Mario Regazzi

Clinically Significant Drug Interactions with Cyclosporin An Update

SummarySince its approval in 1983 for immunosuppressive therapy in patients undergoing organ and bone marrow transplants, cyclosporin has had a major impact on organ transplantation. It has significantly improved 1-year and 2-year graft survival rates, and decreased morbidity in kidney, liver, heart, heart-lung and pancreas transplantation. Several studies have supported the efficacy of cyclosporin in preventing graft-versus-host disease in bone marrow transplantation. Cyclosporin is also possibly effective in treating diseases of autoimmune origin and as an antineoplastic agent.The introduction of therapeutic drug monitoring of cyclosporin was extremely useful because of the wide inter- and intraindividual variability in the pharmacokinetics of cyclosporin after oral or intravenous administration. Optimal long term use of cyclosporin requires careful monitoring of the blood (or plasma) concentrations.Sustained and clinically significant drug-drug interactions can occur during long term therapy with cyclosporin. The coadministration of multiple drugs with cyclosporin could result in graft rejection, renal dysfunction or other undesirable effects. Any interaction that leads to modified cyclosporin concentrations is of potential clinical importance.Cyclosporin itself may have significant effects on the pharmacokinetics and/or pharmacodynamics of coadministered drugs, such as digoxin, HMG-CoA reductase inhibitors and antineoplastic drugs affected by multidrug resistance.Many drugs have been shown to affect the pharmacokinetics and/or pharmacodynamics of cyclosporin. Interactions between cyclosporin and danazol, diltiazem, erythromycin, fluconazole, itraconazole, ketoconazole, metoclopramide, nicardipine, verapamil, carbamazepine, phenobarbital (phenobarbitone), phenytoin, rifampicin (rifampin) and cotrimoxazole (trimethoprim/sulfamethoxazole) are well documented in a large number of patients. Other interactions (such as those with aciclovir, estradiol and imipenem) are documented only in isolated case studies.

Alemtuzumab As Consolidation After a Response to Fludarabine Is Effective in Purging Residual Disease in Patients With Chronic Lymphocytic Leukemia

PURPOSE Treatment with alemtuzumab has resulted in negative responses for minimal residual disease (MRD) in patients with chronic lymphocytic leukemia (CLL). In a prior analysis we demonstrated that it is possible to achieved MRD negativity, as assessed by polyclonality of immunoglobulin heavy chain after consolidation with alemtuzumab. This phase II study evaluated 34 patients with CLL who received alemtuzumab consolidation in an effort to improve the quality of their response to fludarabine-based induction. Subsequent peripheral blood stem-cell (PBSC) collection and transplantation, tolerability, and pharmacokinetics also were assessed. PATIENTS AND METHODS Thirty-four patients younger than 65 years who had a clinical response to fludarabine-based induction therapy received alemtuzumab 10 mg subcutaneously three times per week for 6 weeks. PBSCs were collected after mobilization with cytarabine and granulocyte colony-stimulating factor. Blood samples for pharmacokinetics study were taken between days 1 and 31. RESULTS The complete response rate improved from 35% after fludarabine induction to 79.4% after alemtuzumab consolidation, including 19 patients (56%) who achieved MRD negativity. The most common adverse events were injection-site reactions and fever. Cytomegalovirus reactivation occurred in 18 patients, all of whom were successfully treated with oral ganciclovir. PBSC collection was successful in 24 (92%) of 26 patients, and 18 patients underwent autologous PBSC transplantation. Alemtuzumab plasma concentrations increased gradually during the first 2 weeks and accumulated more rapidly thereafter. CONCLUSION Subcutaneously administered alemtuzumab was effective, safe, and well tolerated as consolidation therapy in patients with CLL who responded to fludarabine induction therapy. Subsequent PBSCT was feasible thereafter.

Steady-State Pharmacokinetics and BAL Concentration of Colistin in Critically Ill Patients After IV Colistin Methanesulfonate Administration

BACKGROUND Infections caused by multidrug-resistant gram-negative bacteria have caused a resurgence of interest in colistin. To date, information about pharmacokinetics of colistin is very limited in critically ill patients, and no attempts have been made to evaluate its concentration in BAL. METHODS In this prospective, open-label study, 13 adult patients with ventilator-associated pneumonia caused by gram-negative bacteria were treated with colistin methanesulfonate (CMS) IV, 2 million International Units (174 mg) q8h, a usually recommended dose, for at least 2 days. Blood samples were collected from each patient at time intervals after the end of infusion. BAL was performed at 2 h. Colistin was measured by a selective, sensitive high-performance liquid chromatography-based method. Pharmacokinetic parameters were determined by noncompartmental analysis. RESULTS Patients received 2.19 ± 0.38 mg/kg (range, 1.58-3.16) of CMS per dose. At steady state, mean ± SD plasma colistin maximum (Cmax) and trough (Ctrough) concentrations were 2.21 ± 1.08 and 1.03 ± 0.69 μg/mL, respectively. Mean ± SD area under the plasma concentration-time curve from 0 to 8 h (AUC(0-8)), apparent elimination half-life, and apparent volume of distribution were 11.5 ± 6.2 μg × h/mL, 5.9 ± 2.6 h, and 1.5 ± 1.1 L/kg, respectively. Cmax/minimum inhibitory concentration (MIC) ratio and AUC(0-24)/MIC ratio (MIC = 2 μg/mL) were 1.1 ± 0.5 and 17.3 ± 9.3, respectively. Colistin was undetectable in BAL. Nephrotoxicity was not observed. CONCLUSIONS Although the pharmacodynamic parameters that better predict the efficacy of colistin are not known in humans, in critically ill adult patients the IV administration of CMS 2 million International Units (174 mg) q8h results in apparently suboptimal plasma concentrations of colistin, which is undetectable in BAL. A better understanding of the pharmacokinetic-pharmacodynamic relationship of colistin is urgently needed to determine the optimal dosing regimen.

Rituximab in Children with Resistant Idiopathic Nephrotic Syndrome

Idiopathic nephrotic syndrome resistant to standard treatments remains a therapeutic dilemma in pediatric nephrology. To test whether the anti-CD20 monoclonal antibody rituximab may benefit these patients, we conducted an open-label, randomized, controlled trial in 31 children with idiopathic nephrotic syndrome unresponsive to the combination of calcineurin inhibitors and prednisone. All children continued prednisone and calcineurin inhibitors at the doses prescribed before enrollment, and one treatment group received two doses of rituximab (375 mg/m(2) intravenously) as add-on therapy. The mean age was 8 years (range, 2-16 years). Rituximab did not reduce proteinuria at 3 months (change, -12% [95% confidence interval, -73% to 110%]; P=0.77 in analysis of covariance model adjusted for baseline proteinuria). Additional adjustment for previous remission and interaction terms (treatment by baseline proteinuria and treatment by previous remission) did not change the results. In conclusion, these data do not support the addition of rituximab to prednisone and calcineurin inhibitors in children with resistant idiopathic nephrotic syndrome.

Lower dose rituximab is active in adults patients with idiopathic thrombocytopenic purpura

Rituximab 375 mg/m2 weekly for four weeks has significant activity in patients with immune thrombocytopenia. We evaluated the activity of lower dose rituximab (100 mg iv weekly for 4 weeks) in 28 adults with idiopathic thrombocytopenic purpura. Overall (platelet count > 50×109/L) and complete responses (platelet count > 100×109/L) were achieved in 21/28 (75%) and 12/28 (43%) patients respectively. The median time to response and time to complete response were 31 and 44 days respectively. After a median follow-up of 11 months (range 3–18), 7/21 (33%) patients relapsed and 3 needed further treatments. In patients with idiopathic thrombocytopenic purpura, lower dose rituximab seems to show similar activity to standard dose.

Antiretrovirals: Simultaneous determination of five protease inhibitors and three nonnucleoside transcriptase inhibitors in human plasma by a rapid high-performance liquid chromatography-mass spectrometry assay

An analytical technique using liquid chromatography (LC) coupled with electrospray–mass spectrometry (ESI–MS) has been developed for the simultaneous determination of five protease inhibitors (PIs): saquinavir, indinavir, ritonavir, nelfinavir, and amprenavir; and three non-nucleoside reverse transcriptase inhibitors (NNRTIs): nevirapine, delavirdine, and efavirenz, in human plasma. This assay allows the elution and identification of these drugs in a single run (10 minutes) using a linear gradient with water and acetonitrile. The procedure involves liquid–liquid extraction. High-performance liquid chromatography (HPLC) separation was achieved on a C18 reversed-phase column, with a linear gradient elution followed by mass spectrometry detection. The calibration curves, obtained by automatic process peak area integration, show a good linearity in a range of concentrations between 20 and 10,000 ng/mL (40–10,000 ng/mL for efavirenz). The limit of detection was approximately 10 ng/mL for seven drugs (25 ng/mL for efavirenz). The coefficients of variation (CV) were always less than 15% for both intraday and interday precision for each compound. The recovery of the eight drugs ranged from 88.5% to 100%. This novel LC/ESI–MS assay provides an excellent method for simultaneous quantitative monitoring of different components of the highly active antiretroviral treatments (HAARTs) in patients treated simultaneously with PIs and NNRTIs, and it has been successfully applied to therapeutic drug monitoring and pharmacokinetic studies.

Rationale and design of a trial evaluating the effects of losartan vs. nebivolol vs. the association of both on the progression of aortic root dilation in Marfan syndrome with FBN1 gene mutations.

Background The major clinical problem of Marfan syndrome (MFS) is the aortic root aneurysm, with risk of dissection when the root diameter approximates 5 cm. In MFS, a key molecule, transforming growth factor-β (TGF-β), normally bound to the extracellular matrix, is free and activated. In an experimental setting, TGF-β blockade prevents the aortic root structural damage and dilatation. The angiotensin receptor 1 blockers (sartanics) exert an anti-TGF-β effect; trials are now ongoing for evaluating the effect of losartan compared with atenolol in MFS. β-Adrenergic blockers are the drugs most commonly used in MFS. The third-generation β-adrenergic blocker nebivolol retains the β-adrenergic blocker effects on heart rate and further exerts antistiffness effects, typically increased in MFS. Methods The open-label phase III study will include 291 patients with MFS and proven FBN1 gene mutations, with aortic root dilation (z-score ≥2.5). The patients will be randomized to nebivolol, losartan and the combination of the two drugs. The primary end point is the comparative evaluation of the effects of losartan, nebivolol and the association of both on the progression of aortic root growth rate. Secondary end points include the pharmacokinetics of the two drugs, comparative evaluation of serum levels of total and active TGF-β, quantitative assessment of the expression of the mutated gene (FBN1, both 5′ and 3′), pharmacogenetic bases of drug responsiveness. The quality of life evaluation in the three groups will be assessed. Statistical evaluation includes an interim analysis at month 24 and conclusive analyses at month 48. Conclusion The present study will add information about pharmacological therapy in MFS, supporting the new application of angiotensin receptor 1 blockers and finding β-adrenergic blockers that may give more specific effects. Moreover, the study will further deepen understanding of the pathogenetic mechanisms that are active in Marfan syndrome through the pharmacogenomic and transcriptomic mechanisms that may explain MFS phenotype variability.

Rituximab (IDEC-C2B8): validation of a sensitive enzyme-linked immunoassay applied to a clinical pharmacokinetic study.

Rituximab is a chimeric monoclonal antibody (MAb) directed against the B-cell CD20 antigen that has been approved for therapy of relapsed and resistant follicular non-Hodgkins lymphoma (NHL). This study describes the development and validation of a highly sensitive, rapid, accurate, precise enzyme-linked immunosorbent assay (ELISA) to measure Rituximab serum concentrations. This study also describes the application of the ELISA method to a pharmacokinetic study in a homogeneous group of patients with follicular lymphoma who received 4 weekly doses of MAb at the standard dose of 375 mg/m2 as consolidation of chemotherapy. In the patients in this study, the median Rituximab serum concentrations increased during therapy, and showed a slow decline during the posttreatment period. The Rituximab elimination half-life of approximately 20 days accounts for the demonstrated accumulation of MAb in serum samples. Because previous pharmacokinetic studies showed a correlation between Rituximab serum levels and tumor response, the ELISA method used in this study, which allows a precise control of serum concentrations, could be useful for predicting the final response to the MAb and for selecting patients able to benefit from higher dosage or repeated drug administration.

Morphine metabolism, transport and brain disposition

The chemical structures of morphine and its metabolites are closely related to the clinical effects of drugs (analgesia and side-effects) and to their capability to cross the Blood Brain Barrier (BBB). Morphine-6-glucuronide (M6G) and Morphine-3-glucuronide (M3G) are both highly hydrophilic, but only M6G can penetrate the BBB; accordingly, M6G is considered a more attractive analgesic than the parent drug and the M3G. Several hypotheses have been made to explain these differences. In this review we will discuss recent advances in the field, considering brain disposition of M6G, UDP-glucoronosyltransferases (UGT) involved in morphine metabolism, UGT interindividual variability and transport proteins.

A sequence of immuno‐chemotherapy with Rituximab, mobilization of in vivo purged stem cells, high‐dose chemotherapy and autotransplant is an effective and non‐toxic treatment for advanced follicular and mantle cell lymphoma

Summary. Options for relapsed/refractory indolent lymphoma include chemotherapy, immunotherapy and high‐dose therapy with autologous support. The best combination of these approaches, however, is not defined. We treated 10 patients with relapsed/refractory follicular (n = 7) or mantle cell lymphoma (n = 3) using chemotherapy, immunotherapy, high‐dose therapy and autotransplant in a sequence of four phases, each designed to play a specific role in tumour eradication. After the debulking with VACOP‐B (doxorubicin, cyclophosphamide, etoposide, vincristine, prednisone, bleomycin) (phase 1), 9/10 patients responded but none achieved a molecular response. After the immuno‐chemotherapy phase, which combined Rituximab with vincristine and cyclophosphamide, seven patients were in complete response (CR) and three in good partial response (PR), and all those with a molecular marker of disease showed a disappearance of the signal from marrow and blood. Phase 3, which coupled high‐dose cytarabine with Rituximab, was effective in mobilizing an adequate number of progenitor cells that were polymerase chain reaction negative in all informative cases. Phase 4 consisted of high‐dose therapy with autologous support followed by two doses of Rituximab. Autograft was performed in nine patients. The haematopoietic recovery was as expected. This sequence of chemotherapy, immuno‐chemotherapy, stem cell mobilization with in vivo purging and autotransplant, organized in four blocks of treatment, was simple to administer and devoid of toxic effects. It permits rapid attainment of clinical and molecular response and enables the harvest of lymphoma‐free peripheral blood progenitor cells even in heavily pretreated patients with relapsed or refractory disease.