Interference of Herbal Medicine with Axitinib in Metastatic Renal Cell Cancer Treatment: A Case Study.

Introduction: The awareness and the clinical relevance of the potential interactions between standard and complementary medicine are increasing in medical oncology. Nonetheless, the research and experience of the efficacy, safety, and toxicity of herbal substances are poorly documented. Case Presentation: Here, we report the case of a 68-year-old female patient who had been diagnosed with advanced renal cell cancer with metastasis in the liver and pancreas and had undergone surgical resection with hemi-hepatectomy and resection of metastasis in the pancreas in November 2021. Thereafter, chemotherapy was immediately initiated with three-weekly infusions of pembrolizumab and daily intake of the tyrosine kinase inhibitor axitinib. Surprisingly, 3 months after initiation of systemic treatment, the patient developed early progression and metastasis in the liver, which was then treated with selective internal radiotherapy. Despite continued axitinib and pembrolizumab treatment, a short-term follow-up in November 2022 revealed another metastatic lesion in her pancreas. Due to the presumed lack of response to treatment, the plasma concentration of axitinib was measured and found to demonstrate subtherapeutic levels of exposure. Upon extended anamnesis, the patient reported regular intake of herbal substances prescribed by her oncology acupuncturist for gastrointestinal complaints associated with the primary operation. Conclusion: Further clinical-pharmacological workup strikingly demonstrated a reduction of the therapeutic concentration of axitinib of about 90%, likely caused by herbal drugs such as Dang gui and Bai zhu.

Acetylcholine and noradrenaline enhance foraging optimality in humans.

Foraging theory prescribes when optimal foragers should leave the current option for more rewarding alternatives. Actual foragers often exploit options longer than prescribed by the theory, but it is unclear how this foraging suboptimality arises. We investigated whether the upregulation of cholinergic, noradrenergic, and dopaminergic systems increases foraging optimality. In a double-blind, between-subject design, participants (N = 160) received placebo, the nicotinic acetylcholine receptor agonist nicotine, a noradrenaline reuptake inhibitor reboxetine, or a preferential dopamine reuptake inhibitor methylphenidate, and played the role of a farmer who collected milk from patches with different yield. Across all groups, participants on average overharvested. While methylphenidate had no effects on this bias, nicotine, and to some extent also reboxetine, significantly reduced deviation from foraging optimality, which resulted in better performance compared to placebo. Concurring with amplified goal-directedness and excluding heuristic explanations, nicotine independently also improved trial initiation and time perception. Our findings elucidate the neurochemical basis of behavioral flexibility and decision optimality and open unique perspectives on psychiatric disorders affecting these functions.

Phase Ib dose-escalation study of the hypoxia-modifier Myo-inositol trispyrophosphate in patients with hepatopancreatobiliary tumors.

Hypoxia is prominent in solid tumors and a recognized driver of malignancy. Thus far, targeting tumor hypoxia has remained unsuccessful. Myo-inositol trispyrophosphate (ITPP) is a re-oxygenating compound without apparent toxicity. In preclinical models, ITPP potentiates the efficacy of subsequent chemotherapy through vascular normalization. Here, we report the results of an unrandomized, open-labeled, 3 + 3 dose-escalation phase Ib study (NCT02528526) including 28 patients with advanced primary hepatopancreatobiliary malignancies and liver metastases of colorectal cancer receiving nine 8h-infusions of ITPP over three weeks across eight dose levels (1'866-14'500 mg/m2/dose), followed by standard chemotherapy. Primary objectives are assessment of the safety and tolerability and establishment of the maximum tolerated dose, while secondary objectives include assessment of pharmacokinetics, antitumor activity via radiological evaluation and assessment of circulatory tumor-specific and angiogenic markers. The maximum tolerated dose is 12,390 mg/m2, and ITPP treatment results in 32 treatment-related toxicities (mostly hypercalcemia) that require little or no intervention. 52% of patients have morphological disease stabilization under ITPP monotherapy. Following subsequent chemotherapy, 10% show partial responses while 60% have stable disease. Decreases in angiogenic markers are noted in ∼60% of patients after ITPP and tend to correlate with responses and survival after chemotherapy.

Prediction of exposure-driven myelotoxicity of continuous infusion 5-fluorouracil by a semi-physiological pharmacokinetic-pharmacodynamic model in gastrointestinal cancer patients.

PURPOSE: To describe 5-fluorouracil (5FU) pharmacokinetics, myelotoxicity and respective covariates using a simultaneous nonlinear mixed effect modelling approach. METHODS: Thirty patients with gastrointestinal cancer received 5FU 650 or 1000 mg/m2/day as 5-day continuous venous infusion (14 of whom also received cisplatin 20 mg/m2/day). 5FU and 5-fluoro-5,6-dihydrouracil (5FUH2) plasma concentrations were described by a pharmacokinetic model using NONMEM. Absolute leukocyte counts were described by a semi-mechanistic myelosuppression model. Covariate relationships were evaluated to explain the possible sources of variability in 5FU pharmacokinetics and pharmacodynamics. RESULTS: Total clearance of 5FU correlated with body surface area (BSA). Population estimate for total clearance was 249 L/h. Clearances of 5FU and 5FUH2 fractionally changed by 77%/m2 difference from the median BSA. 5FU central and peripheral volumes of distribution were 5.56 L and 28.5 L, respectively. Estimated 5FUH2 clearance and volume of distribution were 121 L/h and 96.7 L, respectively. Baseline leukocyte count of 6.86 × 109/L, as well as mean leukocyte transit time of 281 h accounting for time delay between proliferating and circulating cells, was estimated. The relationship between 5FU plasma concentrations and absolute leukocyte count was found to be linear. A higher degree of myelosuppression was attributed to combination therapy (slope = 2.82 L/mg) with cisplatin as compared to 5FU monotherapy (slope = 1.17 L/mg). CONCLUSIONS: BSA should be taken into account for predicting 5FU exposure. Myelosuppression was influenced by 5FU exposure and concomitant administration of cisplatin.

Drugs and hepatic transporters: A review.

The liver is the primary organ for the metabolic degradation of xenobiotics. Transmembrane transport proteins from the ABC and the SLC families mediate the uptake of endogenous compounds and xenobiotics into the hepatocyte as well as their elimination from the cells. Multiple processes are involved. The uptake of xenobiotics in hepatocytes is mediated by organic anion transporting polypeptides (OATPs) and by organic anion and cation transporters (OATs and OCTs). The elimination of drugs and metabolites from the liver cell back to the bloodstream is accomplished mainly by multidrug resistance-associated protein 3 (MRP3) and MRP4, while the elimination towards the biliary canaliculi is mediated by several different transporters (MRP2, BCRP, MDR1 and MATE1). Since bile acids and their salts are toxic detergents for hepatocytes, they have to be eliminated efficiently. This task is accomplished by the bile salt export pump BSEP. Two further transporters, MDR3 and ATP8B1 are involved in the proper constitution of bile. All these transporters can be influenced, mainly inhibited by a number of drugs, but also by metabolites from endogenous compounds such as estrogens. Additionally, rare monogenetic diseases exist which can be explained by absence of function or dysfunction of specific hepatic transporters, such as progressive familial intrahepatic cholestasis type 2 by genetic modifications in BSEP that lead to a loss of transporter function. Functional impairment of other transporters by genetics or by drugs also leads to liver injury, a potentially life-threatening disease that is still not fully understood. Hence, the interplay between drugs and hepatic transporters is multiple, and the knowledge of this interplay helps in understanding the etiology and molecular mechanisms behind some forms of (drug-induced) liver injury.

Intracavitary cisplatin-fibrin chemotherapy after surgery for malignant pleural mesothelioma: A phase I trial.

OBJECTIVES: Intracavitary chemotherapy is a promising concept to improve local tumor control for malignant pleural mesothelioma with reported high morbidity rates. We have demonstrated that administration of cisplatin loaded to fibrin increased local drug concentration and reduced systemic toxicity in preclinical models. We present a phase I trial of intracavitary cisplatin-fibrin after surgical tumor resection. METHODS: A total of 12 patients (75% International Mesothelioma Interest Group stage III-IV) were treated with 4 dose levels of intracavitary cisplatin-fibrin (11-44 mg/m2 body surface area) in a dose-escalating design. Cisplatin-fibrin was sprayed on the resected surfaces after pleurectomy/decortication. Blood and tissue samples were taken to assess toxicity and pharmacokinetics. Patients were regularly followed up. RESULTS: No dose-limiting toxicity was observed. Major morbidity occurred in 4 patients (33%). The 30-day and 90-day mortality were both 0%. Of 80 adverse events, 9 were classified serious, but none of these were related to study treatment. Local cisplatin concentration in the chest wall tissue was high at all dose levels (median, 46.3 µg/g [12-133 µg/g]). In serum, median cisplatin area under the concentration time curve values were always below renal toxicity levels. The median overall survival with 95% confidence interval was 21 months (10-31 months). In 1 patient with epithelioid malignant pleural mesothelioma (International Mesothelioma Interest Group stage I), there was no sign of relapse 48 months after treatment (44 mg/m2 body surface area). CONCLUSIONS: The administration of intracavitary cisplatin-fibrin is safe with favorable pharmacokinetics. Although most patients had advanced disease, long-term outcomes are comparable to other multimodal concepts. A confirmation phase II trial is ongoing.

Danger of Herbal Tea: A Case of Acute Cholestatic Hepatitis Due to Artemisia annua Tea.

Background: Artemisia annua is a Chinese medicinal herb. Artemisinin-derivatives are recommended as part of a combination treatment for uncomplicated malaria. Herbal and dietary supplements (HDS) are increasingly used worldwide and HDS-induced liver injury is becoming a growing concern. Case Report: We present the first case of severe acute cholestatic hepatitis due to the intake of Artemisia annua tea as chemoprophylaxis for malaria in a patient returning from Ethiopia. The patients presented with jaundice, elevated transaminases, and parameters of cholestasis (total bilirubin 186.6 µmol/L, conjugated bilirubin 168.5 µmol/L). A liver biopsy showed a portal hepatitis with lymphocytic infiltration of the bile ducts and diffuse intra-canalicular and intra-cytoplasmic bilirubinostasis. The toxicologic analysis of the Artemisia tea revealed the ingredients arteannuin b, deoxyartemisin, campher, and scopoletin. There were no other identifiable etiologies of liver disease. The Roussel Uclaf Causality Assessment Method (RUCAM) score assessed a "probably" causal relationship. Sequencing of genes encoding for hepatic transporters for bile acid homeostasis (BSEP, MDR3, and FIC1) found no genetic variants typically associated with hereditary cholestasis syndromes. Normalization of bilirubin occurred 3 months after the onset of disease. Conclusion: The use of artemisinin-derivatives for malaria prevention is ineffective and potentially harmful and should thus be discouraged. Moreover, the case demonstrates our as yet inadequate understanding of the pathophysiology and susceptibility to HDS induced liver injury.

Risk Factors for Higher-than-Expected Residual Rivaroxaban Plasma Concentrations in Real-Life Patients.

INTRODUCTION: Rivaroxaban (RXA) is a direct oral factor Xa (Xa) antagonist with a short half-life and a fast onset and offset of effect. Before elective surgery, discontinuation is recommended with an interval of at least > 24 hours. In clinical practice, this is, however, not always sufficient to achieve a residual RXA plasma concentration deemed appropriate for surgery, defined as ≤ 50 mcg/L. Our study aimed at identifying factors associated with a higher-than-expected residual RXA plasma concentration in a large group of real-life patients. MATERIALS AND METHODS: This retrospective single-centre study included all patients taking RXA between 2012 and 2016 where RXA plasma concentration was determined by pharmacodynamic anti-Xa assay (518 measurements in 368 patients). Medical records were reviewed. Residual RXA plasma concentrations were then compared with expected values according to a pharmacokinetic model. RESULTS: Residual RXA plasma concentration was significantly higher-than-expected in patients with atrial fibrillation, impaired kidney function (glomerular filtration rate [GFR] < 60 mL/min), CYP3A4-, CYP2J2- and PGP-inhibitory co-medication including amiodarone. Impaired kidney function (odds ratio [OR], 2.22, 95% confidence interval [CI], 1.30-3.78, p = 0.003) and concomitant amiodarone intake (OR, 1.97, 95% CI, 1.04-3.72, p = 0.036) were significantly associated with RXA plasma concentrations > 50 mcg/L at 24 to 48 hours after the last RXA intake. CONCLUSION: In our group of real-life patients, impaired kidney function (GFR < 60 mL/min) and co-medication with amiodarone were independently associated with higher-than-expected residual RXA plasma concentrations. In these patients, standard intervals of RXA discontinuation may not always be sufficient before elective surgery and routine pre-operative determination of the residual RXA concentration could be advisable.

Development of OXY111A, a novel hypoxia-modifier as a potential antitumor agent in patients with hepato-pancreato-biliary neoplasms - Protocol of a first Ib/IIa clinical trial.

BACKGROUND: Solid tumors, such as hepato-pancreato-biliary cancer, develop tumor hypoxia with tumor growth. Despite advances in surgery, a majority of these patients are in an unresectable condition. At this stage standard cytotoxic chemotherapy regimens are applied with limited success. Novel biological treatment options based on an antiangiogenic mechanism of action neglect other hypoxia mediated mechanisms (e.g. epithelial-mesenchymal transition, Warburg effect, and immunological response) leading to an increased invasiveness with a poor outcome. The novel antihypoxic molecule myo-inositoltrispyrophosphate (ITPP, OXY111A) acts as an allosteric effector of hemoglobin and promotes normoxia in hypoxic tumors. In preclinical studies, tumor growth was reduced and survival prolonged. Additionally, a beneficial side effect profile was observed. METHODS: In this first Ib/IIa clinical trial we will assess safety and tolerability of OXY111A as well as a proof of concept regarding efficacy in patients with non-resectable primary and secondary tumors of the liver, pancreas, and biliary tract. The study design is exploratory, prospective, open-labelled and mono-centric. The study is divided in a dose escalation part with a maximum of 48 subjects and an extension part, in which 21 subjects will be included. DISCUSSION: The novel antihypoxic compound OXY111A has been tested in several cancer animal models showing beneficial effects for both survival and low side effect profiles. This first in patient application of OXY111A will reveal potential beneficial outcomes if anti-hypoxic therapy is added to standard cytotoxic treatment in patients with primary and secondary hepatopancreatobiliary tumors. TRIAL REGISTRATION: Institution Ethical Board Approval ID: KEK-ZH-Nr. 2014-0374; Swiss regulatory authority Swissmedic (2015DR1009); ClinicalTrials.gov Identifier: NCT02528526 , prospectively registered on November 11th, 2014.

No major effects of vitamin D3 (1,25 dihydroxyvitamin D3) on absorption and pharmacokinetics of folic acid and fexofenadine in healthy volunteers.

PURPOSE: In Caco-2 cells, folate uptake via the proton-coupled folate transporter (PCFT) increases significantly by a 3-day treatment with 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Additionally, mRNA content and protein expression of the transporter OATP1A2 were increased up to ninefold with 1,25(OH)2D3. We investigated whether these in vitro findings can be confirmed in humans in vivo. METHODS: Ten healthy volunteers (six women) received 5 mg folic acid orally once before and once together with the last intake of a 10-day course of 0.5 µg 1,25(OH)2D3 orally. One hundred twenty milligrams fexofenadine, an OATP1A2 substrate, was taken in 1 day before the first folic acid intake, and again on the ninth day of 1,25(OH)2D3 intake. Duodenal biopsies were taken for transporter mRNA assessments once before and once on the ninth or tenth day of the vitamin D3 course. Serum folic acid and fexofenadine concentrations were quantified with a chemiluminescence immunoassay and LC-MS/MS, respectively. Pharmacokinetics were compared between periods with standard bioequivalence approaches. RESULTS: While geometric mean folic acid AUC0-2h, which mainly reflects absorption, was 0.403 and 0.414 mg/L·h before and after the vitamin D3 course (geometric mean ratio (GMR), 1.027; 90 % confidence interval (90 % CI), 0.788-1.340), the geometric mean fexofenadine AUC0-2h was 1.932 and 2.761 mg/L·h, respectively (GMR, 1.429; 90 % CI, 0.890-2.294). PCFT- and OATP1A2-mRNA expressions in duodenal biopsies were essentially unchanged. CONCLUSIONS: No significant changes in folic acid and fexofenadine absorption were observed after a 10-day course of 1,25(OH)2D3 in humans in vivo. This study underlines the importance of confirming in vitro findings in vivo in humans.

Urinary excretion of melatonin and association with breast cancer: meta-analysis and review of the literature.

BACKGROUND: Melatonin is an endocrine hormone secreted by the pineal gland during night hours that provides several biological functions in the circadian rhythm of humans. Due to anti-estrogenic properties, melatonin is considered to exhibit a protective role against the development of breast cancer (BC). Moreover, disruption of melatonin production through environmental influences, such as night work, is assumed to be a risk factor for BC. MATERIALS AND METHODS: We reviewed recent findings concerning biological effects of melatonin on BC and conducted a meta-analysis to evaluate the association between melatonin and BC incidence. In random and fixed effects statistical models, concentrations (tertiles, quartiles) of the primary urinary metabolite of melatonin, 6-sulfatoxymelatonin (aMT6s), were tested for the assumption that women with the highest values would exhibit a lower risk of BC. RESULTS: Statistical analysis of data from 5 prospective case-control studies indicates an inverse association between BC risk and the highest levels of urinary aMT6s. This effect seems to be influenced by lag intervals between aMT6s collection and the occurrence of BC, timing and methods of urine sampling, as well as genetic and environmental factors. CONCLUSION: On the basis of the results of our meta-analysis, melatonin is likely to affect BC occurrence in women. However, methodological dissonances may require further studies.

Impact of variable CYP genotypes on breast cancer relapse in patients undergoing adjuvant tamoxifen therapy.

BACKGROUND: Tamoxifen is frequently used for the treatment of hormone receptor positive breast cancer (BC). Mainly CYP2D6 is responsible for the transformation to therapeutically active metabolites, but CYP2C19, CYP2C9 and CYP2B6 also are involved. We investigated the impact of polymorphisms within the genes encoding these CYP enzymes on the relapse-free time (RFT) in patients with BC. METHODS: Ninety-nine patients with hormone receptor positive BC, who had undergone adjuvant tamoxifen therapy, were genotyped for seventeen common variants within the genes encoding CYP2D6, CYP2C9, CYP2C19 and CYP2B6 using TaqMan and PCR-RFLP technology. Kaplan-Meier and Cox regression analyses were performed to elucidate the impact of genetic variants on RFT. Furthermore, CYP2D6 metabolic activity was determined in a subset of 50 patients by assessing dextromethorphan/dextrorphan urinary excretion ratios. CYP2D6 activity was compared to the CYP2D6 allelic combinations to evaluate the predictive value of the CYP2D6 genotyping results on phenotype. RESULTS: Although a trend toward longer RFTs in carriers of CYP2D6 allele combinations encoding for extensive and ultrafast metabolizer phenotypes was observed, none of the investigated genetic variants had a statistically significant impact on RFT. The combined analysis of five major CYP2D6 variants was useful for the discrimination between poor and non-poor metabolizers. CONCLUSIONS: Comprehensive CYP2D6 genotyping has a good predictive value for CYP2D6 activity. Common variants in CYP2C9, CYP2C19, CYP2D6, and CYP2B6 did not have a significant impact on the RFT in this cohort of patients with BC.

Low allopurinol doses are sufficient to optimize azathioprine therapy in inflammatory bowel disease patients with inadequate thiopurine metabolite concentrations.

PURPOSE: Recent studies in patients with inflammatory bowel diseases (IBD) on thiopurine therapy suggest that too low 6-thioguanine nucleotide concentrations (6-TGN) and too high methylmercaptopurine nucleotide concentrations (MMPN) can be reversed by a combination therapy of allopurinol and low-dose thiopurines. To date, however, optimal dosing has not been established. The aim of this study was to evaluate the minimal allopurinol doses necessary to achieve adequate 6-TGN concentrations in combination with low-dose azathioprine. METHODS: A stepwise dose-escalation of allopurinol was performed in 11 azathioprine-pretreated IBD patients with inadequately low 6-TGN concentrations (<235 pmol/8 × 10(8) erythrocytes) and/or elevated MMPN concentrations (>5,000 pmol/8 × 10(8) erythrocytes) and/or elevated liver enzymes (alanine aminotransferase and/or aspartate aminotransferase levels one- to threefold the upper limit of normal). Six patients were recruited into an open study, and five were treated in the context of an individualized therapeutic approach. Adverse effects, azathioprine metabolites, liver enzymes and whole blood counts were monitored two to three times per month. RESULTS: Adequate 6-TGN concentrations were achieved with a combination of 25 mg allopurinol and 50 mg azathioprine in one patient and with 50 mg allopurinol and 50 mg azathioprine in nine patients. Median 6-TGN concentrations (range) were 336 (290-488) pmol/8 × 10(8) erythrocytes after an 8-week-long intake of the final dose combination. One patient dropped out due to nausea after the first intake. MMPN concentrations and liver enzymes normalized immediately in all affected patients. All patients finishing the dose-escalation regimen tolerated the treatment without toxicity. CONCLUSIONS: Combination therapy with only 50 mg allopurinol and 50 mg azathioprine daily is sufficient, efficacious and safe in most IBD patients with inadequate thiopurine metabolite concentrations to optimize azathioprine-based IBD therapy.

Bilberry ingestion improves disease activity in mild to moderate ulcerative colitis - an open pilot study.

BACKGROUND AND AIMS: A significant fraction of patients with ulcerative colitis (UC) is not sufficiently controlled with conventional therapy or suffers from therapy related side effects. Anthocyanins, highly abundant in bilberries (Vaccinium myrtillus), were shown to have antioxidative and anti-inflammatory effects. We aimed to explore the therapeutic potential of bilberries in active UC. METHODS: In an open pilot trial with a total follow-up of 9 weeks the effect of a daily standardized anthocyanin-rich bilberry preparation was tested in 13 patients with mild to moderate UC. Clinical, biochemical, endoscopic and histologic parameters were assessed. RESULTS: At the end of the 6 week treatment interval 63.4% of patients achieved remission, the primary endpoint, while 90.9% of patients showed a response. In all patients a decrease in total Mayo score was detected (mean: 6.5 and 3.6 at screening and week 7, respectively; p<0.001). Fecal calprotectin levels significantly decreased during the treatment phase (baseline: mean 778 µg/g, range 192-1790 µg/g; end of treatment: mean 305 µg/g, range <30-1586 µg/g; p=0.049), including 4 patients achieving undetectable levels at end of treatment. A decrease in endoscopic Mayo score and histologic Riley index confirmed the beneficial effect. However, an increase of calprotectin levels and disease activity was observed after cessation of bilberry intake. No serious adverse events were observed. CONCLUSIONS: This is the first report on the promising therapeutic potential of a standardized anthocyanin-rich bilberry preparation in UC in humans. These results clearly indicate a therapeutic potential of bilberries in UC. Further studies on mechanisms and randomized clinical trials are warranted.

Cytochrome P450 2B6 (CYP2B6) and constitutive androstane receptor (CAR) polymorphisms are associated with early discontinuation of efavirenz-containing regimens.

OBJECTIVES: Cytochrome P450 2B6 (CYP2B6) is responsible for the metabolic clearance of efavirenz and single nucleotide polymorphisms (SNPs) in the CYP2B6 gene are associated with efavirenz pharmacokinetics. Since the constitutive androstane receptor (CAR) and the pregnane X receptor (PXR) correlate with CYP2B6 in liver, and a CAR polymorphism (rs2307424) and smoking correlate with efavirenz plasma concentrations, we investigated their association with early (<3 months) discontinuation of efavirenz therapy. METHODS: Three hundred and seventy-three patients initiating therapy with an efavirenz-based regimen were included (278 white patients and 95 black patients; 293 male). DNA was extracted from whole blood and genotyping for CYP2B6 (516G → T, rs3745274), CAR (540C → T, rs2307424) and PXR (44477T → C, rs1523130; 63396C → T, rs2472677; and 69789A → G, rs763645) was conducted. Binary logistic regression using the backwards method was employed to assess the influence of SNPs and demographics on early discontinuation. RESULTS: Of the 373 patients, 131 withdrew from therapy within the first 3 months. Black ethnicity [odds ratio (OR) = 0.27; P = 0.0001], CYP2B6 516TT (OR = 2.81; P = 0.006), CAR rs2307424 CC (OR = 1.92; P = 0.007) and smoking status (OR = 0.45; P = 0.002) were associated with discontinuation within 3 months. CONCLUSIONS: These data indicate that genetic variability in CYP2B6 and CAR contributes to early treatment discontinuation for efavirenz-based antiretroviral regimens. Further studies are now required to define the clinical utility of these associations.

Effect of the CYP2C8 genotype on the pharmacokinetics and pharmacodynamics of repaglinide.

The pharmacokinetics of repaglinide shows pronounced interindividual variability, for which several reasons have been considered, including interactions with drugs inhibiting CYP2C8 and CYP2C8 genetic polymorphism. However, existing data on the role of genetic polymorphisms in repaglinide disposition are not fully consistent. We studied the effect of CYP2C8*3 on the pharmacokinetics and pharmacodynamics of repaglinide in 29 healthy whites carrying CYP2C8*3/*3 (n = 4), CYP2C8*1/*3 (n = 13), or CYP2C8*1/*1 (n = 12). After administration of a single dose of 2 mg of repaglinide, blood was drawn for assessment of repaglinide pharmacokinetics and pharmacodynamics, and urine was collected to quantify the main repaglinide metabolites M1 and M4 up to 24 h postdose. Repaglinide and the metabolites were quantified by liquid chromatography-tandem mass spectrometry. Considering only the effect of CYP2C8*3, the mean (95% confidence interval) area under the time-concentration curve (AUC) from zero to infinity of repaglinide was 72.4 (6.7-138.0), 97.2 (59.2-135.2), and 105.9 (52.4-159.3) ng · ml(-1) · h and the maximal concentration (C(max)) was 38.5 (3.8-73.2), 50.3 (37.5-63.0), and 60.3 (31.5-89.1) ng · ml(-1), respectively, in carriers of CYP2C8*3/*3, CYP2C8*1/*3, and CYP2C8*1/*1 [p > 0.05, one-way analysis of variance (ANOVA)]. In addition, for urinary metabolite excretion and pharmacodynamic parameters, i.e., mean and maximal changes in insulin and glucose concentration, no significant differences between CYP2C8 genotypes were observed. Likewise, no significant effects on the pharmacokinetics or pharmacodynamics were observed when AUC and C(max) of repaglinide were corrected for reported effects of the SLCO1B1 521T>C polymorphism or when both polymorphisms were tested in a two-way ANOVA. In conclusion, CYP2C8*3 does not seem to play an important role in the pharmacokinetics and pharmacodynamics of repaglinide given in a therapeutic dose.

Optimized intrapleural cisplatin chemotherapy with a fibrin carrier after extrapleural pneumonectomy: a preclinical study.

OBJECTIVE: Our objective was to evaluate whether platinum concentrations in chest wall tissue and in serum are optimized by intracavitary application of cisplatin loaded to a fibrin carrier compared with cisplatin solution in a randomized setting of a pig model. METHODS: After left-sided pneumonectomy including parietal pleurectomy, pigs were randomly assigned to receive either 90 mg/m(2) cisplatin intracavitary solution (n = 6) or to receive 5 mg cisplatin-fibrin (n = 5) applied on a predefined area of the chest wall. Platinum concentration in serum as well as in chest wall tissue was determined at several early time points until day 5 after treatment. Platinum levels were measured by inductively coupled plasma sector field mass spectrometric detection with a matrix-matched calibration procedure. RESULTS: The dose- and surface-corrected (geometric) mean concentration of cisplatin in chest wall tissue 2 hours but also at day 5 after the application was doubled in animals treated with cisplatin-fibrin compared with the animals treated with cisplatin-solution. In serum, the dose- and surface-corrected exposure toward cisplatin (area under the curve(0-5d)) was significantly lower with cisplatin-fibrin than with cisplatin-solution (P < .0005). This is also reflected by significantly reduced serum creatinine and urea values in the cisplatin-fibrin group (P < .0001). Animals treated with cisplatin-fibrin additionally had a significantly better postoperative course as assessed by a well-being score (P < .001). CONCLUSIONS: After cisplatin-fibrin treatment, cisplatin tissue concentration was increased whereas systemic cisplatin concentrations were significantly reduced in comparison with cisplatin-solution treatment. This finding offers a clear advantage inasmuch as rate and severity of systemic adverse events can be reduced while local cytotoxic concentrations are at least maintained.

Do activities of cytochrome P450 (CYP)3A, CYP2D6 and P-glycoprotein differ between healthy volunteers and HIV-infected patients?

BACKGROUND: In inflammation and infection, cytochrome P450 (CYP) enzyme activities are down-regulated. Information on possible discrepancies in activities of CYP enzymes and drug transporters between HIV-infected patients and healthy people is limited. METHODS: We used midazolam, dextromethorphan and digoxin as in vivo phenotyping probes for CYP3A (CYP3A4/5), CYP2D6 and P-glycoprotein activities, respectively, and compared these activities between 12 healthy Caucasian volunteers and 30 treatment-naive HIV-infected patients. RESULTS: Among the HIV-infected patients, the overall CYP3A activity (apparent oral midazolam clearance) was approximately 50% of the activity observed in healthy volunteers (point estimate 0.490, 90% confidence interval [CI] 0.377-0.638). The CYP2D6 activity (plasma ratio area under the curve [AUC]; AUC(dextromethorphan)/AUC(dextrorphan)) was essentially unchanged (point estimate 1.289, 90% CI 0.778-2.136). P-glycoprotein activity was slightly lower in patients (digoxin maximum concentration point estimate 1.304, 90% CI 1.034-1.644). CONCLUSIONS: The overall CYP3A activity was approximately 50% lower in HIV-infected patients than in healthy volunteers. The CYP2D6 activity was highly variable, but, on average was not different between groups, whereas a marginally lower P-glycoprotein activity was observed in treatment-naive HIV-infected patients.

The role of human CYP2C8 and CYP2C9 variants in pioglitazone metabolism in vitro.

The cytochrome P450 enzyme CYP2C8 appears to have a major role in pioglitazone metabolism. The present study was conducted to further clarify the role of individual CYPs and of the CYP2C8/9 polymorphisms in the primary metabolism of pioglitazone in vitro. Pioglitazone (2-400 microM) was incubated with isolated cytochrome P450 enzymes or human liver microsomes, some of them carrying either the CYP2C8*3/*3 genotype (and also the CYP2C9*2/*2 genotype) or the CYP2C8*1/*1 genotype (five samples each). The formation of the primary pioglitazone metabolite M-IV was monitored by HPLC. Enzyme kinetics were estimated assuming a single binding site. Mean intrinsic clearance of pioglitazone to the metabolite M-IV was highest for CYP2C8 and CYP1A2 with 58 pmol M-IV/min/nmol CYP P450/microM pioglitazone each, 53 for CYP2D6*1, 40 for CYP2C19*1, and 34 for CYP2C9*2, respectively. CYP2A6, CYP2B6, CYP2C9*1, CYP2C9*3, CYP2E1, CYP3A4 and CYP3A5 did not form quantifiable amounts of M-IV. CYP2C8*1/*1 microsomes (25 +/- 4 pmol M-IV/min/mg protein/muM pioglitazone) showed lower intrinsic clearance of pioglitazone than CYP2C8*3/*3 microsomes (35 +/- 9, p = 0.04). In all samples, metabolite formation showed substrate inhibition, while pioglitazone did not inhibit CYP2C8-mediated paclitaxel metabolism. CYP2C8, CYP1A2 and CYP2D6 are major CYPs forming M-IV in vitro. The higher activity of CYP2C8*3/CYP2C9*2 microsomes may result from a contribution of CYP2C9*2, or from differences in CYP2C8 expression. The evidence for substrate-specific inhibitory effects of pioglitazone on CYP2C-mediated metabolism needs to be tested in further studies.