Hydroxycloroquine blood concentration in lupus nephritis: a determinant of disease outcome?

Background: Hydroxychloroquine (HCQ) is a recommended drug in systemic lupus erythematosus (SLE). It has a long terminal half-life, making it an attractive target for therapeutic drug monitoring. The aim of this study was to establish a relationship between blood HCQ concentration and lupus nephritis activity. Methods: We conducted a retrospective observational study with data collected from clinical and laboratory records. Inclusion criteria were patients followed in the lupus clinic with biopsy-proven International Society of Nephrology/Renal Pathology Society Classes III, IV or V lupus nephritis on HCQ for at least 3 months (200-400 mg daily) and with HCQ levels measured during treatment. Exclusion criteria were patients on renal replacement therapy at baseline or patients lost to follow-up. Results: In 171 patients, the HCQ level was measured in 1282 samples. The mean HCQ blood level was 0.75±0.54mg/L and it was bimodally distributed. An HCQ level <0.20 mg/L [232 samples (18.1%)] appeared to define a distinct group of abnormally low HCQ levels. For patients in complete or partial remission at baseline compared with those remaining in remission, patients with renal flare during follow-up had a significantly lower average HCQ level (0.59 versus 0.81 mg/L; P= 0.005). Our data suggest an HCQ target level to reduce the likelihood of renal flares >0.6 mg/L (600 ng/mL) in those patients with lupus nephritis. Conclusion: HCQ level monitoring may offer a new approach to identify non-adherent patients and support them appropriately. We propose an HCQ minimum target level of at least 0.6 mg/L to reduce the renal flare rate, but this will require a prospective study for validation.

Anaemia and congestive heart failure early post-renal transplantation.

BACKGROUND: Anaemia is common following renal transplantation and is associated with the development of congestive heart failure (CHF). However the prevalence of anaemia in the first year following transplantation and the association between anaemia occurring early and the development of CHF have been understudied. METHODS: In this study, 132 incident patients undergoing tacrolimus and mycophenolate mofetil-based renal transplantation were studied for the prevalence of, and risk factors for, anaemia and CHF in the early period post transplantation. RESULTS: Anaemia occurred in 94.5% and 53.1% of patients at 1 week and 12 months, respectively, and was associated with allograft dysfunction, hypoalbuminaemia, higher mycophenolic acid (MPA) levels, bacterial infection and hypoalbuminaemia. The association with hypoalbuminaemia may reflect the presence of chronic inflammation post-transplantation. Of patients displaying haemoglobin <11 g/dl, 41.1% and 29.4% were treated with erythropoiesis stimulating agents (ESAs) at 1 and 12 months respectively. CHF developed in 26 patients beyond 1 month post-transplantation, with echocardiographic left ventricular systolic function preserved in all but one. CHF was associated with anaemia and lower haemoglobin, allograft dysfunction, duration of dialysis and left ventricular hypertrophy on echocardiography prior to transplantation, suggesting the aetiology of CHF may involve the interplay of diastolic cardiac dysfunction, pre-load mismatch and after-load mismatch. CONCLUSIONS: Modification of risk factors may improve anaemia management post transplantation. Reducing the prevalence of anaemia may in turn reduce the incidence of CHF-these observations support the need for clinical trials to determine how anaemia management may impact CHF incidence.

Breastfeeding and tacrolimus: serial monitoring in breast-fed and bottle-fed infants.

BACKGROUND AND OBJECTIVES: Women have traditionally been advised not to breastfeed while taking tacrolimus, based on theoretical risks of neonatal immunosuppression and assumed secretion into breast milk, rather than clinical data suggesting neonatal absorption. The aim of this study was to assess tacrolimus levels in breast milk and neonatal exposure during breastfeeding. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: An observational cohort study was performed in two tertiary referral high-risk obstetric medicine clinics. Fourteen women taking tacrolimus during pregnancy and lactation, and their 15 infants, 11 of whom were exclusively breast-fed, were assessed. Tacrolimus levels were analyzed by liquid chromatography-tandem mass spectrometry. Samples from mothers and cord blood were collected at delivery and from mothers, infants, and breast milk postnatally where possible. RESULTS: All infants with serial sampling had a decline in tacrolimus level, which was approximately 15% per day (ratio of geometric mean concentrations 0.85; 95% confidence interval, 0.82-0.88; P<0.001). Breast-fed infants did not have higher tacrolimus levels compared with bottle-fed infants (median 1.3 µg/L [range, 0.0-4.0] versus 1.0 µg/L [range, 0.0-2.3], respectively; P=0.91). Maximum estimated absorption from breast milk is 0.23% of maternal dose (weight-adjusted). CONCLUSIONS: Ingestion of tacrolimus by infants via breast milk is negligible. Breastfeeding does not appear to slow the decline of infant tacrolimus levels from higher levels present at birth. Women taking tacrolimus should not be discouraged from breastfeeding if monitoring of infant levels is available.

A new and clinically relevant murine model of solid-organ transplant aspergillosis.

Invasive fungal infections (IFIs) are a major cause of death in organ transplant patients. The murine hydrocortisone-mediated immunosuppression model of pulmonary aspergillosis is commonly used to characterise IFIs in these patients. However, this model does not take into account the effects of calcineurin inhibitors on transplant immunity to IFIs or the fungal calcineurin pathway, which is required for both virulence and antifungal drug resistance. To address these two issues, a new and clinically relevant transplant immunosuppression model of tacrolimus (FK506) and hydrocortisone-associated pulmonary aspergillosis was developed. We first characterised IFIs in 406 patients with a lung transplant. This showed that all of the patients with pulmonary aspergillosis were immunosuppressed with calcineurin inhibitors and steroids. Murine pharmacokinetic studies demonstrated that an ideal dose of 1 mg/kg/day of FK506 intraperitoneally produced blood trough levels in the human therapeutic range (5-12 ng/ml). There was increased mortality from pulmonary aspergillosis in a transplant-relevant immunosuppression model using both FK506 and hydrocortisone as compared with immunosuppression using hydrocortisone only. Lung histopathology showed neutrophil invasion and tracheobronchitis that was associated with reduced lung tumour necrosis factor-α (TNFα), JE (homologue of human MCP-1) and KC (homologue of human IL-8) at 24 hours, but increased lung TNFα, JE and KC at 48 hours when fungal burden was high. Furthermore, FK506 directly impaired fungal killing in alveolar macrophages in vitro, with FK506-mediated inhibition of the radial growth of Aspergillus fumigatus in vitro occurring at the low concentration of 5 ng/ml. Taken together, these findings show that the immunosuppressive activity of FK506 outweighs its antifungal activity in vivo. These observations demonstrate that FK506 impairs innate immune responses and leads to an incremental increase in susceptibility to IFIs when it is combined with steroids. This new and clinically relevant mouse model of invasive aspergillosis is a valuable addition to the further study of both fungal immunity and antifungal therapy in organ transplantation.

The magnitude and time course of changes in mycophenolic acid 12-hour predose levels during antibiotic therapy in mycophenolate mofetil-based renal transplantation.

There is increasing evidence that monitoring predose plasma levels of mycophenolic acid (MPA) is of benefit in renal transplant recipients treated with mycophenolate mofetil (MMF). Concomitant treatment with oral antibiotics leads to a 10% to 30% reduction in MPA area under the curve (AUC)0-12, probably by reducing enterohepatic recirculation (EHR). Because of the timing of EHR (6 to 12 hours postdose), the magnitude of predose MPA level reduction may be disproportionately larger than that of AUC0-12. However, changes in predose MPA levels and the time course over which these changes occur and resolve during antibiotic treatment have not been studied. The purpose of this study was to define the extent and time course of MPA predose level reduction during antibiotic therapy. A total of 64 MMF-treated renal transplant recipients (with tacrolimus cotherapy) were prospectively studied. Clinically indicated cotherapy with either oral ciprofloxacin or amoxicillin with clavulanic acid resulted in a reduction in 12 hour predose MPA level to 46% of baseline within 3 days of antibiotic commencement. No demographic or biochemical variables were associated with the magnitude of MPA level reduction. No further fall in MPA level was seen by day 7, but MPA levels recovered spontaneously to 79% of baseline after 14 days of antibiotics. Levels normalized within 3 days of antibiotic cessation. No changes in daily MMF dose (normalized for body weight) were made during antibiotic treatment. This data should help the clinician to recognize the extent of MPA predose level reduction during antibiotic therapy, and to avoid inappropriate MMF dose escalation and potential risk of toxicity.

Clinical outcomes of renal transplantation using liquid chromatographic monitoring of tacrolimus.

It is suggested that specific methods of Tacrolimus monitoring rather than immunoassays which over-estimate Tacrolimus levels, should be used in transplant recipients. There is limited data, however, comparing clinical outcomes of renal transplantation using each of these techniques. In this study, 40 renal transplant recipients with Tacrolimus monitoring by Microparticle Enzyme Immunoassay (MEIA; target trough level 10-15 ng/ml) were compared with 40 patients monitored by High Performance Liquid Chromatography with Tandem Mass Spectrometry (HPLC-MS; target trough level 8-13 ng/ml). All received anti CD25 antibody induction and Mycophenolate Mofetil in a steroid sparing protocol. No demographic differences were seen between MEIA and HPLC-MS groups. All patients were followed for 6 months. Patient survival was 100% in both groups; graft survival was 100% in the MEIA group and 97.5% in the HPLC-MS group. The groups did not differ in the number of dose changes required in the first 6 months or in the number of patients displaying Tacrolimus levels within target range at three and six months. Delayed graft function occurred in 14 patients in the MEIA group and 12 patients in the HPLC-MS group (P = NS). Biopsy-proven acute rejection occurred in 4 patients in the MEIA group and 1 patient in the HPLC-MS group (P = 0.17). Biopsy proven acute Tacrolimus nephrotoxicity occurred in 6 patients in the MEIA group, and 7 in the HPLC-MS group (P = NS). No difference was seen in serum creatinine or estimated creatinine clearance at 3 or 6 months. No difference between groups was seen in systolic or diastolic blood pressure, or total cholesterol at 3 or 6 months. 2 patients in the MEIA group developed CMV disease and 1 developed posttransplantation diabetes mellitus. CMV and posttransplantation diabetes were not seen in the HPLC-MS group. 2 patients in each group developed reversible tremor. This study suggests that renal transplantation with HPLC-MS monitoring of Tacrolimus is safe and effective.

Determinants of mycophenolic acid levels after renal transplantation.

There are data suggesting an association between mycophenolic acid (MPA) levels and acute rejection and toxicity in renal transplant recipients treated with mycophenolate mofetil (MMF), and therefore, knowledge of factors determining MPA levels may aid in accurate adjustment of MMF dosage. A total of 4970 samples taken 12 hours postdose were analyzed for MPA by immunoassay at regular intervals from the first week posttransplantation in 117 renal transplant patients immunosuppressed with MMF and tacrolimus in a steroid-sparing regimen (prednisolone for the first 7 days only). MPA levels rose in the first 3 months and stabilized thereafter; dose-normalized MPA levels rose throughout the first 12 months and subsequently stabilized. Multivariate analysis by means of a population-averaged linear regression showed positive associations between MPA level and total daily dose (P < 0.001) but not individual dose or total daily dose corrected for body weight. Positive associations were also seen with serum albumin (P = 0.01), tacrolimus trough level (P = 0.01), and female gender (P = 0.002). The association with tacrolimus levels diminished with time. Negative associations were seen between MPA level and higher estimated creatinine clearance (P < 0.001), and also with increasing alanine transaminase levels (P = 0.002), the use of oral antibiotics (P < 0.001), and infective diarrhea (P < 0.001). The latter findings may be related to changes in enterohepatic recirculation of MPA. Many clinical variables show associations with trough MPA levels. An understanding of these factors may aid therapeutic monitoring of MMF.

Monitoring cyclosporin in blood: between-assay differences at trough and 2 hours post-dose (C2).

With the introduction of a cyclosporin monitoring strategy based on the use of a sample collected 2 hours after dosing (C2) rather than the predose sample (C0), there was concern that the differences in blood cyclosporin results from the various assay systems would result in assay-specific target ranges for C2 monitoring. In addition, it was not known if the different proportion of cyclosporin metabolites in the blood 2 hours after dosing compared with that seen in predose samples would alter the relationship between the various assay methodologies. The aim of this study was to address these issues using blood samples from patients who had undergone kidney and liver transplantation. To do this, paired samples were collected predose and 2 hours after cyclosporin dosing at various periods following transplantation in kidney (88 paired samples) and liver (165 paired samples) transplant recipients. Cyclosporin was measured in these samples using five different immunoassays (radioimmunoassay, two fluorescent polarization immunoassays, and two homogeneous immunoassays) and high-performance liquid chromatography-mass spectrometry. The results of the study showed that when using these immunoassays to measure blood cyclosporin concentrations at C0, the cross-reactivity of the antibodies in the different immunoassay kits resulted in target therapeutic ranges that would need to vary between assays to maintain parity. However, when the same assays were used to measure the blood cyclosporin concentration at C2, the results were congruent, and assay-specific target therapeutic ranges should not be necessary. Thus, when adopting a C2 monitoring strategy, it is possible to use target therapeutic ranges that are independent of the assay system used.