Treprostinil palmitil inhibits the hemodynamic and histopathological changes in the pulmonary vasculature and heart in an animal model of pulmonary arterial hypertension.

Treprostinil palmitil (TP) is a long-acting inhaled pulmonary vasodilator prodrug of treprostinil (TRE). In this study, TP was delivered by inhalation (treprostinil palmitil inhalation suspension, TPIS) in a rat Sugen 5416 (Su)/hypoxia (Hx) model of pulmonary arterial hypertension (PAH) to evaluate its effects on hemodynamics, pulmonary vascular remodeling, and cardiac performance and histopathology. Male Sprague-Dawley rats received Su (20 mg/kg, s.c), three weeks of Hx (10% O2) and 5 or 10 weeks of normoxia (Nx). TPIS was given during the 5-10 week Nx period after the Su/Hx challenge. Su/Hx increased the mean pulmonary arterial blood pressure (mPAP) and right heart size (Fulton index), reduced cardiac output (CO), stroke volume (SV) and heart rate (HR), and increased the thickness and muscularization of the pulmonary arteries along with obliteration of small pulmonary vessels. In both the 8- and 13-week experiments, TPIS at inhaled doses ranging from 39.6 to 134.1 µg/kg, QD, dose-dependently improved pulmonary vascular hemodynamics, reduced the increase in right heart size, enhanced cardiac performance, and attenuated most of the histological changes induced by the Su/Hx challenge. The PDE5 inhibitor sildenafil, administered at an oral dose of 50 mg/kg, BID for 10 weeks, was not as effective as TPIS. These results in Su/Hx challenged rats demonstrate that inhaled TPIS may have superior effects to oral sildenafil. We speculate that the improvement of the pathobiology in this PAH model induced by TPIS involves effects on pulmonary vascular remodeling due to the local effects of TRE in the lungs.

Comparison of Pharmacokinetic Profiles of Beraprost Sustained Release in Japanese, Chinese, and Korean Healthy Adult Males.

BACKGROUND AND OBJECTIVES: Beraprost sodium (BPS), an orally administrable prostaglandin I2 derivative, is used for the treatment of chronic arterial occlusion and pulmonary arterial hypertension and has potential efficacy in nephropathy. Beraprost sustained release (beraprost SR) is an oral sustained-release formulation of BPS. To confirm the dose rationale reported in a multi-regional study of nephropathy patients in Asia, this open-label study evaluated ethnic differences in the pharmacokinetic profiles of BPS and its active diastereomer (BPS-314d) after beraprost SR administration among healthy Japanese, Chinese, and Korean adult males. METHODS: Twelve healthy subjects in each ethnic group were enrolled. Subjects received a single oral dose of 120 µg beraprost SR under fasting conditions. RESULTS: The geometric mean ratio (90% confidence interval) of the maximum plasma concentration (Cmax) and area under the plasma concentration-time curve from time 0 to time of the last quantifiable concentration (AUClast) of BPS was 1.12 (0.85-1.48) and 1.40 (1.05-1.86) in Chinese, and 1.18 (0.90-1.55) and 1.18 (0.89-1.58) in Korean compared to Japanese subjects. These differences were not clinically relevant. Similarly, differences in the Cmax and AUClast of BPS-314d were also small among the ethnic groups. Urinary excretion of BPS and BPS-314d was limited in all ethnic groups. Together, these findings indicate that the pharmacokinetics of beraprost SR are not affected by ethnic background. CONCLUSIONS: There were no clinically meaningful ethnic differences in the pharmacokinetics of BPS and BPS-314d following beraprost SR administration among Japanese, Chinese and Korean populations.

Comparative bioavailability of inhaled treprostinil administered as LIQ861 and Tyvaso® in healthy subjects.

INTRODUCTION: Treprostinil is a synthetic prostacyclin analogue approved for inhalation administration to patients with pulmonary arterial hypertension (PAH) via nebulized Tyvaso® inhalation solution. LIQ861 is an inhaled, dry-powder formulation of treprostinil produced using Print® (Particle Replication in Nonwetting Templates) technology, a proprietary process for designing and producing highly uniform drug particles. METHODS: We conducted comparative bioavailability analyses of treprostinil exposure from LIQ861 (79.5 µg capsule [approximate delivered dose of 58.1 µg treprostinil]) compared with Tyvaso® (9 breaths [approximate delivered dose of 54 µg treprostinil]). RESULTS: Treprostinil exposure parameters had least squares geometric mean ratios (LIQ861: Tyvaso®) between 0.9 and 1.0 with 90% confidence intervals contained within 0.8 to 1.25. LIQ861 and Tyvaso® were both well tolerated. DISCUSSION: Results showed comparable bioavailability of treprostinil and similar tolerability for LIQ861 and Tyvaso® administered to healthy adults. CONCLUSIONS: Given the comparable treprostinil bioavailability and similar safety profiles of LIQ861 and Tyvaso®, LIQ861 fulfills a significant unmet need for PAH patients by maximizing the therapeutic benefits of treprostinil by safely delivering doses to the lungs in 1 to 2 breaths using a discreet, convenient, easy-to-use inhaler.

Treprostinil Attains Clinically Therapeutic Concentrations in Neonates with Pulmonary Hypertension on Extracorporeal Membrane Oxygenation Support.

BACKGROUND: TREPROSTINIL IS A PROSTACYCLIN ANALOG USED FOR TREATMENT OF PULMONARY HYPERTENSION (PH) IN ADULTS AND CHILDREN, CURRENTLY AWAITING CLINICAL ASSESSMENT FOR USE IN NEONATES.: OBJECTIVES: WE AIMED TO INVESTIGATE THE USE OF TREPROSTINIL IN NEONATES WITH PH ON EXTRACORPOREAL MEMBRANE OXYGENATION (ECMO) SUPPORT AND MEASURE PLASMA CONCENTRATIONS OF THE DRUG.: METHODS: THIS IS A RETROSPECTIVE CASE-SERIES WITH PROSPECTIVELY COLLECTED BLOOD SAMPLES, CONDUCTED IN A QUATERNARY CARE NEONATAL INTENSIVE CARE UNIT. BRAIN NATRIURETIC PEPTIDE, CARDIAC FUNCTION ON DOPPLER ECHOCARDIOGRAPHY, AND THE OCCURRENCE OF ADVERSE EFFECTS WAS MONITORED. PLASMA CONCENTRATIONS WERE MEASURED USING HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY AND MASS SPECTROMETRY.: RESULTS: FOUR PATIENTS WITH PH REQUIRING ECMO THERAPY WERE STUDIED. TREPROSTINIL DOSES OF 20-58 NG/KG/MIN REACHED CONCENTRATIONS OF 0.99-4.39 NG/ML AND INDUCED CLINICAL IMPROVEMENT. INFUSION OF TREPROSTINIL WAS ASSOCIATED WITH IMPROVED RIGHT VENTRICULAR FUNCTION, REVERSED RIGHT-TO-LEFT SHUNTING THROUGH THE DUCTUS ARTERIOSUS, AND STABLE OR DECREASING NEED FOR VASOPRESSOR SUPPORT. NO ADVERSE EFFECTS WERE OBSERVED: CONCLUSIONS: THIS IS THE FIRST STUDY TO REPORT CLINICALLY THERAPEUTIC TREPROSTINIL CONCENTRATIONS IN CIRCULATING PLASMA AFTER TREPROSTINIL ADMINISTRATION IN NEONATES ON ECMO, WITH ASSOCIATED CLINICAL IMPROVEMENT OF PH AND NO SIGNS OF HEMODYNAMIC INSTABILITY.

Pharmacokinetics of Oral Treprostinil in Children With Pulmonary Arterial Hypertension.

As part of a clinical trial, this study examined the pharmacokinetics (PK) of oral treprostinil (TRE) in children with pulmonary arterial hypertension. The trial consisted of the following 3 cohorts: transition from parenteral (cohort 1) or inhaled (cohort 2) TRE, or de novo addition (cohort 3). Oral TRE was dosed 3 times daily. PK samples were obtained before an oral TRE dose, and at 2, 4, 6, and 8 hours thereafter. The PK parameters were calculated using noncompartmental analysis. Thirty-two children (n = 10 in cohorts 1 and 2, n = 12 in cohort 3) were enrolled; the median age was 12 years (range 7-17 years), and the median weight was 42.2 kg (range 19.3-78 kg). The median oral TRE dose for all subjects was 3.8 mg (5.9, 3.5, and 4.0 mg for cohorts 1, 2, and 3, respectively). The TRE concentration versus time profile demonstrated a peak concentration at a median of 3.8 hours with wide variability. In cohort 1, oral dosing led to higher peak (5.9 ng/mL) and lower trough (1 ng/mL) concentrations than parenteral (peak 5.4 ng/mL and trough 4.2 ng/mL), but a lower mean concentration (3.61 vs. 4.46 ng/mL), likely due to variable metabolism and noncomparable dosing. Both the area under the curve and average concentration were linearly correlated with oral TRE dose and dose normalized to body weight, but not with weight or age alone. In pediatric patients, an increased oral TRE dose or dose frequency may be required to minimize PK variability and achieve greater correlation with parenteral dosing.

Pharmacokinetics and vasodilating effect study of beraprost sodium in healthy volunteers.

Currently beraprost sodium (BPS) is widely proposed to ameliorate the symptoms caused by chronic arterial occlusive disease. The objective of this study is to investigate the BPS pharmacokinetic characteristics, its vasodilating effect and the relationship between plasma concentration vs response effect. 12 healthy Chinese volunteers (6 male, 6 female) were chosen to participate in a single center, random, and open design study. After overnight fasting, BPS (dose = 40µg) was administrated orally to each volunteer. The blood samples were collected at different time points (from 0 to 5 h after administration) and BPS concentration was analyzed by LC-MS/MS method. The vasodilating effect was evaluated by detecting the skin microcirculation blood flow of volunteers' fingers with laser Doppler fluxmetry. The Cmax of BPS was (601.14 ± 214.81) pg/mL, the Tmax was (0.58 ± 0.48) h, and AUC0-t was (1020.41±214.63) pg/mL•h. BPS exhibited significant vasodilating effect since the skin microcirculation blood flow increased definitely at 0.25, 0.5, and 0.75 h (all p<0.05) after drug administration, and a positive correlation was presented between the pharmacokinetics and the vasodilating effect, which would be beneficial for guiding BPS dosage in clinical.

Subcutaneous and Intravenous Treprostinil Pharmacokinetics in Children With Pulmonary Vascular Disease.

This study evaluated the pharmacokinetics of intravenous (IV) and subcutaneous (SC) treprostinil in pediatric patients with pulmonary vascular disease, and compared them with existing adult data from a similar cohort. Blood samples were collected from pediatric patients receiving steady-state IV or SC treprostinil and were assessed for plasma treprostinil concentration using liquid chromatography and tandem mass spectrometry. Forty participants, 15 receiving IV and 25 receiving SC treprostinil, were included in the analysis. Age ranged from 0.1 to 15.6 years. The median dose of treprostinil was 45.5 ng·kg·min with a range of 8-146 ng·kg·min. There was a linear relationship between treprostinil dose and plasma concentration with an R of 0.57. On average, there were higher blood concentrations per given dose of IV treprostinil compared with those per given dose of SC, but the difference was not significant. Compared with adult data, the slope of the pediatric data was similar, but the y-intercept was significantly lower. Additionally, the concentration per dose ratio was significantly higher in adults compared with children. Pediatric patients have significantly lower average blood concentrations of treprostinil per given dose compared with adults, and higher, but not significantly so, blood concentrations when treprostinil is administered IV as compared with SC administration.

Study on bioequivalence of beraprost in healthy volunteers by liquid chromatography with tandem mass spectrometry.

Beraprost sodium is an oral prostacyclin analog that was first approved in 1992 (Japan) for the treatment of peripheral vascular disorders. It is administered orally as a tablet available in strength 20 µg. In this paper, we described a liquid chromatography tandem mass spectrometry method that was developed for the quantification of beraprost in human plasma with high sensitivity at picogram per milliliter concentration. The method had been validated in terms of selectivity, sensitivity, accuracy and precision, matrix effect, linearity, recovery and carry-over according to the Guideline on Bioanalytical Validation from the European Medicines Agency. The standard calibration curve for beraprost was 9.5-1419 pg/mL. This method has been applied successfully to a bioequivalence study with 60 µg of beraprost (three tablets) in 29 healthy volunteers. The results showed that the two formulations of beraprost are bioequivalent.

Inhaled Treprostinil-Prodrug Lipid Nanoparticle Formulations Provide Long-Acting Pulmonary Vasodilation.

Treprostinil (TRE), a prostanoid analogue approved in the USA for the treatment of pulmonary arterial hypertension, requires continuous infusion or multiple dosing sessions per day for inhaled and oral routes of administration due to its short half-life. The inhaled drug is known to induce adverse systemic and local effects including headache, nausea, cough, and throat irritation which may be due at least in part to transiently high drug concentrations in the lungs and plasma immediately following administration [1]. To ameliorate these side effects and reduce dosing frequency we designed an inhaled slow-release TRE formulation. TRE was chemically modified to be an alkyl prodrug (TPD) which was then packaged into a lipid nanoparticle (LNP) carrier. Preclinical screening in a rat model of hypoxia-induced pulmonary vasoconstriction led to selection of a 16-carbon alkyl ester derivative of TRE. The TPD-LNP demonstrated approximately 10-fold lower TRE plasma Cmax compared to inhaled TRE solution while maintaining an extended vasodilatory effect. The favorable PK profile is attributed to gradual dissociation of TPD from the LNP and subsequent conversion to TRE. Together, this sustained presentation of TRE to the lungs and plasma is consistent with a once- or twice-daily dosing schedule in the absence of high Cmax-associated adverse events which could provide patients with an improved treprostinil therapy.

Extended-release oral treprostinil in the management of pulmonary arterial hypertension: clinical evidence and experience.

Treprostinil diolamine is the first oral prostacyclin approved for the treatment of pulmonary arterial hypertension (PAH) to improve exercise capacity. Clinical studies have demonstrated modest benefit as monotherapy, whereas no difference in exercise capacity was observed with combination therapy. However, these trials were limited by subtherapeutic dosing owing to intolerable adverse effects. Prostacyclin-related adverse effects, such as nausea, diarrhea, headache, flushing, and jaw pain, are prevalent. More recent pharmacokinetic and clinical studies illustrate the dose-response relationship and the importance of achieving clinically effective doses. Therefore, efforts to improve tolerability are paramount. Oral treprostinil is recommended to be administered three times daily in order to facilitate more rapid titration, higher doses achieved, and improved tolerability. Oral treprostinil has also been studied in carefully selected, stable patients that transitioned from parenteral or inhaled therapy with close monitoring for late deterioration. Ongoing clinical trials will determine the long-term effects of higher doses of oral treprostinil on clinical outcomes. This review describes the clinical evidence and practical experience with the use of oral treprostinil for PAH.

Therapeutic administration of inhaled INS1009, a treprostinil prodrug formulation, inhibits bleomycin-induced pulmonary fibrosis in rats.

Idiopathic pulmonary fibrosis is a progressive and lethal disease and while there are now two approved drugs (Esbriet® and Ofev®) additional effective treatments are still needed. Recently, prostacyclin analogs such as iloprost and treprostinil (TRE) have been shown to exert some protection against bleomycin-induced pulmonary fibrosis in mice when administered in a prophylactic regimen. In this study, we evaluated the effect of the inhaled treprostinil prodrug hexadecyl-treprostinil (C16TR) formulated in a lipid nanoparticle (INS1009) administered therapeutically in a fibrotic rat model. Male Fischer 344 rats challenged with intra-tracheal saline instillation were then treated with daily inhaled phosphate buffered saline (PBS) while rats challenged with bleomycin sulfate (3.5-4.0 mg/kg) instillation were treated with either daily inhaled PBS, daily inhaled INS1009 (10, 30, or 100 µg/kg), or twice-daily orally with the anti-fibrotic compound pirfenidone (100 mg/kg). Dosing started on day 10 post-bleomycin challenge and continued until day 27 after bleomycin. Lungs were harvested 24 h after the last dose of treatment for evaluation of lung hydroxyproline content and pulmonary histology. Lung hydroxyproline content increased from 421 µg/lung lobe in saline challenged and PBS treated animals to 673 µg/lung lobe in bleomycin challenged and PBS treated rats. Treatment of bleomycin challenged rats with 10, 30, or 100 µg/kg INS1009 dose-dependently reduced lung hydroxyproline content to 563, 501, and 451 µg/lung lobe, respectively, and pirfenidone decreased hydroxyproline content to 522 µg/lung lobe. Histologically, both INS1009 (100 µg/kg) and pirfenidone (100 mg/kg) reduced the severity of subepithelial fibrosis. Single dose pharmacokinetic (PK) studies of inhaled INS1009 in bleomycin challenged rats showed dose-dependent increases in lung C16TR concentration and plasma TRE on day 10 post-bleomycin challenge. Multiple dose PK studies of inhaled INS1009 showed dose-dependent increases only in lung C16TR concentration on day 27 post-bleomycin challenge. We also investigated the effects of TRE on the cytokine transforming growth factor-ß1 (TGF-ß1)-stimulated collagen gene and protein expressions in cultured human lung fibroblasts, assessed by real-time PCR and Sirius Red staining, respectively. In human fibroblasts, TRE (0.001-10 µM) inhibited TGF-ß1 (20 ng/mL)-induced expression of collagen mRNA and protein in a concentration-dependent manner. These results demonstrated that inhaled INS1009, administered in a therapeutic dosing paradigm, dose-dependently (10-100 µg/kg) inhibited bleomycin-induced pulmonary fibrosis in rats. This effect may involve direct actions of TRE in suppressing collagen expression in lung fibroblasts.

Inhaled hexadecyl-treprostinil provides pulmonary vasodilator activity at significantly lower plasma concentrations than infused treprostinil.

INS1009 is a long acting pulmonary vasodilator prodrug of treprostinil (TRE) that is formulated in a lipid nanoparticle for inhaled delivery by nebulization. This study examined the ability of INS1009 to inhibit vasoconstriction in the pulmonary vasculature of rats and dogs and the extent to which local activity within the lung contributes to its activity. Rats received a single dose of INS1009 by nose-only inhalation or were given a continuous intravenous (i.v.) infusion of TRE, followed by an i.v. challenge of the thromboxane mimetic pulmonary vasoconstrictor U46619 and the increase in pulmonary arterial pressure (PAP) was measured. In beagle dogs, INS1009 was given by inhalation via face mask and TRE was given by continuous i.v. infusion; vasoconstriction was then induced by inhaled hypoxia with reduction of FIO2 to 0.10. Changes in the dog's right ventricular pulse pressure (RVPP) were measured using implanted telemetry probes. Blood samples were collected in rats and dogs immediately after the challenge to measure the plasma TRE concentration. Exposure of rats to inhaled INS1009 (0.5, 3.0 and 20.9 µg/kg) inhibited the U46619-induced increase in PAP at all doses up to 6 h with statistically significant inhibition up to 24 h with the pooled dose-response data. The concentration of TRE in the plasma at which PAP was reduced by 50% was approximately 60-fold lower for INS1009 (EC50 = 0.08 ng/mL) as compared to i.v. TRE (EC50 = 4.9 ng/mL). In dogs, INS1009 (2.7-80.9 µg/kg) inhibited the hypoxia-induced increase in RVPP at all doses up to 6 h with activity once again observed with the pooled dose-response of 10 µg/kg and higher at 24 h. The concentration of TRE in the plasma at which RVPP was reduced by 50% was approximately 550-fold lower for INS1009 (EC50 = 0.0075 ng/mL) as compared to i.v. TRE (EC50 = 4.1 ng/mL). These studies, in two species and by two different pulmonary vasoconstrictor challenges, demonstrate that inhaled INS1009 not only has long-acting vasodilatory effects but also that the local activity within the lung contributes to this response. Therefore, INS1009 may offer the opportunity to effect pulmonary vasodilation for long periods but with substantially lower systemic exposure than infused TRE.

Preclinical Pharmacology and Pharmacokinetics of Inhaled Hexadecyl-Treprostinil (C16TR), a Pulmonary Vasodilator Prodrug.

This article describes the preclinical pharmacology and pharmacokinetics (PK) of hexadecyl-treprostinil (C16TR), a prodrug of treprostinil (TRE), formulated in a lipid nanoparticle (LNP) for inhalation as a pulmonary vasodilator. C16TR showed no activity (>10 µM) in receptor binding and enzyme inhibition assays, including binding to prostaglandin E2 receptor 2, prostaglandin D2 receptor 1, prostaglandin I2 receptor, and prostaglandin E2 receptor 4; TRE potently bound to each of these prostanoid receptors. C16TR had no effect (up to 200 nM) on platelet aggregation induced by ADP in rat blood. In hypoxia-challenged rats, inhaled C16TR-LNP produced dose-dependent (0.06-6 µg/kg), sustained pulmonary vasodilation over 3 hours; inhaled TRE (6 µg/kg) was active at earlier times but lost its effect by 3 hours. Single- and multiple-dose PK studies of inhaled C16TR-LNP in rats showed proportionate dose-dependent increases in TRE Cmax and area under the curve (AUC) for both plasma and lung; similar results were observed for dog plasma levels in single-dose PK studies. In both species, inhaled C16TR-LNP yielded prolonged plasma TRE levels and a lower plasma TRE Cmax compared with inhaled TRE. Inhaled C16TR-LNP was well tolerated in rats and dogs; TRE-related side effects included cough, respiratory tract irritation, and emesis and were seen only after high inhaled doses of C16TR-LNP in dogs. In guinea pigs, inhaled TRE (30 µg/ml) consistently produced cough, but C16TR-LNP (30 µg/ml) elicited no effect. These results demonstrate that C16TR-LNP provides long-acting pulmonary vasodilation, is well tolerated in animal studies, and may necessitate less frequent dosing than inhaled TRE with possibly fewer side effects.

Identification of Transporters Involved in Beraprost Sodium Transport In Vitro.

BACKGROUND AND OBJECTIVE: Beraprost sodium (BPS) is a chemically stable and orally active prostacyclin analog that is used in the treatment of chronic arterial occlusive disease since 1992 and primary pulmonary hypertension since 1999 in Japan. Multiple-drug therapy is common in clinical practice, and BPS is co-administered with other drugs. Membrane transporters are known to markedly affect pharmacokinetics, safety and efficacy, and many transporter-based drug-drug interactions have been recently reported. However, information on the transporters involved in the pharmacokinetics of BPS is limited. METHODS: First of all, we have examined 11 transporters, ABCB1 (P-glycoprotein: P-gp), ABCG2 (breast cancer resistance protein: BCRP), SLC22A6 (organic anion transporter 1: OAT1), SLC22A8 (organic anion transporter 3: OAT3), SLCO1B1 (organic anion transporting polypeptide 1B1: OATP1B1), SLCO1B3 (organic anion transporting polypeptide 1B3: OATP1B3), SLCO2B1 (organic anion transporting polypeptide 2B1: OATP2B1), SLC22A1 (organic cation transporter 1: OCT1), SLC22A2 (organic cation transporter 2: OCT2), ABCB11 (bile-salt export pump: BSEP), and ABCC2 (multidrug resistance associated protein 2: MRP2) to clarify which of them would be candidates that might recognize BPS as their substrate in transporter-expressing LLC-PK1, S2, and HEK293 cells as well as in membrane vesicles. Furthermore, we determined whether the transport of BPS was inhibited by the typical inhibitors of each transporter, i.e., verapamil for P-gp, Ko143 for BCRP, probenecid for OAT3, rifampicin for OATP1B1 and OATP1B3, cyclosporine for BSEP, and sulfobromophthalein (BSP) for MRP2. RESULTS: The results obtained showed that P-gp, BCRP, OAT3, OATP1B1, OATP1B3, BSEP and MRP2 might be candidates for BPS transporters. From the further evaluation with the typical inhibitors of each transporter, it was confirmed that BPS is a substrate for P-gp, BCRP, OAT3, OATP1B1, OATP1B3 and MRP2, because the typical inhibitor, cyclosporine, had no effects on BPS transport by BSEP. CONCLUSIONS: BPS is a substrate of 6 transporters: P-gp, BCRP, OAT3, OATP1B1, OATP1B3, and MRP2, because their expressing cells and vesicles transported BPS more than in the controls, and BPS transport activities were reduced by the typical inhibitors of tested transporters. Although there are no reports regarding drug-drug interactions between BPS and possible combination drugs expected due to transporters, it may be necessary to notice that that substrates or inhibitors for the 6 mentioned transporters may have effects on pharmacokinetics of BPS when co-administered.

The Pharmacokinetics of Beraprost Sodium Following Single Oral Administration to Subjects With Impaired Kidney Function.

The purpose of the present study was to evaluate the pharmacokinetics of beraprost sodium (BPS) and its active enantiomer, BPS-314d, in Japanese subjects with impaired kidney function. The plasma and urine concentrations of BPS and BPS-314d were measured following the single oral administration of 120 µg of BPS as the sustained-release tablet, TRK-100STP, under fasting conditions to 18 subjects with impaired kidney function (stage 2, 3, and 4 chronic kidney disease [CKD] as categorized by the estimated glomerular filtration rate) and to 6 age-, body weight-, and gender-matched subjects with normal kidney function (stage 1 CKD). The Cmax values (mean ± SD) of BPS in stage 1, 2, 3, and 4 CKD, respectively, were 84.9 ± 22.9, 119.8 ± 36.4, 190.6 ± 137.3, and 240.2 ± 110.5 pg/mL; its AUC0-48h were 978 ± 226, 1252 ± 427, 1862 ± 964, and 1766 ± 806 pg·h/mL, respectively, and its cumulative urinary excretion rates were 0.704 ± 0.351%, 0.638 ± 0.292%, 0.485 ± 0.294%, and 0.159 ± 0.136%. The Cmax values of BPS-314d were 22.4 ± 6.4, 30.8 ± 8.5, 46.7 ± 30.6, and 54.4 ± 25.2 pg/mL, its AUC0-48h were 155 ± 56, 226 ± 67, 341 ± 176, and 329 ± 143 pg·h/mL, and its cumulative urinary excretion rates were 0.428 ± 0.242%, 0.349 ± 0.179%, 0.356 ± 0.270%, and 0.096 ± 0.099%, respectively. Adverse events were reported in 2 subjects with stage 2 CKD and 1 subject with stage 4 CKD. The Cmax and AUC0-48h of BPS and BPS-314d were higher based on the severity of impaired kidney function. No relationship was observed between the incidence of adverse events and the severity, and tolerability was confirmed. We consider that dose adjustment is not necessary, but BPS is more carefully treated in patients with impaired kidney function.

Selexipag in the treatment of pulmonary arterial hypertension: design, development, and therapy.

Pulmonary arterial hypertension is characterized by abnormalities in the small pulmonary arteries including increased vasoconstriction, vascular remodeling, proliferation of smooth muscle cells, and in situ thrombosis. Selexipag, a novel, oral prostacyclin receptor agonist, has been shown to improve hemodynamics in a phase II clinical trial and reduce clinical worsening in a large phase III clinical trial involving patients with pulmonary arterial hypertension. In this paper, we describe the prostacyclin signaling pathway, currently available oral prostanoid medications, and the development and clinical use of selexipag.

A Comprehensive Review of Treprostinil Pharmacokinetics via Four Routes of Administration.

Treprostinil is available in three different formulations and four different routes of administration: Remodulin® (treprostinil sodium, intravenous and subcutaneous administration), Tyvaso® (treprostinil sodium, inhaled administration), and Orenitram® (treprostinil diolamine, oral administration) for the treatment of pulmonary arterial hypertension (PAH). Pharmacokinetic studies have been performed in healthy volunteers and patients with PAH. The intent of this review is to outline pharmacokinetic considerations of the three treprostinil formulations and provide clinicians with a resource that may support clinical decisions in treating patients with PAH.

Inhibition of cyclooxygenase-2 causes a decrease in coronary flow in diabetic mice. The possible role of PGE2 and dysfunctional vasodilation mediated by prostacyclin receptor

Several lines of evidence suggest that cyclooxygenase-2 (COX-2) activity can have a beneficial role in the maintenance of vascular tone of the blood vessels in diabetes. Specifically, the increased production of prostacyclin (PGI2) and prostaglandin E2 (PGE2), mediated by COX-2, has been suggested to compensate for decreased synthesis of nitric oxide (NO). The study investigates whether inhibition of COX-2 may reduce the coronary flow in diabetic animals and may also lead to decreased synthesis of prostaglandins. Mice aged 18–20 weeks were used for the study: those with leptin receptor deficiency (db/db) served as a model of diabetes while heterozygous (db/+) mice served as controls. Coronary flow was measured by the Langendorff method, and prostaglandin synthesis by myocardia was assayed in heart perfusates. COX-2 inhibition was found to reduce basal coronary flow in db/db mice but had no effect in db/+ mice. Secretion of PGE2 was found to be higher in db/db mice, while prostacyclin synthesis did not differ. COX-2 inhibition decreased production of both prostaglandins to similar levels in both groups. The use of ONO-1301, a specific agonist for the prostacyclin receptor revealed that vasodilating responses mediated by the receptor were impaired in db/db mice. The expression levels of the receptor in cardiac tissue did not differ between the groups. It is concluded that the increased COX-2 contribution to vasodilation in diabetic animals appears to be partially a result of increased COX-2-dependent synthesis of PGE2 and also may be caused by impaired vasodilation mediated by the prostacyclin receptor

Cutaneous iontophoresis of treprostinil, a prostacyclin analog, increases microvascular blood flux in diabetic malleolus area.

Diabetic foot ulcers are one of the most common and serious complications of diabetes mellitus. Few drugs are effective in enhancing the healing of microvascular skin ulcers. The main objective of the present study was to determine whether iontophoresis of treprostinil, a prostacyclin analog, increases skin microvascular blood flux in the malleolus area of healthy subjects and diabetic patients. We recruited 12 healthy subjects and 12 type 2 diabetic patients. Cathodal iontophoresis (40mC/cm²) of treprostinil 250µM and NaCl 0.9% was performed in the malleolus area. Skin hyperemia was quantified using non-invasive laser speckle contrast imaging, and expressed as the area under the curve (AUC) of cutaneous vascular conductance (CVC). In healthy controls and diabetic patients, treprostinil 250µM induced a significant increase in CVC compared with NaCl (for diabetic patients, AUC0-6h was 19970±8697; versus 2893±5481%BL.min, respectively; P=0.002). In both groups, the peak flux was obtained between 30min and 1h after the end of treprostinil iontophoresis and flux remained higher than baseline up to 6h after ending of iontophoresis. No significant side-effect occurred. Cutaneous iontophoresis of 250µM treprostinil increases microvascular blood flux in the malleolus area in healthy volunteers and diabetic patients, without inducing systemic or local side-effects. Treprostinil cathodal iontophoresis should be further investigated as a new local therapy for diabetic ulcers.

KAG-308, a newly-identified EP4-selective agonist shows efficacy for treating ulcerative colitis and can bring about lower risk of colorectal carcinogenesis by oral administration.

Agonists for EP4 receptor, a prostaglandin E2 receptor subtype, appear to be a promising therapeutic strategy for ulcerative colitis (UC) due to their anti-inflammatory and epithelial regeneration activities. However, the clinical development of orally-available EP4 agonists for mild to moderate UC has not yet been reported. Furthermore, the possibility of an increased risk of colitis-associated cancer (CAC) through direct proliferative effects on epithelial cells via EP4 signaling has not been ruled out. Recently, we identified KAG-308 as an orally-available EP4-selective agonist. Here, we investigated the pharmacological and pharmacokinetic profiles of KAG-308. Then, we compared KAG-308 and sulfasalazine (SASP) for their abilities to prevent colitis and promote mucosal healing in a mouse model of dextran sulfate sodium (DSS)-induced colitis. Finally, the effect of KAG-308 treatment on CAC was evaluated in an azoxymethane (AOM)/DSS-induced CAC mouse model. KAG-308 selectively activated EP4 and potently inhibited tumor necrosis factor-α production in peripheral whole blood and T cells. Oral administration of KAG-308, which showed relatively high bioavailability, suppressed the onset of DSS-induced colitis and promoted histological mucosal healing, while SASP did not. KAG-308 also prevented colorectal carcinogenesis by inhibiting colitis development and consequently decreasing mortality in a CAC model, whereas SASP had marginal effects. In contrast, MF-482, an EP4 antagonist, increased mortality. These results indicated that orally-administered KAG-308 suppressed colitis development and promoted mucosal healing. Moreover, it exhibited preventive effects on colorectal carcinogenesis, and thus may be a new therapeutic strategy for the management of UC that confers a reduced risk of colorectal carcinogenesis.