Pharmacokinetics, pharmacodynamics and safety assessment of multiple doses of soticlestat in healthy volunteers.

AIMS: Soticlestat, a first-in-class inhibitor of cholesterol 24-hydroxylase (also known as cytochrome P450 46A1), is currently in development for the treatment of developmental and epileptic encephalopathies. Here, we report safety, tolerability, pharmacokinetic and pharmacodynamic outcomes from a phase I, randomized, double-blind, placebo-controlled, multiple-rising-dose study of soticlestat in healthy adults. METHODS: Five cohorts of healthy subjects (n = 8 each, randomized 6:2 soticlestat:placebo) received oral soticlestat 100-600 mg once daily (QD) or 300 mg twice daily (BID) for 10-14 days. Serial blood and urine samples were obtained on days 1, 7 (blood only) and 14. RESULTS: Soticlestat in the dose range 100-400 mg/day for up to 14 days was generally well tolerated. In total, 45 treatment-emergent adverse events (TEAEs) were reported; most (91%) were transient and mild in intensity. Two subjects experienced TEAEs leading to discontinuation: one receiving soticlestat 600 mg QD reported a severe event of acute psychosis; another receiving 300 mg BID reported a mild event of confusional state. Steady-state exposure to soticlestat increased in a slightly greater than dose-proportional manner across the dose range 100-400 mg QD. Peak plasma concentrations were reached within 0.33-0.5 hour, and soticlestat elimination half-life was approximately 4 hours. Renal excretion of soticlestat was negligible. Soticlestat 100-400 mg QD reduced 24S-hydroxycholesterol levels by 46.8 (coefficient of variation [CV%] -9.2) to -62.7% (CV% -7.3) at steady state; values of enzymatic inhibition were compatible with antiepileptic effects observed in preclinical models. CONCLUSION: The pharmacokinetic and pharmacodynamic profiles of soticlestat characterized here provided a data-driven rationale for clinical trial dose selection.

Evaluation of the Pharmacokinetics of Felcisetrag (TAK-954), a 5-HT4 Receptor Agonist, in the Presence and Absence of Itraconazole, a Potent CYP3A4 Inhibitor.

The 5-hydroxytryptamine type-4 receptor agonist felcisetrag (TAK-954) is being investigated for improving gastrointestinal motility in postoperative gastrointestinal dysfunction. Polypharmacy often occurs in this setting, and as in vitro data indicate, felcisetrag is primarily metabolized by cytochrome P450 (CYP) 3A4, its CYP3A4-mediated drug-drug interaction potential requires consideration. This phase 1, fixed-sequence, open-label, crossover trial (ClinicalTrials.gov identifier NCT03173170) investigated the effect of itraconazole, a potent CYP3A4 inhibitor, on felcisetrag pharmacokinetics in healthy adults. Over 2 study periods (period 1, 6 days; period 2, 9 days), participants received a single felcisetrag 0.2-mg intravenous dose (day 1, period 1; and day 4, period 2), and once-daily oral itraconazole 200-mg doses (days 1-8, period 2). For felcisetrag alone, felcisetrag total systemic exposure was lower than with itraconazole coadministration. The geometric mean ratio for area under the plasma concentration-time curve from time 0 to infinity of felcisetrag plus itraconazole: felcisetrag alone was 1.49 (90% confidence interval, 1.39-1.60). Peak exposure was similar between regimens (geometric mean ratio, 1.06; 90% confidence interval, 0.96-1.18), and both treatments were well tolerated. These data suggest limited CYP3A4-mediated drug-drug interaction inhibition for felcisetrag.

Novel sequential immunocapture microflow LC/MS/MS approach to measuring PTH-Fc protein in human serum.

The quantitation of PTH-Fc in circulation by ligand binding assay presented a significant challenge due to the extremely low doses of administration, interference from the endogenous. A robust LC-MS/MS method to quantify the extremely low concentration of PTH-Fc in human serum utilized sequential immunoaffinity enrichment at PTH and Fc domains in conjunction with microflow LC-MS/MS technology significantly improved the sensitivity and selectivity. The assay displayed a quantitation range of 0.025-5.0 ng/ml and acceptable intraday and interday precision (%CV ≤ 15%) and accuracy (%bias ≤ ±15%) and can be routinely used for pharmacokinetic measurement of the drug. The novel sequential immunocapture workflow described herein can be applied to the quantitation of other recombinant therapeutic proteins to support clinical studies.

Safety, tolerability, pharmacokinetics, pharmacodynamics, bioavailability and food effect of single doses of soticlestat in healthy subjects.

AIMS: Soticlestat is a first-in-class selective inhibitor of cholesterol 24-hydroxylase, the enzyme that converts brain cholesterol to 24S-hydroxycholesterol (24HC), a positive allosteric modulator of N-methyl-D-aspartate receptors. Soticlestat is under development as treatment for rare developmental and epileptic encephalopathies. METHODS: In this first-in-human study, 48 healthy men and women received single ascending doses of soticlestat oral solution or placebo. Subsequently, nine healthy subjects received soticlestat tablets under fed and fasting conditions to assess the relative oral bioavailability and effects of food. Serial blood and urine samples were collected for pharmacokinetic and pharmacodynamic assessments. RESULTS: Soticlestat appeared to be well tolerated up to a single dose of 1350 mg. Adverse events (AEs) were mild in intensity, and dose-dependent increase in AE prevalence was not apparent. Soticlestat administered via oral solution was rapidly absorbed (median time to maximum plasma concentration [Cmax ] 0.250-0.520 h). Mean Cmax and area under plasma concentration-time curve from zero to infinity increased by 183- and 581-fold, respectively, over a 90-fold dose increase. Mean terminal elimination half-life was 0.820-7.16 hours across doses. Renal excretion was negligible. Administration of soticlestat tablets, and with food, lowered Cmax but did not affect overall exposure. Plasma 24HC concentrations generally decreased with increasing dose. CONCLUSIONS: Soticlestat appeared to be well tolerated after a single oral administration of up to 1350 mg and dose-dependently reduced plasma 24HC concentrations. Systemic exposure increased in a greater than dose-proportional manner over the dose range evaluated but was not affected by formulation or administration with food.

A robust multiplexed assay to quantify C1-inhibitor, C1q, and C4 proteins for in vitro diagnosis of hereditary angioedema from dried blood spot.

Hereditary angioedema (HAE) is a rare genetic disease caused by deficiency or dysfunction of C1 esterase inhibitor (C1-INH). Plasma C1-INH activity and concentrations of C1-INH and complement components 1q and 4 (C1q, C4) are critical to the HAE diagnosis. We describe a novel multiplexed assay to simultaneously measure C1-INH, C1q, and C4 levels in dried blood spot (DBS) of HAE patients. The blood proteins were extracted from 3 mm punches of DBS samples and were subsequently digested by trypsin. The signature peptide derived from each protein was quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Analyte-depleted blood was generated as a surrogate matrix for the preparation of calibration curves to overcome the interference of endogenous proteins, and the assay reproducibility was further monitored by assessing the signal of plasma transferrin as a house-keeping protein. The assay was fully validated following regulatory guideline, with a quantification range of 12.5-800 µg/mL for C1-INH and C4 and 3.13-200 µg/mL for C1q. The precision and accuracy ranged from 3.3%-9.8% and -8.2%-12.6%, respectively. All the patient samples exhibited C1-INH levels lower than normal range except the Type II patient and the C4 and C1q concentrations were as expected. Results from the DBS-based LC-MS assay were highly correlated with the ELISA data measured in plasma of the same subjects. The method described here offers unique advantages such as less invasive sampling, minimal blood processing, and easy transportation and sample storage, allowing, for the first time, C1-INH, C4, and C1q levels to be simultaneously determined in a drop of dried blood.

Assessment of brain cholesterol metabolism biomarker 24S-hydroxycholesterol in schizophrenia.

Plasma 24S-hydroxycholesterol mostly originates in brain tissue and likely reflects the turnover of cholesterol in the central nervous system. As cholesterol is disproportionally enriched in many key brain structures, 24S-hydroxycholesterol is a promising biomarker for psychiatric and neurologic disorders that impact brain structure. We hypothesized that, as schizophrenia patients have widely reported gray and white matter deficits, they would have abnormal levels of plasma 24S-hydroxycholesterol, and that plasma levels of 24S-hydroxycholesterol would be associated with brain structural and functional biomarkers for schizophrenia. Plasma levels of 24S-hydroxycholesterol were measured in 226 individuals with schizophrenia and 204 healthy controls. The results showed that levels of 24S-hydroxycholesterol were not significantly different between patients and controls. Age was significantly and negatively correlated with 24S-hydroxycholesterol in both groups, and in both groups, females had significantly higher levels of 24S-hydroxycholesterol compared to males. Levels of 24S-hydroxycholesterol were not related to average fractional anisotropy of white matter or cortical thickness, or to cognitive deficits in schizophrenia. Based on these results from a large sample and using multiple brain biomarkers, we conclude there is little to no value of plasma 24S-hydroxycholesterol as a brain metabolite biomarker for schizophrenia.

Murine oncogenicity and pharmacokinetics studies of 9-cis-UAB30, an RXR agonist, for breast cancer chemoprevention.

The synthetic retinoic acid analog, 9-cis-UAB30 [(2E,4E,6Z,8E)-8-(3',4'-dihydro-1'(2'H)-naphthalen-1'-ylidene)-3,7-dimethyl-2,4,6-octatrienoic acid], is a specific ligand for the retinoid X receptor. Murine oncogenicity and pharmacokinetics studies were performed as part of the preclinical development of 9-cis-UAB30 for breast cancer chemoprevention. In the oncogenicity study, TSG-p53((+/-)) (p53 knockout) mice (25 per sex per group) received daily gavage exposure to 9-cis-UAB30 doses of 0 (control), 30, 100, or 300 mg/kg/d for 6 months. Positive controls received p-cresidine (400 mg/kg/d) for 6 months. 9-cis-UAB30 had no biologically significant effects on survival, body weight, body weight gain, clinical signs, hematology, or clinical chemistry but induced dose-related hepatomegaly in both sexes and decreased thymus weights in high-dose females. Gross and microscopic pathology provided no evidence of 9-cis-UAB30 toxicity or oncogenicity; by contrast, p-cresidine induced urinary bladder neoplasms in more than 60% of male and female mice. It was concluded that 9-cis-UAB30 is not oncogenic in p53((+/-)) mice. In the pharmacokinetics study, C57BL/6 mice received daily gavage exposure to 9-cis-UAB30 (100 or 300 mg/kg/d) for 1 or 7 days. Pharmacokinetic parameters were similar after 1 and 7 days of dosing. Dose-related peak plasma levels of 9-cis-UAB30 were seen between 0.25 and 3 hours; volume of distribution was comparable at both dose levels. Increases in area under the curve were less than proportional to dose and were associated with an increased rate of apparent clearance and decreased elimination half-life. These results suggest decreased absorption and/or possible induction of clearance mechanisms. Enzyme induction may underlie the hepatomegaly seen in mice treated with 9-cis-UAB30 for 6 months in the oncogenicity study.

Direct quantitation of glucoraphanin in dog and rat plasma by LC-MS/MS.

A rapid method to quantify levels of the beta-thioglycoside N-hydroxyl sulfate, glucoraphanin, in dog and rat plasma to support pre-clinical toxicological and pharmacological studies has been developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Glucoraphanin was extracted from plasma by protein precipitation with acetonitrile and separated via hydrophilic interaction liquid chromatography (HILIC) using a Luna 5microm Silica (2) 100A column (50mmx2.0mm) at a flow rate of 0.3mL/min. Solvent A consisted of 200mM ammonium acetate and formic acid (99:1, v/v) and Solvent B was acetonitrile. Initial conditions (90% Solvent B) were held for 0.01min after injection, decreased to 40% in 0.5min and held constant for 2.5min, returning to initial conditions for 3min (reequilibration time). Glucoraphanin was detected by MS/MS using a turbo ion spray interface as the ion source operating in negative ion mode. Acquisition was performed in multiple reaction monitoring mode at m/z 435.8-->96.7. The method was validated for the calibration range 10-2000ng/mL. Within- and between-run precision for the low, mid and high QC levels was 8% R.S.D. or less and accuracy ranged from 100 to 113%. The lower limit of quantification was 10ng/mL; calibration curves encompassed the range of plasma concentrations expected to be found in bioavailability and pharmacokinetics studies with glucoraphanin. The method has successfully been applied to the determination of glucoraphanin in dog and rat plasma and should be extendable to other species as well.

Subchronic toxicity and toxicogenomic evaluation of tamoxifen citrate + bexarotene in female rats.

Tamoxifen (TAM) is a nonsteroidal antiestrogen that prevents estrogen receptor-positive breast cancer in rodents and humans. Bexarotene (BEX), a selective agonist for retinoid X receptors, inhibits mammary carcinogenesis in rodents. The present study was conducted to support the preclinical development of TAM (tamoxifen citrate) + BEX for use in breast cancer chemoprevention, and to investigate the influence of these agents on hepatic gene expression. Female CD rats (20 per group) received daily oral (gavage) exposure to TAM (0 or 60 microg/kg/day) and/or BEX (0, 5, 15, or 45 mg/kg/day) for a minimum of 90 days. BEX induced mild, dose-related anemia and dose-related increases in serum alkaline phosphatase, cholesterol, triglycerides, and calcium levels, and increased platelet counts. TAM had no biologically significant effect on any clinical pathology parameter and did not alter the effects of BEX on these endpoints. Microscopic alterations induced by BEX included epidermal hyperplasia, hyperkeratosis (stomach), and cytoplasmic clearing (liver). Microscopic changes in TAM-treated rats were limited to mucous cell hypertrophy in the cervix and vagina. The toxicity of administration of the combination of TAM + BEX can generally be predicted on the basis of the toxicity of each drug as a single agent. BEX induced dose-related alterations in the expression of several genes involved in steroid, drug, and/or fatty acid metabolism; TAM did not alter these effects of BEX. Differential expression of genes involved in drug and lipid metabolism may underlie the observed effects of BEX on cholesterol and triglyceride levels and its effects on liver histology.

Serum, tissue and body fluid concentrations of tigecycline after a single 100 mg dose.

OBJECTIVES: The purpose of this study was to determine the tissue and corresponding serum concentration of tigecycline at selected time points in gall bladder, bile, colon, bone, synovial fluid (SF), lung and CSF in subjects undergoing surgical or medical procedures. METHODS: One hundred and four adult subjects (aged 24-83 years; 64 women, 40 men) received a single intravenous (i.v.) dose of tigecycline (100 mg infused over 30 min). Subjects were randomly assigned to one of four collection times at 4, 8, 12 and 24 h after the start of the infusion. For CSF, samples were collected at approximately 1.5 and 24 h after the start of the infusion. All subjects had serum samples collected before the administration of tigecycline, at the end of the infusion and at the time corresponding to tissue or body fluid collection. Drug concentrations in serum, tissues and body fluids were determined by LC/MS/MS. The area under the mean concentration-time curve from 0 to 24 h (AUC(0-24)) was determined for the comparison of systemic exposure between tissue or body fluid to serum. RESULTS: The mean serum concentrations of tigecycline were similar to those previously published. Tissue penetration, expressed as the ratio of AUC(0-24) in tissue or body fluid to serum, was 537 for bile, 23 for gall bladder, 2.6 for colon, 2.0 for lung, 0.41 for bone, 0.31 for SF and 0.11 for CSF. CONCLUSIONS: A single 100 mg dose of intravenous tigecycline produced considerably higher tissue/fluid concentrations in bile, gall bladder, colon and lung compared with simultaneous serum concentrations. On average, the systemic exposure of tigecycline in bone, SF and CSF ranged from 11% to 41% of serum concentrations. The results in bone are inconsistent with previous radiolabelled studies in animals and it is unclear if tight binding to bone (versus low bone uptake) or poor extraction of tigecycline for LC/MS/MS detection or both may have contributed to the differences we observed in humans.

Modulation of hepatic and renal drug metabolizing enzyme activities in rats by subchronic administration of farnesol.

Farnesol demonstrates antitumor activity in several animal models for human cancer and was being considered for development as a cancer chemopreventive agent. This study was performed to characterize the effects of minimally toxic doses of farnesol on the activity of phase I and II drug metabolizing enzymes. CD((R)) rats (20/sex/group) received daily gavage exposure to farnesol doses of 0, 500, or 1000 mg/kg/day for 28 days; 10 rats/sex/group were necropsied at the termination of farnesol exposure; remaining animals were necropsied after a 28-day recovery period. No deaths occurred during the study, and farnesol had no significant effects on body weight, food consumption, clinical signs, or hematology/coagulation parameters. Modest but statistically significant alterations in several clinical chemistry parameters were observed at the termination of farnesol exposure; all clinical pathology effects were reversed during the recovery period. At the termination of dosing, the activities of CYP1A, CYP2A1-3, CYP2B1/2, CYP2C11/12, CYP2E1, CYP3A1/2, CYP4A1-3, CYP19, glutathione reductase, NADPH/quinone oxidoreductase and UDP-glucuronosyltransferase were significantly increased in the livers of farnesol-treated rats; farnesol also increased the activity of glutathione S-transferase in the kidney. The effects of farnesol on hepatic and renal enzymes were reversed during the recovery period. At the end of the dosing period, increases in absolute and relative liver and kidney weights were seen in farnesol-treated rats. These increases may be secondary to induction of drug metabolizing enzymes, since organ weight increases were not associated with histopathologic alterations and were reversed upon discontinuation of farnesol exposure. Administration of farnesol at doses of up to 1000 mg/kg/day induced reversible increases in the activities of several hepatic and renal drug metabolizing enzymes in rats, while inducing only minimal toxicity. It is concluded that non-toxic or minimally toxic doses of farnesol could alter the metabolism, efficacy, and/or toxicity of drugs with which it is co-administered.