Mass Balance and Absorption, Distribution, Metabolism, and Excretion Properties of Balcinrenone following Oral Administration in Combination with Intravenous Microtracer in Healthy Subjects.

An absorption, distribution, metabolism, and excretion study was performed to determine the basic pharmacokinetic parameters, mass balance, and metabolite profiles of balcinrenone, a mineralocorticoid receptor modulator, in humans. This open-label, single-center, nonrandomized study had a two-period design. In period 1, eight healthy male subjects were dosed with a microtracer intravenous infusion of [14C]balcinrenone shortly after receiving an oral dose of unlabeled balcinrenone in a capsule. Following a 7-day washout, the same group of subjects subsequently received an oral dose of [14C]balcinrenone as a suspension in period 2. Clearance and absolute bioavailability of balcinrenone were determined to be 14.2 l/h and 52%, respectively. Renal clearance was determined to be 5.4 l/h (>fu • glomerular filtration rate), indicating elimination via active tubular secretion, which was potentially mediated by P-glycoprotein 1 and/or organic anion transporter 3, according to in vitro transporter data. In total, 94.1% of the oral dose was recovered: 45.2% in the urine and 48.9% in the feces. Balcinrenone was primarily metabolized via oxidation, and in vitro data suggest that cytochrome P450 3A4 was the main enzyme responsible. Intact [14C]balcinrenone accounted for 55% of drug-related material in the plasma; four metabolites were identified, each representing <6% of the total plasma radioactivity. In conclusion, this two-period study has determined the basic pharmacokinetic parameters of balcinrenone in humans, including absolute bioavailability and disposition. No metabolites warranted further evaluation on account of their low representation, and any contribution to the pharmacodynamic response or potential drug-drug interactions was deemed negligible. SIGNIFICANCE STATEMENT: This study provides a detailed understanding of the pharmacokinetics, disposition, and metabolism of balcinrenone following oral and microtracer intravenous administration in humans. In vitro phenotyping and transporter data granted mechanistic insights into the absorption, distribution, metabolism, and excretion properties of balcinrenone. This knowledge will guide future nonclinical and clinical studies evaluating drug-drug interactions, organ dysfunction, and safety of metabolites.

Accelerated drug discovery by rapid candidate drug identification.

The eventual candidate drug (CD) is often already synthesized during early drug discovery but not nominated until much later. To facilitate the rapid identification of a potential CD, a thoroughly worked-out CD target profile (CDTP) with criteria acceptable for the disease target product profile (TPP) is required at the start of lead generation (LG). In addition to driving the compound property optimization, the preclinical project team has to understand the ultimate goal to be able to rapidly identify and progress a potential CD. A screening cascade with meaningful and well-balanced progression criteria based on the CDTP is required to rapidly filter out unwanted compounds and to progress a potential CD through the cascade to candidate selection.

Identification of Mineralocorticoid Receptor Modulators with Low Impact on Electrolyte Homeostasis but Maintained Organ Protection.

The mechanism-based risk for hyperkalemia has limited the use of mineralocorticoid receptor antagonists (MRAs) like eplerenone in cardio-renal diseases. Here, we describe the structure and property-driven lead generation and optimization, which resulted in identification of MR modulators ( S)-1 and ( S)-33. Both compounds were partial MRAs but still demonstrated equally efficacious organ protection as eplerenone after 4 weeks of treatment in uni-nephrectomized rats on high-salt diet and aldosterone infusion. Importantly, and in sharp contrast to eplerenone, this was achieved without substantial changes to the urine Na+/K+ ratio after acute treatment in rat, which predicts a reduced risk for hyperkalemia. This work led to selection of ( S)-1 (AZD9977) as the clinical candidate for treating MR-mediated cardio-renal diseases, including chronic kidney disease and heart failure. On the basis of our findings, we propose an empirical model for prediction of compounds with low risk of affecting the urinary Na+/K+ ratio in vivo.

Human hepatocytes and cytochrome P450-selective inhibitors predict variability in human drug exposure more accurately than human recombinant P450s.

BACKGROUND AND PURPOSE: Drugs metabolically eliminated by several enzymes are less vulnerable to variable compound exposure in patients due to drug-drug interactions (DDI) or if a polymorphic enzyme is involved in their elimination. Therefore, it is vital in drug discovery to accurately and efficiently estimate and optimize the metabolic elimination profile. EXPERIMENTAL APPROACH: CYP3A and/or CYP2D6 substrates with well described variability in vivo in humans due to CYP3A DDI and CYP2D6 polymorphism were selected for assessment of fraction metabolized by each enzyme (fmCYP ) in two in vitro systems: (i) human recombinant P450s (hrP450s) and (ii) human hepatocytes combined with selective P450 inhibitors. Increases in compound exposure in poor versus extensive CYP2D6 metabolizers and by the strong CYP3A inhibitor ketoconazole were mathematically modelled and predicted changes in exposure were compared with in vivo data. KEY RESULTS: Predicted changes in exposure were within twofold of reported in vivo values using fmCYP estimated in human hepatocytes and there was a strong linear correlation between predicted and observed changes in exposure (r2  = 0.83 for CYP3A, r2  = 0.82 for CYP2D6). Predictions using fmCYP in hrP450s were not as accurate (r2  = 0.55 for CYP3A, r2  = 0.20 for CYP2D6). CONCLUSIONS AND IMPLICATIONS: The results suggest that variability in human drug exposure due to DDI and enzyme polymorphism can be accurately predicted using fmCYP from human hepatocytes and CYP-selective inhibitors. This approach can be efficiently applied in drug discovery to aid optimization of candidate drugs with a favourable metabolic elimination profile and limited variability in patients.

Structure-Based Drug Design of Mineralocorticoid Receptor Antagonists to Explore Oxosteroid Receptor Selectivity.

The mineralocorticoid receptor (MR) is a nuclear hormone receptor involved in the regulation of body fluid and electrolyte homeostasis. In this study we explore selectivity triggers for a series of nonsteroidal MR antagonists to improve selectivity over other members of the oxosteroid receptor family. A biaryl sulfonamide compound was identified in a high-throughput screening (HTS) campaign. The compound bound to MR with pKi =6.6, but displayed poor selectivity over the glucocorticoid receptor (GR) and the progesterone receptor (PR). Following X-ray crystallography of MR in complex with the HTS hit, a compound library was designed that explored an induced-fit hypothesis that required movement of the Met852 side chain. An improvement in MR selectivity of 11- to 79-fold over PR and 23- to 234-fold over GR was obtained. Given the U-shaped binding conformation, macrocyclizations were explored, yielding a macrocycle that bound to MR with pKi =7.3. Two protein-ligand X-ray structures were determined, confirming the hypothesized binding mode for the designed compounds.

Time dependent analysis of assay comparability: a novel approach to understand intra- and inter-site variability over time.

We demonstrate here a novel use of statistical tools to study intra- and inter-site assay variability of five early drug metabolism and pharmacokinetics in vitro assays over time. Firstly, a tool for process control is presented. It shows the overall assay variability but allows also the following of changes due to assay adjustments and can additionally highlight other, potentially unexpected variations. Secondly, we define the minimum discriminatory difference/ratio to support projects to understand how experimental values measured at different sites at a given time can be compared. Such discriminatory values are calculated for 3 month periods and followed over time for each assay. Again assay modifications, especially assay harmonization efforts, can be noted. Both the process control tool and the variability estimates are based on the results of control compounds tested every time an assay is run. Variability estimates for a limited set of project compounds were computed as well and found to be comparable. This analysis reinforces the need to consider assay variability in decision making, compound ranking and in silico modeling.

Inhibition of AMP deaminase activity does not improve glucose control in rodent models of insulin resistance or diabetes.

Inhibition of AMP deaminase (AMPD) holds the potential to elevate intracellular adenosine and AMP levels and, therefore, to augment adenosine signaling and activation of AMP-activated protein kinase (AMPK). To test the latter hypothesis, novel AMPD pan inhibitors were synthesized and explored using a panel of in vitro, ex vivo, and in vivo models focusing on confirming AMPD inhibitory potency and the potential of AMPD inhibition to improve glucose control in vivo. Repeated dosing of selected inhibitors did not improve glucose control in insulin-resistant or diabetic rodent disease models. Mice with genetic deletion of the muscle-specific isoform Ampd1 did not showany favorable metabolic phenotype despite being challenged with high-fat diet feeding. Therefore, these results do not support the development of AMPD inhibitors for the treatment of type 2 diabetes.

Design and optimization of pyrazinecarboxamide-based inhibitors of diacylglycerol acyltransferase 1 (DGAT1) leading to a clinical candidate dimethylpyrazinecarboxamide phenylcyclohexylacetic acid (AZD7687).

A new series of pyrazinecarboxamide DGAT1 inhibitors was designed to address the need for a candidate drug with good potency, selectivity, and physical and DMPK properties combined with a low predicted dose in man. Rational design and optimization of this series led to the discovery of compound 30 (AZD7687), which met the project objectives for potency, selectivity, in particular over ACAT1, solubility, and preclinical PK profiles. This compound showed the anticipated excellent pharmacokinetic properties in human volunteers.

Determination of melagatran, a novel, direct thrombin inhibitor, in human plasma and urine by liquid chromatography-mass spectrometry.

Analytical methods for the determination of melagatran (H 319/68) in biological samples by liquid chromatography (LC)-positive electrospray ionization mass spectrometry using multiple reaction monitoring are described. Melagatran in plasma was isolated by solid-phase extraction on octylsilica, either in separate extraction tubes or in 96-well plates. Absolute recovery of melagatran from plasma was >92%. Melagatran and the internal standard, H 319/68 D2 13C2, were separated from other sample components by LC utilizing a C18 stationary phase and a mobile phase comprising 35% acetonitrile and 0.08% formic acid in 0.0013 mol/l ammonium acetate solution. After dilution, urine was injected directly onto the LC column and subjected to gradient LC. The relative standard deviation was 1-5% for concentrations above the limit of quantification, which was estimated for plasma at 10 or 25 nmol/l for sample volumes of 500 or 200 microl, respectively, and 100 nmol/l for urine.

Enantioselective determination of felodipine in human plasma by chiral normal-phase liquid chromatography and electrospray ionisation mass spectrometry.

An analytical method was developed for the determination of the enantiomers of felodipine, a dihydropyridine-type calcium antagonist, in human blood plasma. Felodipine was extracted from plasma using toluene as extraction solvent. The enantiomers were separated on a cellulose tris(4-methyl benzoate) stationary phase (Chiralcel OJ-R) using 2-propanol-iso-hexane (11:89) as mobile phase. Post-column addition of ammonium acetate in ethanol-water (95:5) allowed sensitive detection of the ammonium adduct by electrospray ionisation and selected reaction monitoring. Deuterated felodipine racemate was used as internal standard. Within-run repeatability was determined and a coefficient of variation below 2% was achieved at 22 nmol/l and below 10% at 0.27 nmol/l. Between-day precision was evaluated and a coefficient of variation of 3.6% at 4 nmol/l plasma was obtained. Limit of quantification (LOQ) was set at 0.25 nmol/l (0.10 microg/l). The method proved adequate for pharmacokinetic studies of R- and S-felodipine after oral administration of therapeutic doses of felodipine.