[Benefit of therapeutic drug monitoring of immunosuppressants and immunomodulators in the management of autoimmune diseases]. / Intérêt des dosages pharmacologiques d'immunosuppresseurs et immunomodulateurs dans la prise en charge des maladies autoimmunes.

The pharmacokinetics of drugs, such as immunosuppressants, justify the need of measuring their blood concentrations in order to adjust their dosage. Therapeutic Drug Monitoring (TDM) of ciclosporin, tacrolimus and mycophenolate mofetil has shown its benefit particularly in the management of renal transplantees, in order to prevent graft rejection. When prescribed in autoimmune diseases, their pharmacokinetic variability and the variability of clinical response would justify TDM in practice. TDM may be useful in systemic lupus, for hydroxychloroquine, in order to monitor patient compliance. Despite insufficient data in the literature, for mycophenolate mofetil, TDM would permit to maintain clinical remission in adults and children with lupus nephritis, as well as in mucosal pemphigoid and idiopathic nephrotic syndrome in children. Studies are still necessary to validate the thresholds and TDM conditions. For azathioprine, TPMT phenotyping is recommended before prescription. For methotrexate, tacrolimus and ciclosporin, data are still sparse on the benefit of TDM, although it may improve tolerance to tacrolimus in lupus. Finally, for infliximab, in case of loss of response in maintenance, TDM may be proposed in parallel with detection of anti-drug antibodies.

Impact of ribavirin plasma level on sustained virological response in patients treated with pegylated interferon and ribavirin for chronic hepatitis C.

BACKGROUND: The main goal of therapy in hepatitis C virus (HCV) infection is to achieve a sustained virological response (SVR). However, the impact of the pharmacological properties of ribavirin on the SVR has not been fully investigated. AIM: To evaluate, through a prospective study, the association between ribavirin plasma level and SVR response in HCV patients treated with pegylated interferon (PEG-IFN) and ribavirin. PATIENTS AND METHODS: Patients treated with PEG-IFN and ribavirin had plasmatic ribavirin dosage at weeks 4 and 12. SVR was evaluated 6 months after the end of treatment. RESULTS: At week 4, a strong correlation was found between HCV-RNA and C(min) of ribavirin plasma level (r = -0.376, P = 0.002) and AUC(0-->12h) of ribavirin plasma level (r = -0.277, P = 0.018). At week 12, a strong correlation was found between HCV-RNA and C(min) of ribavirin plasma level (r = -0.384, P < 0.0001) and AUC(0-->12h) of ribavirin plasma level (r = -0.257, P = 0.002). In genotype 1 patients, AUC(0-->12h) ribavirin and C(min) were significantly correlated with negative HCV-RNA at week 12 and SVR. In the multiple logistic regression model, the only factor independently associated with SVR in genotype 1 patients was negative HCV-RNA at week 12. CONCLUSION: C(min) of ribavirin at weeks 4 and 12 was significantly higher in sustained virological responders compared with relapser or nonresponder patients. However, in genotype 1 patients, plasma ribavirin level at weeks 4 and 2 was not associated with SVR.

Diffusion of ertapenem into bone and synovial tissues.

OBJECTIVES: The degree of penetration of an antibiotic into the infected site is an important criterion for therapeutic success. Ertapenem is a new carbapenem, exhibiting activity against most Gram-positive and Gram-negative aerobic and anaerobic bacteria commonly recovered from community-acquired infections. However, no studies concerning its diffusion into bone and synovial tissue are available. Our objective was to quantify ertapenem bone and synovial tissue penetration and to compare our data with the MIC(90)s for causative pathogens. PATIENTS AND METHODS: In an open-label study, 18 patients who were undergoing elective total hip replacement received a single, parenteral, 1 g dose of ertapenem. One serum, one cortical and cancellous bone and one synovial tissue sample was collected per patient a median [interquartile range (IQR)] of 1.6 (1.5-1.7), 12.4 (11.9-13.1) or 23.8 h (22.6-25.2) later and analysed by HPLC. RESULTS: The median (IQR) serum concentrations of ertapenem were 70.1 (56.1-75.9), 10.0 (9.1-11.2) and 2.6 mg/L (2.3-3.0), respectively, at the different time points. The median (IQR) cancellous bone tissue concentrations were 13.2 (10.2-14.8), 1.9 (1.7-2.1) and 0.6 microg/g (0.4-0.6) at the different time points, corresponding to a median (IQR) tissue/serum penetration ratio of 0.19 (0.18-0.23). The median (IQR) cortical bone tissue concentrations were 8.0 (6.5-9.5), 1.3 (1.2-1.3) and 0.3 microg/g (0.3-0.4) at the different time points, corresponding to a median (IQR) tissue/serum penetration ratio of 0.13 (0.12-0.14). The median (IQR) synovial tissue concentrations were 26.2 microg/g (22.7-28.4), 4.0 mg/L (3.7-4.4) and 1.0 mg/L (0.9-1.2) at the different time points, corresponding to a median (IQR) tissue/serum penetration ratio of 0.41 (0.39-0.42). CONCLUSIONS: The concentrations after an ertapenem 1 g dose achieved in cancellous and cortical bone tissue and in synovial tissue were greater than the MIC(90)s for most aerobic organisms for 24 h, and for 12 to 24 h for anaerobic bacteria in healthy volunteers undergoing total hip replacement.

Diffusion of levofloxacin into bone and synovial tissues.

OBJECTIVES: The degree of penetration of an antibiotic into the infected site is an important determinant of therapeutic success. Levofloxacin is widely used in the treatment of serious infections. However, there are only few studies concerning its diffusion into bone tissue and none concerning its diffusion into synovial tissue. Our objective was to quantify levofloxacin bone and synovial tissue penetration and to compare our data with the breakpoint for susceptible organisms. PATIENTS AND METHODS: In an open-label study, 12 subjects who were undergoing elective total hip replacement received a single, parenteral, 500 mg dose of levofloxacin. Plasma, cortical and cancellous bone, and synovial tissue samples were collected a mean of 1.2 h later and analysed by a validated HPLC method. RESULTS: The mean +/- S.D. plasma concentration of levofloxacin at the time of bone removal was 7.5 +/- 1.3 mg/L. The levofloxacin concentrations were 7.4 +/- 2.2 mg/kg in cancellous bone tissue and 3.9 +/- 1.2 mg/kg in cortical bone tissue. The levofloxacin concentration was 8.9 +/- 2.1 mg/kg in synovial tissue. The mean +/- S.D. ratios of levofloxacin concentration in bone and plasma (bone/plasma) were 1.0 +/- 0.4 for cancellous bone tissue and 0.5 +/- 0.1 for cortical bone tissue. The ratio of levofloxacin concentration in synovial tissue and plasma (synovial tissue/plasma) was 1.2 +/- 0.4. CONCLUSIONS: The concentrations of levofloxacin achieved in cancellous and cortical bone tissue and in synovial tissue are greater than the breakpoint for susceptible organisms, which is < or =2 mg/L.

Determination of levofloxacin in plasma, bronchoalveolar lavage and bone tissues by high-performance liquid chromatography with ultraviolet detection using a fully automated extraction method.

The aim of this study was to develop a specific and sensitive high-performance liquid chromatographic (HPLC) assay for the determination of levofloxacin in human plasma, bronchoalveolar lavage and bone tissues. The sample extraction was based on a fully automated liquid-solid extraction with an OASIS cartridge. The method used ultraviolet detection set at a wavelength of 299 nm and a separation with a Supelcosil ABZ+ column. The assay has been found linear over the concentration range 0.25-25 microg/ml for levofloxacin in plasma, 1-6 microg/ml in bronchoalveolar lavage and 0.5-10 microg/g for bone tissues and it provided good validation data for accuracy and precision. The assay will be applied to determine the penetration of levofloxacin in human bronchoalveolar lavage (BAL) and bone tissues during pharmacokinetic steady state.

Diffusion of oral and intravenous 400 mg once-daily moxifloxacin into lung tissue at pharmacokinetic steady-state.

The degree of penetration of an antibiotic into the infection site is an important factor for its therapeutic efficacy, particularly in respiratory tract infections. In the present study, we examined the lung tissue diffusion of moxifloxacin at a dose of 400 mg administered intravenously or orally once-daily, and the results were correlated to microbiological data to estimate the clinical efficacy of moxifloxacin in lower community-acquired respiratory infections. This was a prospective, randomized, parallel-group trial, open-label, single-center study. Patients undergoing lung surgery for bronchial cancer which necessitates the removal of an anatomical piece of lung tissue were randomized into twelve treatment groups, dependent upon the time of surgery and the moxifloxacin formulation, i.v. or oral, administered. During surgery, one blood sample was taken at the time of tissue collection to determine moxifloxacin plasma concentration. At the same time, tissue samples were taken by pulmonary exeresis. A validated new high performance liquid chromatography assay was used to determine moxifloxacin concentrations in plasma and lung tissue. A total of 49 patients (25 for i.v. administration, 24 for oral administration, 44 men and 5 women, mean age, 61 years, mean body weight, 72 kg, mean creatinine clearance was 84 ml/min/1.73 m2) were enrolled. The mean +/- SD steady-state moxifloxacin ratios between lung and plasma concentrations were respectively: 3.53 +/- 1.89 and 4.36 +/- 1.48 for i.v. and oral administration. The mean steady-state moxifloxacin maximal lung concentrations (Cmax) were respectively 12.37 microg/g and 16.21 microg/g for i.v. and oral administration. Moxifloxacin both intravenously and orally exhibits high penetration in lung tissue, with tissue concentrations far above the MIC90s for most of the susceptible pathogens commonly involved, thus underlining its suitability for the treatment of community-acquired, lower respiratory tract infections.