A pharmacokinetics-based approach to the monitoring of patient adherence to atorvastatin therapy.

The inadequate adherence of patients whose hyperlipidemia is treated with atorvastatin (ATR) to medical instructions presents a serious health risk. Our aim was to develop a flexible approach based on therapeutic drug monitoring (TDM), nonparametric population pharmacokinetic modeling, and Monte Carlo simulation to differentiate adherent patients from partially and nonadherent individuals in a nonrandomized, unicentric, observational study. Sixty-five subjects were enrolled. Nonparametric, mixed-effect population pharmacokinetic models of the sums of atorvastatin and atorvastatin lactone concentrations (ATR+ATRL) and of the concentrations of the acid and lactone forms of ATR and its 2- and 4-hydroxylated pharmacologically active metabolites (ATR+MET) were elaborated by including the TDM results obtained in 128 samples collected from thirty-nine subjects. Monte Carlo simulation was performed based on the elaborated models to establish the probabilities of attaining a specific ATR+ATRL or ATR+MET concentration in the range of 0.002-10 nmol (mg dose)-1 L-1 at 1-24 h postdose by adherent, partially adherent, and nonadherent patients. The results of the simulations were processed to allow the estimation of the adherence of further 26 subjects who were phlebotomized at sampling times of 2-20 h postdose by calculating the probabilities of attaining the ATR+ATRL and ATR+MET concentrations measured in these subjects in adherent, partially adherent, and nonadherent individuals. The best predictive values of the estimates of adherence could be obtained with sampling at early sampling times. 61.54% and 38.46% of subjects in the adherence testing set were estimated to be fully and partially adherent, respectively, while in all cases the probability of nonadherence was extremely low. The evaluation of patient adherence to ATR therapy based on pharmacokinetic modeling and Monte Carlo simulation has important advantages over the collection of trough samples and the use of therapeutic ranges.

Sensitive, High-Throughput Liquid Chromatography-Tandem Mass Spectrometry Analysis of Atorvastatin and Its Pharmacologically Active Metabolites in Serum for Supporting Precision Pharmacotherapy.

The antihyerlipidemic drug atorvastatin (ATR) is used worldwide as part of the strategy to prevent cardiovascular events. The high prevalence of patient nonadherence remains an important challenge which could be addressed efficiently by precision pharmacotherapy based on therapeutic drug monitoring (TDM). ATR is metabolized to pharmacologically active metabolites, and evidence shows that the sums of ATR acid and lactone form concentrations (ATR + ATRL), or of ATR and hydroxylated metabolites (ATR + MET) should be assayed. A method is presented for the analysis of these substances in serum. Method validation included the estimation of the quantitative relationship between the concentrations and the standard deviations (SD), which supports the optimal incorporation of TDM results into nonparametric pharmacokinetic models. The concentrations of the analytes were evaluated in human subjects receiving ATR. The method's performance improved by taking the sums of acid and lactone concentrations into account. The concentration-SD relationship was linear, and we recommend applying Theil's regression for estimating the assay error. All analytes could be detected by 2 h post dose in the samples of human subjects. The changes in metabolite/parent drug concentration ratios in time depended on the dose. The method is suitable for the TDM of ATR with a focus on precision pharmacotherapy.

Flow-mediated vasodilation assay indicates no endothelial dysfunction in hereditary angioedema patients with C1-inhibitor deficiency.

BACKGROUND: Hereditary angioedema with C1 inhibitor deficiency (C1-INH-HAE) is a rare, potentially life-threatening disorder characterized by recurrent edematous attacks. The edema formation is the consequence of interaction of bradykinin and various vasoactive peptides with endothelium. Besides these agents, danazol, a modified testosterone derivative used in these patients to prevent edematous attacks, can also affect the function of the endothelium, because it shifts the blood lipid profile to a pro-atherogenic phenotype. OBJECTIVE: To assess the endothelial function in C1-INH-HAE patients and in healthy matched controls. METHODS: To evaluate the endothelial function, we used the flow-mediated dilation method measured in the region of the brachial artery in 33 C1-INH-HAE patients and in 30 healthy matched controls. Laboratory measurements of standard biochemical parameters were performed on computerized laboratory analyzers. RESULTS: No difference was found in endothelial function (reactive hyperemia, RH) between patients (median, 9.0; 25%-75% percentile, 6.3-12.9) and controls (median, 7.37; 25%-75% percentile, 4.52-9.93). Although we found elevated cardiovascular risk (high body mass index and low-density lipoprotein/high-density lipoprotein ratio) in danazol-treated C1-INH-HAE patients, RH values did not differ between danazol-treated and nontreated patients. Furthermore, risk factors correlated with the endothelial function only in healthy controls and patients not treated with danazol. CONCLUSION: In summary, our results did not indicate any signs of endothelial dysfunction in C1-INH-HAE patients. Moreover, the normal endothelial function in danazol-treated patients with pro-atherogenic lipid profile suggests that elevated bradykinin level or other factor(s) involved in the pathogenesis of edematous attacks may have a protective role against endothelial dysfunction and atherosclerosis.

Doxorubicin selectively suppresses mRNA expression and production of endothelin-1 in endothelial cells.

Doxorubicin (DXR) is a widely used cytostatic agent, but its administration is limited by its cardiovascular side effects. The endothelium is one of the largest organs in the human body and due to its direct contact with blood; it is exposed to the toxic effects of DXR. The aim of this study was to investigate in endothelial cells the effects of DXR on the expression of genes involved in cardiovascular diseases. We used in vitro cultured human umbilical vein endothelial cells (HUVEC) as a model; gene expression was assessed by SuperArray and qPCR. Out of the 96 representative genes of cardiovascular importance, the expression of only the ET-1 gene changed significantly. ET-1 mRNA expression was 10.9% of the untreated control (p=0.0049). This result was confirmed by qPCR (2.41% of control, p=0.0022). DXR also suppressed ET-1 production at protein level (p=0.0116). Both the early decrease in endothelial ET-1 production in the presence of DXR and the high plasma level of DXR during chemotherapy may influence the toxic effects of the drug.

Endothelins: a possible mechanism of cytostatics-induced cardiomyopathy.

Endothelium responds to physical and chemical stimuli by synthesis and release of a variety of vasoactive and signal molecules. Cardiac performance is regulated by cardiac endothelial cells in a paracrine manner, analogous to vascular endothelial control of vascular tone. Endothelin-1 (ET-1), one of the most potent vasoconstrictor peptides, which is synthetized and released by endothelial cells. The role of ET-1 in some special pathological state is still unclear. Authors have investigated the effect of anthracyclines (maximal dose: 450 mg/bodysurface m2) on left ventricular systolic and diastolic function and on the level of plasma ET-1, in 31 (13 male, aged 19-70 years, mean: 38.9) patients suffered from Hodgkin (24) and Non-Hodgkin (7) lymphomas. They have also studied the association between plasma ET-1 concentration and echocardiographic parameters. Serum ET-1 was measured by ELISA method. Left ventricular function analyzed by echocardiography: ejection fraction (EF), time velocity integral (VTI), E and A waves, E/A ratio, deceleration time (DT), Doppler index were assessed. Statistical analysis was made by the Wilcoxon rank test. ET-1 plasma level decreased significantly after therapy (5.6 +/- 3.5 vs. 3.1 +/- 0.9 pg/ml, P < 0.0006). EF (56.4 +/- 5.0% vs. 48.7 +/- 5.1%, P < 0.0001) decreased, and DT (168.1 +/- 36.8 ms vs. 206.5 +/- 58.8 ms, P < 0.0073) increased significantly after administration of anthracycline, showing that both systolic and diastolic left ventricular performance was deteriorated. There was no difference in other echocardiographic parameters before and after therapy. In conclusion, decrease of serum ET-1 concentration might be a result of anthracyclin's direct cytotoxic effect and the decreasing level of ET-1 may play a role in the reduction of the EF. More studies are needed to evaluate the presence and severity of endothelial damage, and long-term follow-up may reveal the importance of low ET-1 level and may show the time is needed for the restoration of the ET-1 concentration to the basic level after cessation of cytostatic therapy.

Endothelin gene expression during ischemia and reperfusion.

Endothelin-1 (ET-1) probably plays an important role in myocardial damage in acute ischemia. Coronary sinus ET-1 and its precursor big endothelin-1 (big ET-1) levels and also tissue levels of preproendothelin-1 mRNA (ET-1 mRNA) were investigated in an in vivo canine ischemia-reperfusion model in nine consecutive mongrel dogs, surviving 30-minute ligation of the left descending coronary artery followed by a 90-minute reperfusion period. Samples were collected before and at the end of ischemia and during reperfusion. ET-1 and big ET-1 were obtained by immunoprecipitation and detected by western blotting. The ET-1 mRNA level was assessed by reverse transcription-polymerase chain reaction. During ischemia the plasma ET-1 levels and big ET-1 levels did not change significantly, while the myocardial ET-1 mRNA level decreased to 57.8%. During reperfusion an increase of the coronary sinus ET-1 and big ET-1 levels was observed (control versus reperfusion, 90 minutes; ET-1, 15.2 +/- 4.18 fmol/mL versus 23.2 +/- 5.23 fmol/mL, P < 0.01; big ET-1, 14.7 +/- 5.9 fmol/mL versus 27.2 +/- 7.1 fmol/mL, P < 0.001). Simultaneously, the ET-1 mRNA level increased by 322% relative to the ischemic and by 214% relative to the baseline level. The decrease of ET-1 mRNA during ischemia may be due to degradation and decreased metabolism in the hypoxic cells locally. The elevation of the ET-1 mRNA level during reperfusion indicates rapid big ET-1 synthesis. This was confirmed by the increases in big ET-1 and ET-1 plasma levels. This latter can be associated with the generation of reperfusion arrhythmias or other complications of acute myocardial infarction.

Endothelin-1 and cardiac function in anthracycline-treated patients: a 1-year follow-up.

Anthracyclines are widely used chemotherapeutic agents in the treatment of lymphomas known to induce cardiomyopathy in more than 20% of patients. There is increasing experimental evidence that cardiac endothelial cells regulate cardiac performance and that endothelin-1 (ET-1) is a central substance in this regulatory mechanism. Twenty (seven male, aged 20-68 years) patients with Hodgkin's or non-Hodgkin's lymphoma treated with anthracycline were followed-up for 1 year. At baseline, after cessation of anthracycline treatment and at 1 year, the plasma ET-1 level was measured by enzyme-linked immunosorbent assay and cardiac function was estimated by echocardiographic measurement of the ejection fraction, the E/A ratio and the deceleration time. The ET-1 level decreased significantly after therapy (5.47 +/- 3.34 pg/mL versus 3.44 +/- 0.69 pg/mL, P < 0.02), and remained significant at 1 year (3.43 +/- 0.57 pg/mL, P < 0.008). The ejection fraction (57.80 +/- 4.73% versus 48.05 +/- 5.65%, P < 0.0001) and the E/A ratio (1.35 +/- 0.40 versus 1.15 +/- 0.40, P < 0.01) decreased, and the deceleration time (177.00 +/- 44.96 ms versus 209.50 +/- 66.25 ms, P < 0.04) increased significantly after therapy, showing that both systolic and diastolic left ventricular performance were deteriorated. Compared with the baseline, the same significant changes were found at 1 year (ejection fraction, 50.65 +/- 8.87%, P < 0.0007; E/A ratio, 1.10 +/- 0.34, P < 0.003; deceleration time, 223.25 +/- 46.85 ms, P < 0.002). The decrease of the ET-1 concentration might be a result of anthracyclines' direct cytotoxic effect and the decreasing level of ET-1 may play a role in the ejection fraction reduction. The results of 1-year follow-up suggest that, although anthracycline toxicity occurs shortly after treatment, the undesirable effect remains.