Intravenous Mineralocorticoid Receptor Antagonist Use in Acutely Decompensated Heart Failure with Diuretic Resistance.

Intravenous mineralocorticoid receptor antagonists (MRAs) have been used in some centers for decades to reduce the risk of hypokalemia and boost diuresis in acutely decompensated heart failure (ADHF). We report the well-tolerated use of intravenous MRAs as a rescue procedure in 3 patients admitted for ADHF with important diuretic resistance. Undertaking trials evaluating the effect of this therapeutic strategy in ADHF could represent a promising avenue.

Topical Administration of Spironolactone-Loaded Nanomicelles Prevents Glucocorticoid-Induced Delayed Corneal Wound Healing in Rabbits.

The objective was to investigate whether mineralocorticoid receptor antagonism using a novel topical micellar formulation of spironolactone could prevent glucocorticoid-induced delayed corneal wound healing in New Zealand white rabbits. Spironolactone micelles (0.1%, w/v) with a mean number weighted diameter of 20 nm were prepared using a pegylated copolymer (mPEG-dihexPLA) and showed a preliminary stability of at least 12 months at 5 °C. Preclinical studies in New Zealand white rabbits demonstrated that the 0.1% spironolactone micellar formulation was well-tolerated since no reaction was observed in the cornea following multiple daily instillation over 5 days. As expected, the preclinical studies also confirmed that dexamethasone significantly delayed epithelial wound healing as compared to untreated control (percentage re-epithelialization after day 4: 84.6 ± 13.9% versus 99.5 ± 1.0% for the control, p < 0.05). However, the addition of the 0.1% spironolactone micellar formulation significantly improved the extent of re-epithelialization, countering the dexamethasone induced delayed wound healing with a percentage re-epithelialization that was statistically equivalent to the control (96.9 ± 7.3% versus 99.5 ± 1.0%, p > 0.05). The biodistribution study provided insight into the ocular metabolism of spironolactone and hence the relative contributions of the parent molecule and its two principal metabolites, 7α-thiomethylspironolactone and canrenone, to the observed pharmacological effects. Comparison of the efficacies of spironolactone and potassium canrenoate (a water-soluble precursor of canrenone) in overcoming the dexamethasone-induced delayed wound healing confirmed that the former had greater efficacy. The results pointed to the greater potency of 7α-thiomethylspironolactone over canrenone as a mineralocorticoid receptor antagonist, which explained its superior ability in countering the glucocorticoid-induced overactivation that was responsible for the delayed wound healing. In conclusion, the preliminary results supported the above-mentioned hypothesis suggesting that coadministration of mineralocorticoid receptor antagonists to patients under glucocorticoid therapy might prevent the deleterious effects of glucocorticoids on complex corneal wound healing processes.

Population pharmacokinetic model of canrenone after intravenous administration of potassium canrenoate to paediatric patients.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Little is known about the pharmacokinetics of potassium canrenoate/canrenone in paediatric patients WHAT THIS STUDY ADDS: A population pharmacokinetic model has been developed to evaluate the pharmacokinetics of canrenone in paediatric patients who received potassium canrenoate as part of their therapy in the intensive care unit. AIMS To characterize the population pharmacokinetics of canrenone following administration of potassium canrenoate to paediatric patients. METHODS: Data were collected prospectively from 23 paediatric patients (2 days to 10 years of age; median weight 4 kg, range 2.16-28.0 kg) who received intravenous potassium canrenoate (K-canrenoate) as part of their intensive care therapy for removal of retained fluids, e.g. in pulmonary oedema due to chronic lung disease and for the management of congestive heart failure. Plasma samples were analyzed by HPLC for determination of canrenone (the major metabolite and pharmacologically active moiety) and the data subjected to pharmacokinetic analysis using NONMEM. RESULTS: A one compartment model best described the data. The only significant covariate was weight (WT). The final population models for canrenone clearance (CL/F) and volume of distribution (V/F) were CL/F (l h(-1) ) = 11.4 × (WT/70.0)(0.75) and V/F (l) = 374.2 × (WT/70) where WT is in kg. The values of CL/F and V/F in a 4 kg child would be 1.33 l h(-1) and 21.4 l, respectively, resulting in an elimination half-life of 11.2 h. CONCLUSIONS: The range of estimated CL/F in the study population was 0.67-7.38 l h(-1) . The data suggest that adjustment of K-canrenoate dosage according to body weight is appropriate in paediatric patients.

Combined versus sequential diuretic treatment of ascites in non-azotaemic patients with cirrhosis: results of an open randomised clinical trial.

OBJECTIVE: The aim of the study was to compare sequential versus combined diuretic therapy in patients with cirrhosis, moderate ascites and without renal failure. DESIGN: One hundred patients were randomly assigned to the two diuretic treatments. The sequential treatment provided potassium canrenoate at the initial dose of 200 mg/day, then increased to 400 mg/day. Non-responders were treated with 400 mg/day of potassium canrenoate and furosemide at an initial dose of 50 mg/day, then increased to 150 mg/day. The combined treatment provided the initial dose of 200 mg/day of potassium canrenoate and 50 mg/day of furosemide, then increased to 400 mg/day and 150 mg/day, respectively. RESULTS: Most patients who received sequential treatment responded to potassium canrenoate alone (19% to 200 mg/day and 52.63% to 400 mg/day, respectively). Most patients who received the combined treatment responded to the first two steps (40% to the first step and 50% to the second, ie, 400 mg/day of potassium canrenoate plus 100 mg/day of furosemide). Adverse effects (38% vs 20%, p<0.05), in particular, hyperkalaemia (18% vs 4%, p<0.05), were more frequent in patients who received sequential therapy. As a consequence, the per cent of patients who resolved ascites without changing the effective diuretic step was higher in those who received the combined treatment (56% vs 76%, p<0.05). CONCLUSIONS: The combined diuretic treatment is preferable to the sequential one in the treatment of moderate ascites in patients with cirrhosis and without renal failure. NCT00741663. This work is an open randomised clinical trial.

Amiloride reduces portal hypertension in rat liver cirrhosis.

OBJECTIVE: This study aimed to investigate the effect of amiloride on portal hypertension. Amiloride is known to inhibit Na(+)/H(+) exchangers on activated hepatic stellate cells. METHODS: Liver cirrhosis in rats was induced by bile duct ligation (BDL) or thioacetamide (TAA) administration. The effects of zymosan for Kupffer cell (KC) activation or a thromboxane (TX) analogue (U46619) were tested in isolated perfused livers of cirrhotic rats and in vivo. Downstream mechanisms were investigated using Rho kinase inhibitor (Y-27632) or amiloride. Acute and chronic effects of amiloride and canrenoate on portal pressure were compared in perfused livers and in vivo. TXB(2) efflux was measured by ELISA. The phosphorylation state of moesin (p-moesin) as an indicator of Rho kinase activity and expression of the thromboxane synthase were assessed by western blot analyses. The activity of hepatic stellate cells was analysed by western blot and staining for alpha-smooth muscle actin (alpha-SMA). RESULTS: In BDL rats, KC activation via zymosan increased portal pressure. This was attenuated by the Rho kinase inhibitor Y-27632. Increased thromboxane efflux following zymosan infusion remained unaltered by Y-27632. The infusion of amiloride attenuated zymosan- and U46619-induced increases in portal perfusion pressure. In vivo, direct administration of amiloride, but not of canrenoate, lowered portal pressure. In TAA and BDL rats, treatment with amiloride for 3 days reduced basal portal pressure and KC-induced increases in portal pressure whereas canrenoate had no effect. In livers of amiloride-treated animals, the phosphorylation state of moesin and the number of alpha-SMA positive cells were reduced. CONCLUSIONS: Amiloride lowers portal pressure in rat liver cirrhosis by inhibition of intrahepatic vasocontraction. Therefore, patients with cirrhosis and portal hypertension may benefit from amiloride therapy.

Rationale for an early aldosterone blockade in acute myocardial infarction and design of the ALBATROSS trial.

BACKGROUND: Aldosterone is at its highest levels at presentation for acute myocardial infarction (AMI). High aldosterone levels are predictive of poor outcome regardless of heart failure. Angiotensin-converting enzyme inhibitors have delayed partial and temporary effects on aldosterone levels. We hypothesize that aldosterone receptor blockade, early after AMI onset on top of standard therapy, may improve clinical outcome. STUDY DESIGN: ALBATROSS is a nationwide, multicenter, open-labeled, randomized trial designed to assess the superiority of aldosterone blockade by a 200-mg intravenous bolus of potassium canrenoate followed by a daily 25-mg dose of spirinolactone for 6 months, on top of standard therapy compared to standard therapy alone among 1,600 patients admitted for ST-segment elevation or high risk non-ST-segment elevation acute AMI -TIMI score ≥3-within 72 hours after symptom onset regardless of heart failure and treatment strategy. The primary efficacy end point of the study is the 6-month rate of the composite of death, resuscitated cardiac arrest, significant ventricular arrhythmia, class IA American College of Cardiology/American Heart Association/European Society of Cardiology indication for implantable cardioverter device, and new or worsening heart failure. Secondary end points include each of the components of the primary end point, different combinations of such components, the primary end point assessed at hospital discharge and 30-day follow-up, and rates of acute renal failure. Safety end points include rates of hyperkalemia and premature drug discontinuation. CONCLUSIONS: ALBATROSS will assess the cardiovascular benefit of a low-cost aldosterone receptor blocker on top of standard therapy in all-coming AMI patients.

Patients with acute heart failure treated with the CARRESS-HF diuretic protocol in association with canrenoate potassium: Tolerance of high doses of canrenoate potassium.

BACKGROUND: Oral mineralocorticoid receptor antagonists have failed to prove their efficacy for decongestion and potassium homeostasis in acute heart failure. Intravenous mineralocorticoid receptor antagonists have yet to be studied. AIM: The aim of this study was to confirm the safety of high-dose potassium canrenoate in association with classic diuretics in acute heart failure. METHODS: This retrospective single-centre study included consecutive patients who were hospitalized with acute heart failure between 2013 and 2018. One hundred patients with overload treated with the standardized diuretic protocol from the CARRESS-HF trial were included. There were no exclusion criteria relating to creatinine or kalaemia at the time of admission. Two groups were constituted on the basis of potassium canrenoate posology: a low-dose group (<300mg/day) and a high-dose group (≥300mg/day); the groups were similar in terms of baseline characteristics. RESULTS: Mean daily potassium canrenoate doses were 198mg/day (range 100-280mg/day) in the low-dose group and 360mg/day (range 300-600mg/day) in the high-dose group. There was no significant difference between the high-dose and low-dose groups in terms of mortality, dialysis, renal function, hyperkalaemia, haemorrhage, sepsis or confusion. CONCLUSIONS: Potassium canrenoate at high doses can be used safely in association with standard diuretics in acute heart failure, even in patients with altered renal function. A prospective study is required to evaluate the efficacy of high-dose potassium canrenoate in preventing hypokalaemia and improving decongestion.

Clinical efficacy of potassium canreonate-canrenone in sinus rhythm restoration among patients with atrial fibrillation - a protocol of a pilot, randomized, double -blind, placebo-controlled study (CANREN-AF trial).

BACKGROUND: Atrial fibrillation (AF) is the most frequent cardiac arrhythmia which increases the risk of thromboembolic complications and impairs quality of life. An important part of a therapeutic approach for AF is sinus rhythm restoration. Antiarrhythmic agents used in pharmacological cardioversion have limited efficacy and potential risk of proarrhythmia. Simultaneously, underlying conditions of AF should be treated (e.g. electrolyte imbalance, increased blood pressure, neurohormonal disturbances, atrial volume overload). There is still the need for an effective and safe approach to increase AF cardioversion efficacy. This randomized, double-blind, placebo-controlled, superiority clinical study is performed in patients with AF in order to evaluate the clinical efficacy of intravenous canrenone in sinus rhythm restoration. METHODS: Eighty eligible patients with an episode of AF lasting less than 48 h are randomized in a 1:1 ratio to receive canrenone or placebo. Patients randomized to a treatment intervention are receiving canrenone intravenously at a dose of 200 mg within 2-3 min. Subjects assigned to a control group obtain the same volume of 0.9% saline within the same time. The primary endpoint includes return of sinus rhythm documented in the electrocardiogram within 2 h after drug or placebo administration. Other endpoints and safety outcomes analyses, due to expected lack of statistical power, are exploratory. DISCUSSION: Current evidence supports renin-angiotensin-aldosterone system (RAAS) inhibition as an upstream therapy in AF management. Excess aldosterone secretion results in proarrhythmic effects. Among the RAAS inhibitors, only canrenone is administered intravenously. Canrenone additionally increases the plasma level of potassium, lowers blood pressure and reduces preload. It has been already used in primary and secondary hyperaldosteronism in the course of chronic liver dysfunction and in heart failure. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03536806. Registered on 25 May 2018.

Individual participant data analysis of two trials on aldosterone blockade in myocardial infarction.

BACKGROUND: Two recent randomised trials studied the benefit of mineralocorticoid receptor antagonists (MRAs) in ST-segment elevation myocardial infarction (STEMI) irrespective or in absence of heart failure. The studies were both undersized to assess hard clinical endpoints. A pooled analysis was preplanned by the steering committees. METHODS: We conducted a prespecified meta-analysis of patient-level data of patients with STEMI recruited in two multicentre superiority trials, randomised within 72 hours after symptom onset. Patients were allocated (1:1) to two MRA regimens: (1) an intravenous bolus of potassium canrenoate (200 mg) followed by oral spironolactone (25 mg once daily) versus standard therapy or (2) oral eplerenone (25-50 mg) versus placebo. The primary and key secondary outcomes, all-cause death and the composite of all-cause death or resuscitated sudden death, respectively, were assessed in the intention-to-treat population using a Cox model stratified on the study identifier. RESULTS: Patients were randomly assigned to receive (n=1118) or not the MRA regimen (n=1123). After a median follow-up time of 188 days, the primary and secondary outcomes occurred in 5 (0.4%) and 17 (1.5%) patients (adjusted HR (adjHR) 0.31, 95% CI 0.11 to 0.86, p=0.03) and 6 (0.5%) and 22 (2%) patients (adjHR 0.26, 95% CI 0.10 to 0.65, p=0.004) in the MRA and control groups, respectively. There were also trends towards lower rates of cardiovascular death (p=0.06) and ventricular fibrillation (p=0.08) in the MRA group. CONCLUSION: Our analysis suggests that compared with standard therapy, MRA regimens are associated with a reduction of death and death or resuscitated sudden death in STEMI.

Differential impacts of mineralocorticoid receptor antagonist potassium canrenoate on liver and renal changes in high fat diet-mediated early hepatocarcinogenesis model rats.

Mineralocorticoid receptor (MR)/NADPH oxidase (NOX) signaling is involved in the development of obesity, insulin resistance, and renal diseases; however, the role of this signaling on steatotic preneoplastic liver lesions is not fully elucidated. We determined the effects of the MR antagonist potassium canrenoate (PC) on MR/NOX signaling in hepatic steatosis and preneoplastic glutathione S-transferase placental form (GST-P)-positive liver foci. Rats were subjected to a two-stage hepatocarcinogenesis model and fed with basal diet or high fat diet (HFD) that was co-administered with PC alone or in combination with the antioxidant alpha-glycosyl isoquercitrin (AGIQ). PC reduced obesity and renal changes (basophilic tubules that expressed MR and p22phox) but did not affect blood glucose tolerance and non-alcoholic fatty liver disease activity score (NAS) in HFD-fed rats. However, the drug increased the area of GST-P-positive liver foci that expressed MR and p22phox as well as increased expression of NOX genes (p22phox, Poldip2, and NOX4). PC in combination with AGIQ had the potential of inhibiting the effects of PC on the area of GST-P-positive liver foci and the effects were associated with increasing expression of an anti-oxidative enzyme (Catalase). The results suggested that MR/NOX signaling might be involved in development of preneoplastic liver foci and renal basophilic changes in HFD-fed rats; however, the impacts of PC were different in each organ.

Primary hyperaldosteronism is associated with derangement in the regulation of the hypothalamus-pituitary-adrenal axis in humans.

Hippocampal mineralocorticoid receptors (MR) play a major role in the control of hypothalamus- pituitary-adrenal (HPA) axis. The functional profile of HPA axis and the impact of MR blockade under chronic exposure to mineralocorticoid excess are unknown. To clarify this issue, ACT H, cortisol, and aldosterone secretions were studied in 6 patients with primary hyperaldosteronism (HA) and 8 controls (NS) during placebo, placebo+human CR H (hCR H) (2 microg/kg iv bolus at 22:00 h), potassium canrenoate (CAN, 200 mg iv bolus at 20:00 h followed by 200 mg infused over 4 h) or CAN+hCR H. During placebo, both aldosterone and ACT H levels were higher (p<0.01) in HA than in NS, while cortisol levels were not significantly different. Both HA and NS showed significant ACT H and cortisol responses to hCR H (p<0.004), although the hormonal responses in HA were higher (p<0.02) than in NS. CAN infusion did not modify aldosterone levels in both HA and NS. Under CAN infusion, ACT H showed progressive rise in NS (p<0.05) but not in HA, while cortisol levels showed a significant (p<0.05) but less marked and delayed increase in HA compared to NS. CAN enhanced hCRH-induced ACTH and cortisol responses in NS (p<0.05), but not in HA. In conclusion, in humans primary hyperaldosteronism is associated with deranged function of the HPA axis. In fact, hyperaldosteronemic patients show basal and hCR H-stimulated HPA hyperactivity that is, at least partially, refractory to further stimulation by mineralocorticoid blockade with canrenoate. Whether this hormonal alteration can influence the clinical feature of hypertensive patients with primary hyperaldosteronism needs to be clarified.

Tolerance of high and low amounts of PLGA microspheres loaded with mineralocorticoid receptor antagonist in retinal target site.

Mineralocorticoid receptor (MR) contributes to retinal/choroidal homeostasis. Excess MR activation has been shown to be involved in pathogenesis of central serous chorioretinopathy (CSCR). Systemic administration of MR antagonist (MRA) reduces subretinal fluid and choroidal vasodilation, and improves the visual acuity in CSCR patients. To achieve long term beneficial effects in the eye while avoiding systemic side-effects, we propose the use of biodegradable spironolactone-loaded poly-lactic-co-glycolic acid (PLGA) microspheres (MSs). In this work we have evaluated the ocular tolerance of MSs containing spironolactone in rat' eyes. As previous step, we have also studied the tolerance of the commercial solution of canrenoate salt, active metabolite of spironolactone. PLGA MSs allowed in vitro sustained release of spironolactone for 30days. Rat eyes injected with high intravitreous concentration of PLGA MSs (10mg/mL) unloaded and loaded with spironolactone maintained intact retinal lamination at 1month. However enhanced glial fibrillary acidic protein immunostaining and activated microglia/macrophages witness retinal stress were observed. ERG also showed impaired photoreceptor function. Intravitreous PLGA MSs concentration of 2mg/mL unloaded and loaded with spironolactone resulted well tolerated. We observed reduced microglial/macrophage activation in rat retina compared to high concentration of MSs with normal retinal function according to ERG. Spironolactone released from low concentration of MSs was active in the rat retina. Low concentration of spironolactone-loaded PLGA MSs could be a safe therapeutic choice for chorioretinal disorders in which illicit MR activation could be pathogenic.

Alpha-2A Adrenoceptor Agonist Guanfacine Restores Diuretic Efficiency in Experimental Cirrhotic Ascites: Comparison with Clonidine.

BACKGROUND: In human cirrhosis, adrenergic hyperfunction causes proximal tubular fluid retention and contributes to diuretic-resistant ascites, and clonidine, a sympatholytic drug, improves natriuresis in difficult-to-treat ascites. AIM: To compare clonidine (aspecific α2-adrenoceptor agonist) to SSP-002021R (prodrug of guanfacine, specific α2A-receptor agonist), both associated with diuretics, in experimental cirrhotic ascites. METHODS AND RESULTS: Six groups of 12 rats were studied: controls (G1); controls receiving furosemide and potassium canrenoate (G2); rats with ascitic cirrhosis due to 14-week CCl4 treatment (G3); cirrhotic rats treated (over the 11th-14th CCl4 weeks) with furosemide and canrenoate (G4), furosemide, canrenoate and clonidine (G5), or diuretics and SSP002021R (G6). Three rats of each group had their hormonal status and renal function assessed at the end of 11th, 12th, 13th, and 14th weeks of respective treatments.Cirrhotic rats in G3 and G4 gained weight over the 12th-14th CCl4 weeks. In G4, brief increase in sodium excretion over the 11th-12th weeks preceded worsening of inulin clearance and natriuresis (diuretic resistance). In comparison with G4, the addition of clonidine (G5) or guanfacine (G6) to diuretics improved, respectively, sodium excretion over the 11th-12th CCl4 weeks, or GFR and electrolytes excretion over the 13th-14th CCl4 weeks. Natriuretic responses in G5 and G6 were accompanied by reduced catecholamine serum levels. CONCLUSIONS: α2A-receptor agonists restore glomerular filtration rate and natriuresis, and delay diuretic-resistant ascites in experimental advanced cirrhosis. Clonidine ameliorates diuretic-dependent natriuresis just for a short time.

Early Aldosterone Blockade in Acute Myocardial Infarction: The ALBATROSS Randomized Clinical Trial.

BACKGROUND: Mineralocorticoid receptor antagonists (MRA) improve outcome in the setting of post-myocardial infarction (MI) heart failure (HF). OBJECTIVES: The study sought to assess the benefit of an early MRA regimen in acute MI irrespective of the presence of HF or left ventricular (LV) dysfunction. METHODS: We randomized 1,603 patients to receive an MRA regimen with a single intravenous bolus of potassium canrenoate (200 mg) followed by oral spironolactone (25 mg once daily) for 6 months in addition to standard therapy or standard therapy alone. The primary outcome of the study was the composite of death, resuscitated cardiac arrest, significant ventricular arrhythmia, indication for implantable defibrillator, or new or worsening HF at 6-month follow-up. Key secondary/safety outcomes included death and other individual components of the primary outcome and rates of hyperkalemia at 6 months. RESULTS: The primary outcome occurred in 95 (11.8%) and 98 (12.2%) patients in the treatment and control groups, respectively (hazard ratio [HR]: 0.97; 95% confidence interval [CI]: 0.73 to 1.28). Death occurred in 11 (1.4%) and 17 (2.1%) patients in the treatment and control groups, respectively (HR: 0.65; 95% CI: 0.30 to 1.38). In a non-pre-specified exploratory analysis, the odds of death were reduced in the treatment group (3 [0.5%] vs. 15 [2.4%]; HR: 0.20; 95% CI: 0.06 to 0.70) in the subgroup of ST-segment elevation MI (n = 1,229), but not in non-ST-segment elevation MI (p for interaction = 0.01). Hyperkalemia >5.5 mmol/l(-1) occurred in 3% and 0.2% of patients in the treatment and standard therapy groups, respectively (p < 0.0001). CONCLUSIONS: The study failed to show the benefit of early MRA use in addition to standard therapy in patients admitted for MI. (Aldosterone Lethal effects Blockade in Acute myocardial infarction Treated with or without Reperfusion to improve Outcome and Survival at Six months follow-up; NCT01059136).

Effects of canrenoate plus angiotensin-converting enzyme inhibitors versus angiotensin-converting enzyme inhibitors alone on systolic and diastolic function in patients with acute anterior myocardial infarction.

BACKGROUND: Aldosterone (ALDO) exerts profibrotic effects, acting via the mineralocorticoid receptors in cardiovascular tissues. Aldosterone antagonism in combination with angiotensin-converting enzyme inhibition may better protect against the untoward effects of ALDO than angiotensin-converting enzyme inhibition alone. METHODS: In a double-blind randomized study, the tolerability and efficacy of canrenoate (25 mg/d) plus captopril versus captopril alone were evaluated in 510 patients with an acute anterior myocardial infarction (MI), a serum creatinine concentration < 2.0 mg/dL, and a serum potassium level < 5.0 mmol/L. Three hundred forty-one patients received captopril and 25-mg canrenoate (group A). Group B (346 patients) received captopril and placebo. At baseline and at 10, 90, and 180 days after admission, Doppler echocardiography was performed. RESULTS: Clinical and demographic aspects were similar in both groups. In addition, baseline cardiac enzyme levels, left ventricular function, and incidence of surgical interventions and angioplasty were comparable. Overall, creatinine, blood urea, and serum potassium levels did not show significant differences between groups. However, in 18 patients in group A, increases in serum potassium levels to > 5.5 mEq/L and creatinine levels to > 2.0 mg/L after 10 days of treatment were observed. At 180 days, the mitral E-wave-A-wave ratio was higher (P = .0001) and left ventricular end-systolic volume was smaller (P = .0001) in patients treated with canrenoate than in those receiving placebo. No further side effects were observed during the study period. CONCLUSIONS: Our data suggest that the combination of captopril plus canrenoate is well tolerated after an acute MI and has beneficial effect on systolic and diastolic parameters and may decrease post-MI remodeling.

Aldosterone blunts human baroreflex sensitivity by a nongenomic mechanism.

BACKGROUND: Impaired baroreflex sensitivity (BRS) is a negative predictive factor of mortality in cardiovascular disease. Aldosterone has been shown to decrease BRS in humans and animal models. However, the mode of aldosterone action, whether genomic or nongenomic has not been determined. Therefore, we conducted a clinical study to examine whether BRS, as measured by the phenylephrine method, is impaired in humans by aldosterone by a nongenomic mechanism. METHODS: In a randomised, double-blinded, fourfold cross-over trial in 16 healthy male volunteers, BRS was tested 15 minutes after initiation of a continuous infusion of aldosterone (3 microg/minute) or placebo. 6 hours earlier, this period was preceded by an injection of either canrenoate (400 mg) or placebo. RESULTS: BRS was 34.6 +/- 4.7 ms/mm Hg in the placebo/placebo period. It was significantly blunted in the placebo/aldosterone (25.5 +/- 1.8 ms/mm Hg) as well as in the canrenoate/placebo (24.0 +/- 1.5 ms/mm Hg) and the canrenoate/aldosterone (25.4 +/- 2.5 ms/mm Hg) periods. CONCLUSION: These data suggest that the decreased BRS caused by aldosterone is due to a rapid, thus presumably nongenomic mechanism, as these effects occur in a time frame that excludes genomic aldosterone effects at large. The mineralocorticoid receptor (MR) antagonist canrenoate does not block these effects, but blunts BRS by itself.

Elevated resting and exercise-induced cortisol levels after mineralocorticoid receptor blockade with canrenoate in healthy humans.

Activation of central nervous mineralocorticoid receptors (MRs) has been shown to inhibit the activity of the hypothalamo-pituitary-adrenocortical (HPA) axis in animals. Here, we examined whether MRs in humans likewise regulate HPA activity in response to a physiological stressor. In a balanced, randomized, double-blind, cross-over trial, 12 healthy men were treated with either two injections of 200 mg canrenoate or placebo 24 and 8 h before an intense physical exercise taking place between 1600 and 1700 h. Exercising was preceded by a 60-min rest period and followed by another 90-min rest. Blood was collected in regular intervals to determine ACTH, cortisol, and human GH (hGH). Exercise induced a significant rise in cortisol, ACTH, and hGH. Cortisol levels, however, were significantly higher after canrenoate, compared with placebo, whereas ACTH and hGH concentrations did not differ. The increase in cortisol was already significant during rest before exercise and continued to be elevated throughout the whole experiment. We conclude that MR blockade leads to a tonically increased cortisol secretion both during rest and under stimulation. The undiminished concentration of ACTH in the presence of elevated cortisol levels suggests that blockade of MR shifts the set point for cortisol feedback inhibition of the HPA axis toward higher cortisol levels.

Effects of acute mineralocorticoid and glucocorticoid receptor blockade on the excretion of an acute potassium load in healthy humans.

To examine the role of mineralocorticoid and glucocorticoid in potassium (K) tolerance in healthy humans, we studied the effects of canrenoate, a mineralocorticoid antagonist, and RU486, a glucocorticoid antagonist, on the excretion of a KCl load. Canrenoate (200 mg, iv) or RU486 (400 mg, orally) was administered 150 min before a KCl load (1 mmol/kg BW, orally) in seven healthy males undergoing maximal water diuresis. Clearance studies were extended for 5 h after the KCl load, and the data were compared with time control, KCl load alone, and canrenoate alone. KCl increased K excretion (from 18.8 +/- 2.4 to 63.3 +/- 3.9 mmol/5 h; P < 0.01) and sodium (Na) excretion (from 35.9 +/- 2.1 to 72.9 +/- 6.0 mmol/5 h; P < 0.01). Clearance calculations, based on maximal water diuresis, were compatible with increased distal Na and volume delivery. Canrenoate alone modestly increased basal cumulative NaCl excretion and had no effect on K excretion. However, canrenoate blunted the kaliuresis after the KCl load (51.9 +/- 4.4 mmol/5 h; P < 0.05 compared to KCl alone) and stimulated natriuresis in a complementary way. Clearance data were compatible with diminished distal Na reabsorption and K secretion in response to an undisturbed KCl-induced increase in distal Na delivery. RU486 did not influence the excretion of the KCl load or its effects on renal sodium handling parameters, although effective glucocorticoid receptor blockade was likely to be present in view of the increase in plasma cortisol. These data suggest that in healthy humans, mineralocorticoid activity, but not glucocorticoid activity, is involved in the elimination of a K load. The latter contrasts with data in adrenalectomized animals, in which situation glucocorticoid as well as aldosterone are indispensible for normal K tolerance.

The stimulatory effect of canrenoate, a mineralocorticoid antagonist, on the activity of the hypothalamus-pituitary-adrenal axis is abolished by alprazolam, a benzodiazepine, in humans.

Mineralocorticoid receptors (MR) in the hippocampus play a major role in the control of the hypothalamus-pituitary-adrenal (HPA) axis, mediating the proactive feedback of glucocorticoids in the maintenance of basal activity. Intracerebroventricular and intrahippocampal MR blockade stimulates HPA axis in animals; the systemic administration of mineralocorticoid antagonists enhances spontaneous and CRH-stimulated ACTH and cortisol secretion in humans. Benzodiazepines, namely alprazolam, activate central gamma-aminobutyric acid (GABA)ergic receptors, which are mainly distributed in the hippocampus. Alprazolam has a inhibitory effect on HPA axis either in basal conditions or after central nervous system-mediated stimuli. In humans, alprazolam strongly reduces the corticotroph responsiveness to removal of glucocorticoid feedback by metyrapone. We studied the effect of alprazolam (0.02 mg/kg, orally) on the effect of canrenoate (CAN), an MR antagonist (200 mg as an iv bolus, followed by 200 mg infused in 250 ml saline) or placebo on ACTH, cortisol, and dehydroepiandrosterone (DHEA) secretion in six normal young women (aged 25-32 yr; body mass index, 19-23 kg/m(2)). During placebo, ACTH, cortisol, and DHEA secretion showed a progressive decrease (baseline vs. nadir, mean +/- SEM, from 1830-2400 h, 2.6 +/- 0.3 vs. 1.4 +/- 0.3 pmol/liter, 133.2 +/- 16.4 vs. 46.9 +/- 5.2 nmol/liter, and 22.6 +/- 2.3 vs. 18.6 +/- 2.3 nmol/liter, respectively), although statistical significance was obtained for ACTH and cortisol only (P < 0.05). During CAN treatment, ACTH, cortisol, and DHEA secretion showed a progressive rise, which began at approximately 2100 h and peaked between 2300 and 2400 h (2.9 +/- 0.3 pmol/liter, 172.6 +/- 27.9 nmol/liter, and 45.3 +/- 10.7 nmol/liter, respectively; P < 0.05). Alprazolam abolished the CAN-induced increases in ACTH, cortisol, and DHEA levels (1.8 +/- 0.1 pmol/liter, 59.7 +/- 8.6 nmol/liter, and 19.8 +/- 6.7 nmol/liter; P < 0.05), inducing hormonal peaks overlapping with those recorded after placebo in the absence of any treatment. In conclusion, our study demonstrates that the inhibitory effect of GABAergic activation by alprazolam overrides the stimulatory effect of mineralocorticoid blockade by canrenoate on the HPA axis in humans. These findings emphasize the role of GABA in the control of the HPA axis in humans.

Mineralocorticoid receptor blockade by canrenoate increases both spontaneous and stimulated adrenal function in humans.

Animal studies indicate that mineralocorticoid receptors (MR) in the hippocampus play a major role in the glucocorticoid feedback control of the hypothalamo-pituitary-adrenal (HPA) axis. Specifically, MR mediate the proactive feedback of glucocorticoids in the maintenance of basal HPA activity. The stimulatory effect of intracerebroventricular and intrahippocampal MR blockade on the HPA axis in animals has been clearly shown, whereas the effect of systemic administration of mineralocorticoid antagonists in humans is still contradictory. To clarify this point, in seven normal young women (aged 25-32 yr; body mass index, 19.0-23.0 kg/m(2)) we studied the effects of canrenoate (CAN; 200 mg as iv bolus at 2000 h, followed by 200 mg infused in 500 mL saline over 4 h up to 2400 h) or placebo (saline, 1.0 mL as iv bolus at 2000 h, followed by 500 mL over 4 h up to 2400 h) on the spontaneous ACTH, cortisol, dehydroepiandrosterone (DHEA) and aldosterone secretion as well as on the ACTH, cortisol, and DHEA responses to human CRH (2.0 microg/kg as iv bolus at 2200 h) or arginine vasopressin (AVP; 0.17 U/kg as im bolus at 2200 h). Blood samples were taken every 15 min from 2000-2400 h. During placebo, spontaneous ACTH and cortisol levels showed progressive decreases (P < 0.05) from 2000-2400 h (baseline vs. nadir, mean +/- SEM, 2.0 +/- 0.3 vs. 1.4 +/- 0.2 pmol/L and 115.1 +/- 23.7 vs. 63.5 +/- 24.3 nmol/L), whereas DHEA and aldosterone levels did not change. CRH induced clear increases in ACTH, cortisol, and DHEA levels (peaks, mean +/- SEM, 7.1 +/- 1.1 vs. 1.6 +/- 0.2 pmol/L, 322.9 +/- 19.5 vs. 92.8 +/- 24.5 nmol/L, and 44.2 +/- 2.7 vs. 20.0 +/- 3.0 nmol/L; P < 0.05). Similarly, AVP elicited significant increases in ACTH, cortisol, and DHEA levels (3.8 +/- 0.3 vs. 1.5 +/- 0.1 pmol/L, 211.9 +/- 27.2 vs. 67.7 +/- 9.7 nmol/L, and 51.6 +/- 4.0 vs. 16.3 +/- 2.0 nmol/L; P < 0.05). During CAN treatment, ACTH, cortisol, and DHEA levels showed progressive rises, which begun at approximately 60 min and peaked between 2300 and 2400 h (ACTH, 3.4 +/- 0.4 vs. 1.1 +/- 0.3 pmol/L; cortisol, 314.5 +/- 49.6 vs. 123.3 +/- 13.2 nmol/L; DHEA, 52.0 +/- 8.8 vs. 21.0 +/- 2.3 nmol/L; P < 0.05 vs. baseline as well as vs. the same time points during placebo). Aldosterone secretion was not modified by CAN. The ACTH, cortisol, and DHEA responses to human CRH were enhanced by CAN (10.0 +/- 1.7 pmol/L, 462.2 +/- 36.9 nmol/L, and 66.3 +/- 8.8 nmol/L), although statistical significance (P < 0.05) was obtained for cortisol and DHEA only. Also the ACTH, cortisol and DHEA responses to AVP were amplified by CAN (8.0 +/- 2.6 pmol/L, 324.0 +/- 34.8 nmol/L, and 77.8 +/- 4.0 nmol/L); again, statistical significance (P < 0.05) was obtained for cortisol and DHEA only. In conclusion, our study shows that the blockade of MR by CAN significantly enhances the activity of the HPA axis in humans, indicating a physiological role for MR in its control. These results also suggest that the stimulatory effect of CAN on HPA axis is mediated by concomitant modulation of CRH and AVP release.