Associations between vitamin D status, VDR gene polymorphisms and echocardiographic markers in Polish patients with cardiovascular disease

Aim: This work was designed to investigate the associations between vitamin D metabolites, VDR gene polymorphisms and echocardiographic markers in a population of patients with cardiovascular disease. Methods: Echocardiographic markers for 42 patients were determined with tissue Doppler techniques. PCR-restriction fragment length polymorphism analysis identified genetic variants ApaI, TaqI, BsmI and FokI. A validated UHPLC-MS/MS method determined vitamin D metabolites. Results: Patients with the ApaI-GT genotype exhibited a lower pressure gradient across the aortic valve than ApaI-TT carriers. BMI, ApaI-GT, TaqI-TC, aortic arch diameter and maximal pressure gradient were significant univariate predictors of hypertension. Conclusion: A potential link exists between VDR gene polymorphisms and cardiovascular function.

Influence of Genetic and Epigenetic Factors of P2Y12 Receptor on the Safety and Efficacy of Antiplatelet Drugs

PURPOSE

P2Y12 receptor inhibitors are drugs that decrease the risk of stent thrombosis and lower the long-term risk of non-stent-related myocardial infarction and stroke. They inhibit the binding of adenosine diphosphate (ADP) to the P2Y12 receptor and effectively reduce platelet reactivity. However, considerable variability in the pharmacodynamics response contributes to a failure of antiplatelet therapy; this phenomenon is especially notorious for older drugs, such as clopidogrel. Some genetic polymorphisms associated with these drugs' metabolic pathway, especially in the CYP2C19 gene, can significantly decrease antiplatelet efficacy. There are few reports on the variability stemming from the target of this drug class that is the P2Y12 receptor itself.

RESULTS AND CONCLUSION

This review summarizes the results of research that focus on the influence of P2Y12 genetic polymorphisms on the pharmacodynamics and the efficacy of P2Y12 inhibitors. We found that the conclusions of the studies are unequivocal, and despite several strong candidates, such as G52T (rs6809699) or T744C (rs2046934), they may not be independent predictors of the inadequate response to the drug. Most probably, P2Y12 genetic polymorphisms contribute to the effect exerted by other gene variants (such as CYP2C19*2/*3/*17), drug interactions, or patient habits, such as smoking. Also, epigenetic modifications, such as methylation or miRNA levels, may play a role in the efficacy of antiplatelet treatment.

Vitamin D Metabolism Gene Polymorphisms and Their Associated Disorders: A Literature Review

BACKGROUND

Vitamin D is a fat-soluble vitamin, and it is a potential key factor in maintaining a healthy status. Various observational studies have reported the association between vitamin D deficiency and an elevated risk of osteoporosis, cardiovascular disease, diabetes mellitus, and certain types of cancer. The number of studies that investigates the genetic determinants of vitamin D hydroxy metabolism has been growing. Still, its association with the genetic variants remains unclear, particularly those genes related to vitamin D metabolism.

AIMS

This work is a comprehensive review of available evidence of the effect of genetic variants on vitamin D metabolism and their impact on vitamin D status in the human body, disorders including coronavirus disease 2019 infection, and its importance for clinical investigators and public health.

RESULTS

Genome-wide association studies and candidate gene studies show that genetic factors are influencing the circulating levels of vitamin D. These genetic changes are implicated in various pathways of vitamin D, such as metabolism and transport. It is also involved in the formation of the ternary complex (vitamin D receptor - retinoid receptor - transcription factor II B).

CONCLUSION

Linkage studies may fail to identify replicated genetic architecture of vitD metabolism. Genome-wide association studies and the candidate gene approach have shown reproducible influences of gene control on vitD status.

Measurement of plasma 25-hydroxyvitamin D2, 25-hydroxyvitamin D3 and 3-epi-25-hydroxyvitamin D3 in population of patients with cardiovascular disease by UPLC-MS/MS method

Vitamin D has a potential role in protecting against cardiovascular disease (CVD). Serum 25-hydroxyvitamin D (25D) is the most widely used indicator of vitamin D status in the human body. 25D is estimated as total of 25-hydroxyvitamin D2 (25D2) and 25-hydroxyvitamin D3 (25D3). However, the presence of 3-epi-25-hydroxyvitamin D3 (3epi25D3) can affect 25D measurement. In this research a novel validated UPLC-MS/MS technique was developed to measure three vitamin D metabolites, 25D2, 25D3 and 3epi25D3 in human plasma. A liquid-liquid extraction using hexane was applied for isolation of the analytes from the samples. A chromatographic separation was achieved in a Kinetex F5 analytical column with isocratic elution (water and methanol with 0.1% methanoic acid, 20:80 v/v). Mass spectrometry detection of the metabolites was performed in a triple-quadruple tandem mass spectrometer under positive ion mode. Concentrations of the analytes were estimated in plasma samples of 54 patients. Validation parameters of the UPLC-MS/MS method, including linearity, precision, accuracy, and stability, fulfilled the requirements for bioanalytical assays. The deficient concentration of 25D (<20 ng/mL) was stated in over 60% of patients. 3epi25D3 was present in 78% of samples and its relative amount ranged from 0 to 54.1% of 25D concentration. The analysis of 25D2, 25D3 and 3epi25D3 by the validated UPLC-MS/MS method in plasma of patients with CVD permitted the classification of the patients with insufficient levels of 25D. 3epi25D3 might be relevant in the classification of vitamin D status.

Pharmacokinetic Interaction between Sorafenib and Atorvastatin, and Sorafenib and Metformin in Rats

The tyrosine kinase inhibitor sorafenib is the first-line treatment for patients with hepatocellular carcinoma (HCC), in which hyperlipidemia and type 2 diabetes mellitus (T2DM) may often coexist. Protein transporters like organic cation (OCT) and multidrug and toxin extrusion (MATE) are involved in the response to sorafenib, as well as in that to the anti-diabetic drug metformin or atorvastatin, used in hyperlipidemia. Changes in the activity of these transporters may lead to pharmacokinetic interactions, which are of clinical significance. The study aimed to assess the sorafenib−metformin and sorafenib−atorvastatin interactions in rats. The rats were divided into five groups (eight animals in each) that received sorafenib and atorvastatin (I_SOR+AT), sorafenib and metformin (II_SOR+MET), sorafenib (III_SOR), atorvastatin (IV_AT), and metformin (V_MET). Atorvastatin significantly increased the maximum plasma concentration (C_max) and the area under the plasma concentration–time curve (AUC) of sorafenib by 134.4% (p < 0.0001) and 66.6% (p < 0.0001), respectively. Sorafenib, in turn, caused a significant increase in the AUC of atorvastatin by 94.0% (p = 0.0038) and its metabolites 2−hydroxy atorvastatin (p = 0.0239) and 4−hydroxy atorvastatin (p = 0.0002) by 55.3% and 209.4%, respectively. Metformin significantly decreased the AUC of sorafenib (p = 0.0065). The AUC ratio (II_SOR+MET group/III_SOR group) for sorafenib was equal to 0.6. Sorafenib did not statistically significantly influence the exposure to metformin. The pharmacokinetic interactions observed in this study may be of clinical relevance in HCC patients with coexistent hyperlipidemia or T2DM.

Impact of genetic variants of selected cytochrome P450 isoenzymes on pharmacokinetics and pharmacodynamics of clopidogrel in patients co-treated with atorvastatin or rosuvastatin

PURPOSE

Impaired antiplatelet effect of clopidogrel (CLP) can result from drug-drug interactions and genetic polymorphisms of drug-metabolizing enzymes. The aim of the study was to evaluate the effect of genetic polymorphisms of ABCB1 and the selected cytochrome P450 isoenzymes on the pharmacodynamics and pharmacokinetics of CLP and its metabolites in patients co-treated with atorvastatin or rosuvastatin.

METHODS

The study involved 50 patients after coronary angiography/angioplasty treated with CLP and atorvastatin (n = 25) or rosuvastatin (n = 25) for at least 6 months. Plasma concentrations of CLP, diastereoisomers of thiol metabolite (inactive H3 and active H4), and inactive CLP carboxylic acid metabolite were measured by UPLC-MS/MS method. Identification of the CYP2C19*2, CYP2C19*17, CYP3A4*1G, CYP1A2*1F, and ABCB1 C3435T genetic polymorphisms was performed by PCR-RFLP, while platelet reactivity units (PRU) were tested using the VerifyNow P2Y12 assay.

RESULTS

There were significant differences in the pharmacokinetic parameters of the H4 active metabolite of CLP in the atorvastatin and rosuvastatin group divided according to their CYP2C19 genotype. There were no significant associations between CYP3A4, CYP1A2, and ABCB1 genotypes and pharmacokinetic parameters in either statin groups. In the multivariate analysis, CYP2C19*2 genotype and non-genetic factors including BMI, age, and diabetes significantly affected platelet reactivity in the studied groups of patients (P < 0.01). In the atorvastatin group, CYP2C19*2, CYP3A4*1G, and ABCB1 C3435T TT genotypes were independent determinants of PRU values (P < 0.01).

CONCLUSION

The CYP2C19*2 allele is the primary determinant of the exposition to the H4 active metabolite of clopidogrel and platelet reactivity in patients co-treated with atorvastatin or rosuvastatin.

Assessment of the Risk of Rhabdomyolysis and Myopathy During Concomitant Treatment with Ticagrelor and Statins

The introduction of ticagrelor, one of the first directly-acting oral antiplatelet drugs, provided new possibilities in the prevention of thrombotic events in patients with acute coronary syndromes (ACS). Current guidelines recommend ticagrelor in dual antiplatelet therapy with aspirin over clopidogrel for prevention of stent thrombosis in patients with ACS. Moreover, in the management of ACS, lipid-lowering treatment with high-intensity statin therapy is advised for secondary prevention of cardiovascular events over the long term. Despite the apparent advantages of combined antiplatelet and lipid-lowering treatments, a possible interaction between statins and ticagrelor may lead to myopathy and rhabdomyolysis. In this review, relevant information was gathered on the ticagrelor-statin interaction that might lead to this life-threatening condition. This review focuses on the most widely used statins—simvastatin, atorvastatin, and rosuvastatin. Possible mechanisms of this interaction are discussed, including CYP3A4 isoenzymes, organic anion transporter polypeptide (OATPs), P-glycoprotein and glucuronidation. PubMed database was searched for relevant case reports and all data gathered from the introduction of ticagrelor to March 2018 are presented and discussed. In summary, co-administration of statins and ticagrelor was found to be relatively safe in routinely prescribed doses. However, caution should be exercised, especially in elder populations.

Development of an LC-MS/MS method for simultaneous determination of ticagrelor and its active metabolite during concomitant treatment with atorvastatin

A combination of antiplatelet drugs with high-intensity statin therapy is a standard in patients with coronary events. Concomitant treatment with ticagrelor, a moderate CYP3A4 inhibitor, and CYP3A4-metabolized statins such as atorvastatin, might lead to an increased risk of muscle-related adverse events. Therefore, investigation of concentrations of these compounds in clinical samples is necessary. For this purpose, an LC-MS/MS method was developed for simultaneous determination of ticagrelor and its active metabolite (AR-C124910XX), as well as 2-hydroxyatorvastatin, which is the main metabolite of atorvastatin. Protein precipitation was used for sample preparation and afterwards the analytes were separated on a Kinetex XB-C18 column with an isocratic elution (water and acetonitrile with 0.1% formic acid, 57:43, v/v). Detection was performed on a triple-quadrupole MS with multiple-reaction-monitoring via electrospray ionization. The method was fully validated according to the EMA's recommendations. Determination was possible within ranges: 1.25-2000 ng/mL for ticagrelor, 1.25-1000 ng/mL for its AR-C124910XX, 1.25-50 ng/mL for atorvastatin and 1.14-45.73 for 2-hydroxyatorvastatin. Within and between-run accuracy, expressed as a relative error, was within 0.05-10.56% for all analytes, while within and between-run precision, expressed as coefficient of variation, was within 0.61-9.91%. Ticagrelor, atorvastatin and their main metabolites were found to be stable in acetonitrile stock solutions, and in plasma samples stored for 24 h at room temperature, 1 month at -25 °C, after 3 cycles of freezing and thawing, and in processed samples stored as a dry residue for 24 h at 4 °C and for 24 h in autosampler at room temperature. This simple and rapid method allowed simultaneous determination of the analytes for the first time. The procedure was applied for the pharmacokinetic study of ticagrelor, its active metabolite AR-C124910XX, and 2-hydroxyatorvastatin in patients simultaneously treated with ticagrelor and atorvastatin.

High-performance liquid chromatography methods for the analysis of endogenous cortisol and cortisone in human urine: comparison of mass spectrometry and fluorescence detection

BACKGROUND

The analysis of steroids in biological matrices is challenging. One can apply immunoassay as well as gas and liquid chromatography with various types of detection, depending on the available equipment and the experience of the analyst. The question is how the methods are interchangeable between themselves. Doubts were reported having compared immunoassays and chromatography-mass spectrometry, but there are scarce data on chromatographic methods with detection types other than mass spectrometry.

METHODS

Here, we present the detailed comparison of two liquid chromatographic methods for the determination of free urinary cortisol and cortisone: one with fluorescence detection (high-performance liquid chromatography [HPLC-FLD]) and the other with tandem mass spectrometry (HPLC-MS/MS). The comparison was made with 199 human urine samples. The data analysis included Passing-Bablok and Deming regression, Bland-Altman test, Wilcoxon test, mountain plot and Lin's concordance correlation coefficient.

RESULTS

The validation data indicated that both methods met the requirements of the European Medicines Agency. However, the statistical analysis revealed the systematic bias between the two assays. The Passing-Bablok and the Deming tests showed that the HPLC-FLD method overestimated results for cortisol and underestimated measurements for cortisone. The Bland-Altman analysis estimated the mean differences between the methods: 18.8 nmol/L for cortisol and -16.9 nmol/L for cortisone measurement.

CONCLUSIONS

Both methods' results led to the same conclusion in observational studies, but the techniques are not interchangeable. The literature data, the observations from the clinical setting and our experience clearly indicate that the future of steroid measurements will belong to chromatography coupled with mass spectrometry.

Relationship between exposure to treosulfan and its monoepoxytransformer - An insight from population pharmacokinetic study in pediatric patients before hematopoietic stem cell transplantation

Treosulfan (TREO), a structural analog of busulfan, is currently studied as a myeloablative agent in conditioning regimens before hematopoietic stem cell transplantation in pediatric patients. High exposure to TREO (>1650 mg∗h/mL) might be related to early toxicity, especially skin toxicity and mucositis. The aim of the present study was to investigate a potential relationship between exposure to TREO and its monoepoxytransformer (S,S-EBDM), as well as variability of the pharmacokinetics of these entities by means of a population pharmacokinetic approach with a non-linear mixed-effects analysis. The study included data from 14 children with malignant and non-malignant diseases treated with TREO in daily doses 10-14 g/m². The parent-metabolite population pharmacokinetic model was developed in NONMEM 7.3 software. Upon the constructed model, an extensive simulation was performed to assess the correlation between exposure to TREO and S,S-EBDM. It was found that TREO and S,S-EBDM pharmacokinetics was best described with 2-compartmental and 1-compartmental linear models, respectively. The vast majority (>65%) of TREO was transformed to S,S-EBDM. Overall, a considerable interpatient variability of pharmacokinetic parameters was observed, especially the clearance of S,S-EBDM. A weak correlation was found between the exposure to TREO and S,S-EBDM (r = 0.1681, p < 0.0001). Also, patients with an exposure to TREO above 1650 mg∗h/mL were most likely to have also a high exposure to S,S-EBDM (35.38 μM∗h vs. 43.14 μM∗h, p < 0.0001). In summary, a parent-metabolite population pharmacokinetic model for TREO and S,S-EBDM was developed for the first time. It was shown that there is a weak correlation between exposure to TREO and S,S-EBDM. Therefore therapeutic drug monitoring of not only prodrug but also its active epoxide might be needed.

Clinical bioanalysis of treosulfan and its epoxides: The importance of collected blood processing for valid pharmacokinetic results

Currently, there is an urgent need to establish the optimal dosing of TREO in conditioning prior to hematopoietic stem cell transplantation, especially in children. For that purpose, pharmacokinetic analyses are ongoing within clinical phase II and III trials. In this paper, HPLC methods for determination of prodrug treosulfan and/or its biologically active epoxides in human plasma or serum are reviewed for the first time, including the spectrum of analytes being quantified, detection type, and derivatization methodology. The major focus is addressed to the stability of TREO and its monoepoxide related with different strategies of patients' blood processing, e.g. blood pH lowering to different values, no pH adjustment; centrifugation of blood immediately after collection or within a few hours later. This issue is crucially important for the robust bioanalysis because the epoxytransformation of TREO is a nonenzymatic, highly pH and temperature-dependent reaction. In-depth analysis of the literature results demonstrates that some methodologies of blood treatment could produce the systematic underestimation of TREO concentrations. Consequently, the drug clearance and volume of distribution will be overestimated, which might false the association of the drug exposure with the regimen-related toxicity and clinical outcomes. The paper indicates the deficiencies of the blood processing strategies and offers hints for their refinement. The provided information ought to be important in the current investigations of the personalized TREO pharmacokinetics.

Influence of genetic co-factors on the population pharmacokinetic model for clopidogrel and its active thiol metabolite

PURPOSE

A high interindividual variability is observed in the pharmacokinetics of clopidogrel, a widely used antiplatelet drug. In the present study, a joint parent-metabolite population pharmacokinetic model was developed to adequately describe observed concentrations of clopidogrel and its active thiol metabolite (H4).

METHODS

The study included 63 patients undergoing elective coronarography or percutaneous coronary intervention. The population pharmacokinetic model was developed in the NONMEM 7.3 software, and first-order conditional estimation method with interaction was applied. Also, the influence of covariates was evaluated (age, weight, body mass index (BMI), obesity defined as BMI ≥ 30 kg/m2, sex, diabetes mellitus, co-administration of PPI or statins, presence of CYP2C19*2, CYP2C19*17, CYP3A4*1G alleles, and ABCB1 3435 TT genotype).

RESULTS

It was found that the only significant covariate was the presence of CYP2C19*2 allele, which had an impact on lower conversion of clopidogrel to H4. As a result, predicted area under the time-concentration curve values was lower in carriers of this allele, with median 5.94 ng h/ml (interquartile range 3.92-12.51 [ng∙h/ml]) vs. 12.70 ng h/ml in non-carriers (interquartile range, 7.00-19.39 [ng∙h/ml]), respectively (p = 0.004).

CONCLUSIONS

Developed model predicts that the only significant covariate influencing the observed concentrations and therefore the exposure to the active H4 metabolite is the presence of CYP2C19*2 allele.

Population pharmacokinetics of treosulfan and development of a limited sampling strategy in children prior to hematopoietic stem cell transplantation

Purpose

There is an increasing interest in use of treosulfan (TREO), a structural analogue of busulfan, as an agent in conditioning regimens prior to hematopoietic stem cell transplantation (HSCT), both in pediatric and adult populations. The aim of this study was to develop a population pharmacokinetic model and to establish limited sampling strategies (LSSs) enabling accurate estimation of exposure to this drug.

Methods

The study included 15 pediatric patients with malignant and non-malignant diseases, undergoing conditioning regimens prior to HSCT including TREO administered as a 1 h or 2 h infusion at daily doses of 10, 12, or 14 g/m². A population pharmacokinetic model was developed by means of non-linear mixed-effect modeling approach in Monolix® software. Multivariate regression analysis and Bayesian method were used to develop 2- and 3-point strategies for estimation of exposure to TREO.

Results

Pharmacokinetics of TREO was best described with a two-compartmental linear model with proportional residual error. Following sampling schedules allowed accurate estimation of exposure to TREO: 1 h and 6 h or 1 h, 2 h, and 6 h for a TREO dose 12 g/m² in a 1 h infusion, or at 2 h and 6 h or 2 h, 4 h, and 8 h for a TREO dose of 12 g/m² and 14 g/m² in a 2 h infusion.

Conclusions

A two-compartmental population pharmacokinetic model of TREO was developed and successfully used to establish 2- and 3-point LSSs for accurate and precise estimation of TREO AUC_0→∞.

Disposition of treosulfan and its active monoepoxide in a bone marrow, liver, lungs, brain, and muscle: Studies in a rat model with clinical relevance

For the recent years, the application of treosulfan (TREO)-based conditioning prior to hematopoietic stem cell transplantation (HSCT) has been increasing as an alternative to busulfan-based therapy, especially for patients presenting high risk of developing hepato-, pulmo-, and neurotoxicity. So far, the penetration of TREO and its epoxy-derivatives into central nervous system and aqueous humor of the eye has been investigated. However, lacking knowledge on the compounds distribution into the other key tissues precludes comprehensive understanding and assessment of TREO clinical efficacy and toxicity. In this paper, the disposition of TREO and its active monoepoxide (S,S-EBDM) in a bone marrow, liver, lungs, brain, and quadriceps femoris was studied in an animal model. Male and female adult Wistar rats (n=48/48) received an intraperitoneal injection of TREO at the dose of 500mg/kg b.w. Concentrations of TREO and S,S-EBDM in tissues were determined with a validated HPLC-MS/MS method. Pharmacokinetic calculations were performed in WinNonlin using a noncompartmental analysis. Mean values of the maximal concentrations of TREO and S,S-EBDM in the organs were sex-independent and ranged from 61 to 1650μM and 25-105μM, respectively. No quantifiable levels of S,S-EBDM were found in the liver. Average tissue/plasma area under the curve (AUC) ratio for unbound TREO increased in the sequence: brain (0.10)<muscle (0.77)<bone marrow=lungs (0.82)<liver (0.96). The tissue/plasma AUC ratio for unbound S,S-EBDM changed as follows: brain (0.35)<lungs (0.50)<bone marrow (0.75)<muscle (1.14). Elimination half-lives of the compounds in plasma and the organs ranged from 0.7h to 2.1h. Scaling of the obtained AUCs of TREO and S,S-EBDM and the literature AUCs of busulfan to concentrations of the drugs in HSCT patients' plasma show that TREO reaches much higher levels in the organs than busulfan. Nonetheless, low S,S-EBDM exposure in a liver, lungs, and brain, even compared with busulfan, may contribute to relatively low organ toxicity of TREO-based conditioning regimens. Similarity of the scaled bone marrow AUCs of S,S-EBDM and busulfan corresponds to comparable myeloablative potency of TREO- and busulfan-based conditioning. The biological half-lives of TREO and S,S-EBDM in plasma and the studied organs indicate that 48h lag time following administration of the last dose of TREO to HSCT patients is sufficient to protect the transplanted stem cells from the compounds' exposure.

Impact of CYP3A4*1G Allele on Clinical Pharmacokinetics and Pharmacodynamics of Clopidogrel

BACKGROUND AND OBJECTIVES

Resistance to the antiplatelet treatment with clopidogrel has both genetic and non-genetic causes. Polymorphic variants of cytochrome P450 3A4 isoenzyme involved in the bioactivation of clopidogrel might have an influence on responsiveness to the drug. The aim of this study was to evaluate the influence of CYP3A4*1G (IVS10+12G>A, rs2242480) on the pharmacokinetics and pharmacodynamics of clopidogrel.

METHODS

CYP3A4*1G polymorphism was determined in a group of 82 patients undergoing percutaneous coronary intervention and taking 75 mg of clopidogrel daily. Concentrations of clopidogrel and its metabolites, inactive carboxylic acid derivative and two diastereoisomers of active thiol metabolite: H3 and H4, were determined by a validated HPLC-MS/MS method. Pharmacodynamic effect was measured by an impedance method with a Multiplate analyzer. Moreover, an effect of factors, such as CYP2C19 phenotype, age, gender, body mass index and interactions with drugs metabolized by CYP3A4 were also investigated.

RESULTS

In the studied group allele frequencies were: wt-0.921, *1G-0.079. Pharmacokinetic parameters of clopidogrel and its metabolites were not significantly different in carriers of *1G allele, comparing to wt/wt homozygotes. Platelet aggregation was higher in heterozygotes than in wt/wt carriers; however, the difference was not statistically significant (p = 0.484). In a multivariate analysis, which included age, body mass index, co-morbidities and coadministered drugs, CYP3A4*1G was not a predictor of values of H3 and H4 pharmacokinetic parameters and platelet aggregation.

CONCLUSION

CYP3A4*1G might not be a significant contributor to the variability in pharmacokinetic and pharmacodynamic response to clopidogrel therapy.

Variants of HSD11B2 gene in hypertensive disorders of pregnancy

INTRODUCTION

One of the hypotheses concerning the etiology of gestational hypertension (GH) and pre-eclampsia (PE) assumes that they develop as a result of placenta malfunctioning at the early stage of pregnancy. Placental dysfunction is also associated with the decreased activity of 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2), which in normal pregnancy protects the fetus from the excess of maternal cortisol.

OBJECTIVE

The aim of the study was to analyze the sequence of HSD11B2, a gene that encodes 11β-HSD2, searching for mutations and haplotypes associated with the increased risk of GH or PE. Those may serve as potential genetic markers of GH and PE.

METHODS

The study was performed in case-control structure and included pregnant women (in third trimester) diagnosed with: GH, PE or being normotensive (control group). The research comprised DNA sequencing of HSD11B2, followed by restriction analysis (PCR-RFLP). The linkage disequilibrium analysis and haplotype-based case-control analysis were performed.

RESULTS

Six sequence variations were observed. Four mutations were indicated in the coding region of HSD11B2 and the other two in 3'-UTR. Two SNPs: c.468C > A and c.534G > A were found to be in total disequilibrium.

CONCLUSIONS

High variability in HSD11B2 sequence was indicated in the study population, but the relevance of observed SNPs to GH or PE development was not confirmed.

DISSOLUTION KINETICS STUDIES OF CLOPIDOGREL FROM SELECTED MULTISOURCE COATED TABLETS WITH APPLICATION OF CAPILLARY ZONE ELECTROPHORESIS METHOD

Resistance to an anti-platelet agent clopidogrel (CLP) and the growing number of products with the drug cause the need for comparison of their quality to assure patients safe and effective treatment. Therefore, the aim of the study was to compare in vitro dissolution kinetics of CLP immediate-release tablets, commonly used in anti-platelet therapy in Poland. For analysis of CLP in samples obtained from dissolution test a capillary zone electrophoresis (CZE) method was elaborated and validated. Separation of CLP and ticlopidine, used as an internal standard, was performed in silica capillary filled with phosphate buffer of pH 2.5, at the applied voltage of 20 kV. The CZE method fulfilled the validation requirements for determination of drugs in pharmaceutical matrices and was successfully applied for analysis of CLP dissolved from the tablets. Dissolution profiles were prepared for each product and mean dose fractions of CLP dissolved from tablets at 30 min were calculated. Kinetic parameters of the CLP dissolution from the studied products were compared. Analysis of variance (ANOVA) did not reveal differences between CLP fractions dissolved at 30 min time point from the tested drug products. However, ANOVA with Tukey multiple comparison test revealed significant differences in first-order dissolution rate constants and t₀.₅ values (times at which 50% of drug is dissolved) of CLP among tested tablets. It was concluded that the studied CLP products met the acceptance criteria regarding dissolution test but differed with each other in dissolution kinetics.

Impact of common ABCB1 polymorphism on pharmacokinetics and pharmacodynamics of clopidogrel and its metabolites

WHAT IS KNOWN AND OBJECTIVE

The reasons of clopidogrel (CLP) resistance are still unclear. The response to CLP may be influenced by both genetic and non-genetic factors. Among genetic factors, common polymorphisms in the gene coding glycoprotein-P (P-gp, MDR1 and ABCB1) are considered as potential determinants of the efficacy of CLP treatment. The aim of this study was to evaluate the influence of ABCB1 3435C>T genetic polymorphism on the pharmacokinetics and pharmacodynamics of CLP and its metabolites: diastereoisomers of thiol metabolite (the inactive H3 and the active H4) and inactive carboxylic derivative.

METHODS

The study group included 42 patients undergoing elective coronary angiography and percutaneous coronary intervention. The plasma concentrations of CLP and its metabolites were measured by a validated HPLC-MS/MS method. Whole-blood aggregation was determined with Multiplate analyzer. For evaluation of ABCB1 3435C>T polymorphism, PCR-RFLP method was applied.

RESULTS AND DISCUSSION

It was found that Exposition to the unchanged CLP, measured by AUC0-t of the drug, was significantly lower (P = 0·012) in TT homozygotes comparing to that observed in CC and CT genotypes, although no correlation was found between platelet aggregation and ABCB1 genetic polymorphism.

WHAT IS NEW AND CONCLUSION

Our findings show that the presence of 3435C>T allele has an impact on CLP pharmacokinetics but not on the drug pharmacodynamics. Therefore, the 3435C>T genotype may not be the primary determinant influencing the pharmacokinetics of the active H4 metabolite and antiplatelet effect of the drug.

Bupivacaine administered intrathecally versus rectally in the management of intractable rectal cancer pain in palliative care

Background

Unacceptable adverse effects, contraindications to and/or ineffectiveness of World Health Organization step III “pain ladder” drugs causes needless suffering among a population of cancer patients. Successful management of severe cancer pain may require invasive treatment. However, a patient’s refusal of an invasive procedure necessitates that clinicians consider alternative options.

Objective

Intrathecal bupivacaine delivery as a viable treatment of intractable pain is well documented. There are no data on rectal bupivacaine use in cancer patients or in the treatment of cancer tenesmoid pain. This study aims to demonstrate that bupivacaine administered rectally could be a step in between the current treatment options for intractable cancer pain (conventional/conservative analgesia or invasive procedures), and to evaluate the effect of the mode of administration (intrathecal versus rectal) on the bupivacaine plasma concentration.

Cases

We present two Caucasian, elderly inpatients admitted to hospice due to intractable rectal/tenesmoid pain. The first case is a female with vulvar cancer, and malignant infiltration of the rectum/vagina. Bupivacaine was used intrathecally (0.25–0.5%, 1–2 mL every 6 hours). The second case is a female with ovarian cancer and malignant rectal infiltration. Bupivacaine was adminstered rectally (0.05–0.1%, 100 mL every 4.5–11 hours).

Methods

Total bupivacaine plasma concentrations were determined using the high-performance liquid chromatography-ultraviolet method.

Results

Effective pain control was achieved with intrathecal bupivacaine (0.077–0.154 mg·kg⁻¹) and bupivacaine in enema (1.820 mg·kg⁻¹). Intrathecal bupivacaine (0.5%, 2 mL) caused a drop in blood pressure; other side effects were absent in both cases. Total plasma bupivacaine concentrations following intrathecal and rectal bupivacaine application did not exceed 317.2 ng·mL⁻¹ and 235.7 ng·mL⁻¹, respectively. Bupivacaine elimination was slower after rectal than after intrathecal administration (t_½= 5.50 versus 2.02 hours, respectively).

Limitations

This study reports two cases only, and there could be inter-patient variation.

Conclusion

Bupivacaine in boluses administered intrathecally (0.25%, 2 mL) provided effective, safe analgesia in advanced cancer patients. Bupivacaine enema (100 mg·100 mL⁻¹) was shown to be a valuable option for control of end-of-life tenesmoid cancer pain.

The influence of diabetic status on the pharmacokinetics of clopidogrel and its metabolites in patients suffered from cardiovascular diseases

Aim. A significant percentage of individuals treated with an anti-platelet agent clopidogrel do not receive the expected therapeutic effect. Clopidogrel resistance is even more prevalent in patients with type 2 diabetes mellitus (DM). An extensive investigation on pharmacokinetics of clopidogrel and its metabolites in patients with type 2 DM suffering from cardiovascular diseases were performed following an administration of 75 mg of the drug.Material and methods. Plasma concentrations of clopidogrel, its carboxylic metabolite (CLPM) and diastereoisomers of a thiol metabolite (the inactive H3 and the active H4) were determined by a validated HPLC-MS/MS method. The pharmacokinetic parameters of the analytes in diabetic (n = 16) and non-diabetic (n = 28) patients were compared and correlated with platelet aggregation. Results. DM patients exhibited a slightly higher Cmax of clopidogrel (2.34 ± 2.29 ng/mL) compared with non-diabetic group (1.82 ± 1.86 ng/mL), whereas plasma levels of clopidogrel metabolites were lower in DM than in non-DM patients (2339 ± 989 ng/mL vs. 2662 ± 2090 ng/mL, 4.64 ± 4.79 ng/mL vs. 5.42 ± 4.55 ng/mL and 6.42 ± 4.80 ng/mL vs. 7.44 ± 7.18 ng/mL, respectively for CLPM, H3 and H4). A significant correlation was found between platelet aggregation and the Cmax of the active H4 metabolite in non-diabetic patients. Conclusions. Pharmacokinetic parameters of clopidogrel, CLPM, H3 and H4 isomers in patients with DM did not differ significantly from those determined in non-diabetic group. Moreover, the antiplatelet response to clopidogrel therapy measured by ADP-stimulated platelet aggregation was similar in both groups of patients.

Clinical pharmacokinetics of clopidogrel and its metabolites in patients with cardiovascular diseases

Background and Objective

Approximately 5–40 % of patients treated with clopidogrel do not display an adequate antiplatelet response. Clopidogrel resistance may be caused by insufficient drug absorption or impaired metabolic activation of the drug. The aim of this study was to evaluate the pharmacokinetics of clopidogrel and its metabolites in plasma samples from patients treated with high and low doses of clopidogrel, to obtain a possible explanation for antiplatelet resistance.

Methods

The study included patients receiving either a single 300 mg loading dose of clopidogrel (n = 17) or a 75 mg dose (n = 45) for at least 7 days before sample collection. The concentrations of clopidogrel and its metabolites—the inactive H3 and the pharmacologically active H4 isomers of the thiol metabolite and the inactive carboxylic acid metabolite—in plasma samples (stabilized with 2-bromo-3′-methoxyacetophenone) from three patients after 300 mg and from 41 patients after 75 mg of the drug were determined using a validated high-performance liquid chromatography method with tandem mass spectrometry. The non-stabilized samples from the remaining patients were analysed using a validated capillary electrophoresis method. The calculated concentrations were used to determine the pharmacokinetic parameters of the analytes. The pharmacodynamic response to clopidogrel treatment, expressed as adenosine diphosphate-induced platelet aggregation, was measured using a Multiplate analyser.

Results

The pharmacokinetic parameter values for the H3 and H4 isomers determined in the studied group of patients treated with clopidogrel 75 mg (maximum plasma concentration [C_max] 5.29 ± 5.54 and 7.13 ± 6.32 ng/mL for H3 and H4, respectively; area under the plasma concentration-time curve from time zero to time t [AUC_t] 7.37 ± 6.71 and 11.30 ± 9.58 ng·h/mL for H3 and H4, respectively) were lower than those reported in healthy volunteers, according to the literature data. Platelet aggregation measured with a Multiplate analyser ranged between 37 and 747 AU·min. A significant correlation was found between the C_max of the active H4 isomer and platelet aggregation (p = 0.025).

Conclusion

The C_max of the active H4 isomer and platelet aggregation measured by the Multiplate analyser may serve as markers of the patient response to clopidogrel therapy.

Lumbar paravertebral blockade as intractable pain management method in palliative care

Optimal symptoms control in advanced cancer disease, with refractory to conventional pain treatment, needs an interventional procedure. This paper presents coadministration of local anesthetic (LA) via paravertebral blockade (PVB) as the alternative to an unsuccessful subcutaneous fentanyl pain control in a 71-year old cancer patient with pathological fracture of femoral neck, bone metastases, and contraindications to morphine. Bupivacaine in continuous infusion (0.25%, 5 mL · hour⁻¹) or in boluses (10 mL of 0.125%–0.5% solution), used for lumbar PVB, resulted in pain relief, decreased demand for opioids, and led to better social interactions. The factors contributing to an increased risk of systemic toxicity from LA in the patient were: renal impairment; heart failure; hypoalbuminemia; hypocalcemia; and a complex therapy with possible drug-drug interactions. These factors were taken into consideration during treatment. Bupivacaine’s side effects were absent. Coadministered drugs could mask LA’s toxicity. Elevated plasma α1-acid glycoprotein levels were a protective factor. To evaluate the benefit-risk ratio of the PVB treatment in boluses and in constant infusion, bupivacaine serum levels were determined and the drug plasma half-lives were calculated. Bupivacaine’s elimination was slower when administered in constant infusion than in boluses (t_½ = 7.80 hours versus 2.64 hours). Total drug serum concentrations remained within the safe ranges during the whole treatment course (22.9–927.4 ng mL⁻¹). In the case presented, lumbar PVB with bupivacaine in boluses (≤ 137.5 mg · 24 hours⁻¹) was an easy to perform, safe, effective method for pain control. Bupivacaine in continuous infusion (≤150 mg · 12 hours⁻¹) had an acceptable risk-benefits ratio, but was ineffective.

Clinical pharmacokinetics of ketoprofen enantiomers in wild type of Cyp 2c8 and Cyp 2c9 patients with rheumatoid arthritis

Pharmacokinetics of ketoprofen (KTP) enantiomers has been studied in patients with rheumatoid arthritis (RA) following administration of a single oral dose of 100 mg rac-KTP during multidrug therapy taking into consideration the genotype of RA patients Concentrations of (−)-R and (+)-S enantiomers of KTP in plasma, urine and synovial fluid samples were determined using a validated HPCE method. The genotype of the patients was analyzed using PCR-RFLP method to determine the polymorphic variants of genes coding CYP2C8 and CYP2C9 isoenzymes. The levels of KTP enantiomers in synovial fluid at 4 h following administration were insignificantly greater [(−)-R = 1.34 ± 0.91 mg/L; (+)-S = 1.38 ± 0.91 mg/L] than in plasma [(−)-R = 1.15 ± 0.95 mg/L; (+)-S = 1.22 ± 0.95 mg/L]. The values of AUC_0−∞ were 11.89 ± 5.00 and 10.92 ± 4.10 mg h/L for (−)-R and (+)-S enantiomer, respectively, and were lower compared with data obtained in healthy volunteers following administration of the same dose of rac-KTP. But, no statistically significant differences were observed also for C_max, Cl, V_d, t_0.5 and MRT of KTP enantiomers. The total percentage of unchanged KTP eliminated with urine of RA patients was in the range of 30–50% of the administered dose. Though RA patients represented the same wild genotype, quite significant variabilities (Cl_(−)-R = 2.37–13.50 L/h and Cl_(+)-S = 2.44–9.90 L/h) existed in the pharmacokinetics parameters of KTP. We concluded that KTP data obtained from healthy volunteers cannot be sufficient to predict disposition of KTP enantiomers in RA patients, especially when undergoing long-term multidrug therapy.

Enantioselective CE method for pharmacokinetic studies on ibuprofen and its chiral metabolites with reference to genetic polymorphism

A stereospecific CE method was elaborated for the quantification of ibuprofen enantiomers and their major phase I metabolites: 2'-hydroxy-ibuprofen and 2'-carboxy-ibuprofen in plasma and urine. Optimal temperature and pH of BGE were established to obtain complete separation of eight ibuprofen chiral compounds and (+)-S indobufen, applied as an internal standard, during one analytical run. After isolation from biological matrices using SPE on an octadecyl stationary phase, the analytes were separated and resolved up to 10 min in a silica capillary filled with BGE, consisting of heptakis 2,3,6-tri-O-methyl-beta-CD in triethanolamine-phosphate buffer, pH 5.0. Complete enantioseparation of the all analytes confirmed specificity of the method. The calibration curves were linear in the range of 0.1-25.0 mg/L for IBP enantiomers and their chiral metabolites in 0.5 mL of plasma and 1.0-200.0 mg/L in 0.05 mL of urine. Following SPE procedure, recovery of the chiral analytes from the two media was in the ranges of 82-87%, 90-95% and 70-76% for ibuprofen, 2'-hydroxy-ibuprofen and 2'-carboxy-ibuprofen enantiomers, respectively. The validated method was successfully applied in pharmacokinetic investigations of IBP enantiomers as well as free chiral metabolites in reference to the genetic polymorphism of CYP450 2C isoenzymes.

Studies on the metabolism of ibuprofen in isolated rat hepatocytes

Ibuprofen (IBP) was used to demonstrate that freshly isolated rat hepatocytes offer a suitable model to investigate the oxidative metabolism of antiinflammatory 2-arylpropionic acids (profens). The formation of two major oxidative metabolites of IBP (metabolite A--hydroxyibuprofen and metabolite B--carboxyibuprofen) was observed with the use of rat hepatocytes. The incubation of ibuprofen with a suspension of rat hepatocytes in Hanks' buffer during 60 min. resulted in a decrease of racemic IBP and both R(-)-IBP and S(+)-IBP concentration coincided with the appearance of its major racemic metabolites (metabolite A and metabolite B). The relative abundance of the above IBP metabolites produced by hepatocytes was consistent with their quantitative profiles in vivo in rat. The results confirm the value of isolated hepatocytes as a predictive model for the in vivo metabolism pattern of profens.