Synthesis, Biological, Spectroscopic and Computational Investigations of Novel N-Acylhydrazone Derivatives of Pyrrolo[3,4-d]pyridazinone as Dual COX/LOX Inhibitors

Secure and efficient treatment of diverse pain and inflammatory disorders is continually challenging. Although NSAIDs and other painkillers are well-known and commonly available, they are sometimes insufficient and can cause dangerous adverse effects. As yet reported, derivatives of pyrrolo[3,4-d]pyridazinone are potent COX-2 inhibitors with a COX-2/COX-1 selectivity index better than meloxicam. Considering that N-acylhydrazone (NAH) moiety is a privileged structure occurring in many promising drug candidates, we decided to introduce this pharmacophore into new series of pyrrolo[3,4-d]pyridazinone derivatives. The current paper presents the synthesis and in vitro, spectroscopic, and in silico studies evaluating the biological and physicochemical properties of NAH derivatives of pyrrolo[3,4-d]pyridazinone. Novel compounds 5a-c-7a-c were received with high purity and good yields and did not show cytotoxicity in the MTT assay. Their COX-1, COX-2, and 15-LOX inhibitory activities were estimated using enzymatic tests and molecular docking studies. The title N-acylhydrazones appeared to be promising dual COX/LOX inhibitors. Moreover, spectroscopic and computational methods revealed that new compounds form stable complexes with the most abundant plasma proteins-AAG and HSA, but do not destabilize their secondary structure. Additionally, predicted pharmacokinetic and drug-likeness properties of investigated molecules suggest their potentially good membrane permeability and satisfactory bioavailability.

Evaluation of herb-drug interaction of ambrisentan with shikonin based on UPLC-MS/MS

CONTEXT

Ambrisentan is an oral endothelin-receptor antagonist (ERA). However, there is no report on the interaction between ambrisentan and shikonin.

OBJECTIVE

To investigate the effect of shikonin on ambrisentan metabolism in vivo and in vitro.

MATERIALS AND METHODS

This study developed an ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for simultaneous determination of ambrisentan and (S)-4-hydroxymethyl ambrisentan in rat plasma. Twelve male Sprague-Dawley (SD) rats were divided into two groups (n = 6): the control group and shikonin (20 mg/kg) group. The pharmacokinetics of ambrisentan (2.5 mg/kg) were investigated after 30 min. Additionally, human and rat liver microsomes were used to investigate the herb-drug interaction.

RESULTS

The UPLC-MS/MS method was shown to be accurate, precise and reliable, and was successfully applied to the herb-drug interaction study of ambrisentan with shikonin. When co-administrated with 20 mg/kg shikonin, the C_max and AUC_(0-∞) of ambrisentan were significantly increased by 44.96 and 16.65%, respectively (p < 0.05). In addition, there were modest decreases in (S)-4-hydroxymethyl ambrisentan C_max and AUC_(0-∞) in the presence of shikonin (p < 0.05), which indicated that these results were in accordance with the inhibition of shikonin on ambrisentan metabolism. Moreover, enzyme kinetic study indicated that shikonin had an inhibitory effect on human and rat microsomes where the IC₅₀ values of shikonin were 5.865 and 6.358 μM, respectively.

CONCLUSIONS

Our study indicated that shikonin could inhibit ambrisentan metabolism. Further studies need to be carried out to verify whether similar interaction truly apply in humans and whether this interaction has clinical significance.

Serial evaluation of the pharmacokinetics of ponatinib in patients with CML and Ph + ALL

Although tyrosine kinase inhibitors (TKIs) play a crucial role in the treatment of chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL), intolerance and resistance to TKIs have been serious problems. Due to a lack of research, the importance of the pharmacokinetics (PK) of TKIs is currently unclear. We examined the PK of the third-generation TKI ponatinib to monitor side effects and efficacy during treatments for one patient with CML-chronic phase (CP-CML) and two who received allogeneic hematopoietic stem cell transplantation (allo-HSCT), one for CML-blastic crisis (BC-CML) and one for Ph + ALL. The patient with CP-CML was intolerant to multiple TKIs (dasatinib, nilotinib, imatinib, and bosutinib) and thus was switched to ponatinib (15 mg/day). The patients who received allo-HSCT for BC-CML and Ph + ALL received ponatinib (15 mg/day) as maintenance therapy. Notably, serial evaluation of the PK of ponatinib showed that the median trough values (ng/ml) were 17.2 (12.2-34.5), 33.1 (21.2-40.3) and 27.7 (13.6-29.9) in patients 1, 2, and 3, respectively. These values were around the target concentration (23 ng/ml). All patients are maintaining complete remission without side effects. In conclusion, serial evaluation of PK of ponatinib may yield meaningful information about its safety and efficacy.

Acute pharmacodynamic effects of pimobendan in client-owned cats with subclinical hypertrophic cardiomyopathy

BACKGROUND

Prior studies have suggested that pimobendan is associated with several positive effects in cats, including improved survival in cats with congestive heart failure and improved left atrial function in research colony cats with hypertrophic cardiomyopathy (HCM) and normal cats. However, there is still a paucity of pharmacodynamic data refuting or supporting the use of pimobendan in a clinical cat population. This clinical trial aimed to evaluate the pharmacodynamic effects and tolerability of a single dose of pimobendan in cats with HCM. Echocardiograms and Doppler-derived systolic blood pressures were performed in 21 client-owned cats with subclinical HCM at baseline and 90-min after oral administration of 1.25 mg of pimobendan (Vetmedin). Seven additional cats were evaluated post-placebo administration to account for intra-day variability.

RESULTS

Heart rate, systolic blood pressure, and murmur grade were not significantly different between baseline and post-pimobendan evaluations. Left auricular blood flow velocity, left atrial size, and left ventricular fractional shortening were not significantly different between baseline and post-pimobendan evaluations. Mean (± standard deviation) tissue Doppler peak systolic velocity of the mitral annulus was significantly higher following pimobendan (7.4 cm/s ± 1.5 vs 8.5 ± 1.6; p = 0.02). Median (min, max) left-ventricular outflow tract maximum velocity was significantly higher following pimobendan [1.9 m/sec (1.5, 3.4) vs 2.6 m/sec (2.0, 4.0); p = 0.01]. Mean right-ventricular outflow tract maximum velocity was also significantly higher following pimobendan (1.5 m/s ± 0.51 vs 2.0 ± 0.53; p = 0.004). Mean left atrial fractional shortening was significantly higher following pimobendan (28% ± 6 vs 32% ± 7; p = 0.02). No adverse events were observed following pimobendan administration. Right ventricular outflow tract velocity was significantly higher following placebo in control cats (1.02 ± 0.21 versus 1.31 ± 0.31; p = 0.01). No other significant differences were detected.

CONCLUSIONS

In client-owned cats with HCM, pimobendan acutely increased left atrial function and mildly increased left ventricular systolic function. Left ventricular outflow tract velocity was increased after pimobendan. Pimobendan was well tolerated in the acute setting in cats with HCM. The findings of this prospective, acute-dosing study confirm previous findings in research animals and retrospective analyses and suggest that chronic dosing studies are safe and warranted.

Translational Development Strategies for TAK-063, a Phosphodiesterase 10A Inhibitor

BACKGROUND

TAK-063 is an inhibitor of phosphodiesterase 10A (PDE10A), an enzyme highly expressed in medium spiny neurons of the striatum. PDE10A hydrolyzes both cyclic adenosine monophosphate and cyclic guanosine monophosphate and modulates dopamine signaling downstream of receptor activation in both direct and indirect pathways of the striatum. TAK-063 exhibited antipsychotic-like effects in animal models; however, the translatability of these models to the clinical manifestations of schizophrenia and the meaningfulness for new targets such as PDE10A has not been established.

METHODS

The TAK-063 phase 1 program included a comprehensive translational development strategy with the main objective of determining whether the antipsychotic-like pharmacodynamic effects seen in nonclinical models would translate to human subjects. To evaluate this objective, we conducted a single-rising dose study (84 healthy subjects), a positron emission tomography (PET) study (12 healthy subjects), a functional magnetic resonance imaging blood oxygen level-dependent (BOLD) study (27 healthy subjects), and a multiple-rising dose study that included people with schizophrenia (30 healthy Japanese subjects and 47 subjects with stable schizophrenia). In addition, assessments of cognition and electroencephalography (27 healthy subjects and 47 subjects with stable schizophrenia) were included.

RESULTS

PDE10A engagement by TAK-063 was verified with a novel PET radiotracer for use in primates and humans. TAK-063 showed favorable pharmacokinetic and safety profiles in humans, and TAK-063 reduced ketamine-induced changes in electroencephalography and BOLD signaling in animal models and healthy human subjects. In addition, analogous effects on cognition were observed in animal models and human subjects.

CONCLUSIONS

Overall, the phase 1 results showed some consistent evidence of antipsychotic activity. This translational strategy may be valuable for the future development of novel therapeutic approaches, even when relevant nonclinical models are not available.

Determination, risk assessment and processing factors for pyridaben in field-incurred kiwifruit samples

Field trials in six agricultural sites were carried out to investigate the dissipation and residue levels of pyridaben in kiwifruit. Each sample was extracted with acetonitrile, purified with octadecylsilane and analyzed with high-performance liquid chromatography-tandem mass spectrometry. The method had good linearity (R² > 0.99), accuracy (recoveries of 78.53-98.00%) and precision (relative standard deviation of 0.86-6.11%). The dissipation of pyrdaben in kiwifruit followed first-order kinetics with a half-life < 8 d, and terminal residues in kiwifruit were lower than 0.5 mg/kg after 14 d of application. Risk assessment indicated that both chronic and acute dietary intake risk values were far below 100%, suggesting that pyridaben residues in kiwifruit were relatively safe to humans. Moreover, the effects of traditional household processes on kiwifruit were investigated. The processing factors (PFs) indicated that peeling and peeling-juicing processes could remove pyridaben residues from kiwifruit, and the former was more effective than the latter (PF at 0.15 vs. 0.51). Nevertheless, drying kiwifruit with an oven increased the amount of pyridaben (PF at 1.05). These results could provide guidance for the safe and reasonable use of pyridaben in agriculture and may be helpful for the Chinese government to determine maximum residue limit of pyridaben in kiwifruit.

First-in-Human Studies of MW01-6-189WH, a Brain-Penetrant, Antineuroinflammatory Small-Molecule Drug Candidate: Phase 1 Safety, Tolerability, Pharmacokinetic, and Pharmacodynamic Studies in Healthy Adult Volunteers

MW01‐6‐189WH (MW189) is a novel central nervous system–penetrant small‐molecule drug candidate that selectively attenuates stressor‐induced proinflammatory cytokine overproduction and is efficacious in intracerebral hemorrhage and traumatic brain injury animal models. We report first‐in‐human, randomized, double‐blind, placebo‐controlled phase 1 studies to evaluate the safety, tolerability, and pharmacokinetics (PK) of single and multiple ascending intravenous doses of MW189 in healthy adult volunteers. MW189 was safe and well tolerated in single and multiple doses up to 0.25 mg/kg, with no clinically significant concerns. The most common drug‐related treatment‐emergent adverse event was infusion‐site reactions, likely related to drug solution acidity. No clinically concerning changes were seen in vital signs, electrocardiograms, physical or neurological examinations, or safety laboratory results. PK analysis showed dose‐proportional increases in plasma concentrations of MW189 after single or multiple doses, with approximately linear kinetics and no significant drug accumulation. Steady state was achieved by dose 3 for all dosing cohorts. A pilot pharmacodynamic study administering low‐dose endotoxin to induce a systemic inflammatory response was done to evaluate the effects of a single intravenous dose of MW189 on plasma cytokine levels. MW189 treatment resulted in lower levels of the proinflammatory cytokine TNF‐α and higher levels of the anti‐inflammatory cytokine IL‐10 compared with placebo treatment. The outcomes are consistent with the pharmacological mechanism of MW189. Overall, the safety profile, PK properties, and pharmacodynamic effect support further development of MW189 for patients with acute brain injury.

Open-label, single-center, phase I trial to investigate the mass balance and absolute bioavailability of the highly selective oral MET inhibitor tepotinib in healthy volunteers

Tepotinib (MSC2156119J) is an oral, potent, highly selective MET inhibitor. This open-label, phase I study in healthy volunteers (EudraCT 2013-003226-86) investigated its mass balance (part A) and absolute bioavailability (part B). In part A, six participants received tepotinib orally (498 mg spiked with 2.67 MBq [¹⁴C]-tepotinib). Blood, plasma, urine, and feces were collected up to day 25 or until excretion of radioactivity was <1% of the administered dose. In part B, six participants received 500 mg tepotinib orally as a film-coated tablet, followed by an intravenous [¹⁴C]-tepotinib tracer dose (53–54 kBq) 4 h later. Blood samples were collected until day 14. In part A, a median of 92.5% (range, 87.1–96.9%) of the [¹⁴C]-tepotinib dose was recovered in excreta. Radioactivity was mainly excreted via feces (median, 78.7%; range, 69.4–82.5%). Urinary excretion was a minor route of elimination (median, 14.4% [8.8–17.7%]). Parent compound was the main constituent in excreta (45% [feces] and 7% [urine] of the radioactive dose). M506 was the only major metabolite. In part B, absolute bioavailability was 72% (range, 62–81%) after oral administration of 500 mg tablets (the dose and formulation used in phase II trials). In conclusion, tepotinib and its metabolites are mainly excreted via feces; parent drug is the major eliminated constituent. Oral bioavailability of tepotinib is high, supporting the use of the current tablet formulation in clinical trials. Tepotinib was well tolerated in this study with healthy volunteers.

Residues and dissipation kinetic of abamectin, chlorfenapyr and pyridaben acaricides in green beans (Phaseolus vulgaris L.) under field conditions using QuEChERS method and HPLC

The current study estimated the dissipation rates of abamectin, chlorfenapyr and pyridaben acaricides in pods of green beans (Phaseolus vulgaris L.) under field conditions in Egypt. Pesticides were extracted and cleaned-up by QuEChERS method and were analyzed by HPLC. The dissipation of these acaricides followed the first order kinetics model with half-life (t_1/2) values 1.00, 3.50 and 1.50 days for abamectin, chlorfenapyr and pyridaben, respectively. The lowest residues, at different time intervals of field application rate of each pesticide, were observed with abamectin followed by pyridaben and then chlorfenapyr. Pre-harvest intervals (PHIs) were 10.00, 13.50 and 6.00 days for abamectin, chlorfenapyr and pyridaben, respectively and were below the established European maximum residue limits (EU MRLs) 10-14, 14-21 and 7-10 days after application, respectively. If the fresh pods will be consumed after harvest, it is expected that the presence of these pesticides in the food will have a negative impact on human health. Therefore, the elimination of the residues of these harmful pesticides must be carried out.

Dosimetry, biodistribution, and safety of flurpiridaz F 18 in healthy subjects undergoing rest and exercise or pharmacological stress PET myocardial perfusion imaging

The objectives of this study were to evaluate radiation dosimetry, biodistribution, human safety, and tolerability of 18F-labeled flurpiridaz (Flurpiridaz) in normal subjects undergoing rest and separate-day exercise or adenosine pharmacological stress PET imaging.

METHODS

12 normal subjects were injected with 58.5 to 121 MBq (1.58 to 3.27 mCi) of Flurpiridaz intravenously at rest on Day 1 and 57 to 171 MBq (1.54 to 4.61 mCi) during stress on Day 2. Sequential whole-body imaging was performed for 5 hours. Blood samples were collected for up to 8 hours.

RESULTS

The heart wall received the largest mean absorbed dose with both exercise and adenosine stresses. The mean effective dose was 0.054 rem/mCi (0.015 mSv/MBq) with exercise and 0.069 rem/mCi (0.019 mSv/MBq) with adenosine pharmacological stress. The maximum dose that may be administered without exceeding 1 rem (10 mSv) effective dose was 19 mCi (685 MBq) for exercise and 15 mCi (539 MBq) for adenosine pharmacological stress. There were no drug-related adverse events, and the tracer was well tolerated in all subjects.

CONCLUSION

Based on radiation dosimetry, biodistribution, and safety observations, 18F-labeled flurpiridaz is found suitable for clinical PET myocardial perfusion imaging in conjunction with either exercise or pharmacological stress testing.

The oral Janus kinase/spleen tyrosine kinase inhibitor ASN002 demonstrates efficacy and improves associated systemic inflammation in patients with moderate-to-severe atopic dermatitis: results from a randomized double-blind placebo-controlled study

BACKGROUND

ASN002 is an oral dual inhibitor of Janus kinase and spleen tyrosine kinase, which are involved in the pathogenesis of atopic dermatitis (AD) through their regulatory role on T helper (Th)1, Th2 and Th17/Th22 pathways.

OBJECTIVES

The objectives of this study were to evaluate the efficacy, safety, pharmacokinetics and effects on systemic biomarkers of ASN002 in patients with moderate-to-severe AD. Methods A total of 36 patients with moderate-to-severe AD were randomized (3 : 1) to ASN002 or placebo in the phase Ib study. Three dosage cohorts were studied over a 28-day period (20 mg, 40 mg and 80 mg once daily).

RESULTS

ASN002 was superior to placebo for the proportion of patients achieving Eczema Area and Severity Index (EASI) 50 (20 mg 20%, P = 0·93; 40 mg 100%, P = 0·003; 80 mg 83%, P = 0·03; placebo 22%), EASI 75 (20 mg 0%, P = 0·27; 40 mg 71%, P = 0·06; 80 mg 33%, P = 0·65; placebo 22%) and in change from baseline in pruritus (20 mg -1·3 ± 2·1, P = 0·81; 40 mg -3·1 ± 2·7, P = 0·27; 80 mg -4·7 ± 2·1, P = 0·01; placebo -1·6 ± 1·8). Adverse events were generally mild and similar across all groups. ASN002 showed dose-dependent plasma exposure with low interpatient variability, significantly downregulated several serum biomarkers involved in Th1, Th2 and Th17/Th22 immunity, and decreased the atherosclerosis-associated biomarker E selectin/SELE.

CONCLUSIONS

In patients with moderate-to-severe AD, ASN002 showed strong efficacy with rapid onset of action and associated improvements in systemic inflammation.

Nanoparticle-releasing nanofiber composites for enhanced in vivo vaginal retention

Current approaches for topical vaginal administration of nanoparticles result in poor retention and extensive leakage. To overcome these challenges, we developed a nanoparticle-releasing nanofiber delivery platform and evaluated its ability to improve nanoparticle retention in a murine model. We individually tailored two components of this drug delivery system for optimal interaction with mucus, designing (1) mucoadhesive fibers for better retention in the vaginal tract, and (2) PEGylated nanoparticles that diffuse quickly through mucus. We hypothesized that this novel dual-functioning (mucoadhesive/mucus-penetrating) composite material would provide enhanced retention of nanoparticles in the vaginal mucosa. Equivalent doses of fluorescent nanoparticles were vaginally administered to mice in either water (aqueous suspension) or fiber composites, and fluorescent content was quantified in cervicovaginal mucus and vaginal tissue at time points from 24 h to 7d. We also fabricated composite fibers containing etravirine-loaded nanoparticles and evaluated the pharmacokinetics over 7d. We found that our composite materials provided approximately 30-fold greater retention of nanoparticles in the reproductive tract at 24 h compared to aqueous suspensions. Compared to nanoparticles in aqueous suspension, the nanoparticles in fiber composites exhibited sustained and higher etravirine concentrations after 24 h and up to 7d, demonstrating the capabilities of this new delivery platform to sustain nanoparticle release out to 3d and drug retention out to one week after a single administration. This is the first report of nanoparticle-releasing fibers for vaginal drug delivery, as well as the first study of a single delivery system that combines two components uniquely engineered for complementary interactions with mucus.

Discovery and optimization of 3-(4-aryl/heteroarylsulfonyl)piperazin-1-yl)-6-(piperidin-1-yl)pyridazines as novel, CNS penetrant pan-muscarinic antagonists

This letter describes the synthesis and structure activity relationship (SAR) studies of structurally novel M4 antagonists, based on a 3-(4-aryl/heteroarylsulfonyl)piperazin-1-yl)-6-(piperidin-1-yl)pyridazine core, identified from a high-throughput screening campaign. A multi-dimensional optimization effort enhanced potency at human M4 (hM4 IC50s<200nM), with only moderate species differences noted, and with enantioselective inhibition. Moreover, CNS penetration proved attractive for this series (rat brain:plasma Kp=2.1, Kp,uu=1.1). Despite the absence of the prototypical mAChR antagonist basic or quaternary amine moiety, this series displayed pan-muscarinic antagonist activity across M1-5 (with 9- to 16-fold functional selectivity at best). This series further expands the chemical diversity of mAChR antagonists.

Challenges in the development of an M4 PAM in vivo tool compound: The discovery of VU0467154 and unexpected DMPK profiles of close analogs

This letter describes the chemical optimization of a novel series of M4 positive allosteric modulators (PAMs) based on a 5-amino-thieno[2,3-c]pyridazine core, developed via iterative parallel synthesis, and culminating in the highly utilized rodent in vivo tool compound, VU0467154 (5). This is the first report of the optimization campaign (SAR and DMPK profiling) that led to the discovery of VU0467154, and details all of the challenges faced in allosteric modulator programs (steep SAR, species differences in PAM pharmacology and subtle structural changes affecting CNS penetration).

Validated LC-MS/MS Method for the Quantification of Ponatinib in Plasma: Application to Metabolic Stability

In the current work, a rapid, specific, sensitive and validated liquid chromatography tandem mass-spectrometric method was developed for the quantification of ponatinib (PNT) in human plasma and rat liver microsomes (RLMs) with its application to metabolic stability. Chromatographic separation of PNT and vandetanib (IS) were accomplished on Agilent eclipse plus C18 analytical column (50 mm × 2.1 mm, 1.8 μm particle size) maintained at 21±2°C. Flow rate was 0.25 mLmin^-1 with run time of 4 min. Mobile phase consisted of solvent A (10 mM ammonium formate, pH adjusted to 4.1 with formic acid) and solvent B (acetonitrile). Ions were generated by electrospray (ESI) and multiple reaction monitoring (MRM) was used as basis for quantification. The results revealed a linear calibration curve in the range of 5–400 ngmL^-1 (r² ≥ 0.9998) with lower limit of quantification (LOQ) and lower limit of detection (LOD) of 4.66 and 1.53 ngmL^-1 in plasma, 4.19 and 1.38 ngmL^-1 in RLMs. The intra- and inter-day precision and accuracy in plasma ranged from1.06 to 2.54% and -1.48 to -0.17, respectively. Whereas in RLMs ranged from 0.97 to 2.31% and -1.65 to -0.3%. The developed procedure was applied for quantification of PNT in human plasma and RLMs for study metabolic stability of PNT. PNT disappeared rapidly in the 1st 10 minutes of RLM incubation and the disappearance plateaued out for the rest of the incubation. In vitro half-life (t_1/2) was 6.26 min and intrinsic clearance (CL_in) was 15.182± 0.477.

A first-in-human study of AMG 208, an oral MET inhibitor, in adult patients with advanced solid tumors

BACKGROUND

This first-in-human study evaluated AMG 208, a small-molecule MET inhibitor, in patients with advanced solid tumors.

METHODS

Three to nine patients were enrolled into one of seven AMG 208 dose cohorts (25, 50, 100, 150, 200, 300, and 400 mg). Patients received AMG 208 orally on days 1 and days 4-28 once daily. The primary objectives were to evaluate the safety, tolerability, pharmacokinetics, and maximum tolerated dose (MTD) of AMG 208.

RESULTS

Fifty-four patients were enrolled. Six dose-limiting toxicities were observed: grade 3 increased aspartate aminotransferase (200 mg), grade 3 thrombocytopenia (200 mg), grade 4 acute myocardial infarction (300 mg), grade 3 prolonged QT (300 mg), and two cases of grade 3 hypertension (400 mg). The MTD was not reached. The most frequent grade ≥3 treatment-related adverse event was anemia (n = 3) followed by hypertension, prolonged QT, and thrombocytopenia (two patients each). AMG 208 exposure increased linearly with dose; mean plasma half-life estimates were 21.4-68.7 hours. One complete response (prostate cancer) and three partial responses (two in prostate cancer, one in kidney cancer) were observed.

CONCLUSIONS

In this study, AMG 208 had manageable toxicities and showed evidence of antitumor activity, particularly in prostate cancer.

AZD3514, an oral selective androgen receptor down-regulator in patients with castration-resistant prostate cancer - results of two parallel first-in-human phase I studies

BACKGROUND

AZD3514 is a first-in-class, orally bio-available, androgen-dependent and -independent androgen receptor inhibitor and selective androgen-receptor down-regulator (SARD).

METHODS

In study 1 and 2, castration-resistant prostate cancer (CRPC) patients (pts) were initially recruited into a once daily (QD) oral schedule (A). In study 1, pharmacokinetic assessments led to twice daily (BID) dosing (schedule B) to increase exposure. Study 2 explored a once daily schedule.

RESULTS

In study 1, 49 pts were treated with escalating doses of AZD3514 (A 35 pts, B 14 pts). Starting doses were 100 mg (A) and 1000 mg (B). The AZD3514 formulation was switched from capsules to tablets at 1000 mg QD. 2000 mg BID was considered non-tolerable due to grade (G) 2 toxicities (nausea [N], vomiting [V]). No adverse events (AEs) met the dose-limiting toxicity (DLT) definition. Thirteen pts received AZD3514 in study 2, with starting doses of 250 mg QD. The most frequent drug-related AEs were N: G1/2 in 55/70 pts (79 %); G3 in 1 pt (1.4 %); & V: G1/2 in 34/70 pts (49 %) & G3 in 1 pt (1.4 %). PSA declines (≥50 %) were documented in 9/70 patients (13 %). Objective soft tissue responses per RECIST1.1 were observed in 4/24 (17 %) pts in study 1.

CONCLUSION

AZD3514 has moderate anti-tumour activity in pts with advanced CRPC but with significant levels of nausea and vomiting. However, anti-tumour activity as judged by significant PSA declines, objective responses and durable disease stabilisations, provides the rationale for future development of SARD compounds.

Safety, pharmacokinetic, and positron emission tomography evaluation of serotonin and dopamine transporter occupancy following multiple-dose administration of the triple monoamine reuptake inhibitor BMS-820836

RATIONALE

BMS-820836 is a novel antidepressant that selectively inhibits the reuptake of serotonin, norepinephrine, and dopamine.

OBJECTIVE

This Phase I study assessed safety, tolerability, and pharmacokinetics of multiple daily doses of BMS-820836 in healthy subjects. Central serotonin transporter (SERT) and dopamine transporter (DAT) occupancy were assessed using positron emission tomography and [(11)C]MADAM or [(11)C]PE2I, respectively.

METHODS

Fifty-seven healthy volunteers were enrolled in this double-blind, placebo-controlled, ascending multiple-dose study (ClincalTrials.gov identifier: NCT00892840). Eight participants in seven dose cohorts received oral doses of BMS-820836 (0.1-4 mg) or placebo for 14 days to assess safety, tolerability, and pharmacokinetics. Additionally, SERT and DAT occupancies were evaluated in 4-8 subjects per cohort at 8 h post-dose on Day 10 and 24 h post-dose on Day 15 at anticipated steady-state conditions.

RESULTS

Most adverse events were mild to moderate; there were no serious safety concerns. Median maximum concentrations of BMS-820836 were observed at 4.0-5.5 h post-dose; estimated elimination half-life was 44-74 h. About 80 % striatal SERT occupancy was achieved after multiple doses of 0.5 mg BMS-820836 at both 8 and 24 h post-dose. Striatal DAT occupancy ranged between 14 % and 35 % at 8 h post-dose with a slight decline at 24 h post-dose.

CONCLUSIONS

Multiple daily doses of up to 4 mg BMS-820836 appeared to be generally safe and well tolerated in a healthy population. SERT and DAT occupancies were in a range associated with therapeutic efficacy of antidepressants. Together with the pharmacokinetic profile of BMS-820836, the occupancy data support once-daily administration.

Multiple compound-related adverse properties contribute to liver injury caused by endothelin receptor antagonists

Drug-induced liver injury has been observed in patients treated with the endothelin receptor antagonists sitaxentan and bosentan, but not following treatment with ambrisentan. The aim of our studies was to assess the possible role of multiple contributory mechanisms in this clinically relevant toxicity. Inhibition of the bile salt export pump (BSEP) and multidrug resistance-associated protein 2 was quantified using membrane vesicle assays. Inhibition of mitochondrial respiration in human liver-derived HuH-7 cells was determined using a Seahorse XF(e96) analyzer. Cytochrome P450 (P450)-independent and P450-mediated cell toxicity was assessed using transfected SV40-T-antigen-immortalized human liver epithelial (THLE) cell lines. Exposure-adjusted assay ratios were calculated by dividing the maximum human drug plasma concentrations by the IC50 or EC50 values obtained in vitro. Covalent binding (CVB) of radiolabeled drugs to human hepatocytes was quantified, and CVB body burdens were calculated by adjusting CVB values for fractional drug turnover in vitro and daily therapeutic dose. Sitaxentan exhibited positive exposure-adjusted signals in all five in vitro assays and a high CVB body burden. Bosentan exhibited a positive exposure-adjusted signal in one assay (BSEP inhibition) and a moderate CVB body burden. Ambrisentan exhibited no positive exposure-adjusted assay signals and a low CVB body burden. These data indicate that multiple mechanisms contribute to the rare, but potentially severe liver injury caused by sitaxentan in humans; provide a plausible rationale for the markedly lower propensity of bosentan to cause liver injury; and highlight the relative safety of ambrisentan.

An efficacy and mechanism evaluation study of Levosimendan for the Prevention of Acute oRgan Dysfunction in Sepsis (LeoPARDS): protocol for a randomized controlled trial

BACKGROUND

Organ dysfunction consequent to infection ('severe sepsis') is the leading cause of admission to an intensive care unit (ICU). In both animal models and early clinical studies the calcium channel sensitizer levosimendan has been demonstrated to have potentially beneficial effects on organ function. The aims of the Levosimendan for the Prevention of Acute oRgan Dysfunction in Sepsis (LeoPARDS) trial are to identify whether a 24-hour infusion of levosimendan will improve organ dysfunction in adults who have septic shock and to establish the safety profile of levosimendan in this group of patients.

METHODS/DESIGN

This is a multicenter, randomized, double-blind, parallel group, placebo-controlled trial. Adults fulfilling the criteria for systemic inflammatory response syndrome due to infection, and requiring vasopressor therapy, will be eligible for inclusion in the trial. Within 24 hours of meeting these inclusion criteria, patients will be randomized in a 1:1 ratio stratified by the ICU to receive either levosimendan (0.05 to 0.2 μg.kg⁻¹.min⁻¹ or placebo for 24 hours in addition to standard care. The primary outcome measure is the mean Sequential Organ Failure Assessment (SOFA) score while in the ICU. Secondary outcomes include: central venous oxygen saturations and cardiac output; incidence and severity of renal failure using the Acute Kidney Injury Network criteria; duration of renal replacement therapy; serum bilirubin; time to liberation from mechanical ventilation; 28-day, hospital, 3 and 6 month survival; ICU and hospital length-of-stay; and days free from catecholamine therapy. Blood and urine samples will be collected on the day of inclusion, at 24 hours, and on days 4 and 6 post-inclusion for investigation of the mechanisms by which levosimendan might improve organ function. Eighty patients will have additional blood samples taken to measure levels of levosimendan and its active metabolites OR-1896 and OR-1855. A total of 516 patients will be recruited from approximately 25 ICUs in the United Kingdom.

DISCUSSION

This trial will test the efficacy of levosimendan to reduce acute organ dysfunction in adult patients who have septic shock and evaluate its biological mechanisms of action.

TRIAL REGISTRATION

Current controlled trials ISRCTN12776039 (19 September 2013).

Small-molecule activator of glutamate transporter EAAT2 translation provides neuroprotection

Glial glutamate transporter EAAT2 plays a major role in glutamate clearance in synaptic clefts. Several lines of evidence indicate that strategies designed to increase EAAT2 expression have potential for preventing excitotoxicity, which contributes to neuronal injury and death in neurodegenerative diseases. We previously discovered several classes of compounds that can increase EAAT2 expression through translational activation. Here, we present efficacy studies of the compound LDN/OSU-0212320, which is a pyridazine derivative from one of our lead series. In a murine model, LDN/OSU-0212320 had good potency, adequate pharmacokinetic properties, no observed toxicity at the doses examined, and low side effect/toxicity potential. Additionally, LDN/OSU-0212320 protected cultured neurons from glutamate-mediated excitotoxic injury and death via EAAT2 activation. Importantly, LDN/OSU-0212320 markedly delayed motor function decline and extended lifespan in an animal model of amyotrophic lateral sclerosis (ALS). We also found that LDN/OSU-0212320 substantially reduced mortality, neuronal death, and spontaneous recurrent seizures in a pilocarpine-induced temporal lobe epilepsy model. Moreover, our study demonstrated that LDN/OSU-0212320 treatment results in activation of PKC and subsequent Y-box-binding protein 1 (YB-1) activation, which regulates activation of EAAT2 translation. Our data indicate that the use of small molecules to enhance EAAT2 translation may be a therapeutic strategy for the treatment of neurodegenerative diseases.

Discovery of (1R,6S)-5-[4-(1-cyclobutyl-piperidin-4-yloxy)-phenyl]-3,4-diaza-bicyclo[4.1.0]hept-4-en-2-one (R,S-4a): histamine H(3) receptor inverse agonist demonstrating potent cognitive enhancing and wake promoting activity

A series of fused cyclopropyl-4,5-dihydropyridazin-3-one (3,4-diaza-bicyclo[4.1.0]hept-4-en-2-one) phenoxypiperidine analogs was designed and synthesized, leading to the identification of (1R,6S)-5-[4-(1-cyclobutyl-piperidin-4-yloxy)-phenyl]-3,4-diaza-bicyclo[4.1.0]hept-4-en-2-one (R,S-4a) as a second-generation pyridazin-3-one H3R antagonist. Compound R,S-4a was a potent H3R functional antagonist in vivo in the rat dipsogenia model, demonstrated potent wake activity in the rat EEG/EMG model, and enhanced short-term memory in the rat social recognition memory model at doses as low as 0.03-0.3 mg/kg po.

Levosimendan: first in a new class of inodilator for acute and chronic severe heart failure

Heart failure is the most common malignant disease in the developed world. Levosimendan (Simdax) is a novel intravenous agent that exerts inotropic effects through sensitization of myofilaments to calcium and vasodilator effects by opening ATP-dependent potassium channels on vascular smooth muscle. Infusion of levosimendan increases cardiac output due to an increase in stroke volume and heart rate, with a fall in pulmonary capillary wedge pressure. It has an active metabolite with a half-life of about 80 h, therefore infusions of 6 to 24 h result in hemodynamic effects that persist for 7 to 10 days. Preliminary observations suggest that a single infusion of levosimendan lasting 6 to 24 h in patients with severe heart failure due to left ventricular systolic dysfunction results in hemodynamic changes, symptomatic benefit and a reduction in morbidity and mortality over the following 2 to 4 weeks compared with placebo in one study and with dobutamine in another. Long-term follow-up suggests no loss of this early benefit over 6 months. Levosimendan is licensed for the treatment of decompensated heart failure in many countries but not in North America. Further large trials are being conducted comparing levosimendan with placebo and with dobutamine in patients with severe heart failure and left ventricular systolic dysfunction. If these studies confirm the benefits of levosimendan, then it may become routine therapy for the management of severe heart failure.

Pharmacodynamics and Pharmacokinetics of Oral Levosimendan and Its Metabolites in Patients With Severe Congestive Heart Failure: A Dosing Interval Study

The objective of this study was to explore the pharmacodynamics and pharmacokinetics of oral levosimendan in patients with severe congestive heart failure. This was a randomized, parallel-group, double-blind, placebo-controlled trial. Oral levosimendan 2 to 8 mg daily or placebo was administered to 25 patients with New York Heart Association class III-IV congestive heart failure for 4 weeks. Pharmacodynamic variables consisted of heart rate-corrected electromechanical systole, heart rate, and systolic and diastolic blood pressure. The pharmacokinetics of levosimendan and its metabolites, OR-1855 and OR-1896, was assessed. The 4- to 8-mg daily doses of oral levosimendan showed moderate inotropic effects. Blood pressure remained unchanged with all doses. A moderate increase in heart rate was observed except with the 2-mg dose. Pharmacokinetic parameters of the metabolites increased linearly with the dose (P < or = .002 for Cmax and AUC0-8h for both treatment groups). It was concluded that oral levosimendan has inotropic and chronotropic effects in patients with severe congestive heart failure. Plasma concentrations of its metabolites increase dose dependently.

Levosimendan: Implications for Clinicians

Levosimendan is a novel calcium sensitizing agent in development for the treatment of acute and chronic heart failure. The agent increases myocardial force without increasing myocyte calcium concentrations, thus reducing the possibility for myocardial necrosis. In addition, the agent also causes vasodilation of coronary and peripheral vessels to improve coronary blood flow and reduce afterload. The short half-life is a benefit for intravenous administration but could be problematic for the drug's use in chronic heart failure. The risk of the development of arrhythmias from levosimendan appears small secondary to an increase in the QTc interval of 15 msec but needs to be evaluated in light of the ability of levosimendan to open adenosine triphosphate (ATP)-sensitive potassium channels. In addition, the agent has not been studied in patients with additional risks for torsades de pointes. Levosimendan has been shown to have beneficial survival effects in several populations; its use improves patient outcomes relative to the standard of care and has the potential to reduce hospital costs associated with heart failure.

Discovery and optimization of potent and selective imidazopyridine and imidazopyridazine mTOR inhibitors

mTOR is a critical regulator of cellular signaling downstream of multiple growth factors. The mTOR/PI3K/AKT pathway is frequently mutated in human cancers and is thus an important oncology target. Herein we report the evolution of our program to discover ATP-competitive mTOR inhibitors that demonstrate improved pharmacokinetic properties and selectivity compared to our previous leads. Through targeted SAR and structure-guided design, new imidazopyridine and imidazopyridazine scaffolds were identified that demonstrated superior inhibition of mTOR in cellular assays, selectivity over the closely related PIKK family and improved in vivo clearance over our previously reported benzimidazole series.

Pharmacological characterization of A-960656, a histamine H₃ receptor antagonist with efficacy in animal models of osteoarthritis and neuropathic pain

Histamine H(3) receptor antagonists have been widely reported to improve performance in preclinical models of cognition, but more recently efficacy in pain models has also been described. Here, A-960656 ((R)-2-(2-(3-(piperidin-1-yl)pyrrolidin-1-yl)benzo[d]thiazol-6-yl)pyridazin-3(2H)-one) was profiled as a new structural chemotype. A-960656 was potent in vitro in histamine H(3) receptor binding assays (rat K(i)=76 nM, human K(i)=21 nM), and exhibited functional antagonism in blocking agonist-induced [(35)S]GTPγS binding (rat H(3) K(b)=107 nM, human H(3) K(b)=22 nM), and was highly specific for H(3) receptors in broad screens for non-H(3) sites. In a spinal nerve ligation model of neuropathic pain in rat, oral doses of 1 and 3mg/kg were effective 60 min post dosing with an ED(50) of 2.17 mg/kg and a blood EC(50) of 639 ng/ml. In a model of osteoarthritis pain, oral doses of 0.1, 0.3, and 1mg/kg were effective 1h post dosing with an ED(50) of 0.52 mg/kg and a blood EC(50) of 233 ng/ml. The antinociceptive effect of A-960656 in both pain models was maintained after sub-chronic dosing up to 12 days. A-960656 had excellent rat pharmacokinetics (t(1/2)=1.9h, 84% oral bioavailability) with rapid and efficient brain penetration, and was well tolerated in CNS behavioral safety screens. In summary, A-960656 has properties well suited to probe the pharmacology of histamine H(3) receptors in pain. Its potency and efficacy in animal pain models provide support to the notion that histamine H(3) receptor antagonists are effective in attenuating nociceptive processes.

Acceptable plasma concentrations of raltegravir and etravirine when administered by gastrostomy tube in a patient with advanced multidrug-resistant human immunodeficiency virus infection

STUDY OBJECTIVE

To determine whether the absorption of four antiretroviral agents-raltegravir, etravirine, emtricitabine, and tenofovir-is compromised when administered by gastrostomy tube.

DESIGN

Pharmacokinetic analysis.

SETTING

University medical center.

PATIENT

A 52-year-old African-American man coinfected with advanced multidrug-resistant human immunodeficiency virus (HIV) and chronic hepatitis B, who was receiving treatment with raltegravir, etravirine, emtricitabine, and tenofovir, and developed ulcerative esophagitis with perforation, requiring a gastrostomy tube.

MEASUREMENTS AND MAIN RESULTS

Due to the patient's esophageal perforations, all nutrition and drug therapy had to be provided by gastrostomy tube. As his antiretroviral regimen of raltegravir, etravirine, and emtricitabine-tenofovir was not available in liquid or powder formulations, the oral tablets were crushed or dispersed and mixed with water, then administered by gastrostomy tube. To ensure that the absorption of the drugs was sufficient for antiretroviral response, plasma samples were collected at 2 hours and 12 hours after dosing, and drug concentrations were quantitated by using validated assays. The 2- and 12-hour postdose plasma concentrations were 1220 and 446 ng/ml for raltegravir, 212 and 274 ng/ml for etravirine, 1148 and 164 ng/ml for emtricitabine, and 320 and 94 ng/ml for tenofovir, respectively. The patient's plasma concentrations were then compared with those in published pharmacokinetic studies of oral regimens administered to HIV-infected persons and healthy volunteers. Overall, the plasma concentrations of the antiretrovirals administered by gastrostomy tube were similar to published values. No drug toxicities were observed in this patient.

CONCLUSION

These pharmacokinetic data suggest that absorption of raltegravir, etravirine, emtricitabine, and tenofovir was not compromised when the drugs were administered by gastrostomy tube. These findings provide a basis for further investigation of the pharmacokinetics, safety, tolerance, and antiretroviral response to raltegravir, etravirine, and emtricitabine-tenofovir when the oral route of administration is not possible.

Efficacy, safety, and pharmacokinetics of ambrisentan in Japanese adults with pulmonary arterial hypertension

OBJECTIVE

To investigate the efficacy, safety, and pharmacokinetics of ambrisentan in Japanese adults with pulmonary arterial hypertension (PAH).

RESEARCH DESIGN AND METHODS

In this open-label, uncontrolled, dose-escalation study, 25 Japanese patients with PAH were scheduled to receive 5 mg of ambrisentan once daily for the first 12 weeks, and 10 mg once daily for an additional 12 weeks. The primary endpoint was improvement in exercise capacity from baseline which was indicated by 6-minute walk distance; the secondary endpoints included World Health Organization functional class, Borg dyspnea index, plasma brain natriuretic peptide level, and cardiopulmonary hemodynamics.

CLINICAL TRIAL REGISTRATION

NCT00540436.

RESULTS

At week 24, improvements were noted in all endpoints, with no clinically significant elevation of serum aminotransferase level. Pharmacokinetics in these Japanese patients was similar to that of non-Japanese populations, suggesting that once-daily dosing is appropriate in Japanese patients. Ambrisentan was generally well tolerated. No new safety signals were identified.

LIMITATION

This study lacked a control group and was insufficiently powered to reach definitive conclusions on the efficacy of ambrisentan.

CONCLUSION

Ambrisentan is considered as safe and effective for Japanese adults with PAH.

Effects of etravirine alone and with ritonavir-boosted protease inhibitors on the pharmacokinetics of dolutegravir

Dolutegravir (DTG) is an unboosted, once-daily integrase inhibitor currently in phase 3 trials. Two studies evaluated the effects of etravirine (ETR) alone and in combination with ritonavir (RTV)-boosted protease inhibitors (PIs) on DTG pharmacokinetics (PK) in healthy subjects. DTG 50 mg every 24 h (q24h) was administered alone for 5 days in period 1, followed by combination with ETR at 200 mg q12h for 14 days in period 2 (study 1) or with ETR/lopinavir (LPV)/RTV at 200/400/100 mg q12h or ETR/darunavir (DRV)/RTV at 200/600/100 mg q12h for 14 days in period 2 (study 2). PK samples were collected on day 5 in period 1 and day 14 in period 2. All of the treatments were well tolerated. ETR significantly decreased exposures of DTG, with geometric mean ratios of 0.294 (90% confidence intervals, 0.257 to 0.337) for the area under the curve from time zero until the end of the dosage interval (AUC(0-τ)), 0.484 (0.433 to 0.542) for the observed maximum plasma concentration (C(max)), and 0.121 (0.093 to 0.157) for the plasma concentration at the end of the dosage interval (C(τ)). ETR combined with an RTV-boosted PI affected the exposure of DTG to a lesser degree: ETR/LPV/RTV treatment had no effect on the DTG plasma AUC(0-τ) and C(max), whereas the C(τ) increased by 28%. ETR/DRV/RTV modestly decreased the plasma DTG AUC(0-τ), C(max), and C(τ) by 25, 12, and 37%, respectively. Such effects of ETR/LPV/RTV and ETR/DRV/RTV are not considered clinically relevant. The combination of DTG and ETR alone should be avoided; however, DTG may be coadministered with ETR without a dosage adjustment if LPV/RTV or DRV/RTV is concurrently administered.

[Etravirine in highly treatment-experienced patients]

Etravirine (ETR) has demonstrated efficacy in patients with multiple prior treatments with prior virological failure and resistance mutations to various families of antiretroviral drugs. Most of the evidence concerning this drug has been drawn from the DUET studies, consisting of two multicenter, randomized, double-blind clinical trials with identical designs that included 1,200 patients. These trials showed that ETR obtained a superior virological and immunological response to placebo, reducing the incidence of hospital admissions and progression to AIDS/death. The most frequent adverse effect was rash, which was generally mild to moderate and required treatment discontinuation in only 2%. There were no differences in gastrointestinal, liver or lipid toxicities compared with the placebo arm. Because of the recent development of new drugs, effective regimens are now available for multi-treated patients. The TRIO study evaluated the efficacy and tolerability of one of the regimens most widely used today (ETR/raltegravir/darunavir/r) with excellent virological and immunological response (86% of viral load < 50 copies and CD4 +108 at 48 weeks) and excellent tolerance. ETR is effective and well tolerated and is the first non-nucleoside reverse transcriptase inhibitor (NNRTI) that allows the sequential use of drugs in this family, due to its high genetic barrier compared with firstgeneration NNRTI. Moreover, its long half-life allows once daily administration in patients requiring a QD regimen.

Simplification of antiretroviral therapy with etravirine

Etravirine is the first representative of a new generation of nonnucleoside reverse transcriptase inhibitors and demonstrates potent antiviral activity against HIV strains resistant to other available nonnucleoside reverse transcriptase inhibitors. The drug demonstrates efficacy when added to an optimized background regimen in patients who experience virologic failure with multiple drug classes including nonnucleoside reverse transcriptase inhibitors. Although the pill burden (four pills) is currently higher than that for nevirapine and efavirenz, etravirine can be taken once daily and may also be dispersed in water. It appears to be a safe and tolerable option. Due to its lack of significant interactions, its efficacy, and tolerability, it can be considered a suitable option for antiretroviral therapy, even in patients with prior exposure to nonnucleoside reverse transcriptase inhibitors. Long-term trials are necessary to confirm the role of etravirine in simplification strategies, but preliminary clinical data is reassuring.

Effects of food intake and anesthetic on cardiac imaging and uptake of BMS747158-02 in comparison with FDG

BACKGROUND

BMS747158-02 is an (18)F-labeled agent being developed for PET myocardial perfusion imaging. This study examined impacts of feeding state and anesthetic on cardiac imaging and uptake of this agent in rats in comparison with (18)F-fluorodeoxyglucose (FDG).

METHODS AND RESULTS

Studies were performed in rats either nonfasted or food deprived for 20 hours and anesthetized with either sodium pentobarbital (Pentob) or ketamine and xylazine (Ket/Xyl). Influences of the feeding state and anesthesia were examined by measurement of blood glucose levels, and tissue biodistribution and cardiac imaging of BMS747158-02 and FDG. The blood glucose levels were lower in fasted than nonfasted rats before anesthesia (91 +/- 11 vs 122 +/- 10 mg/dL) and the levels did not significantly change when anesthetized with Pentob. However, the levels increased markedly by 262 +/- 64 mg/dL in nonfasted rats anesthetized with Ket/Xyl. At 60 minutes post-injection, the heart uptake of FDG was significantly lower in fasted than nonfasted rats (0.2 +/- 0.1 vs 2.8 +/- 1.5%ID/g). However, the heart uptake of BMS747158-02 did not differ under these conditions (3.3 +/- 0.9 vs 3.6 +/- 0.9%ID/g, respectively). In nonfasted rats, the heart uptake of FDG was markedly lower when anesthetized with Ket/Xyl than with Pentobl (0.2 +/- 0.1 vs 2.8 +/- 1.5%ID/g). In contrast, the heart uptake of BMS747158-02 was similar with both anesthetics (3.6 +/- 0.5 vs 3.6 +/- 0.9%ID/g). Consistent with the biodistribution studies, the myocardium was not visible following FDG imaging in fasted rats, but clearly seen with BMS747158-02 in both fasted and nonfasted rats anesthetized with either anesthetic.

CONCLUSIONS

Unlike FDG, BMS747158-02 cardiac images are clear and not affected by the feeding state and anesthetics.

Metabolism of flufenpyr-ethyl in rats and mice

The metabolism of flufenpyr-ethyl [ethyl 2-chloro-5-[1,6-dihydro-5-methyl-6-oxo-4-(trifluoromethyl)pyridazin-1-yl]-4-fluorophenoxyacetate] was examined in rats and mice. [Phenyl-(14)C]flufenpyr-ethyl was administered to rats and mice as a single oral dose at a level of 500 mg/kg, and (14)C-excretion was examined. Total (14)C-recoveries within 7 days after administration were 93.2 to 97.5% (feces, 42.0 to 46.0%; and urine, 47.2 to 55.5%) in rats and 92.6 to 96.4% (feces, 26.7 to 32.7%; and urine, 59.9 to 69.7%) in mice. (14)C-Excretion into expired air was not detected in rats (expired air of mice was not analyzed). No marked species- or sex-related differences were observed in the rate of (14)C-elimination, but a relatively higher excretion into the urine of mice was observed compared to that in rats. (14)C-residues in tissue 7 days after administration were relatively high for liver, hair, skin, and kidney, but total (14)C-residues were low, below 0.2% of the dose. An ester cleaved metabolite (S-3153acid) was the major metabolite in feces and urine. Hydroxylation of the methyl group on the C5 of the pyridazine ring and ether cleavage were also observed. No sex-related differences were observed in (14)C-elimination, (14)C-distribution, and metabolite profiles, and metabolism of flufenpyr-ethyl in rats and mice was similar. In vitro metabolism of flufenpyr-ethyl was examined using stomach and intestinal contents and blood and liver S9 fractions (postmitochondrial supernatant fractions) in rats. S-3153acid was detected as a major metabolite in the presence of intestinal contents and blood and liver S9 fractions, and a small amount was also formed in the presence of stomach contents, indicating that the parent compound is rapidly metabolized by intestinal contents and blood and liver S9 fractions through ester cleavage.

Effect of steady-state etravirine on the pharmacokinetics and pharmacodynamics of ethinylestradiol and norethindrone

BACKGROUND

Etravirine, a non-nucleoside reverse transcriptase inhibitor (NNRTI) active against NNRTI-resistant HIV, is an inducer of CYP3A4 and an inhibitor of CYP2C9/19.

STUDY DESIGN

The effect of etravirine on the pharmacokinetics and pharmacodynamics of ethinylestradiol and norethindrone was assessed in 30 HIV-negative females. Following a run-in cycle with ethinylestradiol/norethindrone, the pharmacokinetics of ethinylestradiol and norethindrone was assessed on Day 15 of Cycle 2. Etravirine 200 mg bid was coadministered on Day 1 to Day 15 of Cycle 3, with pharmacokinetic assessments of ethinylestradiol, norethindrone and etravirine on Day 15.

RESULTS

When combined with etravirine, the least-squares means (LSM) ratios (90% confidence interval) for ethinylestradiol AUC(24h), C(max) and C(min) were 1.22 (1.13-1.31), 1.33 (1.21-1.46) and 1.09 (1.01-1.18), respectively, compared to administration alone. LSM ratios for norethindrone parameters were 0.95 (0.90-0.99), 1.05 (0.98-1.12) and 0.78 (0.68-0.90), respectively.

CONCLUSION

These changes are not considered clinically relevant. No loss in contraceptive efficacy is expected when coadministered with etravirine.

A pharmacokinetic study of etravirine (TMC125) co-administered with ranitidine and omeprazole in HIV-negative volunteers

AIMS

Etravirine is a next-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) with activity against wild-type and NNRTI-resistant HIV. Proton pump inhibitors and H(2)-antagonists are frequently used in the HIV-negative-infected population, and drug-drug interactions have been described with other antiretrovirals. This study evaluated the effect of steady-state omeprazole and ranitidine on the pharmacokinetics of a single dose of etravirine.

METHODS

In an open-label, randomized, one-way, three-period crossover trial, HIV-negative volunteers randomly received a single dose of 100 mg etravirine alone (treatment A); 11 days of 150 mg ranitidine b.i.d. (treatment B); and 11 days of 40 mg omeprazole q.d. (treatment C). A single dose of 100 mg etravirine was co-administered on day 8 of sessions 2 and 3. Each session was separated by a 14-day wash-out.

RESULTS

Nineteen volunteers (seven female) participated. When a single dose of etravirine was administered in the presence of steady-state ranitidine, etravirine least squares means ratios (90% confidence interval) for AUC(last) and C(max) were 0.86 (0.76, 0.97) and 0.94 (0.75, 1.17), respectively, compared with administration of etravirine alone. When administered with steady-state omeprazole, these values were 1.41 (1.22, 1.62) and 1.17 (0.96, 1.43), respectively. Co-administration of a single dose of etravirine and ranitidine or omeprazole was generally safe and well tolerated.

CONCLUSIONS

Ranitidine slightly decreased etravirine exposure, whereas omeprazole increased it by approximately 41%. The increased exposure of etravirine when co-administered with omeprazole is attributed to CYP2C19 inhibition. Considering the favourable safety profile of etravirine, these changes are not clinically relevant. Etravirine can be co-administered with proton pump inhibitors and H(2) antagonists without dose adjustments.

Marked impact of P-glycoprotein on the absorption of TAK-427 in rats

The role of P-glycoprotein (P-gp, ABCB1) on the absorption process was investigated by drug-drug interaction studies of TAK-427 with P-gp inhibitors (erythromycin, ketoconazole or quinidine) in rats and by transport studies using rat multidrug resistance (MDR1) stably expressing cells and rat small intestine mounted in a Ussing-type chamber. TAK-427 showed high efflux activity with low permeability in rat MDR1a and MDR1b stably expressing cells and was revealed to be a typical substrate for P-gps. Although TAK-427 was mainly absorbed from the small intestine in rats, a large part of the dosed compound remained in the gastrointestinal tract. Orally co-administered P-gp inhibitors (50 mg/kg) increased the AUC of TAK-427 after a 5 mg/kg oral dose 5.4- to 18.3-fold, whereas orally administered P-gp inhibitors had a minor effect on the increase in the AUC of TAK-427 (1.3- to 2.2-fold) after a 0.5 mg/kg intravenous dose. Thus, the bioavailability of TAK-427 after oral administration in rats (7.3%) markedly increased when co-administered with P-gp inhibitors (28.6-57.6%). Moreover, the transport of TAK-427 was predominantly secretory throughout the rat small intestine and was inhibited by P-gp inhibitors. In conclusion, P-gp can markedly reduce the absorption of a typical P-gp substrate by its efflux activity throughout the absorption site.

Pharmacokinetics of elvitegravir and etravirine following coadministration of ritonavir-boosted elvitegravir and etravirine

BACKGROUND

This crossover, open-label clinical study evaluated the potential for clinically relevant drug interactions between ritonavir-boosted elvitegravir (elvitegravir/r), an HIV integrase inhibitor, and etravirine, a non-nucleoside reverse transcriptase inhibitor.

METHODS

Healthy volunteers were randomized into one of two groups, each with two arms. Group 1 (n = 20) followed a sequence of 10-day dosing of elvitegravir/r (150/100 mg once daily) and elvitegravir/r plus etravirine (200 mg twice daily) or the reverse (n = 10 per sequence). Group 2 (n = 14) followed a sequence of 10-day dosing of etravirine and etravirine plus elvitegravir/r or the reverse (n = 7 per sequence), all under fed conditions. Elvitegravir, ritonavir and etravirine pharmacokinetics were determined on days 10 and 20 using non-compartmental analyses. Lack of pharmacokinetic alteration bounds for 90% confidence intervals (CI) about the geometric mean ratio (GMR; coadministration versus alone) were 70-143% for elvitegravir and ritonavir pharmacokinetics (maximum concentration [C(max)], concentration at the end of the dosing interval [C(tau)] and area under the plasma concentration-time curve [AUC(tau); 0-24 h] and 80-125% for etravirine pharmacokinetics (AUC(tau) 0-12 h).

RESULTS

Of the 34 enrolled participants, 31 completed the study. There were three discontinuations, but none were caused by adverse events (AEs). The most common treatment-emergent AE was headache. Elvitegravir pharmacokinetic GMR was 6-7% higher following elvitegravir/r plus etravirine dosing versus elvitegravir/r. The GMR for etravirine and ritonavir AUC(tau) were 2.4% and 12.3% lower, respectively. Importantly, the 90% CI for elvitegravir and etravirine pharmacokinetics and AUC(tau) and C(max) for ritonavir were within the lack of alteration bounds.

CONCLUSIONS

Elvitegravir/r and etravirine do not undergo clinically relevant drug interactions and can be coadministered without dose adjustment.

Single- and multiple-dose pharmacokinetics of etravirine administered as two different formulations in HIV-1-infected patients

BACKGROUND

An open-label, randomized, crossover study to evaluate the pharmacokinetics of two different formulations of etravirine after single and multiple dosing.

METHODS

Treatment-experienced HIV-1-infected patients with viral load <50 copies/ml continued their current antiretroviral regimen and added etravirine twice daily for 7 days with a morning intake on day 8. Etravirine was administered following food as either 800 mg twice daily of the Phase II formulation or 100 mg or 200 mg twice daily of the Phase III formulation. A 12 h pharmacokinetic assessment was performed on days 1 and 8.

RESULTS

After single- and multiple-dose administration, the exposure to etravirine was lower with 100 mg twice daily and higher with 200 mg twice daily compared with 800 mg twice daily. On day 8, the mean (+/-SD) area under the plasma concentration-time curve over 12 h (AUC0-12 h) was 1,284 (+/-958) ng x h/ml when etravirine was administered as 100 mg twice daily (n=33), 3,713 (+/-2,069) ng x h/ml when administered as 200 mg twice daily (n=27) and 2,607 (+/-2,135) ng x h/ml when administered as 800 mg twice daily (n=32). Both formulations and all doses of etravirine tested were generally safe and well tolerated.

CONCLUSIONS

The range of exposure to etravirine was comparable between 200 mg twice daily dose and 800 mg twice daily. The Phase III formulation of etravirine significantly improves the bioavailability of etravirine over the Phase II formulation with reduced interpatient variability in etravirine pharmacokinetics.

Contribution of specific binding to the central benzodiazepine site to the brain concentrations of two novel benzodiazepine site ligands

The in vivo occupancy of brain benzodiazepine binding sites by compounds A and B was measured using a [(3)H]Ro 15-1788 binding assay and related to plasma and brain drug concentrations. The plasma concentration associated with 50% occupancy was higher for compound A than compound B (73 and 3.7 nM, respectively), however, there was little difference in the brain concentrations required (73 and 63 nM). Both compounds showed a non-linear relationship between plasma and brain concentrations such that above brain concentrations of approximately 100 nM increasing plasma concentrations did not result in a concomitant increase in brain concentrations. This is consistent with brain concentrations being dependent on a saturable compartment which was postulated to be the benzodiazepine binding site-containing GABA(A) receptors. This hypothesis was tested in alpha1H101R mice, in which the alpha1 subunit of the GABA(A) receptor is rendered insensitive to benzodiazepine binding resulting in an approximate 50% reduction in the total benzodiazepine-containing GABA(A) receptor population. It was shown that the Occ(50) brain concentrations in the alpha1H101R animals was lower (17 nM) than in wild type mice (63 nM), as was the plateau concentration in the brain (105 and 195 nM, respectively). These data suggest measured concentrations of compounds A and B in brain tissue are dependent on receptor expression with a minimal contribution from unbound and non-specifically bound compound.

Pharmacokinetics and excretion balance of OR-1896, a pharmacologically active metabolite of levosimendan, in healthy men

OBJECTIVE

To investigate the pharmacokinetics and excretion balance of [(14)C]-OR-1896, a pharmacologically active metabolite of levosimendan, in six healthy male subjects. In addition, pharmacokinetic parameters of total radiocarbon and the deacetylated congener, OR-1855, were determined.

METHODS

OR-1896 was administered as a single intravenous infusion of 200 microg of [(14)C]-OR-1896 (specific activity 8.6 MBq/mg) over 10 min. The pharmacokinetic parameters were calculated by three-compartmental methods.

RESULTS

During the 14-day collection of urine and faeces, excretion (+/-S.D.) averaged 94.2+/-1.4% of the [(14)C]-OR-1896 dose. Mean recovery of radiocarbon in urine was 86.8+/-1.9% and in faeces 7.4+/-1.5%. Mean terminal elimination half-life of OR-1896 (t(1/2)) was 70.0+/-44.9 h. Maximum concentrations of OR-1855 were approximately 30% to that of OR-1896. Total clearance and the volume of distribution of OR-1896 were 2.0+/-0.4 l/h and 175.6+/-74.5l, respectively. Renal clearances of OR-1896 and OR-1855 were 0.9+/-0.4 l/h and (5.4+/-2.3)x10(-4) l/h, respectively.

CONCLUSIONS

This study provides data to demonstrate that nearly one half of OR-1896 is eliminated unchanged into urine and that the active metabolites metabolite of levosimendan remain in the body longer than levosimendan. The remaining half of OR-1896 dose is eliminated through other metabolic routes, partially through interconversion back to OR-1855 with further metabolism of OR-1855. Given the fact that the pharmacological activity and potency of OR-1896 is similar to levosimendan, these results emphasize the clinical significance of OR-1896 and its contribution to the long-lasting effects of levosimendan.

[Role of Levosimendan in intensive care treatment of myocardial insufficiency]

Levosimendan is a calcium sensitizer that is currently in the focus of intensive care medicine because it may be superior to standard inotropic agents in the treatment of acute myocardial insufficiency. The effects of levosimendan mainly depend on three predominant mechanisms: 1) positive inotropic effect by increasing the sensitivity of cardiac myofilaments to calcium ions, 2) vasodilatory effect by stimulation of adenosine triphosphate-sensitive potassium channels and 3) inhibition of phosphodiesterase-III. In a large number of experimental and clinical studies further possible indications for levosimendan have been described, e.g. cardioprotection during ischemia, cardiogenic shock, septic myocardial insufficiency and pulmonary hypertension. This review article critically summarizes the current scientific and clinical knowledge about levosimendan, its pharmacologic characteristics, mechanisms of action as well as indications and potential risks.

Clinical pharmacology of levosimendan

Levosimendan has been developed for the treatment of decompensated heart failure and is used intravenously when patients with heart failure require immediate initiation of drug therapy. It increases cardiac contractility and induces vasodilatation. The pharmacokinetics of levosimendan are linear at the therapeutic dose range of 0.05-0.2 microg/kg/minute. The short half-life (about 1 hour) of the parent drug, levosimendan, enables fast onset of drug action, although the effects are long-lasting due to the active metabolite OR-1896, which has an elimination half-life of 70-80 hours in patients with heart failure (New York Heart Association functional class III-IV). Although levosimendan is administered intravenously, it is excreted into the small intestine and reduced by intestinal bacteria to an amino phenolpyridazinone metabolite (OR-1855). This metabolite is further metabolised by acetylation to N-acetylated conjugate (OR-1896). The circulating metabolites OR-1855 and OR-1896 are formed slowly, and their maximum concentrations are seen on average 2 days after stopping a 24-hour infusion. The haemodynamic effects after levosimendan seem to be similar between fast and slow acetylators despite the fact that the enzyme N-acetyltransferase-2, which is responsible for the metabolism of OR-1855 to OR-1896, is polymorphically distributed in the population. Levosimendan reduces peripheral vascular resistance and has direct contractility-enhancing effects on the failing left ventricle. It also improves indices of diastolic function and seems to improve the function of stunned myocardium. Despite an improvement in ventricular function, levosimendan does not increase myocardial oxygen uptake significantly. An increase in coronary blood flow and a reduction in coronary vascular resistance have been observed. Levosimendan reduces plasma brain natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP) levels substantially, and a decrease in plasma endothelin-1 has been observed. Levosimendan also exerts beneficial effects on proinflammatory cytokines and apoptosis mediators. The effects of a 24-hour levosimendan infusion on filling pressure, ventricular function and BNP, as well as NT-proBNP, last for at least 7 days.

Pharmacokinetics and antiretroviral response to darunavir/ritonavir and etravirine combination in patients with high-level viral resistance

BACKGROUND

Cumulative antiretroviral exposure can result in multiclass HIV drug resistance. Experimental antiretroviral agents offer limited therapeutic benefit as resistance quickly develops after their introduction as a sole new agent.

OBJECTIVE

To assess the pharmacokinetic profile, safety and virological response of two novel investigational antiretroviral agents when used in combination in HIV-1-infected subjects with multidrug-resistant virus.

METHODS

HIV-1-infected subjects, with current virological failure on a stable antiretroviral regimen with no viable treatment options were assigned to a regimen comprising two new investigational agents, etravirine, a novel nonnucleoside reverse transcriptase inhibitor, and darunavir, a novel protease inhibitor, plus nucleoside reverse transcriptase inhibitors (and enfuvirtide in selected patients) for 24 weeks. Virological, immunological and safety parameters were collected. Detailed pharmacokinetic assessments of darunavir and etravirine were determined on days 7 and 28.

RESULTS

Follow up of 24 weeks was achieved by 10/12 patients. Median reduction in HIV RNA was 2.7 log10 copies/ml (range, 2.3-3.9) and increase in CD4 lymphocytes was 113 cells/microl (range, 41-268). HIV RNA was < 40 copies/ml in nine. No serious adverse events were recorded. Plasma exposure to darunavir was similar to historic control data and exposure to etravirine similar to historic data when etravirine was administered with a boosted protease inhibitor.

CONCLUSION

This first study to assess the use of etravirine and darunavir in HIV-1-infected subjects with no treatment options showed highly effective virological and immunological responses over 24 weeks of therapy with no new safety concerns or unexpected pharmacokinetic interactions.

Pharmacodynamic and pharmacokinetic effects of TPA023, a GABA(A) alpha(2,3) subtype-selective agonist, compared to lorazepam and placebo in healthy volunteers

TPA023, a GABA(A) alpha2,3 alphasubtype-selective partial agonist, is expected to have comparable anxiolytic efficacy as benzodiazepines with reduced sedating effects. The compound lacks efficacy at the alpha1 subtype, which is believed to mediate these effects. This study investigated the effects of 0.5 and 1.5 mg TPA023 and compared them with placebo and lorazepam 2 mg (therapeutic anxiolytic dose). Twelve healthy male volunteers participated in this placebo-controlled, double-blind, double-dummy, four-way, cross-over study. Saccadic eye movements and visual analogue scales (VAS) were used to assess the sedative properties of TPA023. The effects on posturaL stability and cognition were assessed using body sway and a standardized battery of neurophysiological memory tests. Lorazepam caused a significant reduction in saccadic peak velocity, the VAS alertness score and impairment of memory and body sway. TPA023 had significant dose dependent effects on saccadic peak velocity (85 deg/sec maximum reduction at the higher dose) that approximated the effects of lorazepam. In contrast to lorazepam, TPA023 had no detectabLe effects on saccadic latency or inaccuracy. Also unlike lorazepam, TPA023 did not affect VAS alertness, memory or body sway. These results show that the effect profile of TPA023 differs markedly from that of lorazepam, at doses that were equipotent with regard to effects on saccadic peak veLocity. Contrary to lorazepam, TPA023 caused no detectable memory impairment or postural imbalance. These differences reflect the selectivity of TPA023 for different GABA(A) receptor subtypes.