Isabel Rojo

Sequential determination of pharmacokinetics and pharmacodynamics of mycophenolic acid in liver transplant patients treated with mycophenolate mofetil.

Background. In liver transplantation, mycophenolate mofetil (MMF) is habitually administered using fixed doses. We assessed whether mycophenolic acid (MPA) monitoring could be advisable in liver transplant patients. Methods. In 15 liver transplant patients receiving tacrolimus, daclizumab and MMF (1 g bid, orally), we determined the 12-hour plasma MPA pharmacokinetic profile after one dose of MMF at days 6, 10, and 16, and months 3 and 6. The inhibitory capacity of serum MPA on proliferation of CEM cells, a cell line insensitive to other immunosuppressants, was also determined. Results. A large interindividual variability in MPA profiles was observed at any time. Regardless of a gradual increase in individual MPA AUC and C0 over time following transplantation, a substantial proportion of patients had these parameters below the ranges recommended in other organ transplantations throughout the study. When MPA AUC and C0 were within the recommended ranges, CEM proliferation was inhibited by almost all serum samples, but when these pharmacokinetic parameters were below the recommended ranges, CEM proliferation was very variable and, therefore, unpredictable. No relationship between MPA pharmacokinetics and the efficacy of MMF could be established (only one patient developed rejection), probably due to the concomitant administration of tacrolimus and daclizumab. Gastrointestinal symptoms were the only adverse events with a significant relationship with MPA levels. Conclusions. During the first postoperative months, exposure to MPA is low in a considerable proportion of liver transplant patients receiving MMF at a fixed dose of 1 g bid. MPA monitoring appears necessary in these patients.

Pharmacokinetic and pharmacodynamic correlations of cyclosporine therapy in stable renal transplant patients: evaluation of long-term target C2

We investigated the relationship between the pharmacokinetics and pharmacodynamics of cyclosporine in 15 stable renal transplant patients in order to define an effective and safe therapeutic range. The area under the curve of the first 4 h (AUC0−4), trough (C0) and 2 h (C2) levels showed median values of 1655 ng×h/ml, 114 ng/ml and 384 ng/ml, respectively. C2 showed a strong correlation with AUC0–4 (r=0.942, p=0.0005). C0 correlated poorly with C2 and AUC0–4 (r=0.596, p=0.019 and r=0.538, p=0.031, respectively). Calcineurine activity (CNa) was 6.74% at 0 h and 3.90% at 2 h, representing significant reductions (82% and 89.6%, respectively; p<0.0005) compared with normal healthy controls (median basal value 37.4%). IL-2 production was 349 pg/ml at 0 h and 276.35 pg/ml at 2 h; both results were significantly lower (reductions of 44.5% and 56.1%, respectively; p=0.04 and 0.005) than the controls of 629.1 pg/ml. IFN-γ at 2 h post-dose (8.16 UI/ml) was significantly lower (72.1% reduction, p=0.005) than in controls (29.2 UI/ml). There was a good correlation between CNa and IFN-γ production, particularly at 2 h post-dose (r=0.537, p=0.007), and a fair correlation between CNa and IL-2 concentration (p=0.030, r=0.426). C2 showed an inverse significant correlation with CNa (Spearmans p=0.000, r=−0.753), IL-2 (p=0.000, r=−0.725) and IFN-γ (p=0.000, r=−0.701) production. In treated patients, the Emax inhibitory sigmoidal model showed that a C2 of 279 ng/ml was needed to achieve a 50% inhibition (EC50) of IL-2 and INF-γ production. The results demonstrated a significant inhibition of calcineurin activity and IL-2 and IFN-γ production in patients receiving cyclosporine monotherapy compared to healthy controls. A median C2 value of 384 ng/ml was associated with a good degree of inhibition of CNa and IL-2 and IFN-γ synthesis, and the lack of rejection episodes and relevant toxicity.

Pharmacokinetics and pharmacodynamics of low dose mycophenolate mofetil in HIV-infected patients treated with abacavir, efavirenz and nelfinavir.

BackgroundThe use of mycophenolate mofetil in combination with highly active antiretroviral therapy (HAART) has been proposed in order to inhibit HIV replication. Due to the low doses involved, pharmacokinetic-pharmacodynamic monitoring is recommended.ObjectiveThe aim of this study was to characterise the pharmacokinetic and pharmacodynamic monitoring of low doses of mycophenolate mofetil (0.25g twice daily) in HIV-infected patients treated with HAART and after programmed discontinuation of HAART, in order to assess whether low doses of this immunosuppressive agent provide a biological effect.MethodsMycophenolic acid (MPA) plasma levels (assessed by high-performance liquid chromatography) and the capacity of patients’ sera to inhibit cell line proliferation (assessed by 3H-thymidine uptake) were measured post-dose at 0, 20, 40 minutes and 1, 2, 4, 6, 8, 10 and 12 hours in nine HIV-infected patients treated with a combination of abacavir, nelfinavir and efavirenz (HAART) and mycophenolate mofetil 0.25g twice daily at days 7, 28, 120 and 150 (30 days without HAART) after the treatment initiation. A control group of eight patients was treated with HAART alone.ResultsIn the 35 post-dose curves analysed, no differences were found in MPA levels between days 7, 28, 120 and 150: area under the plasma concentration-time curve — mean value 15.3 mg · h/L, range 10.4−24.4 mg · h/L; minimum plasma concentration — mean value 0.60 mg/L, range 0.20–4.67 mg/L; maximum plasma concentration mean value 2.60 mg/L, range 0.94–7.98 mg/L. Pretreatment patients’ sera did not inhibit proliferation. Post-treatment patients’ sera inhibited proliferation to <40% in 25 of 35 curves at 0 hours (six of nine patients), in 34 of 35 curves at 1 hour, in 32 of 35 curves at 2 hours, in 22 of 35 curves at 4 hours, and in 8 of 35 curves at 12 hours. The MPA level versus proliferation inhibition had a concentration that produces 50% of the maximum drug effect (EC50) of 0.33 mg/L. Viral load at day 150 was >200 copies/mL in all control patients and in three of nine patients receiving mycophenolate mofetil. These three patients were the only ones repeatedly unable to inhibit pre-dose proliferation to <40%.ConclusionsMycophenolate mofetil pharmacokinetic profiles in HIV patients under HAART are not significantly different from those found in transplant patients. Sera from the majority of patients receiving low doses of mycophenolate mofetil inhibited lymphocyte proliferation during most of the inter-dose interval, despite low MPA plasma levels. For some patients, higher doses may be necessary: the capacity of sera to inhibit proliferation may help to identify these patients.

Effects of cyclosporine, tacrolimus and sirolimus on vascular changes related to immune response.

BACKGROUND Despite the use of newer immunosuppressors such as sirolimus (SRL) and tacrolimus (TRL) in heart transplantation, the rate of humoral rejection has remained unchanged. The aim of this study was to analyze the immunologic and histologic effects of cyclosporine (CsA), SRL, and TRL in a porcine model of arterial transplantation. METHODS Each transplant recipient animal (n = 49) received an autograft and an allograft and was then allocated to one of four treatment groups and a 7- or 30-day follow-up period, as follows: a WOT group (without immunosuppressor treatment), 7 days (n = 6) and 30 days (n = 5); a CsA group, 7 days (n = 5) and 30 days (n = 6); an SRL group, 7 days (n = 7) and 30 days (n = 8); and a TRL group, 7 days (n = 6) and 30 days (n = 6). The presence of donor-specific antibodies (DSA) was tested at the end of the follow-up period. Morphometric parameters and inflammatory infiltration were analyzed in the explanted grafts. RESULTS At 30-day follow-up, SRL was the only treatment capable of suppressing DSA formation (0 of 7 vs 4 of 5 in the WOT group; p < 0.05). SRL completely prevented aneurismal dilation and reduced the number of macrophages in the allografts. TRL treatment achieved a greater reduction of T lymphocytes. CsA did not prevent the reduction in total vascular area at 7 days that was achieved with the SRL and TRL groups. Animals treated with CsA had the largest number of T lymphocytes and macrophages in both follow-up periods. CONCLUSIONS SRL prevented DSA formation and reduced the number of macrophages as compared with TRL and CsA.

Human T-cell response to L14 pig cell line transfected with human ligands CD80 and CD86.

MATERIALS AND METHODSIrradiated L14, a B lymphoblastoid pig cell line, was used asstimulator, and human monocyte highly depleted peripheral bloodcells (MHDC) were used as responder cells. Proliferation wasmeasured by H3-Thymydine. IL-2 was measurement in superna-tants by ELISA (Immunotech) at 48 hours. L14 cell line wastransfected separately by electrophoration with hCD80, hCD86,and hICAM1(CD54) using plasmidic vector PCDNA3, which pro-duces a stable transfection. The transfected cells were grown onselective media and cloned by limiting dilution. Three clones wereselected by its high expression of the human antigens: L14-hCD80(5), L14-hCD86(13), and L14-hICAM1(10).RESULTS