each administration of remdesivir. More in vivo experiments are therefore required to rule out any QTc-prolonging effects of remdesivir at clinically recommended dosage. Remdesivir was authorized with conditions in Canada on July 27, 2020 for the treatment of severe COVID-19 in adults and youth (aged ≥ 12 years) with pneumonia requiring supplemental oxygen. In the Canadian Veklury® monograph, it is mentioned that current non-clinical and clinical data do not suggest a risk of QT prolongation, but QT prolongation has not been fully evaluated in humans. Interestingly, in a recent small series of 67 patients treated with remdesivir alone daily (200 mg Day 1, 100 mg Days 2-7); although no instance of torsades de pointes was reported, there was a mean 24.4-ms increase in the QTc, with 9% of all QTc ≥ 500 ms and 9% of all DQTc ≥ 60 ms. Our aim was therefore to further evaluate the effects of remdesivir on cardiac electrophysiology. 1) Ex vivo Langendorff retroperfusion experiments: Isolated hearts from male Hartley guinea pigs were either let at their natural sinus rhythm (SR) or paced at basic cycle lengths (BCL) of 250 or 200 ms. They were allowed to stabilize and were then exposed for 15 minutes to either remdesivir 3 (n=7), 10 (n=7) or 30 (n=5) µmol/L to assess drug-induced effect on monophasic action potential duration measured at 90% repolarization (MAPD90). 2) In vivo wireless cardiac telemetry experiments: Guinea pigs (n=3) implanted with radio transmitters were administered i.p. daily doses of remdesivir (5 mg/kg on Day 1 and 2.5 mg/kg on Days 2-10) and continuous ECG recordings were made. Results: See Tables. Previous clinical studies have shown peak plasma concentrations of remdesivir in the 5-10 µmol/L range after the 200 mg Day 1 dose. In the present study, remdesivir had hardly any significant ex vivo effect on MAPD90 at clinically relevant concentrations (3-30 µmol/L). However, in vivo, the drug caused significant prolongation of the QT at Day 1 and Day 10 and of QTcF at Day 10. Interestingly, a trend toward bradycardia was observed in vivo after each administration of remdesivir. More in vivo experiments are therefore required to rule out any QTc-prolonging effects of remdesivir at clinically recommended dosage.

BackgroundTacrolimus may be administered during hospitalization as an IV formulation or oral suspension. However, literature suggesting appropriate ratios for conversion from these formulations to capsules is limited.ObjectiveTo evaluate conversion ratios after a switch in formulation of tacrolimus for solid-organ transplant recipients.MethodsThis single-centre observational longitudinal study involved hospitalized patients who underwent a switch in formulation of tacrolimus according to 1 of 3 possible scenarios: IV to oral suspension, IV to capsule, or oral suspension to capsule. Data were collected from the earliest accessible electronic file (January 2009) to January 1, 2019. Conversion ratios were calculated for each of the 3 groups using data for blood concentrations and doses before and after the switch. The calculated ratios were then compared with recommended conversion ratios: 1:5 (i.e., 1 mg of IV tacrolimus is converted to 5 mg of oral tacrolimus, expressed as "5") for either of the switches involving an IV formulation and 1:1 (i.e., same amount, expressed as "1") for the switch from oral formulation to capsules.ResultsFor the group who underwent switching from the IV formulation to oral suspension, the mean calculated conversion ratio was 3.04, which was significantly different from the recommended ratio of 5. For the group who underwent switching from the IV formulation to capsules, the calculated conversion ratio was 5.18, which was not significantly different from the recommended ratio of 5. For the group who underwent switching from oral suspension to capsules, the calculated conversion ratio was 1.17, which was not significantly different from the recommended ratio of 1.ConclusionIn this small retrospective study of tacrolimus therapy, the calculated conversion ratio was significantly different from the recommended ratio for patients who were switched from IV administration to oral suspension, but not for those switched from IV administration or oral suspension to capsules. Therapeutic drug monitoring therefore appears indispensable, regardless of conversion ratios.

New Findings What is the role of SCN5A‐C683R? SCN5A‐C683R is a novel variant associated with an uncommon phenotype of adrenaline‐triggered ventricular arrhythmia in the absence of a distinct ECG phenotype. What is the main finding and its importance? Functional studies demonstrated that NaV1.5/C683R results in a mixed electrophysiological phenotype with gain‐of‐function (GOF) and loss‐of‐function (LOF) properties compared with NaV1.5/wild type. Gain‐of‐function properties are characterized by a significant increase of the maximal current density and a hyperpolarizing shift of the steady‐state activation. The LOF effect of NaV1.5/C683R is characterized by increased closed‐state inactivation. Electrophysiological properties and clinical manifestation of SCN5A‐C683R are different from long‐QT‐3 or Brugada syndrome and might represent a distinct inherited arrhythmia syndrome. AbstractMutations of SCN5Ahave been identified as the genetic substrate of various inherited arrhythmia syndromes, including long‐QT‐3 and Brugada syndrome. We recently identified a novel SCN5A variant (C683R) in two genetically unrelated families. The index patients of both families experienced adrenaline‐triggered ventricular arrhythmia with cardiac arrest but did not show a specific ECG phenotype, raising the hypothesis that SCN5A‐C683R might be a susceptibility variant and the genetic substrate of distinct inherited arrhythmia. We conducted functional cellular studies to characterize the electrophysiological properties of NaV1.5/C683R in order to explore the potential pathogenicity of this novel variant. The C683R variant was engineered by site‐directed mutagenesis. NaV1.5/wild type (WT) and NaV1.5/C683R were expressed in tsA201 cells. Electrophysiological characterization of C683R was performed using the whole‐cell patch‐clamp technique. Adrenergic stimulation was mimicked by exposure to the protein kinase A activator 8‐CPT‐cAMP. The impact of β‐blockers was tested by exposing NaV1.5/WT and NaV1.5/C683R currents to propranolol and nadolol. C683R resulted in a co‐association of gain‐of‐function and loss‐of‐function properties of NaV1.5. Gain‐of‐function properties were characterized by a significant increase of the maximal NaV1.5 current density compared with NaV1.5/WT (861 ± 309 vs. 627 ± 489 pA/pF; P < 0.05, n ≥ 9) that was potentiated in NaV1.5/C683R with 8‐CPT‐cAMP stimulation (869 ± 287 vs. 607 ± 320 pA/pF; P < 0.05, n ≥ 12). C683R also resulted in a significant hyperpolarizing shift in the voltage of steady‐state activation (−65.4 ± 3.0 vs. −57.2 ± 4.8 mV; P < 0.001), resulting in an increased window current compared with WT. The loss‐of‐function effect of NaV1.5/C683R was characterized by significantly increased closed‐state inactivation compared with NaV1.5/WT (P < 0.05). C683R is a novel SCN5A variant resulting in a co‐association of gain‐of‐function and loss‐of‐function properties of the cardiac sodium channel NaV1.5. The phenotype is characterized by adrenaline‐triggered ventricular arrhythmias. Electrophysiological properties and clinical manifestations are different from long‐QT‐3 or Brugada syndrome and might represent a distinct inherited arrhythmia syndrome.

Congenital Long QT syndrome (LQTS) is an inherited arrhythmia characterized by prolonged cardiac repolarization that may result in torsades de pointes and sudden cardiac death. Gain-of-function variants of the SCN5A gene, encoding the cardiac sodium channel Nav1.5; INa, underlie nearly 10% of LQTS and cause LQT3. In LQT3 patients, bradycardia and low sympathetic tone (associated with sleep and rest) have been considered to trigger the arrhythmias. Recently, a novel SCN5A variant (C683R) was identified in two unrelated patients with personal/family history of prolonged QT and sudden cardiac arrest. Paradoxically, C683R-associated arrhythmias in these two patients have only been observed during hyperadrenergic states. We therefore conducted a functional study to characterize the electrophysiological effects of the SCN5A C683R variant on Nav1.5 current in a cellular model. The C683R SCN5A variant was engineered into the pcDNA1 vector by using site-directed mutagenesis. Wild-Type (WT) or C683R SCN5A cDNA was transfected into tsA201 cells, along with the human Nav1.5 channel ß1-subunit. Electrophysiological characterization of the C683R variant was performed using the whole cell patch-clamp technique. The selective protein kinase A (PKA) activator 8-CPT-cAMP 50 μM was used in the pipette solution to mimic the effect of epinephrine on either WT or C683R Nav1.5 currents. The C683R variant did not generate any persistent (late) Nav1.5 current when compared to WT. It did not cause any significant change on recovery from inactivation vs WT nor on both steady-state and slow inactivation. However, the C683R variant increased maximal Nav1.5 current density from 341±64 to 766±103 pA/pF when compared to WT (p < 0.05, n≥9) and the midpoint of activation voltage (V½) was negatively shifted from -57.18±1.24 to -63.63±1.40 mV (p < 0.001 vs WT). Moreover, when exposed to the PKA activator 8-CPT-cAMP 50 μM, the C683R variant showed a greater maximal Nav1.5 current density than WT; 993±100 vs 645±137 pA/pF (p < 0.05, n≥6). Our observations suggest a gain-of-function of the Nav1.5 current in the C683R variant compared to the WT protein. This gain of function may be further enhanced upon stimulation with catecholamines. The C683R variant of SCN5A results in a significant gain of function of the Nav1.5 current with increased responsiveness to adrenergic stimulation. Our observations provide a likely explanation for the unusual phenotype in carriers of the C683R variant that is characterized by epinephrine-triggered ventricular arrhythmias. The electrophysiological properties are different from conventional LQT3 and may represent a distinct inherited arrhythmia syndrome.

Inter-organ crosstalk plays an essential role in the physiological homeostasis of the heart and other organs, and requires a complex interaction between a host of cellular, molecular, and neural factors. Derangements in these interactions can initiate multi-organ dysfunction. This is the case, for instance, in the heart or kidneys where a pathological alteration in one organ can unfavorably affect function in another distant organ; attention is currently being paid to understanding the physiopathological consequences of kidney dysfunction on cardiac performance that lead to cardiorenal syndrome. Different cardiorenal connectors (renin–angiotensin or sympathetic nervous system activation, inflammation, uremia, etc.) and non-traditional risk factors potentially contribute to multi-organ failure. Of these, inflammation may be crucial as inflammatory cells contribute to over-production of eicosanoids and lipid second messengers that activate intracellular signaling pathways involved in pathogenesis. Indeed, inflammation biomarkers are often elevated in patients with cardiac or renal dysfunction. Epigenetics, a dynamic process that regulates gene expression and function, is also recognized as an important player in single-organ disease. Principal epigenetic modifications occur at the level of DNA (i.e., methylation) and histone proteins; aberrant DNA methylation is associated with pathogenesis of organ dysfunction through a number of mechanisms (inflammation, nitric oxide bioavailability, endothelin, etc.). Herein, we focus on the potential contribution of inflammation in pathogenesis of cardiorenal syndrome.

Arachidonic acid can be metabolized by cytochrome P450 (CYP450) enzymes in a tissue- and cell-specific manner to generate vasoactive products such as epoxyeicosatrienoic acids (EETs-cardioprotective) and hydroxyeicosatetraenoic acids (HETEs-cardiotoxic). Type II diabetes is a well-recognized risk factor for developing cardiovascular disease. A mouse model of Type II diabetes (C57BLKS/J-db/db) was used. After sacrifice, livers and hearts were collected, washed, and snap frozen. Total proteins were extracted. Western blots were performed to assess cardiac CYP2J and hepatic CYP2C, CYP4A, and CYP4F protein expression, respectively. Significant decreases in relative protein expression of cardiac CYP2J and hepatic CYP2C were observed in Type II diabetes animals compared to controls (CYP2J: 0.80 ± 0.03 vs. 1.05 ± 0.06, n = 20, p < 0.001); (CYP2C: 1.56 ± 0.17 vs. 2.21 ± 0.19, n = 19, p < 0.01). In contrast, significant increases in relative protein expression of both hepatic CYP4A and CYP4F were noted in Type II diabetes mice compared to controls (CYP4A: 1.06 ± 0.09 vs. 0.18 ± 0.01, n = 19, p < 0.001); (CYP4F: 2.53 ± 0.22 vs. 1.10 ± 0.07, n = 19, p < 0.001). These alterations induced by Type II diabetes in the endogenous pathway (CYP450) of arachidonic acid metabolism may increase the risk for cardiovascular disease by disrupting the fine equilibrium between cardioprotective (CYP2J/CYP2C-generated) and cardiotoxic (CYP4A/CYP4F-generated) metabolites of arachidonic acid.

Cardiac arrhythmias and ECG abnormalities including bradycardia, prolongation of the QT interval, and atrioventricular (AV) conduction blocks have been extensively observed with fingolimod, the first marketed oral drug for treating the relapsing-remitting form of multiple sclerosis. This study was aiming to further elucidate the effects of fingolimod on cardiac electrophysiology at three different levels: (i) in vitro, (ii) ex vivo, and (iii) in vivo. (i) Patch-clamp experiments in whole cell configuration were performed on Ca(v)1.2-transfected tsA201 cells exposed to fingolimod-phosphate 100 or 500 nmol/L (n = 27 cells, total) to measure drug effect on L-type calcium current (I-CaL). (ii) Langendorff perfusion experiments were undertaken on male Hartley guinea-pigs isolated hearts (n = 4) exposed to fingolimod 10 and 100 nmol/L to evaluate drug-induced effects on monophasic action potential duration measured at 90% repolarization (MAPD(90)). (iii) Implanted cardiac telemeters were used to record ECGs in guinea-pigs (n = 7) treated with a single dose of fingolimod 0.0625 mg/kg suspension, administered as an oral gavage. (i) In vitro cellular experiments showed that fingolimod-phosphate causes a concentration-dependent reduction in I-CaL. (ii) Ex vivo Langendorff experiments revealed that fingolimod had no significant effect on MAPD(90). (iii) Fingolimod caused significant prolongations of the RR, PR, QT, and QTc(F) intervals in vivo. Reversible AV blocks were also observed in 7/7 animals. Fingolimod possesses I-CaL-blocking properties, further contributing to its AV conduction-slowing effects. These properties are also consistent with its mitigated effect on the QT interval in humans, despite previously shown HERG-blocking effect.

Background/Aims: Cardiovascular events are common in patients with renocardiac syndrome.A direct link between endothelial dysfunction and increased cardiovascular events has not been established for this syndrome; however, a causal role could be attributed to modulations of Cytochrome P450-mediated (CYP450) eicosanoid metabolites including Epoxyeicosatrienoic (EETs), Dihydroxyeicosatrienoic (DHET) and 20-Hydroxyeicosatetraenoic acids (20-HETE).In this study we investigated inter-organ variations in CYP450-mediated eicosanoids in key organs from dogs with renal insufficiency.Methods: Renal insufficiency was induced by two-stage subtotal nephrectomy (SNx).Biochemical markers (serum creatinine, blood urea nitrogen) and cardiac hemodynamics were measured weekly.After 5 weeks, arachidonic acid CYP450-metabolites in heart, remnant kidney and liver biopsies were analyzed.Results: Serum creatinine and blood urea nitrogen were significantly higher in the SNx group (versus timematched sham controls); hematocrit, body weight and creatinine clearance were significantly reduced.The lymphocyte:monocyte ratio, a biomarker of vascular risk, was lower (p=NS) in SNx dogs.Cardiac hemodynamics were similar for both groups.Cardiac levels of 20-HETE were markedly lower (p=0.014) in SNx dogs; however, 14, 15-DHET, a biomarker of soluble epoxide hydrolase levels were unchanged.The 20-HETE/14, 15-DHET ratio was lower in these dogs (p=0.003) and could help to explain a loss of autoregulation in this experimental model.In kidney and liver biopsies from SNx dogs 20-HETE tended to be higher and 14, 15-DHET lower (p=NS) versus time-matched controls; no change was observed for 20-HETE/14, 15-DHET. Conclusion:A marked reduction of cardiac 20-HETE and 20-HETE/14, 15-DHET levels occurred in dogs with kidney injury but no change in these CYP450-metabolites was observed in kidney or liver biopsies.As such, kidney injury appears to trigger significant alterations in CYP450-metabolites that may initiate endothelial dysfunction and vascular inflammation even in distant organs.Manipulating these pathways may eventually constitute a potential pharmacologic target to limit vessel dysfunction in the setting of renocardiac syndrome.

The impact of metabolic syndrome (MetS) on CYP450-mediated metabolism of arachidonic acid (AA) in humans is an emerging concept in the etiology of cardiovascular disease (CVD). Arachidonic acid (AA), an endogenous polyunsaturated fatty acid, is metabolized by CYP2C and CYP2J subfamilies to generate vasodilative epoxyeicosatrienoic acids (EETs). Moreover, CYP4A and CYP4F subfamilies are known to catalyse the production of vasoconstrictive 20-hydroxyeicosatetraeonic acid (20-HETE). There is evidence that pathophysiological conditions such as diabetes and metabolic syndrome (MetS) can alter the expression and function of CYP proteins. We have demonstrated that these conditions alter CYP450 expression and function in mice and guinea pigs. We have recently shown a significant increase in protein expression of hepatic CYP4a and CYP4f in mouse model of type 2 (T2D) diabetes, along with a significant decrease in hepatic CYP2c and cardiac CYP2j in T2D, suggesting a perturbation in the formation of EETs and 20-HETE. In this study, we aimed to investigate if MetS could affect the circulating levels of 14,15-EET and 20-HETE in humans.