Canrenone

Biotransformation of the mineralocorticoid receptor antagonists spironolactone and canrenone by human CYP11B1 and CYP11B2: Characterization of the products and their influence on mineralocorticoid receptor transactivation.[Pubmed:27125452]

J Steroid Biochem Mol Biol. 2016 Oct;163:68-76.

Spironolactone and its major metabolite Canrenone are potent mineralocorticoid receptor antagonists and are, therefore, applied as drugs for the treatment of primary aldosteronism and essential hypertension. We report that both compounds can be converted by the purified adrenocortical cytochromes P450 CYP11B1 and CYP11B2, while no conversion of the selective mineralocorticoid receptor antagonist eplerenone was observed. As their natural function, CYP11B1 and CYP11B2 carry out the final steps in the biosynthesis of gluco- and mineralocorticoids. Dissociation constants for the new exogenous substrates were determined by a spectroscopic binding assay and demonstrated to be comparable to those of the natural substrates, 11-deoxycortisol and 11-deoxycorticosterone. Metabolites were produced at preparative scale with a CYP11B2-dependent Escherichia coli whole-cell system and purified by HPLC. Using NMR spectroscopy, the metabolites of spironolactone were identified as 11beta-OH-spironolactone, 18-OH-spironolactone and 19-OH-spironolactone. Canrenone was converted to 11beta-OH-Canrenone, 18-OH-Canrenone as well as to the CYP11B2-specific product 11beta,18-diOH-Canrenone. Therefore, a contribution of CYP11B1 and CYP11B2 to the biotransformation of drugs should be taken into account and the metabolites should be tested for their potential toxic and pharmacological effects. A mineralocorticoid receptor transactivation assay in antagonist mode revealed 11beta-OH-spironolactone as pharmaceutically active metabolite, whereas all other hydroxylation products negate the antagonist properties of spironolactone and Canrenone. Thus, human CYP11B1 and CYP11B2 turned out to metabolize steroid-based drugs additionally to the liver-dependent biotransformation of drugs. Compared with the action of the parental drug, changed properties of the metabolites at the target site have been observed.

Development of a high-yielding bioprocess for 11-alpha hydroxylation of canrenone under conditions of oxygen-enriched air supply.[Pubmed:27665527]

Steroids. 2016 Dec;116:1-4.

A high yielding bioprocess for 11-alpha hydroxylation of Canrenone (1a) using Aspergillus ochraceus ATCC 18500 was developed. The optimization of the biotransformation involved both fermentation (for achieving highly active mycelium of A. ochraceus) and biotransformation with the aim to obtain 11-alpha hydroxylation with high selectivity and yield. A medium based on sucrose as C-source resulted particularly suitable for conversion of Canrenone into the corresponding 11-hydroxy derivative, whereas the use of O2-enriched air and dimethyl sulfoxide (DMSO) as a co-solvent for increasing substrate solubility played a crucial role for obtaining high yields (>95%) of the desired product in high chemical purity starting from 30mM (10.2g/L) of substrate. The structure of the hydroxylated product was confirmed by a combination of two-dimensional NMR proton-proton correlation techniques.

Efficacy and safety of two dosages of canrenone as add-on therapy in hypertensive patients taking ace-inhibitors or angiotensin II receptor blockers and hydrochlorothiazide at maximum dosage in a randomized clinical trial: The ESCAPE-IT trial.[Pubmed:27860389]

Cardiovasc Ther. 2017 Feb;35(1):47-54.

AIM: To evaluate the effects of Canrenone as add-on therapy in patients already treated with angiotensin-converting enzyme inhibitors (ACE-I) or angiotensin II receptor blockers (ARBs) and hydrochlorothiazide at the maximum dosage (25 mg/d). METHOD: In this randomized, open-label, controlled trial, we enrolled 175 Caucasian patients with essential hypertension not well controlled by concomitant ACE-I or ARBs and hydrochlorothiazide. At baseline, 87 patients (57 males and 30 females) were randomized to add Canrenone 50 mg, and 88 (56 males and 32 females) patients to Canrenone 100 mg, once a day, for 3 months. At baseline and after 3 months, we evaluated blood pressure (BP), pulse pressure (PP), heart rate (HR), fasting plasma glucose (FPG), homeostasis model assessment insulin (HOMA Index), lipid profile, electrolytes, uric acid, estimated glomerular filtration rate (eGFR), plasma urea, aldosterone, B-type natriuretic peptide (BNP), and galectin-3. RESULTS: Blood pressure decreased with both dosages of Canrenone, with a better effect with Canrenone 100 mg (-20.26 vs -23.68 mm Hg for SBP, and -10.58 vs -12.38 mm Hg for DBP), without a clinically relevant increase in potassium levels. We did not observe any differences regarding FPG or HOMA Index, nor of lipid profile, with the exception of triglycerides, which increased compared to baseline with Canrenone 50 mg (+0.25 vs +0.34 mEq/L). Creatinine slightly increased with Canrenone 100 mg (+0.02 vs +0.05 mg/dL), although no variations of eGFR were observed in neither groups. There was an increase in aldosterone levels with Canrenone 50 mg. No changes in BNP or galectin-3 were recorded. CONCLUSION: Both Canrenone dosages gave a decrease in blood pressure, with a better effect with the higher dose, with only a slight increase in potassium and creatinine levels, which were not clinically relevant. Clinical Trials Registration Eudract number: 2010-023606-13; ClinicalTrials.gov NCT02687178.

Simultaneous separation and rapid determination of spironolactone and its metabolite canrenone in different pharmaceutical formulations and urinary matrices by capillary zone electrophoresis.[Pubmed:27257119]

J Sep Sci. 2016 Jul;39(14):2869-75.

The aim of this study was to develop a novel, sensitive, precise, simple, and rapid capillary zone electrophoresis method for the quality control of spironolactone in three different formulation types and a rapid simultaneous determination of the content of spironolactone and Canrenone in urine samples using fluocinonide as an internal standard. After optimization of separation conditions, the electrolyte solution was the pH 5.5, 20 mM phosphate buffer containing 4.5 g/L sulfated-beta-cyclodextrin, 15 kV of electric filed across the capillary applied at 25 degrees C. A diode array detector was used, and the detection wavelength was 260 nm. Under optimum conditions, good linearity was achieved with correlation coefficients from 0.9976 to 0.9997. Detection limits were 0.56 and 0.20 mug/mL, and the quantitation limits were 1.87 and 0.67 mug/mL, respectively. Excellent accuracy and precision were obtained. Recoveries of the analytes varied from 100.8 to 103.1%. The results indicated that baseline separation of analytes was obtained and this method was suitable for quantitative determination of spironolactone in pharmaceutical preparations and rapid simultaneous determination of the content of spironolactone and its major metabolite Canrenone in urine samples.

Mineralocorticoid receptor antagonists: the evolution of utility and pharmacology.[Pubmed:10760075]

Kidney Int. 2000 Apr;57(4):1408-11.

For more than 30 years after the discovery of aldosterone, scientists believed that its sole site of action was at epithelial tissues, most notably the kidney, where it mediated the transport of Na and K. It was soon recognized aldosterone contributed to several diseases by causing edema. Armed with this information, scientists set out more than 30 years ago to develop an antagonist of the mineralocorticoid receptor for the treatment of edematous states. From this effort, spironolactone (Aldactone was discovered. Spironolactone acts functionally as a competitive inhibitor of the mineralocorticoid (aldosterone) receptor, and although spironolactone is an effective mineralocorticoid receptor antagonist, it is not without limitations. These limitations include unwanted progestational and antiadrogenic side effects that limit its use in the chronic treatment of disease. In addition to its actions at the collecting tubule, aldosterone can participate in pathophysiology by actions at the heart, vasculature, and kidney, and it is likely that the most significant contributions to cardiovascular disease are due to actions at these sites rather than those related to Na and water retention. This is underscored by the recent clinical results from the RALES-004 Trial in which treatment with Aldactone demonstrated a significant benefit on mortality in patients with severe heart failure. The limited utility of spironolactone owing to the aforementioned steroid-related side effects has been especially frustrating, given the newly recognized role of aldosterone in cardiovascular disease. To obviate these limitations, eplerenone is currently being developed by Searle. Eplerenone is a competitive antagonist of the mineralocorticoid receptor that takes advantage of replacing the 17alpha-thoacetyl group of spironolactone with a carbomethoxy group, conferring excellent selectivity for the mineralocorticoid receptor over other steroid receptors. The pharmacological profile of eplerenone positions it to be an effective and selective mineralocorticoid receptor antagonist.