Therapeutic Drug Monitoring of Pazopanib in Renal Cell Carcinoma and Soft Tissue Sarcoma: A Systematic Review.

BACKGROUND: Pazopanib, an anti-angiogenic multitarget tyrosine kinase inhibitor, has been approved for the treatment of metastatic renal cell carcinoma and soft tissue sarcoma. However, its recommended dose does not always produce consistent outcomes, with some patients experiencing adverse effects or toxicity. This variability is due to differences in the systemic exposure to pazopanib. This review aimed to establish whether sufficient evidence exists for the routine or selective therapeutic drug monitoring of pazopanib in adult patients with approved indications. METHODS: A systematic search of the PubMed and Web of Science databases using search terms related to pazopanib and therapeutic drug monitoring yielded 186 and 275 articles, respectively. Ten articles associated with treatment outcomes or toxicity due to drug exposure were selected for review. RESULTS: The included studies were evaluated to determine the significance of the relationship between drug exposure/Ctrough and treatment outcomes and between drug exposure and toxicity. A relationship between exposure and treatment outcomes was observed in 5 studies, whereas the trend was nonsignificant in 4 studies. A relationship between exposure and toxicity was observed in 6 studies, whereas 2 studies did not find a significant relationship; significance was not reported in 3 studies. CONCLUSIONS: Sufficient evidence supports the therapeutic drug monitoring of pazopanib in adult patients to improve its efficacy and/or safety in the approved indications.

Longitudinal Monitoring of Hair Cortisol Using Liquid Chromatography-Mass Spectrometry to Prevent Hypercortisolism in Patients Undergoing Glucocorticoid Replacement Therapy.

OBJECTIVE: Currently available methods for endogenous cortisol monitoring in patients with hormonal insufficiency rely on measurements of plasma levels only at a single time point; thus, any kind of chronic exposure to cortisol is challenging to evaluate because it requires collecting samples at different time points. Hair cortisol levels acquired longitudinally better reflected chronic exposure (both cortisol synthesis and deposition) and may significantly contribute to better outcomes in glucocorticoid replacement therapies. DESIGN: Twenty-two patients on cortisol substitution therapy were monitored for plasma, urinary, and hair cortisol levels for 18 months to determine whether hair cortisol may serve as a monitoring option for therapy setting and adjustment. METHODS: Plasma and urinary cortisol levels were measured using standardized immunoassay methods, and segmented (∼1 cm) hair cortisol levels were monitored by liquid chromatography coupled to mass spectrometry. A log-normal model of the changes over time was proposed, and Bayesian statistics were used to compare plasma, urinary, and hair cortisol levels over 18 months. RESULTS AND CONCLUSIONS: Hair cortisol levels decreased over time in patients undergoing substitutional therapy. The residual variance of hair cortisol in comparison to plasma or urinary cortisol levels was much lower. Thus, longitudinal monitoring of hair cortisol levels could prove beneficial as a noninvasive tool to reduce the risk of overdosing and improve the overall patient health.

Therapeutic Drug Monitoring of Sunitinib in Gastrointestinal Stromal Tumors and Metastatic Renal Cell Carcinoma in Adults-A Review.

BACKGROUND: Sunitinib is an inhibitor of multiple receptor tyrosine kinases and is a standard-of-care treatment for advanced and metastatic renal cell carcinoma and a second-line treatment in locally advanced inoperable and metastatic gastrointestinal stromal tumors. A fixed dose of the drug, however, does not produce a uniform therapeutic outcome in all patients, and many face adverse effects and/or toxicity. One of the possible causes of the interindividual variability in the efficacy and toxicity response is the highly variable systemic exposure to sunitinib and its active metabolite. This review aims to summarize all available clinical evidence of the treatment of adult patients using sunitinib in approved indications, addressing the necessity to introduce proper and robust therapeutic drug monitoring (TDM) of sunitinib and its major metabolite, N-desethylsunitinib. METHODS: The authors performed a systematic search of the available scientific literature using the PubMed online database. The search terms were "sunitinib" AND "therapeutic drug monitoring" OR "TDM" OR "plasma levels" OR "concentration" OR "exposure." The search yielded 520 journal articles. In total, 447 publications were excluded because they lacked sufficient relevance to the reviewed topic. The remaining 73 articles were, together with currently valid guidelines, thoroughly reviewed. RESULTS: There is sufficient evidence confirming the concentration-efficacy and concentration-toxicity relationship in the indications of gastrointestinal stromal tumors and metastatic renal clear-cell carcinoma. For optimal therapeutic response, total (sunitinib + N-desethylsunitinib) trough levels of 50-100 ng/mL serve as a reasonable target therapeutic range. To avoid toxicity, the total trough levels should not exceed 100 ng/mL. CONCLUSIONS: According to the current evidence presented in this review, a TDM-guided dose modification of sunitinib in selected groups of patients could provide a better treatment outcome while simultaneously preventing sunitinib toxicity.

Effect of Endocannabinoid Oleamide on Rat and Human Liver Cytochrome P450 Enzymes in In Vitro and In Vivo Models.

The endocannabinoid system is important for many physiologic and pathologic processes, but its role in the regulation of liver cytochromes P450 (P450s) remains unknown. We studied the influence of the endocannabinoid oleamide on rat and human liver P450s. Oleamide was administered intraperitoneally to rats at doses of 0.1, 1, and 10 mg/kg per day for 7 days. The content and activity of key P450s were evaluated in rat liver microsomes. Moreover, interactions with nuclear receptors regulating P450 genes and serum levels of their ligands (prolactin, corticosterone, and free triiodothyronine) were tested in in vitro P450 inhibition assays. Decreased protein levels and metabolic activities of CYP1A2, CYP2B, and CYP2C11, along with a drop in metabolic activity of CYP2D2, were observed in animals treated with oleamide (10 mg/kg per day). The activities of CYP2C6, CYP2A, and CYP3A and the levels of hormones were not altered. In vitro, oleamide exhibited a weak inhibition of rat CYP1A2, CYP2D2, and CYP2C6. The activities of rat CYP2A, CYP2B, CYP2C11, and CYP3A and human CYP1A2, CYP2B6, CYP2C9, and CYP3A4 were not altered. Oleamide did not interact with human pregnane X, constitutive androstane, or aryl hydrocarbon receptors in reporter gene experiments and did not regulate their target P450 genes in primary human hepatocytes. Our results indicate that oleamide caused the downregulation of some rat liver P450s, and hormones are not mediators of this effect. In vitro oleamide inhibits mainly rat CYP2C6 and is neither an agonist nor antagonist of major human nuclear receptors involved in the regulation of xenobiotic metabolism.

Lycopene increases metabolic activity of rat liver CYP2B, CYP2D and CYP3A.

BACKGROUND: Lycopene as a naturally occurring carotenoid is a common part of the human diet. Several beneficial properties of lycopene have been identified, with the most studied being anti-cancer and antioxidant activity. However, no evidence of possible drug-drug or drug-food supplement interactions has been found. METHODS: We studied the in vivo effect of lycopene on the selected rat liver cytochromes P450 (CYPs): CYP1A2, CYP2B, CYP2C11, CYP2C6, CYP2D, and CYP3A. Lycopene was administered to rats intragastrically at doses of 4, 20, and 100 mg/kg/day for 10 consecutive days. Total protein content, P450 Content, and metabolic activity of selected CYPs were evaluated in the rat liver microsomal fraction. RESULTS: Increased CYP2B, CYP2D, and CYP3A metabolic activities were observed in animals treated with the lycopene dose of 100 mg/kg/day. The content of CYP3A1 protein was increased by the dose of 100 mg/kg/day and CYP3A2 protein was increased by all administered doses of lycopene. CONCLUSION: The results of our study indicate that lycopene increased the metabolic activity of enzymes that are orthologues to the most clinically important human enzymes involved in xenobiotic metabolism. The risk of pharmacokinetic interactions between lycopene dietary supplements and co-administered drugs should be evaluated.

Off-line coupling of capillary electrophoresis to substrate-assisted laser desorption inductively coupled plasma mass spectrometry.

A novel off-line coupling of capillary electrophoresis (CE) and inductively coupled plasma mass spectrometry (ICPMS) is reported here. The coupling interface is based on the connection of a separation capillary to a deposition capillary via a liquid junction maintaining high separation efficiency and sample utilization due to the self-focusing effect and lack of pressure-induced flow in comparison with nebulizer-like interfaces. The separation is recorded in the form of droplets of CE effluent on a suitable substrate--a poly(ethylene terephthalate) glycol (PETG) sample plate placed inside a partially evacuated chamber. Substrate-assisted laser desorption (SALD) is used to vaporize the sample fractions and to enable further transfer to the ICPMS. The mechanism of SALD is examined using model samples deposited on a variety of substrates. The highest response is obtained for a PETG substrate; sample desorption due to ablation of PETG is found to outweigh direct ablation of sample. Detection limits are given for several metal elements. Finally, a rapid (2.5-min), high-resolution separation of Cr(III)/Cr(VI) species injected in subpicomolar quantity is shown.

Heavy water enhancement of fluorescence signal in reversed-phase liquid chromatography.

Liquid chromatography with fluorescence detection has been used in analyses demanding high sensitivity and selectivity. As majority systems rely on reversed-phase columns with water being the main component of the mobile phase, fluorescent compounds with emission maxima higher than 500 nm might be dynamically quenched. A simple replacement of H2O with D2O enhanced the sensitivity for selected compounds by 10-200%. Affected compounds included an anti-cancer drug doxorubicin, a luminescent probe fluorescein, and naturally occurring forms of vitamin B2. Similar levels of enhancement were obtained by fluorescence spectrometry. Such simple yet effective approach may greatly improve HPLC analyses coupled to fluorescence detection.

Sanguinarine is reduced by NADH through a covalent adduct.

Sanguinarine is a benzo[c]phenanthridine alkaloid with interesting cytotoxic properties, such as induction of oxidative DNA damage and very rapid apoptosis, which is not mediated by p53-dependent signaling. It has been previously documented that sanguinarine is reduced with NADH even in absence of any enzymes while being converted to its dihydro form. We found that the dark blue fluorescent species, observed during sanguinarine reduction with NADH and misinterpreted by Matkar et al. (Arch. Biochem. Biophys. 2008, 477, 43-52) as an anionic form of the alkaloid, is a covalent adduct formed by the interaction of NADH and sanguinarine. The covalent adduct is then converted slowly to the products, dihydrosanguinarine and NAD+, in the second step of reduction. The product of the reduction, dihydrosanguinarine, was continually re-oxidized by the atmospheric oxygen back to sanguinarine, resulting in further reacting with NADH and eventually depleting all NADH molecules. The ability of sanguinarine to diminish the pool of NADH and NADPH is further considered when explaining the sanguinarine-induced apoptosis in living cells.

Identification of metabolites of selected benzophenanthridine alkaloids and their toxicity evaluation.

Selected benzo[c]phenathridine alkaloids were biotransformed using rat liver microsomes and identified by liquid chromatography and mass spectrometry. While the metabolites of commercially available sanguinarine and chelerythrine have been studied in detail, data about the metabolism of the minor alkaloids remained unknown. Reactions involved in transformation include single and/or double O-demethylation, demethylenation, reduction, and hydroxylation. Two metabolites, when isolated, purified and tested for toxicity, were found to be less toxic than the original compounds.

Modulatory Effects of Eschscholzia californica Alkaloids on Recombinant GABAA Receptors.

The California poppy (Eschscholzia californica Cham.) contains a variety of natural compounds including several alkaloids found exclusively in this plant. Because of the sedative, anxiolytic, and analgesic effects, this herb is currently sold in pharmacies in many countries. However, our understanding of these biological effects at the molecular level is still lacking. Alkaloids detected in E. californica could be hypothesized to act at GABAA receptors, which are widely expressed in the brain mainly at the inhibitory interneurons. Electrophysiological studies on a recombinant α 1 ß 2 γ 2 GABAA receptor showed no effect of N-methyllaurotetanine at concentrations lower than 30 µM. However, (S)-reticuline behaved as positive allosteric modulator at the α 3, α 5, and α 6 isoforms of GABAA receptors. The depressant properties of aerial parts of E. californica are assigned to chloride-current modulation by (S)-reticuline at the α 3 ß 2 γ 2 and α 5 ß 2 γ 2 GABAA receptors. Interestingly, α 1, α 3, and α 5 were not significantly affected by (R)-reticuline, 1,2-tetrahydroreticuline, codeine, and morphine-suspected (S)-reticuline metabolites in the rodent brain.

Prognostic utility of biomarkers in predicting of one-year outcomes in patients with aortic stenosis treated with transcatheter or surgical aortic valve implantation.

OBJECTIVES: The aim of the work was to find biomarkers identifying patients at high risk of adverse clinical outcomes after TAVI and SAVR in addition to currently used predictive model (EuroSCORE). BACKGROUND: There is limited data about the role of biomarkers in predicting prognosis, especially when TAVI is available. METHODS: The multi-biomarker sub-study included 42 consecutive high-risk patients (average age 82.0 years; logistic EuroSCORE 21.0%) allocated to TAVI transfemoral and transapical using the Edwards-Sapien valve (n = 29), or SAVR with the Edwards Perimount bioprosthesis (n = 13). Standardized endpoints were prospectively followed during the 12-month follow-up. RESULTS: The clinical outcomes after both TAVI and SAVR were comparable. Malondialdehyde served as the best predictor of a combined endpoint at 1 year with AUC (ROC analysis) = 0.872 for TAVI group, resp. 0.765 (p<0.05) for both TAVI and SAVR groups. Increased levels of MDA, matrix metalloproteinase 2, tissue inhibitor of metalloproteinase (TIMP1), ferritin-reducing ability of plasma, homocysteine, cysteine and 8-hydroxy-2-deoxyguanosine were all predictors of the occurrence of combined safety endpoints at 30 days (AUC 0.750-0.948; p<0.05 for all). The addition of MDA to a currently used clinical model (EuroSCORE) significantly improved prediction of a combined safety endpoint at 30 days and a combined endpoint (0-365 days) by the net reclassification improvement (NRI) and the integrated discrimination improvement (IDI) (p<0.05). Cystatin C, glutathione, cysteinylglycine, asymmetric dimethylarginine, nitrite/nitrate and MMP9 did not prove to be significant. Total of 14.3% died during 1-year follow-up. CONCLUSION: We identified malondialdehyde, a marker of oxidative stress, as the most promising predictor of adverse outcomes during the 30-day and 1-year follow-up in high-risk patients with symptomatic, severe aortic stenosis treated with TAVI. The development of a clinical "TAVIscore" would be highly appreciated. Such dedicated scoring system would enable further testing of adjunctive value of various biomarkers.

Off-line coupling of microcolumn separations to desorption mass spectrometry.

The presented review provides comprehensive and detailed characteristics on microcolumn separation techniques off-line coupled to mass spectrometry. Major attention is paid to the classification of junctions between the separation column and the deposition needle and to the process by which the liquid is transferred onto the target. Both contact and non-contact deposition techniques are covered. In order to emphasize the significance of the topic of off-line separations, current commercially available devices have been compared in terms of their potential utilization in analytical chemistry with a summarization of applications used over the past few years.