Drug discovery programs are actively exploring for therapeutic agents targeting enzymes and receptors regulating sphingolipid metabolism and biologic functions. FTY720 is a close structural analogue of sphingosine with immunomodulatory properties. After oral administration, FTY720 is phosphorylated by sphingosine kinase to form the active moiety FTY720-phosphate, which subsequently binds to the sphingosine-1-phosphate receptor. In characterizing the safety and pharmacological effects of FTY720, detailed clinical pharmacology studies in healthy subjects and renal transplant recipients have focused on cardiac responses and lymphocyte trafficking. After the first dose, FTY720 causes a mild, transient decrease in heart rate that returns to baseline in approximately 1 to 2 weeks despite continued administration of the drug. FTY720 elicits a prompt and dose-dependent decrease in peripheral blood lymphocytes by redirecting them from the circulation to the lymph nodes without impairing lymphocyte functions. An association among FTY720 blood concentration, decrease in lymphocyte counts, and freedom from acute rejection episodes has been observed in early clinical development trials in de novo kidney transplantation.

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Objective To evaluate the efficacy and safety of 2 canakinumab monotherapy tapering regimens in order to maintain complete clinical remission in children with systemic juvenile idiopathic arthritis (JIA). Methods The study was designed as a 2‐part phase IIIb/IV open‐label, randomized trial. In the first part, patients received 4 mg/kg of canakinumab subcutaneously every 4 weeks and discontinued glucocorticoids and/or methotrexate as appropriate. Patients in whom clinical remission was achieved (inactive disease for at least 24 weeks) with canakinumab monotherapy were entered into the second part of the trial, in which they were randomized 1:1 into 1 of 2 treatment arms. In arm 1, the dose of canakinumab was reduced from 4 mg/kg to 2 mg/kg and then to 1 mg/kg, followed by discontinuation. In arm 2, the 4 mg/kg dose interval was prolonged from every 4 weeks, to every 8 weeks, and then to every 12 weeks, followed by discontinuation. In both arms, canakinumab exposure could be reduced provided systemic JIA remained in clinical remission for 24 weeks with each step. The primary objective was to assess whether >40% of randomized patients in either arm maintained clinical remission of systemic JIA for 24 weeks in the first part of the study. Results In part 1 of the study, 182 patients were enrolled, with 75 of those patients randomized before entering part 2 of the trial. Among the 75 randomized patients, clinical remission was maintained for 24 weeks in 27 (71%) of 38 patients in arm 1 (2 mg/kg every 4 weeks) and 31 (84%) of 37 patients in arm 2 (4 mg/kg every 8 weeks) (P ≤ 0.0001 for arm 1 versus arm 2 among those meeting the 40% threshold). Overall, 25 (33%) of 75 patients discontinued canakinumab, and clinical remission was maintained for at least 24 weeks in all 25 of these patients. No new safety signals were identified. Conclusion Reduction of canakinumab exposure may be feasible in patients who have achieved clinical remission of systemic JIA, but consistent interleukin‐1 inhibition appears necessary to maintain this response.

Treatment of elevated serum phosphorus in hemodialysis patients remains challenging due in part to the lack of a well-tolerated, safe, and effective phosphate binder. Here we report the results of a single-center, open-label, phase I clinical trial of 44 hemodialysis patients to show the safety and efficacy of a novel iron-based phosphate binder, SBR759. After establishing its safety at an initial dose of 3.75 g/day, SBR759 was given to successive cohorts in several divided doses of up to 22.5 g/day. The defined measure of efficacy was the average change in serum phosphorus in the cohorts receiving 11.25 and 15.0 g/day, in whom the mean reduction was 2.1 mg/dl. A clinically and statistically significant reduction in serum phosphorus was found across the entire dose range. All patients were able to achieve mean phosphorus levels within K/DOQI target ranges at the end of the first week. SBR759 was well tolerated within the anticipated clinical dose range of 3.75-15 g/day. No treatment-related serious adverse events were observed nor were there clinically relevant changes in iron indices. While these preliminary studies highlight the clinical efficiency and safety of SBR759, its promise of improved therapeutic options for hyperphosphatemia in patients with chronic kidney disease requires further study.

WHAT IS KNOWN ABOUT THIS SUBJECT• Clinical pharmacology and clinical therapeutic studies of fingolimod demonstrate that heart rate after the initial dose decreases by about 10-20% while normal circadian rhythm is preserved. With continued daily dosing, heart rate returns to normal over the next 2 weeks. • This negative chronotropic effect is consistent with the binding of fingolimod-phosphate to the sphingosine-1-phosphate receptor on atrial myocytes. WHAT THIS STUDY ADDS• The present clinical pharmacology study demonstrates that atropine administered at usual therapeutic doses can prevent the decrease in heart rate when given concomitantly with fingolimod and can counteract the decrease in heart rate when give at the time of the typical heart rate nadir, 4 h after the fingolimod dose.• Although therapeutic intervention is rarely needed for reduced heart rate in patients receiving fingolimod, atropine is an option, should this be desired. AIMSThe authors determined whether intravenous atropine can prevent or counteract the negative chronotropic effect of the immunomodulator fingolimod. METHODSIn this randomized, placebo-controlled, two-period, crossover study, 12 healthy subjects received 5 mg fingolimod orally concurrently with intravenous atropine (titrated to a heart rate of 110-120 beats min -1 ) or intravenous placebo. A second group of 12 subjects received atropine/placebo 4 h after the fingolimod dose. Continuous telemetry measurements were made for 24 h after each fingolimod dose. RESULTSFingolimod administration alone yielded a heart rate nadir of 51 Ϯ 5 beats min -1 at a median 4 h postdose with heart rate remaining depressed at 51-64 beats min -1 over the rest of the day. Concurrent administration of fingolimod and atropine yielded a nadir of 66 Ϯ 6 beats min -1 resulting in an atropine : placebo ratio (90% confidence interval) of 1.30 (1.22, 1.36). When atropine was administered at the time of the nadir, it was able to reverse the negative chronotropic effect of fingolimod from a heart rate of 56 Ϯ 9 beats min -1 (placebo) to 64 Ϯ 8 beats min -1 (atropine) resulting in an atropine : placebo ratio of 1.15 (1.04, 1.26). Atropine had no influence on the pharmacokinetics of fingolimod. CONCLUSIONSAtropine administered concurrently with fingolimod prevented the heart rate nadir that typically occurs 4 h postdose. Atropine administered at the time of the heart rate nadir was able to reverse the negative chronotropic effect of fingolimod.

We present precise iron stable isotope ratios measured by multicollector-ICP mass spectrometry (MC-ICP-MS) of human red blood cells (erythrocytes) and blood plasma from 12 healthy male adults taken during a clinical study. The accurate determination of stable isotope ratios in plasma first required substantial method development work, as minor iron amounts in plasma had to be separated from a large organic matrix prior to mass-spectrometric analysis to avoid spectroscopic interferences and shifts in the mass spectrometer's mass-bias. The (56)Fe/(54)Fe ratio in erythrocytes, expressed as permil difference from the "IRMM-014" iron reference standard (δ(56/54)Fe), ranges from -3.1‰ to -2.2‰, a range typical for male Caucasian adults. The individual subject erythrocyte iron isotope composition can be regarded as uniform over the 21 days investigated, as variations (±0.059 to ±0.15‰) are mostly within the analytical precision of reference materials. In plasma, δ(56/54)Fe values measured in two different laboratories range from -3.0‰ to -2.0‰, and are on average 0.24‰ higher than those in erythrocytes. However, this difference is barely resolvable within one standard deviation of the differences (0.22‰). Taking into account the possible contamination due to hemolysis (iron concentrations are only 0.4 to 2 ppm in plasma compared to approx. 480 ppm in erythrocytes), we model the pure plasma δ(56/54)Fe to be on average 0.4‰ higher than that in erythrocytes. Hence, the plasma iron isotope signature lies between that of the liver and that of erythrocytes. This difference can be explained by redox processes involved during cycling of iron between transferrin and ferritin.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT?• Sotrastaurin is an investigational protein kinase C inhibitor. This represents a new mechanism of action for immunosuppression to prevent acute rejection after organ transplantation. In vitro experiments indicate that sotrastaurin is a substrate of CYP3A4. WHAT THIS STUDY ADDS• This study provides clinical pharmacokinetic information to quantify the effect of the strong CYP3A4 inhibitor ketoconazole on sotrastaurin. The susceptibility of sotrastaurin to CYP3A4-related drug interactions is placed in the context of similar information about calcineurin inhibitors (tacrolimus, ciclosporin) and T-cell proliferation inhibitors (everolimus, sirolimus). AIMSSotrastaurin is an immunosuppressant that reduces T-lymphocyte activation via protein kinase C inhibition. The effect of CYP3A4 inhibition by ketoconazole on the pharmacokinetics of sotrastaurin, a CYP3A4 substrate, was investigated. METHODSThis was a two-period, single-sequence crossover study in 18 healthy subjects. They received a single 50 mg oral dose of sotrastaurin in period 1 followed by a 14-day inter-treatment phase. In period 2 they received ketoconazole 200 mg twice daily for 6 days and a single 50 mg dose of sotrastaurin on the fourth day of ketoconazole administration. RESULTSCo-administration of single-dose sotrastaurin during steady-state ketoconazole increased sotrastaurin Cmax by 2.5-fold (90% confidence interval 2.2, 2.9) from 285 Ϯ 128 to 678 Ϯ 189 ng ml -1 and increased AUC by 4.6-fold (4.1, 5.2) from 1666 Ϯ 808 to 7378 Ϯ 3011 ng ml -1 h. Sotrastaurin half-life was nearly doubled from 5.9 Ϯ 1.7 to 10.6 Ϯ 2.5 h. The AUC of the active metabolite N-desmethyl-sotrastaurin was increased by 6.8-fold. Sotrastaurin did not alter ketoconazole steady-state predose plasma concentrations. CONCLUSIONSThe strong CYP3A4 inhibitor ketoconazole increased sotrastaurin AUC by 4.6-fold. A compensatory reduction in the dose of sotrastaurin is warranted when strong CYP3A4 inhibitors are co-administered.

P>Sotrastaurin is a protein kinase C inhibitor in development for prevention of rejection after liver transplantation. In a pharmacokinetic study, 13 de novo liver transplant recipients received 100 mg sotrastaurin once between days 1-3 and once between days 5-8 post-transplant. Sotrastaurin absorption based on the area under the concentration-time curve (AUC) of total drug in blood (3544 +/- 1434 ng center dot h/ml) was similar to that of healthy subjects in a previous study (4531 +/- 1650 ng center dot h/ml). However, the sotrastaurin binding protein, alpha 1-acid glycoprotein, was nominally higher in patients (1.07 +/- 0.28 vs. 0.87 +/- 0.16 g/l, P = 0.13) yielding a 60% lower AUC based on free drug versus that in healthy subjects (27 +/- 13 vs. 62 +/- 15 ng center dot h/ml, P < 0.0001). There was minor excretion of sotrastaurin in drained bile (1% of dose) consistent with the fact that sotrastaurin is extensively metabolized leaving little unchanged drug to excrete. In the first week after liver transplantation, sotrastaurin is bioavailable after oral administration. However, patients with elevated alpha 1-acid glycoprotein levels may have lower free drug concentrations. Whether a higher dose of sotrastaurin is needed to compensate for this in the short-term after surgery will be addressed in future clinical trials