Quantitation using HRMS: A new tool for rapid, specific and sensitive determination of catecholamines and deconjugated methanephrines metanephrines in urine.

Urinary catecholamines and their methylated metabolites are biochemical indicators of pheochromocytoma, paraganglioma and neuroblastoma. A rapid and precise analytical method based on solid-phase extraction (SPE) and liquid chromatography separation coupled to high-resolution mass spectrometry (LC-HRMS) was developed and validated to measure urinary catecholamines (epinephrine (E), norepinephrine (NorE), dopamine (D)) and total methylated metabolites (normetanephrine (NorMN), metanephrine(MN) and 3-methoxytyramine (3-MT)) in a clinical setting. Results of 51 urine specimens measured using this LC-HRMS method were compared with a liquid chromatography assay with electrochemical detection (LC-EC). Urine samples (200 µL) were spiked with an internal standard solution followed by SPE purification. In the case of total methylated metabolites, urine was hydrolyzed before SPE purification. Separation was achieved on an Acclaim Mixed Mode WCX column, with an 8.5 min runtime. All compounds were detected in electrospray positive ionization mode with a parallel reaction monitoring acquisition and quantified with a linear regression (r2 > 0.998) between 2 and 200 µg/L (10.9-1090; 11.8-1182 nmol/L) for E and NorE respectively and between 10 and 1000 µg/L for others (65.2-6520; 50.7-5070; 54.5-5450 ; 59.8-5980 nmol/L for D, M, NorMN and 3-MT, respectively). Overall imprecision and bias did not exceed 15%. No significant matrix effect was observed. Correlation between the two assays was good except for epinephrine. Epinephrine concentrations measured by LC-EC method were slightly higher than values obtained with LC-HRMS method but without impact on clinical decision. This LC-HRMS assay provides a new tool for simultaneous quantitative catecholamine determination and was successfully applied in routine for the screening or follow up of pheochromocytoma, paraganglioma and neuroblastoma. LC-HRMS method offers significant advantages compared to LC-EC with good sensitivity, an unambiguous analyte determination and high sample throughput.

Voriconazole and squamous cell carcinoma after lung transplantation: A multicenter study.

This study evaluated the independent contribution of voriconazole to the development of squamous cell carcinoma (SCC) in lung transplant recipients, by attempting to account for important confounding factors, particularly immunosuppression. This international, multicenter, retrospective, cohort study included adult patients who underwent lung transplantation during 2005-2008. Cox regression analysis was used to assess the effects of voriconazole and other azoles, analyzed as time-dependent variables, on the risk of developing biopsy-confirmed SCC. Nine hundred lung transplant recipients were included. Median follow-up time from transplantation to end of follow-up was 3.51 years. In a Cox regression model, exposure to voriconazole alone (adjusted hazard ratio 2.39, 95% confidence interval 1.31-4.37) and exposure to voriconazole and other azole(s) (adjusted hazard ratio 3.45, 95% confidence interval 1.07-11.06) were associated with SCC compared with those unexposed after controlling for important confounders including immunosuppressants. Exposure to voriconazole was associated with increased risk of SCC of the skin in lung transplant recipients. Residual confounding could not be ruled out because of the use of proxy variables to control for some confounders. Benefits of voriconazole use when prescribed to lung transplant recipients should be carefully weighed versus the potential risk of SCC. EU PAS registration number: EUPAS5269.

Leflunomide for BKvirus: Report of Seven Kidney-Transplanted Children.

BACKGROUND: Leflunomide is an immunosuppressive agent commercialized for treatment of rheumatoid arthritis. Because of its immunosuppressive and possible antiviral properties, leflunomide has been evaluated in some case series of BKVAN with favorable results, mostly in adult patients. Leflunomide targeted levels are usually between 50 and 100 mg/L in kidney transplant adult patients. Data in pediatric population are scarce. OBJECTIVE: To assess the effect of leflunomide on BKvirus in kidney-transplanted children. METHODS: Therapeutic drug monitoring of leflunomide is routinely performed by measuring its active metabolite, teriflunomide, using a simple HPLC-UV method. Pediatric kidney transplant patients with at least one teriflunomide sample between 2010 and 2017 were retrospectively included in this study. Viremia control was defined as undetectable BK viremia or a decrease of more than 1 log in the viral load from the baseline after two months of treatment. Adverse events were recorded. RESULTS: A total of 7 patients from 3 centers was included. 6 were only kidney transplant recipients; 1 was a lung-kidney transplant recipient with cystic fibrosis. All patients reported high load BK viremia but none developed BKVAN. For 67% of the patients, complete BK viral clearance was observed during leflunomide treatment with drastic immunosuppressive therapy reduction. Mycophenolate was indeed discontinued in almost all patients. Of note, leflunomide concentrations were significantly higher when viremia was controlled. Only 33% of the observed concentrations were >40 mg/L. The patient with cystic fibrosis had lower concentrations with higher drug doses. No hepatotoxicity was observed in this study and no patient experienced graft rejection. Leflunomide was suspected to cause hemolytic anemia and one patient experienced biological pancreatitis. CONCLUSION: This study evidenced the wide interindividual variability of the exposure and supported the routine practice of leflunomide with a suggested target level of 30-40 mg/L in pediatric kidney transplanted patient. However, because of the very limited number of patients in our series, further investigations are needed to validate this suggestion.

Valganciclovir prophylaxis for cytomegalovirus infection in thoracic transplant patients: retrospective study of efficacy, safety, and drug exposure.

Oral ganciclovir (GCV) was replaced by prodrug valganciclovir (vGCV) for cytomegalovirus (CMV) prophylaxis. We assessed retrospectively (2005-2007) vGCV effectiveness and safety during prophylaxis and 4 months after, in heart (HTx) and lung transplantation (LTx), including lung transplant for cystic fibrosis (CFTx). Patients with stable renal function received vGCV 900 mg daily during 3-6 and 8-12 months in HTx and LTx. Effectiveness was assessed by antigenemia (pp65Ag) and a GCV therapeutic drug monitoring to document exposure. A total of 32 patients (11 HTx, 7 LTx, and 14 CFTx) received vGCV for 106+/-67 days in HTx versus 270+/-85 days in LTx and CFTx. Doses were 700+/-225, 915+/-60, and 820+/-150 mg/24 h in HTx, LTx, and CFTx showing acceptable mean trough GCV 0.75+/-0.5 mg/L. Two of 9 cases of neutropenia were attributable to vGCV. Three CMV donor-positive/recipient-negative CFTx patients presented positive pp65Ag; 2 developed CMV disease (6%). We found that vGCV 900 mg, adapted to renal function, was effective and safe for long CMV prophylaxis together with efficient exposure in thoracic transplantation.

Voriconazole pharmacokinetic variability in cystic fibrosis lung transplant patients.

BACKGROUND: Aspergillosis is a high-risk complication in cystic fibrosis (CF) lung transplant patients. Azole antifungal drugs inhibit CYP3A4, resulting in significant metabolic drug-drug interactions. Voriconazole (VRZ) was marketed without therapeutic drug monitoring (TDM) recommendations, consistent with favorable pharmacokinetics, but regular determinations of plasma VRZ concentration were introduced in our center to manage interactions with calcineurin inhibitors and to document the achievement of therapeutic levels. METHODS: VRZ TDM data analysis for trough concentration (C0) and peak concentration (C2) was carried out, using validated liquid chromatography assay with ultraviolet detection, for 35 CF lung transplant patients (mean age 25 years, mean weight 47 kg, balanced sex ratio) since 2003. Therapeutic range (C0: 1.5 +/- 0.5 - C2 : 4.0 +/- 1.0 mg/L) was expressed relative to pivotal pharmacokinetic trial data. RESULTS: The duration of VRZ treatment ranged from 9 days to 22 months. The recommended standard dose of VRZ (200 mg twice a day, following the loading dose) resulted in significant plasma concentrations (>0.5 mg/L) in 20% of CF lung transplant patients. Therapeutic concentrations were obtained using higher doses (average 570 +/- 160 mg/day, +43%, P<0.01). Despite adaptation, C0 remained <0.5 mg/L (11%), even when the drug was administered intravenously, highlighting the variability of VRZ pharmacokinetics, possibly enhanced by CYP2C19 polymorphism. The risk of inefficacy during periods of underdosage was overcome by treatment with antifungal drug combinations (caspofungin, n=10). The therapeutic index was limited by neurologic effects (14%) and hepatic abnormalities (30%). VRZ concentrations correlated significantly (P<0.01) with aspartate aminotransferase levels but not with bilirubin levels. VRZ acted as a metabolic inhibitor of tacrolimus (C0 to dose ratio 5.8 +/- 2.6, n=31/VRZ versus 1.7 +/- 0.9 alone, P<0.001). Large changes in azole concentration affected the magnitude of the drug-drug interactions and adjustment requirements. CONCLUSIONS: TDM is required because VRZ levels are often undetectable in treated CF lung transplant patients, supporting the use of antifungal drug combinations until achievement of VRZ C0 at a steady state between 1 and 2 mg/L. Plasma VRZ concentrations should be determined for the quantitative, individualized management of drug-drug interactions in lung transplant patients, in particular immunosuppressant such as tacrolimus, considering VRZ to be both a target and an inhibitor of CYP3A4.

Clinical pharmacology of immunosuppressive drugs: year 2000--time for alternatives.

Perspectives in immunosuppressive drug therapy have changed rapidly in the past few years with the appearance on the market of several new entities. Used for organ transplantation, bone-marrow transplantation and more recently in some auto-immune diseases, the usual classical scheme consisting of corticoids, azathioprine (1970) and cyclosporin (1980), with or without an induction period with antilymphocyte antibodies, has varied little except for the monoclonal antibody OKT3. The considerable evolution due to the introduction of cyclosporin almost twenty years ago has reached its limits. The new perspectives offer two aspects: (1) on one hand, the specificity of each compound: tacrolimus, Prograf, Fujisawa; mycophenolate mofetyl (MMF), CellCept, Roche; cyclosporin, Neoral, Novartis; basiliximab, Simulect, Novartis; and dacliximab, Zenapax, Roche; monoclonal humanized antibodies, rapamycine or sirolimus, Rapamune, Wyeth; or its derived form RAD Novartis; (2) on the other hand, all these products represent alternatives to the present scheme in a field where coprescription is the rule. These alternatives encounter one main difficulty: the evaluation and the organization of the different possible combinations have to be done within a small series of patients. It is essential to note that the market authorizations have been given on the basis of a precise scheme of dosage regimen from the pivotal studies and that extrapolation from these conditions, in particular choice of the doses, has required thorough reflection. These recent developments need optimization between an improvement of immunosuppression and a higher risk for infection and malignancy.

[Immunosuppression: a case of mucoviscidosis]. / Immunosuppression: cas particulier de la mucoviscidose.

Cystic fibrosis is a recessive disease that causes changes in mucus secretions, affecting different systems: respiratory, digestive, pancreatic, hepatic; resulting in obstructions and secondary infections. Transplantation may be used for the most severe forms and is then complicated by the pediatric context, the existence of malabsorption and secondary infections and the type of transplantation (pulmonary and/or hepatic). The follow-up is characterized by pulmonary infections and pulmonary chronic rejection. In our experience, the initiation of the immunosuppressive treatment must avoid corticoids in the early post-transplantation days and have recourse to intravenous cyclosporin (CyA) 2 mg/kg/day, given on average for one month in an oral form. In case of persistent acute rejection, tacrolimus (FK 506) is instituted. Oral CyA (10-12 mg/kg/day) seems more sensitive to malabsorption syndrome than FK 506 (0.2 mg/kg/day). In both cases, the development of an inhibitory metabolic interaction in the presence of itraconazole must be taken into account: used against aspergillosis, itraconazole is metabolized as CyA and FK 506 by Cyt P450 3A4. The intensity of the interaction is twofold for CyA versus fivefold for FK 506. The strategy for the use of other recently available immunosuppressives such as mycophenolate is under evaluation.

[Absence of labetalol interference on urine metanephrine determination in hypertensive patients]. / Absence d'interférence du labétalol sur la détermination des métanéphrines urinaires chez l'hypertendu.

The dosage of urinary catecholamines and their metabolites is a main element of diagnosis in the research of a pheochromocytoma in patients with high blood pressure. The literature reports high values of these compounds in patients treated with labetalol (an alpha/beta-blocker). An analytical interference has been evoked to explain these misleading results, which have not been observed with other beta-blockers. The goal of this work was to look for this eventual analytical interference in the dosage of urinary metanephrine by reversed phase liquid chromatography coupled with electrochemical detection, in patients with high blood pressure. Eighteen hypertensive patients, 52 +/- 14 years old, were included in the study. In 8 patients, a dosage of metanephrine, normetanephrine and creatinine on a 24 hours urine sample was performed before (D1) and 24 hours after (D3) the prescription of labetalol (200 mg twice a day). In the other group, labetalol was not prescribed but dosage was made in the same conditions. Urinary excretion of these compounds (metanephrine+normetanephrine) divided by urinary creatinine was not modified in the treated group (0.16 +/- 0.08 vs 0.14 +/- 0.04), nor in the reference group (0.17 +/- 0.08 vs 0.17 +/- 0.08). This study shows that administration of labetalol in patients with essential hypertension does not interfere with urinary metanephrine and normetanephrine determination after 48 hours of treatment. This implies that research for a pheochromocytoma is possible in patients with hypertension and receiving labetalol, by using reversed phase liquid chromatography coupled with an electrochemical detector for the dosage of urinary metanephrine and normetanephrine.