Effect of gemfibrozil and rifampicin on the pharmacokinetics of selexipag and its active metabolite in healthy subjects.

AIMS: Based on in vitro data, there is evidence to suggest that cytochrome P450 (CYP) 2C8 is involved in the metabolism of selexipag and its active metabolite, ACT-333679. The present study evaluated the possible pharmacokinetic interactions of selexipag with gemfibrozil, a strong CYP2C8 inhibitor, and rifampicin, an inducer of CYP2C8. METHODS: The study consisted of two independent parts, each conducted according to an open-label, randomized, crossover design. The pharmacokinetics and safety of selexipag and ACT-333679 were studied following single-dose administration either alone or in the presence of multiple-dose gemfibrozil (part I) or rifampicin (part II) in healthy male subjects. RESULTS: Gemfibrozil had comparatively small effects on selexipag (less than 2-fold difference in any pharmacokinetic variable) but, with respect to ACT-333679, increased the maximum plasma concentration (Cmax ) 3.6-fold [90% confidence interval (CI) 3.1, 4.3] and the area under the plasma concentration-time curve from zero to infinity (AUC0-∞ ) 11.1-fold (90% CI 9.2, 13.4). The marked increased exposure to ACT-333679, which mediates the majority of the pharmacological activity of selexipag, was accompanied by significantly more adverse events such as headache, nausea and vomiting. Coadministration of rifampicin increased the Cmax of selexipag 1.8-fold (90% CI 1.4, 2.2) and its AUC0-∞ 1.3-fold (90% CI 1.1, 1.4); its effects on ACT-333679 were to increase its Cmax 1.3-fold (90% CI 1.1, 1.6), shorten its half-life by 63% and reduce its AUC0-∞ by half (90% CI 0.45, 0.59). CONCLUSION: Concomitant administration of selexipag and strong inhibitors of CYP2C8 must be avoided, whereas when coadministered with inducers of CYP2C8, dose adjustments of selexipag should be envisaged.

A pharmacokinetic drug-drug interaction study between selexipag and midazolam, a CYP3A4 substrate, in healthy male subjects.

PURPOSE: In vitro data showed that selexipag and its active metabolite (ACT-333679) have an inductive effect on CYP3A4, CYP2B6, and CYP2C9 at concentrations approximately 100-fold higher than the maximum plasma concentration (C max) measured under steady-state conditions. In order to confirm in vivo the lack of induction at the enterocyte level, we assessed the effect of selexipag on midazolam, a substrate of hepatic and intestinal CYP3A4. METHODS: This study was conducted according to an open-label, randomized, two-way crossover design. A total of 20 subjects received a single oral dose of 7.5 mg midazolam alone (treatment A) or on top of steady-state selexipag (treatment B). Selexipag was administered twice daily using an up-titration scheme consisting of three steps: 400, 600, 1000, and 1600 µg with increments every fourth day. A 24-h pharmacokinetic profile was performed following midazolam administration, and bioequivalence criteria were investigated on an exploratory basis. RESULTS: The C max of midazolam and 1-hydroxymidazolam was decreased by approximately 20 and 14%, respectively, following treatment B compared to A. The time to reach C max for midazolam and 1-hydroxymidazolam was similar between treatments. The terminal half-life was reduced in treatment B compared to A for both midazolam (16%) and 1-hydroxymidazolam (20%). Exposure (area under the curve) to midazolam and 1-hydroxymidazolam was similar between treatments, and the 90% confidence intervals of geometric mean ratios were within the bioequivalence interval. Treatment with midazolam, selexipag, and the combination was safe and well tolerated. CONCLUSION: Exposure to midazolam and 1-hydroxymidazolam was not affected by treatment with selexipag.

Clinical pharmacology of the dual orexin receptor antagonist ACT-541468 in elderly subjects: Exploration of pharmacokinetics, pharmacodynamics and tolerability following single-dose morning and repeated-dose evening administration.

BACKGROUND: The dual orexin receptor antagonist ACT-541468 showed sedative pharmacodynamic effects during initial clinical testing in adult subjects. The present study explored pharmacokinetics, pharmacodynamics and tolerability in healthy elderly subjects. METHODS: Double-blind, placebo-controlled, randomised, single-ascending dose study in 24 male/female elderly (65-80 years, 5, 15 and 25 mg in the morning, 6/2 active/placebo per group). Additionally, 10 subjects (8/2 active/placebo) received 25 mg for 7 days in the evening. Pharmacokinetics, pharmacodynamics (saccadic peak velocity, adaptive tracking, body sway, visual analogue scales according to Bowdle and Bond and Lader, Karolinska Sleepiness Scale) and tolerability were assessed. In particular, pharmacodynamics results are to be interpreted exploratorily. RESULTS: Absorption was quick with a median time to maximum concentration of ∼ 1.0 h. The mean elimination half-life was 8.5-9.8 h, the area under the curve and the maximum plasma concentration increased proportionally with dose. Following repeated evening administration of 25 mg, minimal accumulation was observed. There were no pharmacodynamic effects at 5 mg. At 15 mg, saccadic peak velocity (degree/s; SD) was reduced (69; 38), while other variables showed no effects. At 25 mg, effects on all objective pharmacodynamic parameters were observed. At 8-12 h post-dose, there were no differences to placebo and no next-day effects on pharmacodynamic variables after evening administration. Elderly subjects reported fewer adverse events compared to adults in previous studies. CONCLUSION: ACT-541468 in elderly subjects was well tolerated and pharmacokinetics and pharmacodynamics are compatible with a drug for the treatment of insomnia. Clinicaltrials.gov: NCT02571855.

Clinical Pharmacology of the Reversible and Potent P2Y12 Receptor Antagonist ACT-246475 After Single Subcutaneous Administration in Healthy Male Subjects.

ACT-246475 is a selective and reversible P2Y12 receptor antagonist inducing inhibition of platelet aggregation (IPA). A randomized, double-blind, placebo-controlled, parallel-design study was performed to investigate the safety, tolerability, pharmacokinetics, and pharmacodynamics of escalating single subcutaneous doses of ACT-246475 (1, 2, 4, 8, 16, or 32 mg) in healthy male subjects (N = 8 per dose, 3:1 active:placebo ratio). Pharmacodynamic effects were assessed based on maximum platelet aggregation and P2Y12 reaction units using light transmission aggregometry and VerifyNow® assays, respectively. ACT-246475 was safe and well tolerated up to 32 mg based on adverse event data and absence of clinically relevant changes in hematology, biochemistry, vital signs, and electrocardiogram variables. Median time to reach maximum plasma concentration was 0.5-0.75 hours, and geometric mean terminal half-life ranged from 1.3 to 9.2 hours across the tested dose range. Exposure to ACT-246475 was dose proportional across all dose groups. The maximal %IPA was reached within 30 minutes after subcutaneous administration of ACT-246475. A dose-dependent duration and extent of effect were observed based on area under the effect curve and maximum effect data. Similar results were observed for maximum platelet aggregation and P2Y12 reaction units. The %IPA was ≥85% at doses ≥2 mg. This level of %IPA was extended to at least 12 hours in the 32-mg dose group. The safety and pharmacokinetic/pharmacokinetic profile with quick onset and adequate duration of IPA support further investigation in patients with coronary artery disease.

Biocomparison Study of Adult and Paediatric Dose Strengths of the Prostacyclin Receptor Agonist Selexipag.

BACKGROUND AND OBJECTIVES: Selexipag is an oral, non-prostanoid, selective prostacyclin receptor agonist recently marketed for the treatment of pulmonary arterial hypertension (PAH) in adults. Selexipag may also be an effective treatment in children with PAH. The aim of this study was to compare the pharmacokinetics of selexipag and its active metabolite ACT-333679 following single oral administration of one tablet of 200 µg selexipag (Treatment A) vs. 4 paediatric tablets of 50 µg (Treatment B) in healthy adult male subjects. METHODS: This was an open-label, randomized, two-treatment, two-period, crossover biocomparison study. Bioequivalence criteria were explored and safety variables (vital signs, electrocardiogram, and laboratory parameters) were assessed. RESULTS: The exploratory analysis showed that the 90% confidence intervals of geometric mean ratio (Treatment B/Treatment A) for maximum plasma concentration (C max), area under the plasma concentration-time curve from zero to infinity (AUC0-∞) of ACT-333679, as well as AUC0-∞ of selexipag, were within the bioequivalence interval (0.80, 1.25). In addition, no relevant difference in C max for selexipag between the two treatments can be concluded. Single oral dose administration of 200 µg selexipag as one tablet of 200 µg or four tablets of 50 µg was well tolerated. CONCLUSIONS: Pharmacokinetic characteristics of selexipag and its metabolite ACT-333679 following administration of one adult tablet of 200 µg selexipag and four paediatric tablets of 50 µg selexipag were comparable. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02745860.

Absolute Bioavailability of Ponesimod, a Selective S1P1 Receptor Modulator, in Healthy Male Subjects.

BACKGROUND AND OBJECTIVES: The pharmacokinetic profile of ponesimod, a sphingosine-1-phosphate receptor 1 modulator, is characterized by a rapid absorption [time to maximum concentration (t max) of 2-4 h] and a terminal half-life (t ½) of 32 h after single-dose administration. The aim of this study was to assess additional pharmacokinetic parameters [absolute bioavailability, total clearance (CL), and volume of distribution (V ss)] in healthy male subjects. METHODS: After ensuring in a pilot phase the full pharmacokinetic profile, safety, and tolerability of a 5-mg intravenous infusion of ponesimod over 3 h (treatment A), the study proceeded to the randomized, two-way crossover, single-dose (treatment A; treatment B: 10 mg oral) main phase. RESULTS: The absolute bioavailability of ponesimod was 83.8 % [90 % confidence interval (CI): 80.2-87.5]. CL and V ss (95 % CI) were 3.8 L/h (3.3-4.3) and 160 L (146.1-174.2), respectively. C max (95 % CI) was 48.5 ng/mL (43.9-53.6) and 61.4 ng/mL (55.3-68.3) after intravenous infusion and oral administration, respectively. The t ½ (95 % CI) following intravenous infusion was 32.9 h (28.5-38.1) and 31.7 h (27.9-36.0) following oral administration. Ponesimod administered by both routes of administration was well tolerated and resulted in transient decreases in lymphocyte count and heart rate. CONCLUSIONS: This study indicates high absolute bioavailability, low CL, and moderate V ss of ponesimod.

Decitabine Treatment of Glioma-Initiating Cells Enhances Immune Recognition and Killing.

Malignant gliomas are aggressive brain tumours with very poor prognosis. The majority of glioma cells are differentiated (glioma-differentiated cells: GDCs), whereas the smaller population (glioma-initiating cells, GICs) is undifferentiated and resistant to conventional therapies. Therefore, to better target this pool of heterogeneous cells, a combination of diverse therapeutic approaches is envisaged. Here we investigated whether the immunosensitising properties of the hypomethylating agent decitabine can be extended to GICs. Using the murine GL261 cell line, we demonstrate that decitabine augments the expression of the death receptor FAS both on GDCs and GICs. Interestingly, it had a higher impact on GICs and correlated with an enhanced sensitivity to FASL-mediated cell death. Moreover, the expression of other critical molecules involved in cognate recognition by cytotoxic T lymphocytes, MHCI and ICAM-1, was upregulated by decitabine treatment. Consequently, T-cell mediated killing of both GDCs and GICs was enhanced, as was T cell proliferation after reactivation. Overall, although GICs are described to resist classical therapies, our study shows that hypomethylating agents have the potential to enhance glioma cell recognition and subsequent destruction by immune cells, regardless of their differentiation status. These results support the development of combinatorial treatment modalities including epigenetic modulation together with immunotherapy in order to treat heterogenous malignancies such as glioblastoma.