Moxifloxacin does not alter ciclosporin pharmacokinetics in transplant patients: a multiple-dose, uncontrolled, single-centre study.

BACKGROUND: Moxifloxacin has a broad antibacterial spectrum and rapid bactericidal activity, and is thus a good option for the treatment of bacterial infections in patients who have undergone organ or bone marrow transplantation. Transplant patients also receive immunosuppressant therapy such as ciclosporin. OBJECTIVE: The primary objective of this study was to assess the steady-state pharmacokinetics of ciclosporin with and without concomitant treatment with moxifloxacin in transplant recipients. A secondary objective was to determine the safety and tolerability of the combined treatment. METHODS: Patients (n = 9) with stable graft function after bone marrow or renal transplantation and who were already receiving ciclosporin therapy were enrolled into the study. The patients were given ciclosporin (Sandimmun Optoral) capsules twice daily (total daily dosage 150-380 mg/day) throughout the study period. Moxifloxacin (Avolox) tablets 400 mg once daily were given on days 2-8 inclusive. The primary outcome measure was the change in ciclosporin pharmacokinetics on coadministration with moxifloxacin. Secondary outcomes were the steady-state pharmacokinetics of moxifloxacin and ciclosporin plus its metabolites in patients receiving moxifloxacin and ciclosporin concomitantly. Moxifloxacin pharmacokinetic parameters in the presence of ciclosporin were compared with previously published pharmacokinetic data for moxifloxacin in healthy individuals. RESULTS: No significant changes occurred in the concentration-time curves of ciclosporin and its metabolites following combination therapy with moxifloxacin. The geometric means of whole blood concentrations of ciclosporin and ciclosporin plus its metabolites on day 1 were similar to those on day 8 following combined administration of ciclosporin and moxifloxacin for 7 days. The ratio of combination treatment to monotherapy for ciclosporin was 1.01 (90% CI 0.91, 1.11) for the area under the blood concentration-time curve from time zero to 12 hours at steady state (AUC(12,ss)) and 0.96 (90% CI 0.88, 1.04) for the maximum steady-state blood drug concentration (C(max,ss)). For ciclosporin plus its metabolites the ratio was 1.07 (90% CI 0.99, 1.17) for AUC(12,ss) and 1.03 (90% CI 0.98, 1.09) for C(max,ss). The pharmacokinetic parameters for moxifloxacin were unaffected by the presence of ciclosporin. CONCLUSIONS: Concomitant administration of moxifloxacin does not alter the pharmacokinetic parameters of ciclosporin or ciclosporin plus its metabolites in immunosuppressed patients. Therefore, no dose adjustments or additional drug monitoring are required when ciclosporin is coadministered with moxifloxacin.

Hyperforin content determines the magnitude of the St John's wort-cyclosporine drug interaction.

OBJECTIVE: Hyperforin (HYF) has been discussed as a potential cause of the reduction in the bioavailability of numerous drugs seen with St John's wort (SJW) comedication. This study compared the effects of 2 SJW preparations with high and low HYF content on the pharmacokinetics of cyclosporine (INN, ciclosporin) (CSA). METHODS: In a crossover study, 10 renal transplant patients were randomized into 2 groups and received SJW extract (900 mg/d) containing low or high concentrations of HYF for 14 days in addition to their regular regimen of CSA. After a 27-day washout phase, patients were crossed over to the other SJW treatment for 14 days. Blood concentrations of CSA were measured by immunoassay. RESULTS: The study showed a significant difference between the effects of the 2 SJW preparations on CSA pharmacokinetics (area under the plasma concentration-time curve within one dosing interval [AUC 0-12 ], P < .0001, ANOVA). AUC 0-12 values (monoclonal) with high-HYF SJW comedication were 45% lower (95% confidence interval [CI], -37% to -54%; P < .05, Student-Newman-Keuls test) than for low-HYF SJW. The dose-corrected AUC 0-12 for CSA (monoclonal) decreased significantly compared with baseline by 52% (95% CI, -46% to -56%; P < .05) after 2 weeks of comedication with high-HYF SJW. Values of peak concentration in plasma and drug concentration at the end of one dosing interval were affected to a similar extent, with reductions by 43% (95% CI, -36% to -48%) and 55% (95% CI, -48% to -60%), respectively. In addition, a 65% (95% CI, 53% to 85%; P < .05) increase in daily CSA doses was required during high-HYF SJW treatment. In contrast, coadministration of low-HYF SJW did not significantly affect CSA pharmacokinetics and did not require CSA dose adjustments compared with baseline. CONCLUSION: HYF content of SJW extracts significantly affects the extent of the pharmacokinetic interaction between CSA and SJW.

Modulation of steady-state kinetics of digoxin by haplotypes of the P-glycoprotein MDR1 gene.

OBJECTIVE: We investigated the effect of polymorphisms in the P-glycoprotein (P-gp) MDR1 gene on steady-state pharmacokinetics of digoxin in Caucasians. According to earlier data, homozygous TT of the exon 26 complementary deoxyribonucleic acid (cDNA) 3435C>T polymorphism was associated with low P-gp expression in the human intestine. METHODS: Eight healthy male homozygous carriers of the wild-type exon-26 3435C>T (CC), 8 heterozygous subjects (CT), and 8 homozygous mutant (TT) subjects were selected. Seven further MDR1 polymorphisms were determined. Digoxin was administered orally twice daily on the first two study days; on days 3 to 5, 0.25 mg was given in the morning. On day 5, kinetic parameters were analyzed for genotype-phenotype and haplotype-phenotype relationships. RESULTS: The area under the plasma concentration-time curve from time zero to 4 hours [AUC(0-4)] (P =.042) and C(max) (P =.043) values of digoxin were higher in subjects with the 3435TT genotype than in those with the 3435CC. No influence of other single nucleotide polymorphisms (SNPs) on digoxin parameters was detected. Comparison of genotypes deduced from SNPs 2677G>T (exon 21) and 3435C>T revealed significant differences for AUC(0-4) (P =.034) and C(max) (P =.039), which were substantiated by haplotype analysis. Haplotype 12 (2677G/3435T), which had a frequency of 13.3% in a randomly drawn Caucasian sample (n = 687), was associated (Mann-Whitney test) with higher AUC(0-4) values (P =.009) than were found in noncarriers (mean +/- SD, 5.7 +/- 0.9 microg. h/L [n = 7] versus 4.8 +/- 0.9 microg. h/L [n = 17]). Haplotype 11 (2677G/3435C) had lower AUC(0-4) values (P =.013) compared with those of noncarriers (mean +/- SD, 4.7 +/- 0.9 microg. h/L [n = 16] versus 5.6 +/- 0.9 microg. h/L [n = 8]). Results of haplotype analysis match data of other MDR1 studies. CONCLUSION: Haplotype 12 codes for high values of AUC(0-4) and C(max) of orally administered digoxin. Analysis of MDR1 haplotypes is superior to unphased SNP analysis to predict MDR1 phenotype.

MDR1 haplotypes do not affect the steady-state pharmacokinetics of cyclosporine in renal transplant patients.

This retrospective study investigated the impact of MDR1 haplotypes derived from the single-nucleotide polymorphisms (SNPs) 2677G>T (exon 21) and 3435C>T (exon 26) on the pharmacokinetics of cyclosporine in 98 renal transplant patients. Based on SNPs 2677 and 3435, four different haplotypes and nine different genotypes were identified in the study sample. Frequencies of SNPs, genotypes, and haplotypes were in agreement with previously reported values. Cyclosporine pharmacokinetics were characterized using a 2-hour AUC (AUC0-12), trough concentrations (C0), and blood concentrations 2 hours after cyclosporine administration (C2). No significant differences in dose-corrected AUC0-12, C0, or C2 values were observed between carriers of different SNP variants and genotypes (Kruskal-Wallis test), as well as between carriers and noncarriers of each haplotype (Mann-Whitney U test). Carriers of haplotype 12 (2677G and 3435T), which has previously been associated with increased digoxin AUC values, had a median AUC0-12 of 18.9 micro g*h*L-1 (range: 9.0-35.2) compared to 17.5 micro g*h*L-1 (range: 7.5-37.1) in the noncarrier group. It was concluded that MDR1 haplotypes derived from the SNPs 2677G>T (exon 21) and 3435C>T (exon 26) are not associated with cyclosporine pharmacokinetics in renal transplant patients.

Limitations of C2 monitoring in renal transplant recipients.

BACKGROUND: Recent developments have proposed the cyclosporin (CsA) concentration at 2 h post-dose (C(2)) as the best single time-point predictor of the extent of CsA exposure and as the optimal basis for monitoring immunosuppressive therapy in renal transplant patients. The present study sought to validate the cornerstones of the current concept of C(2) monitoring. METHODS: We assessed the predictive value, dose proportionality and intrapatient variability of C(2) levels in 41 de novo renal transplant recipients treated with CsA microemulsion, steroids, mycophenolate sodium and basiliximab. RESULTS: Patients with rejection and patients with CsA nephrotoxicity had lower C(2) (P = NS) and absorption (P<0.05 for toxicity), while C(0) did not show any significant difference. Receiver operating characteristic analysis did not detect discriminative C(2) values as a predictor of rejection or toxicity. In a substantial number of patients (29%) we observed poor and/or slow absorption, with C(0) >300 ng/ml and C(2) levels <800 ng/ml during the first month and a high rate of complications in these patients (18% rejection, 64% toxicity). Absorption increased over the first month post-transplant. Analysis of dose changes indicated that C(2) levels are not dose-proportional. Intrapatient variability of C(2) was as high as that of C(0). CONCLUSIONS: C(2) levels do not predict rejection or toxicity. C(2) monitoring alone does not detect toxicity in poor and/or slow absorbers, who constitute a significant proportion of patients. Changes in absorption over time, high intrapatient variability and lack of dose proportionality constitute further limitations of the C(2) monitoring concept in the early post-transplant phase.

Impact of St John's wort treatment on the pharmacokinetics of tacrolimus and mycophenolic acid in renal transplant patients.

BACKGROUND: This study investigated the effect of St John's wort (SJW) extract on the pharmacokinetics of the immunosuppressants tacrolimus (TAC) and mycophenolic acid (MPA). METHODS: Ten stable renal transplant patients received 600 mg SJW extract for 14 days in addition to their regular regimen of TAC and mycophenolate mofetil. RESULTS: Dose-corrected AUC((0-12)) of TAC decreased significantly from 180 ng/ml/h at baseline to 75.9 ng/ml/h after 2 weeks of SJW treatment. To maintain therapeutic TAC concentrations, dose adjustments from a median 4.5 mg/day at baseline to 8.0 mg/day under SJW treatment were required. Two weeks after discontinuation of SJW, TAC doses were reduced to a median of 6.5 mg/day. MPA pharmacokinetics remained unaffected by comedication with hypericum extract. CONCLUSIONS: Administration of SJW extract to patients receiving TAC treatment can result in a serious drug interaction leading to markedly reduced TAC blood concentrations associated with the risk of organ rejection.

Pharmacokinetics of mycophenolate mofetil for autoimmune disease in children.

This study describes the pharmacokinetics of mycophenolate mofetil (MMF) in 15 pediatric patients with vasculitis and connective tissue disease involving the kidney. Patients included 10 with systemic lupus erythematosus (SLE), 1 with antiphospholipid antibody syndrome, 2 with Wegener granulomatosis, and 1 each with Goodpasture syndrome, Henoch-Schönlein-associated nephritis, and 1 with severe tubulointerstitial nephritis and uveitis. All patients were treated with steroids and additional therapy prior to treatment with MMF, which was administered for a median of 491 days. Mean starting dose of MMF was 974+/-282 mg/m(2 )in two divided doses. Pharmacokinetic monitoring of the active compound of MMF, mycophenolic acid (MPA), was performed using an EMIT assay. The mean MPA AUC after a median of 39 days was 61.8+/-31.0 micro gxh/ml, median time to maximum concentration was 60 min, and mean maximum concentration was 18.5+/-8.4 micro g/ml. At last follow-up, mean MMF dose was 900+/-341 mg/m(2) per day, and mean trough MPA concentration was 3.1+/-1.1 (range 0.6-4.6) micro g/ml. Therapy was effective in inducing remission in 4 of 9 patients with active disease. Only 1 of the 5 other patients relapsed. All 6 patients with controlled disease maintained remission. There were few side effects: one episode each of diarrhea and leukocytopenia and two viral infections. We conclude that MMF at 900 mg/m(2) per day appears to be effective in these patients.

MDR1 haplotypes derived from exons 21 and 26 do not affect the steady-state pharmacokinetics of tacrolimus in renal transplant patients.

AIM: This retrospective study investigated the influence of MDR1 haplotypes derived from the polymorphisms 2677G > T (exon 21) and 3435C > T (exon 26) on the pharmacokinetics of the immunosuppressant drug tacrolimus in 73 renal transplant patients. METHODS: Based on both variants of SNPs 2677 and 3435, four different haplotypes and eight different genotypes were identified in the study sample. Tacrolimus trough concentrations (C(0)) were compared between different SNP variants and genotypes, as well as between carriers and noncarriers of each haplotype. Additionally, CYP3A5 genotype (6956G > A) was determined. RESULTS: No significant differences were observed between groups. Differences in mean tacrolimus C(0) values between carriers and noncarriers of each haplotype ranged from -0.04 microg/litre (95% confidence interval: -0.53 to 0.60) to -23 microg/litre (-1.07 to 1.53). No association was found between CYP3A5*1/*3 genotype and tacrolimus Co concentractions. CONCLUSION: MDR1 haplotypes derived from the SNPs 2677G > T (exon 21) and 3435C > T (exon 26) do not influence the pharmacokinetics of tacrolimus in renal transplant patients.

Impact of cytochrome P-450 inhibition by cimetidine and induction by carbamazepine on the kinetics of hypericin and pseudohypericin in healthy volunteers.

This study evaluated the influence of cimetidine and carbamazepine on the pharmacokinetics of the St. John's wort (SJW) ingredients hypericin and pseudohypericin. In a placebo-controlled, double blind study, 33 healthy volunteers were randomized into three treatment groups that received SJW extract (LI160) with different comedications (placebo, cimetidine, and carbamazepine) for 7 days after a run-in period of 11 days with SJW alone. Hypericin and pseudohypericin pharmacokinetics were measured on days 10 and 17. Between-group comparisons showed no statistically significant differences in AUC(0-24), C(max), and t(max) values for hypericin and pseudohypericin. Within-group comparisons, however, revealed a statistically significant increase in hypericin AUC(0-24) from a median of 119 (range 82-163 microg h/l) to 149 microg h/l (61-202 microg h/l) with cimetidine comedication and a decrease in pseudohypericin AUC(0-24) from a median of 51.0 (16.4-102.9 microg h/l) to 36.4 microg h/l (14.0-102.0 microg h/l) with carbamazepine comedication compared to the baseline pharmacokinetics in each group. Hypericin and pseudohypericin pharmacokinetics were only marginally influenced by comedication with the enzyme inhibitors and inducers cimetidine and carbamazepine.

Alterations in cyclosporin A pharmacokinetics and metabolism during treatment with St John's wort in renal transplant patients.

AIM: This study investigated the effects of St John's wort extract (SJW) on the pharmacokinetics and metabolism of the immunosuppressant cyclosporin A (CSA). METHODS: In an open-label study, 11 renal transplant patients received 600 mg SJW extract daily for 14 days in addition to their regular regimen of CSA. Blood concentrations of CSA and its metabolites AM1, AM1C, AM9, AM19, and AM4N were measured by HPLC. RESULTS: After 2 weeks of SJW coadministration, dose-corrected AUC0-12, Cmax and Ctrough values for CSA decreased significantly by 46%[geometric mean ratio baseline/SJW (95% CI): 1.83 (1.63-2.05)], 42%[1.72 (1.42-2.08)], and 41%[1.70 (1.17-2.47)], respectively. CSA doses were increased from a median of 2.7 mg day(-1) kg(-1) at baseline to 4.2 mg day(-1) kg(-1) at day 15, with the first dose adjustment required only 3 days after initiation of SJW treatment. Additionally, the metabolite pattern of CSA was substantially altered during SJW treatment. Whereas dose-corrected AUC values for AM1, AM1c and AM4N significantly decreased by 59%, 61%, and 23% compared with baseline, AUC values for AM9 and AM19 were unchanged. Following the increase in CSA dose, observed AUC and Cmax values for AM9, AM19, and AM4N increased by 20-51% and 43-90%, respectively. CONCLUSION: Administration of SJW extract to patients receiving CSA treatment resulted in a rapid and significant reduction of plasma CSA concentrations. Additionally, the substantial alterations in CSA metabolite kinetics observed may affect the toxicity profile of the drug.

The value of C2 monitoring in stable renal allograft recipients on maintenance immunosuppression.

BACKGROUND: Cyclosporin A (CyA) is a drug with a narrow therapeutic window and highly variable pharmacokinetics. Therapeutic drug monitoring is essential and conventionally has been guided by trough levels (C0). Recent evidence indicates that a single blood concentration measurement 2 h after CyA administration (C2) is a more accurate predictor of drug exposure and clinical events than determination of C0. To date, limited prospective data are available with respect to risks and benefits of C2 monitoring in renal transplant recipients, and little experience exists with C2 monitoring in maintenance patients. METHODS: In 127 long-term renal allograft recipients, we determined C2 levels in addition to conventional C0 and observed clinical outcome over a period of 13.6 +/- 3.1 months. To determine the precision of monitoring, we repeatedly determined C0 and C2 levels in 46 stable patients without dose change. RESULTS: Clinical outcome was excellent (patient survival 100%, graft survival 97%), with only two borderline rejections, although C2 levels (564 +/- 186 ng/ml) were lower than recommended so far for maintenance patients. We found no significant differences in C2 levels between patients with rejection and CyA toxicity. Receiver operating characteristic (ROC) analysis showed no prediction for risk of rejection, toxicity or infection by C2 levels. Repeated determinations of both C0 and C2 levels in 46 patients revealed a high intra-patient variability. In these patients, the coefficient of variation for C2 was only marginally better compared with C0. CONCLUSIONS: We conclude that in maintenance patients, C2 concentrations between 500 and 600 ng/ml are well tolerated and provide effective and safe rejection prophylaxis. Although mean C2 levels do not seem to be helpful in identifying patients at risk for rejection, they may be useful to detect over-immunosuppression and to improve long-term allograft survival further by reducing CyA nephrotoxicity.

The effect of sevelamer on the pharmacokinetics of cyclosporin A and mycophenolate mofetil after renal transplantation.

BACKGROUND: After renal transplantation, patients with insufficient graft function may require phosphate binders. It is still unknown if sevelamer, a new calcium-free phosphate binder, interferes with the uptake of immunosuppressants. We studied its effects on the pharmacokinetics of cyclosporin A (CsA) and mycophenolate mofetil. METHODS: We examined 10 adults and eight children with stable renal graft function and stable CsA trough levels. A 12 h pharmacokinetic profile (10 observation points) was conducted without sevelamer, after a single dose and after 4 days of treatment with it. CsA levels were measured with both a monoclonal antibody assay (CEDIA) and a polyclonal antibody assay (FPIA), mycophenolic acid (MPA) levels by EMIT assay and CsA metabolites AM1, AM9 and AM4N by a modified HPLC method. RESULTS: Sevelamer had no significant effect on CsA kinetics [area under the curve (AUC), peak concentration (C(max)), time of C(max)]. The AUC of AM1 was decreased by 30% and C(max) by 25% after 4 days of sevelamer intake. MPA levels were significantly reduced by a mean of 25% of the AUC (P<0.05) and by 30% of the C(max) after a single dose of sevelamer. CONCLUSIONS: A single sevelamer dose reduces the C(max) and the AUC of MPA. Its intake for several days does not significantly influence CsA kinetics.

Antiepileptic drugs and apoptotic neurodegeneration in the developing brain.

Epilepsy is the most common neurological disorder of young humans. Each year 150,000 children in the United States experience their first seizure. Antiepileptic drugs (AEDs), used to treat seizures in children, infants, and pregnant women, cause cognitive impairment, microcephaly, and birth defects. The cause of unwanted effects of therapy with AEDs is unknown. Here we reveal that phenytoin, phenobarbital, diazepam, clonazepam, vigabatrin, and valproate cause apoptotic neurodegeneration in the developing rat brain at plasma concentrations relevant for seizure control in humans. Neuronal death is associated with reduced expression of neurotrophins and decreased concentrations of survival-promoting proteins in the brain. beta-Estradiol, which stimulates pathways that are activated by neurotrophins, ameliorates AED-induced apoptotic neurodegeneration. Our findings present one possible mechanism to explain cognitive impairment and reduced brain mass associated with prenatal or postnatal exposure of humans to antiepileptic therapy.