Pharmacokinetics of AXA1665, a Novel Composition of Amino Acids, in Comparison With Protein Supplement: A Single-Dose, Open-Label, Randomized Study in Healthy Subjects.

We evaluated the safety and tolerability of AXA1665, a novel investigational fixed-ratio amino acid (AA) composition, the pharmacokinetics (PK) of the constituent AAs within AXA1665, and their relative bioavailability versus standard protein supplement. This study was conducted in 2 phases; in the initial phase, healthy subjects (N = 16) were randomly assigned to 4 treatment sequences (AXA1665 4.9, 9.8, and 19.6 g or 35 g protein supplement) in an open-label, single-dose, 4-way crossover study, while in the extension phase, they received single AXA1665 doses of 29.4 and 39.2 g in a sequential crossover manner. The net area under the plasma concentration-time curve (AUC) and observed time to reach maximum plasma concentration were estimated. A dose-dependent increase in plasma AUC from time 0 to the last measurable concentration (AUClast ) and maximum plasma concentration (Cmax ) was observed for all AXA1665-dosed AAs (4.9-39.2 g) except aspartic acid. AXA1665 19.6 g resulted in 1.5- to 9.5-fold higher systemic exposure to all AXA1665-dosed AAs except for aspartic acid and lysine and lower exposure to all nondosed AAs except for glutamine and alanine versus protein supplement. AXA1665 doses, up to 39.2 g, can deliver AXA1665-dosed AAs in the systemic circulation in the linear AUC range.

Safety, Tolerability, and Physiological Effects of AXA1665, a Novel Composition of Amino Acids, in Subjects With Child-Pugh A and B Cirrhosis.

INTRODUCTION: AXA1665 is a novel investigational amino acid (AA) composition specifically designed to impact AA imbalance, ammoniagenesis, and dysregulated anabolic activity associated with cirrhosis. METHODS: This 2-part study examined AXA1665 effects on safety, tolerability, and hepatic/muscle physiology in subjects with Child-Pugh A and B cirrhosis. Part 1 established plasma ammonia and AA concentration baselines with a standardized protein supplement. Part 2 included two 15-day domiciled periods separated by a 14-day washout. In period 1, subjects were randomly distributed to 2 groups: AXA1665 14.7 g t.i.d. (group 1) or control t.i.d. (group 2). In period 2, subjects from group 1 crossed over to control and those in group 2 crossed over to AXA1665 4.9 g t.i.d. All subjects were maintained on standard of care (standardized meals; 30-minute daily, supervised, mandatory physical activity; and daily late-evening snack). RESULTS: In parts 1 and 2, 23 and 17 participants were enrolled, respectively. Dose-dependent increases were observed in plasma concentrations of AXA1665-constituent AAs. Fasted branched-chain AA-to-aromatic AA and valine-to-phenylalanine ratios were both increased (AXA1665 14.7 g t.i.d. control-adjusted change: 44.3% ± 2.7% and 47.2% ± 3.9%, respectively; P < 0.0001). Despite provision of additional nitrogen, mean fasted plasma ammonia concentration at day 15 numerically decreased (-21.1% in AXA1665 14.7 g t.i.d. vs -3.8% in control; P > 0.05). AXA1665 14.7 g t.i.d. produced a leaner body composition and significantly decreased Liver Frailty Index at day 15 vs control (-0.70 ± 0.15 vs -0.14 ± 0.17; P < 0.05). AXA1665 was safe and well tolerated. DISCUSSION: AXA1665 has potential to mitigate core metabolic derangements associated with cirrhosis.

Simultaneous Physiologically Based Pharmacokinetic (PBPK) Modeling of Parent and Active Metabolites to Investigate Complex CYP3A4 Drug-Drug Interaction Potential: A Case Example of Midostaurin.

Midostaurin (PKC412) is being investigated for the treatment of acute myeloid leukemia (AML) and advanced systemic mastocytosis (advSM). It is extensively metabolized by CYP3A4 to form two major active metabolites, CGP52421 and CGP62221. In vitro and clinical drug-drug interaction (DDI) studies indicated that midostaurin and its metabolites are substrates, reversible and time-dependent inhibitors, and inducers of CYP3A4. A simultaneous pharmacokinetic model of parent and active metabolites was initially developed by incorporating data from in vitro, preclinical, and clinical pharmacokinetic studies in healthy volunteers and in patients with AML or advSM. The model reasonably predicted changes in midostaurin exposure after single-dose administration with ketoconazole (a 5.8-fold predicted versus 6.1-fold observed increase) and rifampicin (90% predicted versus 94% observed reduction) as well as changes in midazolam exposure (1.0 predicted versus 1.2 observed ratio) after daily dosing of midostaurin for 4 days. The qualified model was then applied to predict the DDI effect with other CYP3A4 inhibitors or inducers and the DDI potential with midazolam under steady-state conditions. The simulated midazolam area under the curve ratio of 0.54 and an accompanying observed 1.9-fold increase in the CYP3A4 activity of biomarker 4ß-hydroxycholesterol indicated a weak-to-moderate CYP3A4 induction by midostaurin and its metabolites at steady state in patients with advSM. In conclusion, a simultaneous parent-and-active-metabolite modeling approach allowed predictions under steady-state conditions that were not possible to achieve in healthy subjects. Furthermore, endogenous biomarker data enabled evaluation of the net effect of midostaurin and its metabolites on CYP3A4 activity at steady state and increased confidence in DDI predictions.

A Physiologically-Based Pharmacokinetic Modeling Approach To Predict Drug-Drug Interactions of Sonidegib (LDE225) with Perpetrators of CYP3A in Cancer Patients.

Sonidegib (Odomzo) is an orally available Smoothened inhibitor for the treatment of advanced basal cell carcinoma. Sonidegib was found to be metabolized primarily by cytochrome P450 (CYP)3A in vitro. The effect of multiple doses of the strong CYP3A perpetrators, ketoconazole (KTZ) and rifampin (RIF), on sonidegib pharmacokinetics (PK) after a single 800 mg dose in healthy subjects was therefore assessed. These data were used to verify a physiologically-based pharmacokinetic (PBPK) model developed to 1) bridge the clinical drug-drug interaction (DDI) study of sonidegib with KTZ and RIF in healthy subjects to the marketed dose (200 mg) in patients 2) predict acute (14 days) versus long-term dosing of the perpetrators with sonidegib at steady state and 3) predict the effect of moderate CYP3A perpetrators on sonidegib exposure in patients. Treatment of healthy subjects with KTZ resulted in an increased sonidegib exposure of 2.25- and 1.49-fold (area under the curve0-240h and maximal concentration respectively), and RIF decreased exposure by 72% and 54%, respectively. The model simulated the single- and/or multiple-dose PK of sonidegib (healthy subjects and patients) within ∼50% of observed values. The effect of KTZ and RIF on sonidegib in healthy subjects was also simulated well, and the predicted DDI in patients was slightly less and independent of sonidegib dose. At steady state, sonidegib was predicted to have a higher DDI magnitude with strong or moderate CYP3A perpetrators compared with a single dose. Different dosing regimens of sondigeb with the perpetrators were also simulated and provided guidance to the current dosing recommendations incorporated in the product label.

An Exposure-Response Modeling Approach to Examine the Relationship Between Potency of CYP3A Inducer and Plasma 4ß-Hydroxycholesterol in Healthy Subjects.

The objectives of this analysis were to establish the exposure-response relationship between plasma rifampicin and 4ß-hydroxycholesterol (4ßHC) concentration and to estimate the effect of weak, moderate, and potent CYP3A induction. Plasma rifampicin and 4ßHC concentration-time data from a drug-drug interaction study with rifampicin 600 mg were used for model development. An indirect response model with an effect compartment described the relationship between rifampicin and 4ßHC concentrations. The model predicted that the equilibration t1/2 and 4ßHC t1/2 were 72.8 and 142 hours, respectively. EM50 and Emax of rifampicin induction were 32.6 µg and 8.39-fold, respectively. The population PK-PD model was then used to simulate the effects of rifampicin 10, 20, and 100 mg on plasma 4ßHC for up to 21 days, in which rifampicin 10, 20, and 100 mg were used to represent weak, moderate, and strong inducers, respectively. The model-predicted median (5th, 95th percentiles) 1.13 (1.04, 1.44)-, 1.28 (1.10, 1.71)-, and 2.10 (1.45, 3.49)-fold increases in plasma 4ßHC after 14-day treatment with rifampicin 10, 20, and 100 mg, respectively. A new drug candidate can likely be classified as a weak, moderate, or strong inducer if baseline-normalized plasma 4ßHC increases by <1.13-, 1.13- to 2.10-, or >2.10-fold, respectively, after 14 days of dosing.

Pharmacokinetic drug-drug interaction assessment of LCZ696 (an angiotensin receptor neprilysin inhibitor) with omeprazole, metformin or levonorgestrel-ethinyl estradiol in healthy subjects.

LCZ696 is a novel angiotensin receptor neprilysin inhibitor in development for the treatment of cardiovascular diseases. Here, we assessed the potential for pharmacokinetic drug-drug interaction of LCZ696 (400 mg, single dose or once daily [q.d.]) when co-administered with omeprazole 40 mg q.d. (n = 28) or metformin 1000 mg q.d. (n = 27) or levonorgestrel-ethinyl estradiol 150/30 µg single dose (n = 24) in three separate open-label, single-sequence studies in healthy subjects. Pharmacokinetic parameters of LCZ696 analytes (sacubitril, LBQ657, and valsartan), metformin, and levonorgestrel-ethinyl estradiol were assessed. Omeprazole did not alter the AUCinf of sacubitril and pharmacokinetics of LBQ657; however, 7% decrease in the Cmax of sacubitril, and 11% and 13% decreases in AUCinf and Cmax of valsartan were observed. Co-administration of LCZ696 with metformin had no significant effect on the pharmacokinetics of LBQ657 and valsartan; however, AUCtau,ss and Cmax,ss of metformin were decreased by 23%. Co-administration of LCZ696 with levonorgestrel-ethinyl estradiol had no effect on the pharmacokinetics of ethinyl estradiol and LBQ657 or AUCinf of levonorgestrel. The Cmax of levonorgestrel decreased by 15%, and AUCtau,ss and Cmax,ss of valsartan decreased by 14% and 16%, respectively. Co-administration of LCZ696 with omeprazole, metformin, or levonorgestrel-ethinyl estradiol was not associated with any clinically relevant pharmacokinetic drug interactions.

Assessment of pharmacokinetic drug-drug interaction between pradigastat and atazanavir or probenecid.

Pradigastat, a novel diacylglycerol acyltransferase-1 inhibitor, has activity in common metabolic diseases associated with abnormal accumulation of triglycerides. In vitro studies suggest that glucuronidation is the predominant metabolism pathway for elimination of pradigastat in humans and confirmed the role of uridine 5'-diphosphoglucuronosyltransferase (UGT) enzymes, UGT1A1, -1A3, and -2B7. The in vitro studies using atazanavir as a selective inhibitor of UGT1A1 and -1A3 indicated that these enzymes contribute ∼55% toward the overall glucuronidation pathway. Therefore, a clinical study was conducted to assess the potential for drug interaction between pradigastat and probenecid (purported general UGT inhibitor) or atazanavir (selective UGT1A1, -1A3 inhibitor). The study included 2 parallel cohorts, each with 3 sequential treatment periods and 22 healthy subjects per cohort. The 90%CI of the geometric mean ratios for Cmax,ss and AUCτ,ss of pradigastat were within 0.80-1.25 when administered in combination with probenecid. However, the Cmax,ss and AUCτ,ss of pradigastat decreased by 31% (90%CI: 0.62-0.78) and 26% (0.67-0.82), respectively, when administered in combination with atazanavir. This magnitude of decrease in pradigastat steady-state exposure is not considered clinically relevant. Pradigastat was well tolerated by all subjects, either alone or in combination with atazanavir or probenecid.

Effects of age and sex on the pharmacokinetics of LCZ696, an angiotensin receptor neprilysin inhibitor.

LCZ696, a novel angiotensin receptor neprilysin inhibitor, is in development for the treatment of heart failure. Administration of LCZ696 results in systemic exposure to sacubitril (inactive prodrug of LBQ657), LBQ657 (neprilysin inhibitor), and valsartan (angiotensin II receptor blocker). We investigated the potential effects of age and sex on the pharmacokinetics of LCZ696 analytes (LBQ657 and valsartan) in an open-label, single oral dose (400 mg), parallel-group study in healthy subjects. Among 36 enrolled subjects, there were 19 male and 17 female subjects; 18 subjects were 18-45 years old (young), and 18 subjects were 65 years of age or older (elderly). Compared with young subjects, the AUCinf and T1/2 for LBQ657 were 42% and 30% greater, respectively, in elderly subjects. The Cmax for LBQ657 was similar between age groups. The AUCinf, Cmax, and T1/2 for valsartan were 30%, 24% greater, and 3.35 hours longer, respectively, in the elderly when compared with young subjects. All pharmacokinetic parameters of LCZ696 analytes (LBQ657 and valsartan) were similar between male and female subjects, indicating no effect on the pharmacokinetics of LCZ696 analytes based on sex. Considering the magnitude of change and its clinical significance, dose adjustment based on age or sex is not considered necessary.

Evaluation of food effect on the oral bioavailability of pradigastat, a diacylglycerol acyltransferase 1 inhibitor.

Pradigastat, a diacylglycerol acyltransferase 1 inhibitor, is being developed for the treatment of familial chylomicronemia syndrome. The results of two studies that evaluated the effect of food on the oral bioavailability of pradigastat using randomized, open-label, parallel group designs in healthy subjects (n=24/treatment/study) are presented. In study 1, a single dose of 20 mg pradigastat was administered under the fasted condition or with a high-fat meal. In study 2, a single dose of 40 mg pradigastat was administered under the fasted condition or with a low- or high-fat meal. At the 20 mg dose, the pradigastat Cmax and AUClast increased by 38% and 41%, respectively, with a high-fat meal. When 40 mg pradigastat was administered with a low-fat meal, the Cmax and AUClast increased by 8% and 18%, respectively, whereas with a high-fat meal the increase was 20% and 18%, respectively. The population pharmacokinetic analysis with the pooled data from 13 studies indicated that administration of pradigastat with a meal resulted in an increase of 30% in both the Cmax and AUC parameters. Based on these results, food overall increased pradigastat exposure in the range of less than 40%, which is not considered clinically significant. Both 20 and 40 mg doses of pradigastat were well tolerated under fasted or fed conditions.

Assessment of pharmacokinetic drug-drug interaction between pradigastat and acetaminophen in healthy subjects.

PURPOSE: The purpose of this study was to evaluate the effect of pradigastat, a diacylglycerol acyltransferase-1 inhibitor, on the pharmacokinetics of acetaminophen, a gastric emptying marker. METHODS: Twenty-five healthy subjects were enrolled and received 1000 mg acetaminophen with meal in period 1, pradigastat (100 mg × 3 days followed by 40 mg × 7 days, 1 h before meal) in period 2, and 1000 mg acetaminophen at -2, -1, 0, +1, and +3 h with respect to meal timing in presence of steady-state pradigastat (40-mg maintenance dose) during periods 3-7. RESULTS: The geometric mean ratio and 90% confidence interval of Cmax and AUC of acetaminophen were within 80-125% suggesting that the rate ad extent of acetaminophen were not affected when given at various time points with respect to pradigastat/meal timing. The acetaminophen Tmax was also not impacted under all treatment conditions but increased from 0.75 to 2.00 h when administered 1 h after food. CONCLUSION: In the presence of steady-state pradigastat, the pharmacokinetics of acetaminophen is unchanged, when given before, with, or 3 h after a meal. However, when given 1 h after a meal, the Tmax of acetaminophen was delayed by ∼1.25 h without affecting Cmax or AUC.

Effect of pradigastat, a diacylglycerol acyltransferase 1 inhibitor, on the pharmacokinetics of a combination oral contraceptive in healthy female subjects.

OBJECTIVE: We evaluated the potential pharmacokinetic interaction between pradigastat, a potent and selective diacylglycerol acyltransferase 1 inhibitor, and Levora-28®, a combination oral contraceptive (COC) containing 30 µg ethinylestradiol (EE) and 150 µg levonorgestrel (LVG). METHODS: An open-label, single-sequence three-period (period 1, single dose of COC; period 2, pradigastat 100 mg x 3 days followed by 40 mg x 7 days; and period 3, both pradigastat 40 mg and a single dose of COC) study involving 24 healthy female subjects of childbearing potential was conducted. RESULTS: The pharmacokinetic parameters of EE were similar when administered alone or in combination with pradigastat, as the 90% confidence interval (CI) of geometric mean ratios for EE exposure (AUC and C(max)) were all within the range of 0.80 - 1.25. The AUC(∞), AUC(last), and C(max) of LVG were slightly increased in the presence of pradigastat, the geometric mean ratios (90% CI) were 1.25 (1.16, 1.35), 1.24 (1.15, 1.34), and 1.16 (1.06, 1.27), respectively. CONCLUSIONS: Pradigastat did not elicit clinically relevant changes in the magnitude of Levora-28® exposure. Therefore, dose adjustment is not required for Levora-28® when co-administered with pradigastat.

Evaluation of a potential transporter-mediated drug interaction between rosuvastatin and pradigastat, a novel DGAT-1 inhibitor.

OBJECTIVE: An in vitro drugdrug interaction (DDI) study was performed to assess the potential for pradigastat to inhibit breast cancer resistance protein (BCRP), organic anion-transporting polypeptide (OATP), and organic anion transporter 3 (OAT3) transport activities. To understand the relevance of these in vitro findings, a clinical pharmacokinetic DDI study using rosuvastatin as a BCRP, OATP, and OAT3 probe substrate was conducted. METHODS: The study used cell lines that stably expressed or over-expressed the respective transporters. The clinical study was an open-label, single sequence study where subjects (n = 36) received pradigastat (100 mg once daily x 3 days thereafter 40 mg once daily) and rosuvastatin (10 mg once daily), alone and in combination. RESULTS: Pradigastat inhibited BCRP-mediated efflux activity in a dose-dependent fashion in a BCRP over-expressing human ovarian cancer cell line with an IC(50) value of 5 µM. Similarly, pradigastat inhibited OATP1B1, OATP1B3 (estradiol 17ß glucuronide transport), and OAT3 (estrone 3 sulfate transport) activity in a concentrationdependent manner with estimated IC(50) values of 1.66 ± 0.95 µM, 3.34 ± 0.64 µM, and 0.973 ± 0.11 µM, respectively. In the presence of steady state pradigastat concentrations, AUC(τ, ss) of rosuvastatin was unchanged and its Cmax,ss decreased by 14% (5.30 and 4.61 ng/mL when administered alone and coadministered with pradigastat, respectively). Pradigastat AUC(τ, ss) and C(max, ss) were unchanged when coadministered with rosuvastatin at steady state. Both rosuvastatin and pradigastat were well tolerated. CONCLUSION: These data indicate no clinically relevant pharmacokinetic interaction between pradigastat and rosuvastatin.

Effect of Renal Impairment on the Pharmacokinetics of Pradigastat, a Novel Diacylglycerol Acyltransferase1 (DGAT1) Inhibitor.

BACKGROUND AND OBJECTIVE: Pradigastat, a diacylglycerol acyltransferase1 inhibitor, is being developed for the treatment of familial chylomicronemia syndrome. The primary objective of this clinical study was to evaluate the effect of renal impairment on the pharmacokinetics of pradigastat. METHODS: In an open-label, parallel-group study, the single-dose (40 mg) pharmacokinetics of pradigastat were evaluated in patients with mild (n = 9), moderate (n = 10) and severe renal impairment (n = 9) compared with matched healthy subjects (n = 28). The protein binding and urinary excretion of pradigastat were also assessed in this study. RESULTS: In patients with mild and moderate renal impairment the geometric means of the maximum plasma concentration (C max) and the area under the plasma concentration-time curve from time zero to infinity (AUC inf) of pradigastat were similar as compared with healthy subjects. In patients with severe renal impairment, the geometric means of the C max and AUC inf increased by 40 % [geometric mean ratio 1.41; 90 % confidence interval (CI) 0.92-2.14] and 18 % (geometric mean ratio 1.18; 90 % CI 0.68-2.05), respectively. There was no significant correlation between renal function (measured by creatinine clearance) and C max or AUC inf. Protein binding values were >99 % and the urinary excretion of pradigastat was minimal in all subjects. There were no severe adverse events in the study and mild transient diarrhoea was the most common adverse event. The safety profile was similar between patients with renal impairment and healthy subjects. CONCLUSION: There was no change in the pharmacokinetics of pradigastat in patients with mild and moderate renal impairment. In patients with severe renal impairment, the mean exposure C max and AUC inf of pradigastat were increased by 40 and 18 %, respectively.

Effect of Hepatic Impairment on the Pharmacokinetics of Pradigastat, a Diacylglycerol Acyltransferase 1 (DGAT1) Inhibitor.

BACKGROUND AND OBJECTIVE: Pradigastat, a novel diacylglycerol acyltransferase 1 inhibitor, is under development to treat familial chylomicronemia syndrome. The potential impact of hepatic impairment on the pharmacokinetics of pradigastat was evaluated in this study. METHODS: In this study, a single oral dose of 20 mg pradigastat was administered first to patients with mild and moderate hepatic impairment (n = 10/group) and subsequently to patients with severe hepatic impairment (n = 6). The pharmacokinetics of pradigastat were compared between each patient group and the respective matched healthy subjects. RESULTS: As compared with the respective matched healthy groups, the geometric mean ratios of the area under the plasma concentration-time curve from time zero to infinity (AUC inf) (h · ng/mL) were 1.49, 1.06 and 1.99 in mild, moderate and severe hepatic impairment patients, respectively; the observed maximum plasma concentration (C max) (ng/mL) values were 0.97, 1.28 and 2.74, respectively; and the total body clearance of the drug from plasma (CL/F) (L/h) values were 0.67, 0.95 and 0.50, respectively. The elimination half-life and plasma protein binding of pradigastat were comparable among all the patients. There were no apparent relationships between AUC inf or C max and albumin or bilirubin levels (R (2) < 0.3; p > 0.05). Overall, 19 adverse events (AEs) were reported in 13 patients. The incidence of AEs appeared to increase with increasing severity of hepatic impairment. CONCLUSION: No clinically significant differences in the pharmacokinetics of pradigastat were observed in mild and moderate hepatic impairment patients compared with healthy subjects. However, the systemic exposure of pradigastat doubled while the clearance decreased by half in patients with severe hepatic impairment compared with healthy subjects. All treatments were well tolerated in the study.

Pharmacokinetic drug-drug interaction assessment between LCZ696, an angiotensin receptor neprilysin inhibitor, and hydrochlorothiazide, amlodipine, or carvedilol.

LCZ696 is a first-in-class angiotensin receptor neprilysin inhibitor in development for treatments of hypertension and heart failure indications. In 3 separate studies, pharmacokinetic drug-drug interactions (DDIs) potential was assessed when LCZ696 was coadministered with hydrochlorothiazide (HCTZ), amlodipine, or carvedilol. The studies used a open-label, single-sequence, 3-period, crossover design in healthy subjects. Blood samples were collected to determine the pharmacokinetic parameters of LCZ696 analytes (AHU377, LBQ657, and valsartan), HCTZ, amlodipine, or carvedilol (R[+]- and S[-]-carvedilol) for statistical analysis. When coadministered LCZ696 with HCTZ, the 90% CIs of the geometric mean ratios of AUCtau,ss of HCTZ and that of LBQ657 were within a 0.80-1.25 interval, whereas HCTZ Cmax,ss decreased by 26%, LBQ657 Cmax,ss increased by 19%, and the AUCtau,ss and Cmax,ss of valsartan increased by 14% and 16%, respectively. Pharmacokinetics of amlodipine, R(+)- and S(-)-carvedilol, or LBQ657 were not altered after coadministration of LCZ696 with amlodipine or carvedilol. Coadministration of LCZ696 400 mg once daily (qd) with HCTZ 25 mg qd, amlodipine 10 mg qd, or carvedilol 25 mg twice a day (bid) had no clinically relevant pharmacokinetic drug-drug interactions. LCZ696, HCTZ, amlodipine, and carvedilol were safe and well tolerated when given alone or concomitantly in the investigated studies.

Aldosterone synthase inhibition: cardiorenal protection in animal disease models and translation of hormonal effects to human subjects.

BACKGROUND: Aldosterone synthase inhibition provides the potential to attenuate both the mineralocorticoid receptor-dependent and independent actions of aldosterone. In vitro studies with recombinant human enzymes showed LCI699 to be a potent, reversible, competitive inhibitor of aldosterone synthase (K i = 1.4 ± 0.2 nmol/L in humans) with relative selectivity over 11ß-hydroxylase. METHODS: Hormonal effects of orally administered LCI699 were examined in rat and monkey in vivo models of adrenocorticotropic hormone (ACTH) and angiotensin-II-stimulated aldosterone release, and were compared with the mineralocorticoid receptor antagonist eplerenone in a randomized, placebo-controlled study conducted in 99 healthy human subjects. The effects of LCI699 and eplerenone on cardiac and renal sequelae of aldosterone excess were investigated in a double-transgenic rat (dTG rat) model overexpressing human renin and angiotensinogen. RESULTS: Rat and monkey in vivo models of stimulated aldosterone release predicted human dose- and exposure-response relationships, but overestimated the selectivity of LCI699 in humans. In the dTG rat model, LCI699 dose-dependently blocked increases in aldosterone, prevented development of cardiac and renal functional abnormalities independent of blood pressure changes, and prolonged survival. Eplerenone prolonged survival to a similar extent, but was less effective in preventing cardiac and renal damage. In healthy human subjects, LCI699 0.5 mg selectively reduced plasma and 24 h urinary aldosterone by 49 ± 3% and 39 ± 6% respectively (Day 1, mean ± SEM; P < 0.001 vs placebo), which was associated with natriuresis and an increase in plasma renin activity. Doses of LCI699 greater than 1 mg inhibited basal and ACTH-stimulated cortisol. Eplerenone 100 mg increased plasma and 24 h urinary aldosterone while stimulating natriuresis and increasing renin activity. In contrast to eplerenone, LCI699 increased the aldosterone precursor 11-deoxycorticosterone and urinary potassium excretion. CONCLUSIONS: These results provide new insights into the cardiac and renal effects of inhibiting aldosterone synthase in experimental models and translation of the hormonal effects to humans. Selective inhibition of aldosterone synthase appears to be a promising approach to treat diseases associated with aldosterone excess.

A semi-automated LC-MS/MS method for the determination of LCI699, a steroid 11ß-hydroxylase inhibitor, in human plasma.

A novel liquid chromatographic method with tandem mass spectrometric detection (LC-MS/MS) for the determination of LCI699 was developed and validated with dynamic ranges of 0.0500-50.0 ng/mL and 1.00-1,000 ng/mL using 0.0500 mL and 0.100mL, respectively, of human plasma. LCI699 and the internal standard, [M+6]LCI699, were extracted from fortified human plasma via protein precipitation. After transfer or dilution of the supernatant followed by solvent evaporation and/or reconstitution, the extract was injected onto the LC-MS/MS system. Optimal chromatographic separation was achieved on an ACE C18 (50 mm × 4.6mm, 3 µm) column with 30% aqueous methanol (containing 0.5% acetic acid and 0.05% TFA) as the mobile phase run in isocratic at a flow rate of 1.0 mL/min. The total analysis cycle time is approximately 3.5 min per injection. The addition of an ion-pair reagent, TFA (0.05%, v/v), to the mobile phases significantly improved the chromatographic retention and resolution of the analyte on silica based reversed-phase column. Although addition of TFA to the mobile phase suppresses the ESI signals of the analyte due to its ion-pairing characteristics in the gas phase of MS source, this negative impact was effectively alleviated by adding 0.5% acetic acid to the mobile phase. The current method was validated for sensitivity, selectivity, linearity, reproducibility, stability and recovery. For the low curve range (0.0500-50.0 ng/mL), the accuracy and precision for the LLOQs (0.0500 ng/mL) were -13.0 to 2.0% bias and 3.4-19.2% CV, respectively. For other QC samples (0.100, 6.00, 20.0 and 40.0 ng/mL), the precision ranged from 1.2 to 9.0% and from 3.8 to 8.8% CV, respectively, in the intra-day and inter-day evaluations. The accuracy ranged from -11.3 to 8.0% and -7.2 to 1.6% bias, respectively, in the intra-day and inter-day batches. For the high curve range (1.00-1,000 ng/mL), the accuracy and precision for the LLOQs (1.00 ng/mL) were 1.0-15.0% bias and 7.4-9.2% CV, respectively. For the other QC samples (3.00, 20.0, 200 and 750 ng/mL), the precision ranged from 0.8 to 7.0% and from 1.9 to 5.2% CV, respectively, in the intra-day and inter-day evaluations. The accuracy ranged from -2.5 to 4.0% and 0.7-1.0% bias, respectively, in the intra-day and inter-day batches. Additional assessments of incurred sample stability (ISS) and incurred sample reanalysis (ISR) were conducted to demonstrate the ruggedness and robustness of the assay method. The absence of adverse matrix effect and carryover was also demonstrated. The validated method was successfully used to support rapid turnaround human pharmacokinetic studies.

Pharmacokinetic and pharmacodynamic drug-drug interaction assessment between pradigastat and digoxin or warfarin.

Pradigastat, a novel diacylglycerol acyltransferase-1 inhibitor, was evaluated for both pharmacokinetic (PK) and pharmacodynamic (PD) drug-drug interactions when co-administered with digoxin or warfarin in healthy subjects. This open-label study included two parallel subject cohorts each with three sequential treatment periods. Forty subjects were enrolled in the study with 20 subjects allocated to each cohort. PK and PD (PT/INR for warfarin only) samples were collected in each period. The statistical analysis results showed that the 90% CIs of the geometric mean ratios of digoxin, R-warfarin, and S-warfarin PK parameters (AUC and Cmax) were all within 0.80-1.25 interval. The 90% CIs of the geometric mean ratios of pradigastat PK parameters (AUC and Cmax) were within 0.80-1.25 interval when co-administered with warfarin; while co-administration with digoxin slightly reduced pradigastat exposure (∼15%). The results also showed that 90% CIs of the geometric mean ratios of warfarin PD parameters (AUC(PT), PTmax, AUC(INR), and INRmax) were within 0.80-1.25 interval. Pradigastat and digoxin or warfarin had no relevant clinical PK or PD drug-drug interactions. Administration of pradigastat and warfarin or pradigastat and digoxin as a mono or combined treatment appears to be safe and tolerated.

Pharmacokinetics of aliskiren in patients with end-stage renal disease undergoing haemodialysis.

BACKGROUND AND OBJECTIVES: Aliskiren represents a novel class of orally active renin inhibitors. This study analyses the pharmacokinetics, tolerability and safety of single-dose aliskiren inpatients with end-stage renal disease (ESRD) undergoing haemodialysis. METHODS: Six ESRD patients and six matched healthy volunteers were enrolled in an open-label, parallel-group, single-sequence study. The ESRD patients underwent two treatment periods where 300 mg of aliskiren was administered 48 or 1 h before a standardized haemodialysis session (4 h, 1.4 m(2) high-flux filter, blood flow 300 mL/min, dialysate flow 500 mL/min). Washout was >10 days between both periods. Blood and dialysis samples were taken for up to 96 h postdose to determine aliskiren concentrations. RESULTS: Compared with the healthy subjects (1681 ± 1034 ng·h/mL), the area under the plasma concentration-time curve (AUC) from time zero to infinity was 61% (haemodialysis at 48 h) and 41% (haemodialysis at 1 h) higher in ESRD patients receiving single-dose aliskiren 300 mg. The maximum (peak) plasma drug concentration (481 ± 497 ng/mL in healthy subjects) was 17% higher (haemodialysis at 48 h) and 16% lower (haemodialysis at 1 h). In both treatment periods, dialysis clearance was below 2% of oral clearance and the mean fraction eliminated from circulation was 10 and 12% in period 1 and 2, respectively. Drug AUCs were similar in ESRD patients receiving aliskiren 1 or 48 h before dialysis. No severe adverse events occurred. CONCLUSION: The exposure of aliskiren is moderately higher in ESRD patients. Only a minor portion is removed by a typical haemodialysis session. Aliskiren exposure is not significantly affected by intermittent haemodialysis, suggesting that no dose adjustment is necessary in this population.