Sandrine Lefeuvre

Pharmacological considerations for azole antifungal drug management in cystic fibrosis lung transplant patients

This paper aims to present our experience in the pharmacological approach of the management of azole antifungal drugs in cystic fibrosis lung transplant patients. Cystic fibrosis (CF) lung transplantation is associated with multi-factorial care management, because of immunosuppressive requirements, risk of infections, frequency of gastro-oesophageal reflux disease, hepatic alterations and CF pharmacokinetics (PK) specificities that result in important PK variability. CF is associated with frequent colonization of the airways by filamentous fungi, especially by Aspergillus species. Today the antifungal therapeutic arsenal offers several possibilities for long-term oral therapy including azole drugs (itraconazole, voriconazole and posaconazole). Therefore, nephrotoxic amphotericin B should be avoided. The liver is important in the pharmacological profile of azole drugs, due to metabolic elimination, hepatotoxicity and PK drug-drug interaction (DDI) involving CYP3A4 metabolic inhibition. Targets for such DDI are numerous, but immunosuppressive drugs are of major concern, justifying combined therapeutic drug monitoring (TDM) of both azoles (inhibitors) and immunosuppressants (targets) on an individualized patient basis to adjust the coprescription quantitatively. The risk of long under-dosed periods, frequently addressed in this population, could justify, on a PK basis, the need for combination with an exclusive parenteral antifungal while waiting for azole relevant drug level. High PK variability, the risk of low exposure, therapeutic issues and DDI management in this complex underlying disease justify close monitoring with systematic combined TDM of azole and immunosuppressants, in case of coprescription.

Management of Metabolic Cytochrome P450 3A4 Drug-Drug Interaction between Everolimus and Azole Antifungals in a Renal Transplant Patient

We report a case of a 54-year-old male renal transplant patient who received antifungal azole treatment in combination with the recently introduced immunosuppressant agent everolimus to prevent post-transplantation aspergillosis reactivation. Voriconazole was withdrawn after 1 month because of elevated concentrations (5 mg/L trough plasma determination) and hepatotoxicity, and substituted by several months of treatment with posaconazole (observed concentration range 1–2 mg/L). We observed pharmacokinetic drug interactions between both voriconazole and posaconazole, and everolimus cytochrome P450 3A4 metabolism, resulting in 7.5- and 3.8-fold increase, respectively, in everolimus blood trough concentrations. Combined therapeutic drug monitoring (TDM) of both everolimus and azole inhibitors allowed for safe and convenient modification of everolimus dosage, which was tapered to maintain a target range of 5–15 ng/mL during and after antifungal treatments. While significant in their effects, these drug interactions were able to be managed safely through a careful approach to management and use of individual TDM.

Safe Management of Tacrolimus Together With Posaconazole in Lung Transplant Patients With Cystic Fibrosis

Oral posaconazole (PSZ), an azole antifungal drug, was recently introduced for the treatment of invasive fungal infections. The prescription of PSZ together with the immunosuppressant tacrolimus (TRL) was evaluated in 14 lung transplant patients with cystic fibrosis. PSZ inhibited CYP3A4 TRL metabolism, resulting in a decrease of TRL dose by a factor of 3, with tapering to a mean of 2 mg/d. Previous studies with itraconazole and voriconazole showed that TRL dose could be decreased by factors of 5 and 4, respectively. Joint therapeutic drug monitoring of TRL and PSZ was carried out to investigate the high risk of interindividual variability associated with this coprescription in such patients.

Sublingual Tacrolimus as an Alternative to Intravenous Route in Patients With Thoracic Transplant: A Retrospective Study

Tacrolimus (TRL) is an immunosuppressive drug characterized by a narrow therapeutic index, low bioavailability, and pharmacokinetic variability. Intravenous (i.v.) TRL may be needed whenever the oral route is unavailable. The small amount of infusion formulation (5 mg/mL) results in a large dilution and need for careful technical management of the infusion. This study addressed the feasibility to provide sublingual (SL) as an alternative to i.v.. TRL for transplanted patients. In a substudy, we performed a retrospective analysis of 17 lung and heart transplant patients using SL TRL. It included therapeutic drug monitoring and 4 area under curve (AUC) measurements. Patients received SL TRL on a dose-to-dose basis from the oral formulation. The mean age of the subjects (14 male, 3 female) was 35.3 ± 15.6 years; 146 trough (C(0)) samples were collected during the SL period (15.8 ± 20.6 days) showing a conformity level of 90.4%. Mean dose, C(0), and AUC of SL tacrolimus were 0.116 ± 0.096 mg/kg, 12.9 ± 5 ng/mL, and 230 ± 74 ng·h/mL, respectively, with an average 1 hour time to peak concentration. Acute rejection episodes, renal toxicity, and drug interactions were not observed. This study supported the convenience of short-term SL TRL administration, even in unconscious patients. Further investigations are needed to validate the dose range of the SL route.

Therapeutic Drug Monitoring in De Novo Kidney Transplant Receiving the Modified-Release Once-Daily Tacrolimus

INTRODUCTION Advagraf (AVF) a new formulation of tacrolimus (TRL), allows once-daily administration while showing similar efficacy and safety to the conventional Prograf (PGF), which is prescribed twice daily. Our study sought to compare short-term therapeutic drug monitoring (TDM) of AVF and PGF in de novo kidney transplants. PATIENTS AND METHODS We retrospectively collected results of TDM performed on blood trough samples (C0) using an LC- MS/MS assay to quantify TRL exposure in the two groups. Twelve subjects received initial immunosuppression with AVF associated with mycophenolic acid, steroids, and immunoglobulins. We compared median doses and C0 levels with those obtained in 18 cases receiving an equivalent dose of PGF during the same period. RESULTS AND DISCUSSION Although both groups showed similar mean C0, the median dose in the AVF group tended to be higher than the PGF group-respectively, 9.8 and 7.9 mg/d-which may be attributed to the once-daily regimen, which inevitably results in lower C0 levels compared to the twice-a-day regimen, while overall exposure appeared similar in terms of area under the curve (AUC). This observation occurred especially during the first weeks despite the extended release formulation. In fact, one patient who showed a low C0 (5.9 ng/mL) while receiving high doses of AVF (0.28 mg/kg), the AUC of 356 and 211 ng.h/mL performed on days 12 and 18 respectively showed exposure consistent with efficacy. CONCLUSION In conclusion, it seemed to be necessary to use higher doses (25%) of Advagraf to reach the targeted C0 levels during the first weeks posttransplant. For patients who do not reach the targeted C0 despite high doses, TRL exposure should be assessed by AUC or peak levels (C4h).

Management of rifamycins-everolimus drug-drug interactions in a liver-transplant patient with pulmonary tuberculosis.

Dear Sirs, The inhibitors of the mammalian target of rapamycin (mTOR), sirolimus, and everolimus have emerged in Europe as a new class of immunosuppressive drugs in solidorgan transplantation (SOT). After liver transplantation, switching from calcineurin inhibitors (CNI) to mTOR inhibitors is associated with improved outcomes and renal function preservation. Their antiproliferative capabilities suggest a role in preventing malignancies, which is important to liver-transplant patients at risk of recurring hepatocellular carcinoma [1]. Because of their narrow therapeutic index, mTOR inhibitors require therapeutic drug monitoring (TDM). The therapeutic range of everolimus trough blood level (C0) is 3–8 ng/ml when associated with cyclosporine, but was increased to 8–13 ng/ml as a monotherapy use [2]. Post-transplantation tuberculosis is a rare infection with an incidence of 0.4–2.4%. Therefore, the optimal antituberculous regimen is not established [3]. In standard therapeutic regimens, the most potent sterilizing drugs rifampin and rifabutin (rifamycin) are essential in short-courses treatment (6 months) for pulmonary tuberculosis. However, rifamycins are potent inducers of both the cytochrome 3A4 (CYP3A4) and P-glycoprotein efflux transport systems and exhibit significant drug–drug interactions (DDI) with most immunosuppressants [4]. Interactions between rifampin and CNI, or the mTOR inhibitor – sirolimus – have been reported, but have not been studied with everolimus in transplant patients [5,6]. As rifabutin is a weaker CYP3A4 inducer than rifampin, its use over rifampin to treat tuberculosis could be favored as in HIV-infected patients receiving antiretroviral agents [7]. The interactions between rifabutin and CNI were reported in a kidney-transplant recipient, but are largely unknown with mTOR inhibitors [8]. We describe the case of a liver-transplant patient with pulmonary tuberculosis who experienced a complex DDI between rifampin and everolimus, which resolved after switching from rifampin to rifabutin. A 63-year-old man was referred to our institution in December 2009 for sputum-positive pulmonary tuberculosis. He received an orthotopic liver transplant in October 2008 for HCV-induced cirrhosis associated with hepatocellular carcinoma. The initial immunosuppressive regimen consisted of corticosteroids, mycophenolate mofetil, and everolimus combination. Everolimus was favored because of its expected antiproliferative effects on the underlying malignant disease. The starting dose was 0.5 mg BID (1 mg/day), resulting in a C0 of 12 ng/ml, established by LCMS/MS assay. In February 2009, pulmonary localizations of hepatocarcinoma were treated with radiofrequency ablation and sorafenib. In November, the patient presented with cough, highgrade fever, and chills. Chest radiographs showed bilateral infiltrates. Influenza A (H1N1) virus was detected using PCR amplification. Oseltamivir was administrated, but a low-grade fever persisted. Sorafenib and mycophenolate mofetil were withdrawn as a result of drug-induced pancytopenia. In December, chest X-rays showed cavitary-lung lesions. Acid-fast examination of sputum was diagnosed of >100 acid-fast bacilli/microscopic field. Cultures grew fully susceptible Mycobacterium tuberculosis. Antituberculous therapy was started (Day 1): rifampin (600 mg/day), isoniazid (250 mg/day), pyrazinamide (1500 mg/day), and ethambutol (1200 mg/day); without other interferential medications. Despite increases in everolimus dosages up to 8 mg TID (24-fold increase compared with the period without rifamycin), C0 remained <5 ng/ml (Fig. 1). Mycophenolate mofetil was resumed on day 13 to prevent acute liver rejection. On day 45, because everolimus C0 were still low, rifampin was switched to rifabutin (450 mg/day). Within few days, everolimus concentrations increased (Fig. 1); everolimus doses were gradually decreased to 5.25 mg/day over a period of 30 days, resulting in therapeutic steadystate C0 (10.3 ± 1.8 ng/ml). After 10 weeks of antituberculosis treatment; sputum cultures became sterile while microscopic examination was still positive. Pyrazinamide and ethambutol were stopped, while rifabutin and isoniazid were continued. At 12 weeks, mycophenolate mofetil was withdrawn for nosocomial pneumonia. After 4 months, sputum smears became negative. At 5 months, liver-enzyme levels increased to 20 times above the reference value. Rifabutin and isoniazid were

Validation of an Ultra-High Performance Liquid Chromatography Tandem Mass Spectrometric Method for Quantifying Uracil and 5,6-Dihydrouracil in Human Plasma

A simple, rapid, sensitive and specific ultra-high-performance liquid chromatography-tandem mass spectrometry method (Waters UPLC-MS-MS) is developed and validated for the quantification of uracil (U) and 5,6-dihydrouracil (UH2) levels in human plasma. Analytes are extracted using ethyl acetate and isopropanol after deproteination, and separated by high-performance liquid chromatography (HPLC) (Acquity UPLC BEH C18 column) in a binary mobile phase system under gradient elution conditions at a flow rate of 0.4 mL/min. 5-Bromo-uracil (UBr) is used as the internal standard. The detection is performed on a triple-quadrupole mass spectrometer via electrospray positive ionization. Multiple reaction monitoring mode using the transitions m/z 112.82 → 70.05, m/z 114.88 → 55.04 and m/z 190.83 → 117.86 is used to quantify U, UH2 and UBr, respectively. The method is linear in the concentration range of 0.625-160.0 ng/mL. The total run time is 4.5 min per injection. Nine-point calibration curve and four-points quality controls are used. Excellent linearity and precision are observed with correlation coefficient (r(2)) > 0.9999. The intra-batch and inter-batch precisions are ≤ 7.3% and ≤ 8.6%, and accuracy is ≤ 17%. The developed method is shown to be suitable for routine quantitative determination of U, UH2 and 5,6-dihydrouracil-to-uracil ratio in clinical practice.

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

S. Lefeuvre, P. Chevalier, C. Charpentier, R. Zekkour, L. Havard, M. Benammar, C. Amrein, V. Boussaud, A. Lillo‐Le Louët, R. Guillemain, E.M. Billaud. Valganciclovir prophylaxis for cytomegalovirus infection in thoracic transplant patients: retrospective study of efficacy, safety, and drug exposure.
Transpl Infect Dis 2010: 12: 213–219. All rights reserved

Clinical outcome of cystic fibrosis patients colonized by Scedosporium species following lung transplantation: A single-center 15-year experience

Fungi of the genus Scedosporium are emerging pathogens responsible for severe infections in lung transplant recipients. These infections are associated with poor prognosis and some centers consider now Scedosporium species colonization as a contraindication to lung transplantation (LT) even though no published evidence demonstrates that Scedosporium species colonization is associated with higher morbidity or mortality after LT.