Active Metabolites In Patients Research Articles

Development of a Sensitive and High-Throughput Assay for Simultaneous Quantification of 5 Tyrosine Kinase Inhibitors and 2 Active Metabolites in Human Plasma Using Ultra-high Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry.

Breakpoint cluster region-Abelson (BCR-ABL) tyrosine kinase inhibitors (TKIs) demonstrate improved therapeutic efficacy in chronic myeloid leukemia (CML). However, drug-drug interactions, nonadherence, and host-related factors may influence plasma concentrations. Therefore, therapeutic drug monitoring may be necessary for patients presenting inadequate treatment responses or adverse events. Herein, the authors aimed to develop a more sensitive and high-throughput method than those previously reported to simultaneously quantify 5 TKIs (imatinib, nilotinib, dasatinib, bosutinib, and ponatinib) and 2 active metabolites (N-desmethyl imatinib and N-desmethyl ponatinib) using ultra-performance liquid chromatography coupled with tandem mass spectrometry. Plasma samples were prepared according to a solid-phase extraction protocol using an Oasis MCX µElution plate. The assay fulfilled the requirements of the US Food and Drug Administration for assay validation, with a lower limit of quantification of 0.2 ng/mL for dasatinib, 0.3 ng/mL for N-desmethyl ponatinib, 0.5 ng/mL for N-desmethyl imatinib, bosutinib, and ponatinib, and 2.5 ng/mL for imatinib and nilotinib. Within-batch and batch-to-batch precision at the lower limit of quantification and quality control levels were within 14.3% and 10.9%, respectively. Within-batch and batch-to-batch accuracies ranged from 15.5% to 13.0% and 5.70% to 7.03%, respectively. A positive electrospray ionization mode was used with a run time of 6.0 minutes. The assay applicability was verified by the successful measurement of 78 clinical samples from patients undergoing CML therapy. The method allows assessment of trough concentrations of TKIs and active metabolites in patients with CML, and hence can be used to assess blood samples in routine clinical settings.

Exposure-response analysis of adverse events associated with molibresib and its active metabolites in patients with solid tumors.

Molibresib (GSK525762) is an investigational orally bioavailable small‐molecule bromodomain and extraterminal (BET) protein inhibitor for the treatment of advanced solid tumors. In the first‐time‐in‐human BET115521 study of molibresib in patients with solid tumors, thrombocytopenia was the most frequent treatment‐related adverse event (AE), QT prolongation was an AE of special interest based on preclinical signals, and gastrointestinal (GI) AEs (nausea, vomiting, diarrhea, and dysgeusia) were often observed. The aims of this analysis were the following: (i) develop a population pharmacokinetic (PK)/pharmacodynamic (PD) model capable of predicting platelet time courses in individual patients after administration of molibresib and identify covariates of clinical interest; (ii) evaluate the effects of molibresib (and/or its two active metabolites [GSK3529246]) exposure on cardiac repolarization by applying a systematic modeling approach using high‐quality, intensive, PK time‐matched 12‐lead electrocardiogram measurements; (iii) evaluate the exposure–response (ER) relationship between molibresib and/or GSK3529246 exposures and the occurrence of Grade 2 or higher GI AEs. Overall, the PK/PD model (including a maximal drug effect model and molibresib concentration) adequately described platelet counts following molibresib treatment and was used to simulate the impact of molibresib dosing on thrombocytopenia at different doses and regimens. ER analyses showed no clinically meaningful QT interval prolongation with molibresib at up to 100 mg q.d., and no strong correlation between molibresib exposure and the occurrence of Grade 2 or higher GI AEs. The models described here can aid dosing/schedule and drug combination strategies and may support a thorough QT study waiver request for molibresib.

Population pharmacokinetics of azathioprine active metabolite in patients with inflammatory bowel disease and dosage regimens optimisation.

Azathioprine is a first-line drug used to maintain the remission of inflammatory bowel disease (IBD). As a prodrug, azathioprine is metabolised to produce active 6-thioguanine nucleotides (6-TGN). There are large individual variations in the pharmacokinetics/pharmacodynamics of 6-TGN in patients with IBD. Here, we aimed to develop a model to quantitatively investigate factors that affect 6-TGN pharmacokinetics to formulate a dosage guideline for azathioprine. Data were collected prospectively from 100 adult patients with IBD who were receiving azathioprine. Patients were genotyped for two single-nucleotide polymorphisms (TPMT*3C c.719A>G and NUDT15 c.415C>T). Using high-performance liquid chromatography, we measured 156 steady-state trough concentrations of 6-TGN within the range 0.09 to 1.16mg/L (ie 133-1733pmol per 8×108 RBC). The covariates analysed included sex, age, body-weight, laboratory tests and concomitant medications. A population pharmacokinetic model was established using "non-linear mixed-effects modelling" software and the "first-order conditional estimation method with interaction." Body-weight, TPMT*3C polymorphisms and co-therapy with mesalazine were found to be important factors influencing the clearance of 6-TGN. A dosage guideline for azathioprine was developed based on the PPK model that enables individualised azathioprine dosing in adult patients with different body-weights, TPMT*3C genotypes and co-administration with mesalazine.

A LC–MS/MS method for therapeutic drug monitoring of sorafenib, regorafenib and their active metabolites in patients with hepatocellular carcinoma

A liquid chromatography-tandem mass spectrometry (LC–MS/MS) method was developed and validated for the simultaneous quantification of sorafenib (SORA), its N-oxide active metabolite and of regorafenib (REGO) and its two active metabolites regorafenib N-oxide and N-desmethyl regorafenib N-oxide in hepatocellular carcinoma patients’ plasma.A proper analytes’ separation was obtained with Synergi Fusion RP column (4 μm, 80 Å, 50 × 2.0 mm) using a gradient elution of 10 mM ammonium acetate with 0.1% formic acid (mobile phase A) and methanol:isopropanol (90:10, v/v, mobile phase B) containing 0.1% formic acid. The analysis was then performed by electrospray ionization in negative mode coupled with a triple quadrupole mass spectrometry, API 4000QT, monitoring two transitions for each analyte, one for the quantification and the other for confirmation. The method could be easily applied to the clinical practice thanks to the short run (7 min), the low amount of patient plasma necessary for the analysis (5 μL) and the fast sample processing based on protein precipitation. The method was therefore fully validated according to FDA and EMA guidelines. The linearity was assessed (R2≥0.998) over the concentration ranges of 50−8000 ng/mL for SORA and REGO, and 30−4000 ng/mL for their metabolites, that appropriately cover the therapeutic plasma concentrations. The presented method also showed adequate results in terms of intra- and inter-day accuracy and precision (CV ≤ 7.2% and accuracy between 89.4% and 108.8%), recovery (≥85.5%), sensitivity, analytes stability under various conditions and the absence of the matrix effect.Once the validation was successfully completed, the method was applied to perform the Cmin quantification of SORA, REGO and their metabolites in 54 plasma samples collected from patients enrolled in a clinical study ongoing at the National Cancer Institute of Aviano.

Effects of CYP2D6*10 polymorphism on tamoxifen pharmacokinetics in patients with breast cancer in Asia: a meta-analysis.

Insufficient serum metabolite concentrations of tamoxifen can compromise treatment efficacy in patients with breast cancer. The purpose of this meta-analysis was to explore correlations between cytochrome P450 (CYP) 2D6*10 gene polymorphisms and serum concentrations of tamoxifen and its active metabolites in patients with breast cancer in Asia. The study included a systematic literature search for cohort studies published before March 2018 in English databases (PubMed, Embase, Cochrane Library, and Web of Science) and Chinese databases (Chinese National Knowledge Infrastructure and Wan Fang database). The meta-analysis was performed using RevMan 5.3 software. Pooled means and standard deviations were calculated with 95% confidence intervals. Publication bias and sensitivity analyses were also performed using STATA 14.0. In total, 7 studies and 552 patients were included in the meta-analysis. Serum concentrations of endoxifen were significantly different in each CYP2D6*10 genotype group (p < 0.05). The CC genotype was associated with higher concentrations of 4-OH-TAM than the CT/TT genotype (p < 0.05). However, there were no statistically significant between-group differences in serum concentrations of TAM (p > 0.05). Publication bias and sensitivity analyses confirmed that the meta-analysis results were stable and reliable. CYP2D6*10 polymorphisms influence the pharmacokinetics of tamoxifen in patients with breast cancer in Asia.

CYP2D6 activity and the risk of recurrence of Plasmodium vivax malaria in the Brazilian Amazon: a prospective cohort study

BackgroundCYP2D6 pathway mediates the activation of primaquine into active metabolite(s) in hepatocytes. CYP2D6 is highly polymorphic, encoding CYP2D6 isoforms with normal, reduced, null or increased activity. It is hypothesized that Plasmodium vivax malaria patients with defective CYP2D6 function would be at increased risk for primaquine failure to prevent recurrence. The aim of this study was to investigate the association of CYP2D6 polymorphisms and inferred CYP2D6 phenotypes with malaria recurrence in patients from the Western Brazilian Amazon, following chloroquine/primaquine combined therapy.MethodsThe prospective cohort consisted of P. vivax malaria patients who were followed for 6 months after completion of the chloroquine/primaquine therapy. Recurrence was defined as one or more malaria episodes, 28–180 days after the initial episode. Genotyping for nine CYP2D6 SNPs and copy number variation was performed using TaqMan assays in a Fast 7500 Real-Time System. CYP2D6 star alleles (haplotypes), diplotypes and CYP2D6 phenotypes were inferred, and the activity score system was used to define the functionality of the CYP2D6 diplotypes. CYP2D6 activity scores (AS) were dichotomized at ≤ 1 (gPM, gIM and gNM-S phenotypes) and ≥ 1.5 (gNM-F and gUM phenotypes).ResultsGenotyping was successfully performed in 190 patients (44 with recurrence and 146 without recurrences). Recurrence incidence was higher in individuals presenting reduced activity CYP2D6 phenotypes (adjusted relative risk = 1.89, 95% CI 1.01–3.70; p = 0.049). Attributable risk and population attributable fraction were 11.5 and 9.9%, respectively. The time elapsed from the first P. vivax malaria episode until the recurrence did not differ between patients with AS of ≤ 1 versus ≥ 1.5 (p = 0.917).ConclusionsThe results suggest that CYP2D6 polymorphisms are associated with increased risk of recurrence of vivax malaria, following chloroquine–primaquine combined therapy. This association is interpreted as the result of reduced conversion of primaquine into its active metabolites in patients with reduced CYP2D6 enzymatic activity.

Impact of Ageing on Serum Concentrations of Risperidone and Its Active Metabolite in Patients with Known CYP2D6 Genotype

The aim of this study was to investigate the impact of ageing on serum concentrations of risperidone and 9-hydroxyrisperidone in patients with known CYP2D6 genotype. We included retrospective therapeutic drug monitoring data from 464 genotyped patients with measured serum concentrations of risperidone and 9-hydroxyrisperidone after oral administration. Patients were divided into two age subgroups, that is ≤65 (n = 396) and >65 years (n = 68), and dose-adjusted concentrations (C:D ratios) were compared using multiple linear regression analyses with CYP2D6 genotype and gender as covariates. Moreover, absolute concentrations and prescribed daily doses were compared between age subgroups by simple, univariate Mann-Whitney tests. Age had no effect on C:D ratio of risperidone (p > 0.4), but C:D ratios of 9-hydroxyrisperidone and risperidone + 9-hydroxyrisperidone (total active moiety) were estimated to be 2.6 and 2.0 times higher in patients >65 versus ≤65 years (p < 0.001). Female gender and a CYP2D6 poor metabolizer (PM) genotype were also associated with significantly higher C:D ratio of the total active moiety (p < 0.01). Despite lower dosing in patients >65 versus ≤65 years (median 1.5 versus 3.0 mg/day, p < 0.0001), absolute concentration of the total active moiety did not differ between the age subgroups (median 52.5 versus 47.0 nmol/L, p > 0.6). In conclusion, ageing implies significantly increased dose-adjusted serum concentration of risperidone active moiety, and treatment intensity is not generally reduced by halving the oral dose in the elderly. Tolerability of risperidone therapy should therefore be closely monitored in older patients, and female CYP2D6 PMs >65 years might be a particularly vulnerable subgroup of adverse effects.

Does morphine administration affect ticagrelor conversion to its active metabolite in patients with acute myocardial infarction? A sub-analysis of the randomized, double-blind, placebo- -controlled IMPRESSION trial

Background. Therapy with aspirin and one of the platelet P2Y12 receptor inhibitors, preferably ticagrelor or prasugrel, is the mainstay of acute myocardial infarction (AMI) treatment. Morphine is the most commonly used analgesic in AMI patients. The IMPRESSION study was the first randomized trial to confirm that morphine use in this clinical setting leads to a delayed and attenuated exposure to ticagrelor and its active metabolite (AR-C124910XX). The mechanism underlying this drug-drug interaction remains hypothetical. Material and methods. A post hoc sub-analysis of the IMPRESSION study, a phase IV, single center, randomized, double-blind, placebo-controlled trial, was performed to examine whether morphine administration interferes with the proportion of AR-C124910XX produced from ticagrelor in AMI patients. Pharmacokinetic results of all subjects pretreated with placebo (n = 35) and morphine (n = 35) were analyzed. The ratio of total exposure to AR-C124910XX to total exposure to ticagrelor for 12 h was used to illustrate the rate of ticagrelor metabolism. Total exposure to investigated compounds was measured as the area under the plasma concentration-time curve (AUC). Results. The ratios of AUC(0–12) for AR-C124910XX to AUC(0–12) for ticagrelor were comparable between morphine and placebo pretreated patients (20.9 [13.9–34.6] v. 24.7 [18.1–29.6] %; p = 0.58). Importantly, visual inspection of the relationship between AUC(0–12) for AR-C124910XX and AUC(0–12) for ticagrelor revealed that regression lines for the morphine and placebo groups were located closely to each other, with a tendency for superimposing. Additionally, we observed similar values of slope coefficients for both study arms in the linear regression equations illustrating the relationship between AUC(0–12) for AR-C124910XX and AUC(0–12) for ticagrelor (0.19 [± 0.03] v. 0.21 [± 0.04]; p for the statistical significance of both slope coefficients < 0.0001). Conclusions. In the IMPRESSION study, conversion of ticagrelor to AR-C124910XX in AMI patients was not affected by morphine administration.

Incremental Lowering of Low-Density Lipoprotein Cholesterol With Ezetimibe 20 mg vs 10 mg Daily in Patients Receiving Concomitant Statin Therapy

BackgroundEzetimibe is typically administered at a dose of 10 mg daily, with few reports of use at other doses. We compared plasma concentrations of low-density lipoprotein (LDL) cholesterol and other lipid variables in patients with dyslipidemia who were receiving ezetimibe 10 mg and then 20 mg daily. MethodsA retrospective chart review identified 27 patients who received ezetimibe 10 mg and then 20 mg daily at different times; 15 participants were receiving stable statin therapy and 12 were not receiving concomitant statins. Plasma concentrations of lipids, creatine kinase (CK), and aspartate transaminase (AST) were determined. Plasma concentrations of ezetimibe and ezetimibe glucuronide were measured in a second group of patients. ResultsPatients taking statins and ezetimibe 20 mg had further reductions in total and LDL cholesterol of 7.1% and 10.3%, respectively (both P < 0.05) than did those receiving the 10-mg dose. No difference between 20-mg and 10-mg dosing was seen among patients not receiving statins. Plasma concentrations of ezetimibe and its active metabolite were about 2-fold higher (P < 0.05) in patients taking ezetimibe 20 mg than in those receiving 10 mg daily. All patients tolerated ezetimibe 20 mg without side effects. ConclusionsEzetimibe 20 mg daily reduced total and LDL cholesterol further in patients receiving statin therapy compared with 10 mg daily. Prospective studies are required to show whether the higher plasma levels of ezetimibe and its active metabolite in patients taking the 20-mg dose have any detrimental effects. Increasing the ezetimibe dose to 20 mg daily might be an interesting potential approach for patients who fail to reach lipid targets on ezetimibe 10 mg daily along with maximally tolerated doses of statin.

Contribution of Morphine and Morphine-6-Glucuronide to Respiratory Depression in a Child

A morphine plasma concentration/respiratory rate relationship has been described for both adults and children although that of its metabolite, morphine-6-glucuronide, remains uncertain. We describe this relationship in a child with end-stage renal failure who received repeat morphine administration over two days. An EMAX model for additive morphine and morphine-6-glucuronide respiratory effects described respiratory rate better than models describing either alone. Failure to clear morphine-6-glucuronide renally led to respiratory depression episodes occurring later than those predicted by modelling morphine levels only. These findings support the use of alternative analgesics (e.g. fentanyl) that are cleared by non-renal pathways and have no active metabolites in patients with end-stage renal disease.

Effects and serum levels of glibenclamide and its active metabolites in patients with type 2 diabetes.

To study the effects and serum levels of glibenclamide (Gb) and its active metabolites in patients on chronic Gb medication on different daily doses. Fifty patients with type 2 diabetes on regular Gb therapy (1.75-14.0 mg daily). Blood samples were taken immediately before and 90 min after regular Gb intake. A standardized breakfast was served 30 min after drug intake. Serum insulin and proinsulin levels were determined by ELISA methods without cross-reactivities. Serum drug levels were determined by HPLC. Fischer's R to Z-test (correlation coefficients) and paired Student t-tests were used when comparing values within the entire group and unpaired non-parametric Mann-Whitney tests were used when comparing high and low dose levels. A p-value < 0.05 was considered significant. There were significant correlations between daily Gb dose, on the one hand, and, on the other, HbAlc (r = 0.55), Delta-insulin (r = - 0.59) and Delta-proinsulin (r = - 0.52) levels. Significant correlations between Gb therapy duration and insulin (r = - 0.40) and proinsulin (r = - 0.34) secretion and between Gb dose and ratio proinsulin/insulin (RPI) at both time points (r = 0.32 and 0.30) were also found. The RPI was lower after Gb intake. In patients on > or = 10.5 mg steady state serum metabolite levels (Ml and Ml + M2) were higher (29(0-120) and 33 (0-120) ng/ml) than those of Gb itself (18(0-64) ng/ml). A great inter-subject variability in Gb levels at both time points was seen. Our results indicate that, in patients on chronic medication, Gb is capable of stimulating both insulin and proinsulin secretion; the effect on insulin release is relatively greater. The effect was more pronounced in patients on a low Gb dose, either because of less impaired beta-cells in those receiving low doses, or due to reduced sulphonylurea sensitivity in those on high dosage (down-regulation). In patients on a daily dose of 10.5 mg or more, serum metabolite levels of clinical relevance were demonstrated; the metabolites may contribute to hypoglycaemic events.

No effect of reboxetine on plasma concentrations of clozapine, risperidone and their active metabolites in patients with schizophrenia

No effect of reboxetine on plasma concentrations of clozapine, risperidone and their active metabolites in patients with schizophrenia

No Effect of Citalopram on Plasma Levels of Clozapine, Risperidone and their Active Metabolites in Patients with Chronic Schizophrenia

Objective: The effect of citalopram on steady-state plasma concentrations of the newer antipsychotics clozapine and risperidone was studied in 15 schizophrenic patients with residual negative symptoms.

CNS Adverse Effects of Opioids in Cancer Patients

Most of the adverse effects of Opioid analgesics are related to effects on the CNS. This article reviews the causes and treatment of the most frequent CNS adverse effects of Opioid analgesics prescribed for the relief of cancer-related pain. Such effects can occur during short term treatment of opioid-naive patients (e.g. sedation, nausea, vomiting, respiratory depression, mood changes, difficult micturition) and during long term treatment of patients in chronic pain (e.g. delirium, hyperalgesia, generalised myoclonus, tonic-clonic seizures), and can be classified according to their clinical relevance. The symptoms can be associated with high concentrations of Opioids and their metabolites in CSF, but can also be caused by pharmacological interactions between Opioids and other drugs commonly used in clinical practice. Moreover, they may be related to the accumulation of active metabolites in patients with renal impairment. Opioid rotation, hydration of the patient and suspension of drugs that can interfere with the pharmacokinetics of Opioids are suggested approaches to treatment. Psychostimulants can be used to treat opioid-induced sedation. Naloxone can be used to reverse severe respiratory depression caused by high doses of Opioids. Haloperidol and midazolam are useful for the treatment of opioid-induced hyperactive delirium.

Pharmacokinetics of doxorubicin and its active metabolite in patients with normal renal function and in patients on hemodialysis

The comparative pharmacokinetics of doxorubicin (DOX) were investigated in five hemodialysis (HD) and eight non-hemodialysis (non-HD) patients who were infused with a 40- to 60-mg dose of DOX at a constant rate over 30 min. A significant difference was observed in the total body clearance (Cl tot) of DOX between HD and non-HD patients. The area under the curve (AUC) for both DOX and doxorubicinol (DOXol), an active metabolite, showed increases of approximately 1.5 and 3 times in HD patients as compared with non-HD patients. Although these differences were not statistically significant (P < 0.1), the mean residence time (MRT) of DOX and DOXol in HD patients showed a 2-fold increase in comparison with those in non-HD patients. Compartmental analysis indicated that the greater AUC values and longer MRT of DOX and DOXol in HD patients resulted from the lesser DOXol formation and disappearance of rate constants. As a consequence of the decrease in Cl tot for DOX and the marginal hemodialysis clearance of both DOX and DOXol, the present study suggests that the exposure to DOX and DOXol obtained in HD patients greater than achieved in non-HD patients. Careful attention should therefore be paid to HD patients receiving DOX.

Effect of prostaglandin (PG) E 1 and its initial metabolites on neutrophil-induced inhibition of human platelet aggregation

We have investigated the effects of PGE 1, 15-keto-PGE 1, 15-keto-13,14-dihydro-PGE 1 and 13,14-dihydro-PGE 1 on inhibition of human platelet aggregation by rat peritoneal neutrophils (RPN) and human polymorphonuclear neutrophils (PMN). Both RPN and PMN are known to synthesize nitric oxide (NO). In the presence of a threshold concentration of RPN or PMN the inhibitory effects of PGE 1 and 13,14-dihydro-PGE 1 on thrombin- or collagen-induced platelet aggregation were significantly increased as compared to the absence of cells, while 15-keto-PGE 1 and 15-keto-13,14-dihydro-PGE 1 were inactive. Oxyhemoglobin (oxy-Hb) abolished the synergistic effect of RPN and either PGE 1 or 13,14-dihydro-PGE 1 on thrombin-induced platelet aggregation, but under the experimental conditions used had much less effect on inhibition of collagen-induced aggregation. Potentiation of the antiaggregatory effect of PGE 1 and 13,14-dihydro-PGE 1 by NO might contribute to the therapeutic efficacy of exogenous PGE 1. This view is supported by the fact that plasma levels of PGE 1 and its active metabolite in patients receiving infusions of PGE 1 for treatment of peripheral arterial occlusive disease are in the order of magnitude acting synergistically with neutrophil-derived NO, while direct inhibition of platelet aggregation requires considerably higher concentrations of PGE 1 and 13,14-dihydro-PGE 1.