POS1128 COMBINATION TREATMENT OF AR882, A NEW URAT1 INHIBITOR, AND XANTHINE OXIDASE INHIBITORS ALLOPURINOL OR FEBUXOSTAT: EFFECT ON URIC ACID, HYPOXANTHINE AND XANTHINE IN PLASMA OR SERUM AND URINE

Background:

Xanthine oxidase inhibitors (XOI) are commonly used as urate lowering therapy (ULT) for the treatment of gout. Allopurinol, the first-line treatment, demonstrates low response rate (< 40%), defined as serum urate (sUA) lowering effect below 6 mg/dL, in multiple large-scale clinical trials. As recommended in EULAR guidelines and other literatures, targeting sUA <5 mg/dL or even <4 mg/dL, provides a better opportunity to lower incidence of gout flare and resolution of tophi in gout patients. Febuxostat, a more potent XOI, has been classified as a second-line ULT agent due to increased cardiovascular risks in certain patient populations. For XOI intolerance and non-responders, replacing the agent with a potent URAT1 inhibitor or adding an URAT1 inhibitor onto a current treatment regimen provides opportunities to improve response rates in patients with refractory gout. AR882 is a uricosuric agent that blocks the reabsorption of uric acid in the apical side of renal tubule, hence increases excretion of uric acid into the urine. A phase 2a study has demonstrated the additive effects of AR882 in combination with allopurinol or febuxostat.

Objectives:

To evaluate the effect of AR882 alone or in combination with allopurinol or febuxostat on circulating levels and urinary excretion of hypoxanthine, xanthine and uric acid. Furthermore, to elucidate the contribution of each drug towards the combination effect in sUA lowering.

Methods:

Plasma, serum, and urine samples were collected from 17 patients with gout who received a once-daily dosing of AR882 50 mg, allopurinol 300 mg or febuxostat 40 mg, or in combination for one week in a phase 2a study. Samples were collected to measure hypoxanthine, xanthine and uric acid levels in plasma or serum and the amount of each excreted in the urine. Plasma Cmax and AUC and 24-hour urine excretion amount (mg) of hypoxanthine and xanthine were calculated by non-compartmental analysis method.

Results:

In monotherapy, AR882 demonstrated better sUA lowering effect (↓53%) compared to allopurinol (↓35%) or febuxostat (↓39%). Combination of AR882 and allopurinol lowered sUA by 66% while combination of AR882 and febuxostat lowered sUA by 71%. Based on the change of xanthine in plasma following combination treatments, it can be calculated that allopurinol contributed 28% of the urate lowering effect, whereas AR882 contributed 38% of the effect. Similarly, febuxostat contributed 33% of the urate lowering effect and AR882 contributed to about 36-38% of the effect when used in combination. The combination treatments significantly increased the response ratio for patients achieving sUA levels < 5 mg/dL, 4 mg/dL, and even 3 mg/dL. In the combination with allopurinol, 100%, 100%, 100%, and 44% patients achieved sUA < 6 mg/dL, < 5 mg/dL, 4 mg/dL, and 3 mg/dL, respectively. Similar results were seen with the combination of AR882 and febuxostat. Treatment with allopurinol or febuxostat alone resulted in 8 to 10-fold and 16-fold increases of xanthine exposure, respectively. The combination of AR882 and allopurinol or febuxostat showed approximately 5-8 fold or 13-fold increases in plasma xanthine, respectively. Treatment with allopurinol or febuxostat alone resulted in 2-3 fold increase in hypoxanthine exposure. Relative changes of hypoxanthine were not significantly different in the presence versus absence of AR882. Increased excretion of xanthine and hypoxanthine was also observed in urine. AR882 was well tolerated in gout patients, showing a similar safety profile to that observed in healthy volunteer studies.

Conclusion:

AR882 dose alone had no effect on plasma or urine hypoxanthine and xanthine levels. AR882 contributed to a greater portion of the serum urate lowering effects when used in combination with XO inhibitors, and with 100% of patients achieving levels below 4 mg/dL when combined with allopurinol. The use of AR882 in combination with XO inhibitors may provide an option for preventing flares as well as tophi reduction in advanced patients.

Disclosure of Interests:

Zancong Shen Employee of: arthrosi therapeutics, Chris Colton Employee of: Arthrosi therapeutics Inc, Rongzi Yan Employee of: Arthrosi therapeutics Inc, Elizabeth Polvent Employee of: Arthrosi therapeutics Inc, Vijay Hingorani Consultant of: Arthrosi therapeutics Inc, Shunqi Yan Employee of: Arthrosi therapeutics Inc, Li-Tain Yeh Employee of: Arthrosi therapeutics Inc.

POS1130 PHARMACOKINETICS AND SERUM URATE LOWERING EFFECTS OF AR882, A NOVEL, POTENT AND SELECTIVE URICOSURIC AGENT, IN PATIENTS WITH GOUT

Background:

AR882 is a novel, potent and selective uric acid transporter 1 (URAT1) inhibitor in Phase 2 development for the treatment of hyperuricemia and gout. In Phase 1 healthy subject studies, AR882 demonstrated good dose proportionality, a long effective half-life and sustained serum urate (sUA) lowering effects, consequently making it suitable for once-daily dosing. In addition, AR882 was well tolerated following single and multiple dosing.

Objectives:

This Phase 2a study evaluated the pharmacokinetics (PK), pharmacodynamics (PD), and safety of AR882 following monotherapy in patients with gout. PK and sUA lowering effects in patients with renal impairment and normal renal function were also compared.

Methods:

A total of 30 adults with gout (sUA >7 mg/dL) were enrolled and 28 had post-baseline PKPD assessments performed. AR882 was administered at escalating doses of 25, 50 and 75 mg, with each dose administered once daily for 7 days. Serial blood samples were collected to measure AR882 PK and sUA levels at the end of each treatment week. Urine samples were collected for assessment of uric acid excretion. Laboratory safety tests, vital signs, and electrocardiograms were collected throughout the study.

Results:

Following once daily administration in patients with gout, AR882 exposures increased dose proportionally between 25 and 75 mg. Mean sUA levels were maximally reduced from baseline (mean 8.9 mg/dL) to 5.6, 4.2 and 3.2 mg/dL at the 25-, 50- and 75-mg dose levels, respectively. The corresponding percent reductions were 36.8%, 52.7% and 61.5%. The effects were sustained throughout the entire dosing day with minimal fluctuation. In patients receiving 25 mg AR882 (N=9), 56% achieved sUA levels below 6 mg/dL. At 50 mg (N=28), 96% of patients had sUA levels below 6 mg/dL and 93% were below 5 mg/dL. At the 75 mg dose (N=8), all patients (100%) achieved levels below 5 mg/dL, and 88% were below 4 mg/dL. Among these 28 gout patients, 17 patients had normal renal function (CrCL>90 mL/min) and 11 patients had mild impairment (CrCL 60-90 mL/min). AR882 exposures were similar between patients with mild renal impairment and those with normal renal function. Both groups showed nearly identical sUA lowering effects following each 7-day dosing period. Response rates were also similar between these groups, including at the 50 and 75 mg dose levels. Consistent with its sUA lowering effects, dose-dependent increases in fractional excretion of uric acid were observed across all doses.

AR882 was well tolerated at all doses tested. All AEs were mild or moderate in severity and most were considered not related to study treatment. There were no serious AEs or AEs resulting in study drug discontinuation. There were no clinically significant laboratory or ECG abnormalities noted.

Conclusion:

In patients with gout, AR882 exhibited dose proportional increases in plasma exposure and dose-dependent reductions in sUA. Nearly all patients had sUA levels below 5 mg/dL at doses ≥50 mg, and about 90% of patients had sUA levels <4 mg/dL at 75 mg dosing. Similar PK exposures and sUA lowering effects were observed in patients with mild renal impairment compared to those with normal renal function. Current data suggest that AR882 50 mg may offer improved efficacy over existing standard-of-care for gout and AR882 75 mg may have utility in the treatment of patients with severe or refractory gout disease.

Figure 1.

Percent of Patients with sUA below 6 mg/dL, 5 mg/dL, 4 mg/dL or 3 mg/dL Following Once-Daily Oral Doses of AR882.

Table 1.

Mean (SD) sUA Levels Following Once-Daily Oral Doses of AR882.

TreatmentNTime (hr), sUA (mg/dL)061224Baseline308.8 (1.1)8.8 (1.1)9.0 (1.0)8.9 (1.1)25 mg96.1 (0.4)5.6 (0.4)5.6 (0.3)5.8 (0.4)50 mg284.7 (0.9)4.2 (0.9)4.3 (0.8)4.7 (1.0)75 mg83.7 (1.1)3.2 (0.9)3.2 (0.8)3.6 (1.0)50 mg (normal renal function)174.8 (1.1)4.3 (1.1)4.4 (0.9)4.8 (1.2)50 mg (mild impairment)114.5 (0.6)4.1 (0.6)4.3 (0.5)4.6 (0.6)

Disclosure of Interests:

Zancong Shen Employee of: Arthrosi Therapeutics Inc, Elizabeth Polvent Employee of: Arthrosi Therapeutics Inc, Vijay Hingorani Consultant of: Arthrosi Therapeutics Inc, Andrea Clouser Roche Employee of: Arthrosi Therapeutics Inc, Chris Colton Employee of: Arthrosi Therapeutics Inc, Rongzi Yan Employee of: Arthrosi Therapeutics Inc, Shunqi Yan Employee of: Arthrosi Therapeutics Inc, Li-Tain Yeh Employee of: Arthrosi Therapeutics Inc.

Integration of imaging and molecular approaches in selective fetal reduction in twin pregnancies with one carrying a pathogenic genomic aberration

BACKGROUND/PURPOSE

With the evolution of assisted fertility and prenatal diagnostic technology, the prevalence of multi-fetal pregnancy increased, followed by the demand for prenatal intervention if genomic aberration was detected. How to distinguish the affected foetus from the normal co-twin before selective fetal reduction is therefore challenging.

OBJECTIVES

We retrospectively reviewed the cases of dichorionic twins at our centre during 2004-2018, where selective fetal reduction was requested because one foetus carried a pathogenic genomic aberration. Five cases were enrolled, including three foetuses with trisomy 21, one foetus with microduplication and one foetus with microdeletion disorders.

METHOD

We labelled the affected foetus by prenatal ultrasound and rapid molecular tools. For the twins without discriminating sonographic features (e.g., the same gender and no distinct placentae), interphase fluorescence in situ hybridization, rapid microarray and short tandem repeat markers were applied to identify the affected foetus.

RESULTS

Selective fetal reduction was allocated accurately for all individuals. Two cases delivered at term, while two delivered preterm, and one developed fetal loss of the co-twin.

CONCLUSION

We proposed a working scheme of integrating imaging and molecular techniques to correctly identify the affected co-twin before selective fetal reduction to ensure the accuracy of the identification.

Effectiveness and safety of rocuronium-hypnotic sequence for rapid-sequence induction

BACKGROUND

Either succinylcholine or rocuronium administered after a hypnotic is the current technique for rapid-sequence induction. It is assumed that rocuronium administered before a hypnotic (Rocuronium-hypnotic sequence) may equally provide an acceptable intubation condition as well as a shorter period of apnea in rapid-sequence induction. We designed a prospective, randomized study to evaluate the effectiveness and safety of the technique in a similar rapid-sequence induction.

METHODS

Ninety adult patients receiving elective surgeries were enrolled in this study. In all patients the procedure in the study began with i.v. injection of fentanyl 2 micrograms/kg, followed by preoxygenation with 100% O2 for 2 min. Afterward, the patients were randomly allocated to 3 groups with each group consisting of 30 patients. In Rocuronium-thiopental (Ro-Th) group the patients received rocuronium 0.6 mg/kg and then thiopental 5 mg/kg; in Th-Ro group the patients received thiopental 5 mg/kg and then rocuronium 0.6 mg/kg; and in Thiopental-Succinylcholine (Th-Sx) group, the control group, the patients received thiopental 5 mg/kg and then succinylcholine 1 mg/kg. Laryngoscopy and endotracheal intubation were performed 60 s after the injection of the muscle relaxant. The intubation condition, the apneal time before laryngoscopy, the intubation time, and total apneal time were investigated and compared. Presence of injection pain, sense of paralysis, SpO2 less than 95% during induction, and any unexpected adverse event were also recorded.

RESULTS

Six patients (1 in Ro-Th group, 2 in Th-Ro group, and 3 in Th-Sx group, respectively) were excluded from the study. The intubation conditions were acceptable in all patients of three groups who completed the study, and as to excellent intubation condition there was no difference between the three groups. In Ro-Th group both the apneal time before laryngoscopy (32.4 +/- 5.4 s) and total apneal time (48.5 +/- 11.0 s) were the shortest. Th-Ro group (53.2 +/- 5.8 and 67.5 +/- 8.3 s, respectively) and Th-Sx group (54.4 +/- 5.8 and 68.4 +/- 7.7 s, respectively) were similar in both aspects. With respect to intubation time there was no significant difference among the three groups. Five patients in Ro-Th group and one patient in Th-Sx group felt mild injection pain. Three patients in Ro-Th group were noted to have diminished breathing during induction, which was not recalled during enquiry in the postoperative visit. One patient in Ro-Th group saw a fall of SpO2 down below 95% (94% the minimal) during the apnea period.

CONCLUSIONS

Compared with traditional hypnotic-rocuronium or hypnotic-succinylcholine sequence, rocuronium (0.6 mg)-thiopental sequence can provide a similar intubation condition but cause a much shorter apneal period in rapid-sequence induction. In carrying out recuronium-thiopental sequence induction, maintaining a patent infusion line is essential to avoid drug precipitation and awareness of muscular weakness as a result of ill-timed action of thiopental.

Determination of spinosad and its metabolites in food and environmental matrices. 2. Liquid chomatography-mass spectrometry

A selective and sensitive method utilizing liquid chromatography-mass spectrometry (LC-MS) has been developed for determining residues of the natural insect control agent spinosad in several crop matrices that are difficult to analyze by HPLC with UV detection. The method determines the active ingredients (spinosyns A and D) and three minor metabolites (spinosyns B and K and N-demethylspinosyn D) in alfalfa hay, wheat hay, wheat straw, sorghum fodder, and corn stover. The analytes are extracted from the samples with an acetonitrile/water solution, and the extracts are purified by solid phase extraction with a C(18) disk and a silica cartridge. All five analytes are determined simultaneously in a single injection using positive atmospheric pressure chemical ionization LC-MS with selected ion monitoring. The average recoveries ranged from 69 to 96% with standard deviations ranging from 4 to 15%. The method has a validated limit of quantitation of 0. 01 microgram/g and a limit of detection of 0.003 microgram/g. The LC-MS method can also provide residue confirmation in addition to quantitation.

Determination of spinosad and its metabolites in food and environmental matrices. 1. High-performance liquid chromatography with ultraviolet detection

Spinosad is an insect control agent that is derived from a naturally occurring soil bacterium and is effective on several classes of insects, especially Lepidoptera larvae. Spinosad is registered in many countries for use on a variety of crops, including cotton, corn, soybeans, fruits, and vegetables. Residue methods utilizing high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection have been described for determining spinosad and its metabolites in environmental and food matrices. These residue methods typically involve an extraction with organic solvents, followed by purification using liquid-liquid partitioning and/or solid phase extraction prior to measurement by HPLC-UV. The residue methods determine the active ingredients (spinosyns A and D) and up to three minor metabolites (spinosyn B, spinosyn K, and N-demethylspinosyn D). The methods have validated limits of quantitation ranging from 0.010 to 0.040 microgram/g. This paper briefly reviews the residue methodology for spinosad and metabolites in food and environmental matrices and provides a summary of method validation results for 61 different sample types, including newly published results for 37 additional crop matrices and processed commodities.

An alternative continuous caudal block with caudad catheterization via lower lumbar interspace in adult patients

BACKGROUND

Continuous caudal block with caudad catheterization has not yet been mentioned in literatures. We designed a preliminary study to investigate the feasibleness of this technique, spread of contrast medium under fluoroscopy, and its clinical effectiveness.

METHODS

Ten patients were subjected to epidural block (caudal) for elective anal or vaginal procedures. The entry of the epidural needle was made at the L4-5 interspace either with midline or paramedian approach. Through an 18 G Touhy needle with its bevel facing caudally an epidural catheter was threaded until a length of 10 cm was beyond the point of entry. The presence or absence of paresthesia during the passage of catheter and the ease with which the catheter was inserted were recorded. After the procedure, the course on which the catheter traversed and the spread of the medicinal substance in the epidural space were visualized and studied fluoroscopically using 1 and 3 ml iohexol (omnipaque 300 mg/ml) as contrast medium respectively. Then the patients were brought to operating rooms for anesthesia and surgery. Sensory anesthetic level and motor blockade were evaluated fifteen min after 11-15 ml of 2% lidocaine had been injected through the epidural catheter. During anesthesia vital signs were closely monitored, and adverse reaction if any was evaluated and managed.

RESULTS

The insertion of the epidural catheter was considered easy and caused no paresthesia in nine patients. Catheter insertion encountered moderate resistance and induced paresthesia in one patient. Yet, the catheter was advanced successfully to the expected length. In radiological study with contrast medium, the course of the epidural catheter was not always traceable, while the spread of the contrast medium was clearly identified. Epidural spread occurred in eight patients, left paravertebral spread in one patient, and right retrorectal spread in another one patient. As to clinical assessment, adequate sensory blockade with local anesthetic was gained in 8 patients with well-preserved motor function of the lower limbs. In one patient the caudal block worked well after the withdrawal of the catheter 5 cm in length. Spinal anesthesia was supplemented in one patient due to failure of the caudal block.

CONCLUSIONS

Continuous caudal block with caudawise catheterization via lower lumbar interspaces is feasible (eight of 10 patients in this study) with respect to technique and clinical effect. Paravertebral and retrorectal migrations of the catheter may occur in spite of smooth catheterization. Either migration might lead to a failure of caudal block.