Effect of Patiromer in Hyperkalemic Patients Taking and Not Taking RAAS Inhibitors.

INTRODUCTION: Hyperkalemia (potassium >5.0 mEq/L) affects heart failure patients with renal disease regardless of the use of renin-angiotensin-aldosterone system inhibitors (RAASi). The open-label TOURMALINE study showed that patiromer, a sodium-free, nonabsorbed potassium binder, lowers serum potassium of hyperkalemic patients similarly when given with or without food; unlike prior studies, patients were not required to be taking RAASi. We conducted post hoc analyses to provide the first report of patiromer in patients not taking RAASi. METHODS: Hyperkalemic patients received patiromer, 8.4 g/d to start, adjusted to achieve and maintain serum potassium of 3.8 to 5.0 mEq/L. If taking RAASi, stable doses were required. The primary end point was the proportion of patients with serum potassium 3.8 to 5.0 mEq/L at week 3 or 4. This analysis presents data by patients taking or not taking RAASi. RESULTS: Demographics and baseline characteristics were similar in patients taking (n = 67) and not taking RAASi (n = 45). Baseline mean (SD) serum potassium was 5.37 (0.37) mEq/L and 5.42 (0.43) mEq/L in patients taking and not taking RAASi, respectively. Mean (SD) daily patiromer doses were similar (10.7 [3.2] and 11.5 [4.0] g, respectively). The primary end point was achieved in 85% (95% confidence interval [CI]: 74-93) of patients taking RAASi and in 84% (95% CI: 71-94) of patients not taking RAASi. From baseline to week 4, the mean (SE) change in serum potassium was -0.67 (0.08) mEq/L in patients taking RAASi and -0.56 (0.10) mEq/L in patients not taking RAASi (both P < .0001 vs baseline, P = nonsignificant between groups). Adverse events were reported in 26 (39%) patients taking RAASi and 25 (54%) not taking RAASi; the most common adverse event was diarrhea (2% and 11%, respectively; no cases were severe). Five patients (2 taking RAASi) reported 6 serious adverse events; none considered related to patiromer. CONCLUSIONS: Patiromer was effective and generally well-tolerated for hyperkalemia treatment, whether or not patients were taking RAAS inhibitors.

Enhancing clinical trial development for pediatric kidney diseases.

The conduct of clinical trials in small pediatric subspecialties such as pediatric nephrology is hampered by both clinical demands on the pediatric nephrologist and the small number of appropriate patients available for such studies. The American Society of Pediatric Nephrology Therapeutics Development Committee (TDC) was established to (1) identify the various stakeholders with interests and/or expertise related to clinical trials in children with kidney disease and (2) develop more effective partnerships among all parties regarding strategies for successful clinical trial development and execution. This article discusses the rationale, structure, and function of the TDC, the status of progress toward its goals, and the insights gained to date that may be useful for other subspecialties that face similar challenges.

Effect of Patiromer on Urinary Ion Excretion in Healthy Adults.

BACKGROUND AND OBJECTIVES: Patiromer is a nonabsorbed potassium-binding polymer that uses calcium as the counterexchange ion. The calcium released with potassium binding has the potential to be absorbed or bind phosphate. Because binding is not specific for potassium, patiromer can bind other cations. Here, we evaluate the effect of patiromer on urine ion excretion in healthy adults, which reflects gastrointestinal ion absorption. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We analyzed the effect of patiromer on urine potassium, sodium, magnesium, calcium, and phosphate in two studies. Healthy adults on controlled diets in a clinical research unit were given patiromer up to 50.4 g/d divided three times a day for 8 days (dose-finding study) or 25.2 g/d in a crossover design as daily or divided (two or three times a day) doses for 18 days (dosing regimen study). On the basis of 24-hour collections, urinary ion excretion during the baseline period (days 5-11) was compared with that during the treatment period (days 13-19; dose-finding study), and the last 4 days of each period were compared across regimens (dosing regimen study). RESULTS: In the dose-finding study, patiromer induced a dose-dependent decrease in urine potassium, urine magnesium, and urine sodium (P<0.01 for each). Patiromer at 25.2 g/d decreased urine potassium (mean±SD) by 1140±316 mg/d, urine magnesium by 45±1 mg/d, and urine sodium by 225±145 mg/d. Urine calcium increased in a dose-dependent manner, and urine phosphate decreased in parallel (both P<0.01). Patiromer at 25.2 g/d increased urine calcium by 73±23 mg/d and decreased urine phosphate by 64±40 mg/d. Urine potassium, urine sodium, and urine magnesium were unaffected by dosing regimen, whereas the increase in urine calcium was significantly lower with daily compared with three times a day dosing (P=0.01). Urine phosphate also decreased less with daily compared with two or three times a day dosing (P<0.05). CONCLUSIONS: In healthy adults, patiromer reduces urine potassium, urine sodium, urine magnesium, and urine phosphate, while modestly increasing urine calcium. Compared with divided dosing, administration of patiromer once daily provides equivalent reductions in urine potassium, urine sodium, and urine magnesium, with less effect on urine calcium and urine phosphate.

Treatment with patiromer decreases aldosterone in patients with chronic kidney disease and hyperkalemia on renin-angiotensin system inhibitors.

Elevated serum aldosterone can be vasculotoxic and facilitate cardiorenal damage. Renin-angiotensin system inhibitors reduce serum aldosterone levels and/or block its effects but can cause hyperkalemia. Patiromer, a nonabsorbed potassium binder, decreases serum potassium in patients with chronic kidney disease on renin-angiotensin system inhibitors. Here we examined the effect of patiromer treatment on serum aldosterone, blood pressure, and albuminuria in patients with chronic kidney disease on renin-angiotensin system inhibitors with hyperkalemia (serum potassium 5.1-6.5 mEq/l). We analyzed data from the phase 3 OPAL-HK study (4-week initial treatment phase of 243 patients; 8-week randomized withdrawal phase of 107 patients). In the treatment phase, the (mean ± standard error) serum potassium was decreased concordantly with the serum aldosterone (-1.99 ± 0.51 ng/dl), systolic/diastolic blood pressure (-5.64 ± 1.04 mm Hg/-3.84 ± 0.69 mm Hg), and albumin-to-creatinine ratio (-203.7 ± 54.7 mg/g), all in a statistically significant manner. The change in the plasma renin activity (-0.44 ± 0.63 µg/l/hr) was not significant. In the withdrawal phase, mean aldosterone levels were sustained with patiromer (+0.23 ± 1.07 ng/dl) and significantly increased with placebo (+2.78 ± 1.25 ng/dl). Patients on patiromer had significant reductions in mean systolic/diastolic blood pressure (-6.70 ± 1.59/-2.15 ± 1.06 mm Hg), whereas those on placebo did not (-1.21 ± 1.89 mm Hg/+1.72 ± 1.26 mm Hg). Significant changes in plasma renin activity were found only in the placebo group (-3.90 ± 1.41 µg/l/hr). Thus, patiromer reduced serum potassium and aldosterone levels independent of plasma renin activity in patients with chronic kidney disease and hyperkalemia on renin-angiotensin system inhibitors.

Changes in plasma ACTH levels and corticotroph tumor size in patients with Cushing's disease during long-term treatment with the glucocorticoid receptor antagonist mifepristone.

CONTEXT: Pituitary effects of long-term therapy with mifepristone, a glucocorticoid receptor antagonist, in Cushing's disease (CD) patients are not well understood. OBJECTIVE: Our objective was to report changes in ACTH and pituitary magnetic resonance imaging (MRI) findings during long-term use of mifepristone in CD patients. DESIGN AND SETTING: The Study of the Efficacy and Safety of Mifepristone in the Treatment of Endogenous Cushing's Syndrome (SEISMIC) was a 24-week, open-label study of mifepristone, and its long-term extension (LTE) is a multicenter U.S. study. PATIENTS: Forty-three CD patients (mean age 45.3 years) were enrolled in SEISMIC with 27 continuing into the LTE study. INTERVENTIONS: Mifepristone (300-1200 mg) was administered once daily. MAIN OUTCOME MEASURES: ACTH and pituitary MRI were assessed at baseline and at regular intervals during treatment. RESULTS: A ≥2-fold increase in ACTH was observed in 72% of patients treated for a median duration of 11.3 months. The mean peak increase in ACTH was 2.76 ± 1.65-fold during SEISMIC, and mean ACTH concentrations remained stable during the LTE. ACTH was directly correlated with mifepristone dose and declined to near baseline levels after mifepristone discontinuation. Tumor regressed in 2 patients and progressed in 3 patients with macroadenomas. An additional microadenoma was identified after 25 months of treatment after a baseline tumor-negative MRI. CONCLUSIONS: In the largest prospective study to date, long-term mifepristone treatment increased ACTH in approximately two-thirds of patients with CD. ACTH elevations were observed within the first few weeks of treatment, were dose-dependent, and generally remained stable over time. Corticotroph tumor progression and regression may occur over time, but patients may have significant increases in ACTH levels without evidence of tumor growth.

Global clinical response in Cushing's syndrome patients treated with mifepristone.

OBJECTIVE: Mifepristone, a glucocorticoid receptor antagonist, improves clinical status in patients with Cushing's syndrome (CS). We examined the pattern, reliability and correlates of global clinical response (GCR) assessments during a 6-month clinical trial of mifepristone in CS. DESIGN: Post hoc analysis of secondary end-point data from a 24-week multicentre, open-label trial of mifepristone (300-1200 mg daily) in CS. Intraclass correlation coefficient (ICC) was used to examine rater concordance, and drivers of clinical improvement were determined by multivariate regression analysis. PATIENTS: Forty-six adult patients with refractory CS along with diabetes mellitus type 2 or impaired glucose tolerance, and/or a diagnosis of hypertension. MEASUREMENTS: Global clinical assessment made by three independent reviewers using a three-point ordinal scale (+1 = improvement; 0 = no change; -1 = worsening) based on eight broad clinical categories including glucose control, lipids, blood pressure, body composition, clinical appearance, strength, psychiatric/cognitive symptoms and quality of life at Weeks 6, 10, 16, and 24. RESULTS: Positive GCR increased progressively over time with 88% of patients having improved at Week 24 (P < 0·001). The full concordance among reviewers occurred in 76·6% of evaluations resulting in an ICC of 0·652 (P < 0·001). Changes in body weight (P < 0·0001), diastolic blood pressure (P < 0·0001), two-hour postoral glucose challenge glucose concentration (P = 0·0003), and Cushingoid appearance (P = 0·022) were strong correlates of GCR. CONCLUSIONS: Mifepristone treatment for CS results in progressive clinical improvement. Overall agreement among clinical reviewers was substantial and determinants of positive GCR included change in weight, blood pressure, glucose levels and appearance.

A new therapeutic approach in the medical treatment of Cushing's syndrome: glucocorticoid receptor blockade with mifepristone.

OBJECTIVE: Cushing's syndrome (CS) is a serious endocrine disorder caused by prolonged exposure to high cortisol levels. Initial treatment of this condition is dependent upon the cause, but is generally surgical. For patients whose hypercortisolism is not cured by surgery, medical therapy is often required. Drugs that have typically been used for CS medical therapy act by decreasing cortisol levels. Mifepristone is a glucocorticoid receptor antagonist now available for use in patients with CS. Unlike other agents, mifepristone does not decrease cortisol levels, but directly antagonizes its effects. Our objective is to review the pharmacology and clinical use of this novel agent and to discuss detailed guidance on the management of CS patients treated with mifepristone. METHODS: We review the literature regarding mifepristone use in CS and recently published clinical trial data. Detailed information related to clinical assessment of mifepristone use, potential drug interactions, drug initiation and dose titration, and monitoring of drug tolerability are provided. RESULTS: Clinical trial data have shown that mifepristone improves glycemic control and blood pressure, causes weight loss and a decrease in waist circumference, lessens depression, and improves overall wellbeing. However, adverse effects include adrenal insufficiency, hypokalemia, and endometrial thickening with vaginal bleeding. These findings are supported by the earlier literature case reports. CONCLUSION: This article provides a review of the pharmacology and clinical use of mifepristone in Cushing's syndrome, as well as detailed guidance on the management of patients treated with this novel agent.

Mifepristone, a glucocorticoid receptor antagonist, produces clinical and metabolic benefits in patients with Cushing's syndrome.

CONTEXT: Cushing's syndrome (CS) is a disorder associated with significant morbidity and mortality due to prolonged exposure to high cortisol concentrations. OBJECTIVE: Our objective was to evaluate the safety and efficacy of mifepristone, a glucocorticoid receptor antagonist, in endogenous CS. DESIGN AND SETTING: We conducted a 24-wk multicenter, open-label trial after failed multimodality therapy at 14 U.S. academic medical centers and three private research centers. PARTICIPANTS: Participants included 50 adults with endogenous CS associated with type 2 diabetes mellitus/impaired glucose tolerance (C-DM) or a diagnosis of hypertension alone (C-HT). INTERVENTION: Mifepristone was administered at doses of 300-1200 mg daily. MAIN OUTCOME MEASURES: We evaluated change in area under the curve for glucose on 2-h oral glucose test for C-DM and change in diastolic blood pressure from baseline to wk 24 for C-HT. RESULTS: In the C-DM cohort, an area under the curve for glucose (AUC(glucose)) response was seen in 60% of patients (P < 0.0001). Mean ± sd glycated hemoglobin (HbA1c) decreased from 7.43 ± 1.52% to 6.29 ± 0.99% (P < 0.001); fasting plasma glucose decreased from 149.0 ± 75.7 mg/dl (8.3 ± 4.1 mmol/liter) to 104.7 ± 37.5 mg/dl (5.8 ± 2.1 mmol/liter, P < 0.03). In C-HT cohort, a diastolic blood pressure response was seen in 38% of patients (P < 0.05). Mean weight change was -5.7 ± 7.4% (P < 0.001) with waist circumference decrease of -6.78 ± 5.8 cm (P < 0.001) in women and -8.44 ± 5.9 cm (P < 0.001) in men. Overall, 87% (P < 0.0001) had significant improvement in clinical status. Insulin resistance, depression, cognition, and quality of life also improved. Common adverse events were fatigue, nausea, headache, low potassium, arthralgia, vomiting, edema, and endometrial thickening in women. CONCLUSIONS: Mifepristone produced significant clinical and metabolic improvement in patients with CS with an acceptable risk-benefit profile during 6 months of treatment.

Impact of mifepristone, a glucocorticoid/progesterone antagonist, on HDL cholesterol, HDL particle concentration, and HDL function.

CONTEXT: Mifepristone is a glucocorticoid and progestin antagonist under investigation for the treatment of Cushing's syndrome. Mifepristone decreases high-density lipoprotein (HDL) cholesterol (HDL-C) levels in treated patients, but the clinical significance of this is unclear because recent studies suggest that functional properties of HDL predict cardiovascular disease status better than does HDL-C concentration. OBJECTIVE: The aim of the study was to characterize the impact of mifepristone administration on HDL particle concentration and function. DESIGN AND SETTING: We conducted a double-blind, randomized, placebo-controlled trial at a single-site, clinical research center. PARTICIPANTS: Thirty healthy postmenopausal female volunteers participated in the study. INTERVENTION: Individuals were randomized to receive daily oral mifepristone (600 mg) or placebo for 6 wk. MAIN OUTCOME MEASURES: We measured HDL-C, serum HDL particle concentration, and HDL-mediated cholesterol efflux by treatment group. RESULTS: As expected, ACTH, cortisol, estradiol, and testosterone levels increased in the mifepristone group. Mifepristone treatment decreased HDL-C and HDL particle concentration by 26 and 25%, respectively, but did not alter pre-ß HDL concentration. In contrast, the serum HDL-mediated cholesterol efflux decreased with mifepristone treatment by only 12%, resulting in an effective increase of the efflux capacity per HDL particle. No changes were observed in cholesterol ester transfer protein or lecithin:cholesterol acyltransferase activity. CONCLUSIONS: Treatment with mifepristone reduced HDL-C, HDL particle concentration, and serum HDL cholesterol efflux in postmenopausal women. However, on a per particle basis, the efflux capacity of serum HDL increased. These observations support the concept that a decrease in HDL-C may not represent proportional impairment of HDL function.

Mifepristone reduces weight gain and improves metabolic abnormalities associated with risperidone treatment in normal men.

Antipsychotic medications are associated with significant weight gain, type 2 diabetes mellitus, dyslipidemia, and increased cardiovascular risk. The objective of this study was to determine whether mifepristone, a glucocorticoid receptor antagonist, could prevent risperidone-induced weight gain. Using a 2:2:1 randomization scheme, 76 lean, healthy men (BMI 18-23 kg/m(2)) age 18-40 years were randomized to risperidone (n = 30), risperidone plus mifepristone (n = 30) or mifepristone (n = 16) daily for 28 days in an institutional setting. Subjects were provided food ad libitum. Body weight was measured daily. Metabolic measures were taken at study onset, midpoint, and end. Analyses of covariance indicated that the group receiving risperidone plus placebo gained significantly more weight (P < 0.001) and exhibited a significantly greater increase in waist circumference (P < 0.05) than the group receiving risperidone plus mifepristone. Significant differences were also observed for metabolic measures including fasting insulin (P < 0.001) and triglyceride levels (P < 0.05). Mifepristone attenuated increases in weight and reduced the metabolic changes induced by risperidone use, replicating results from a prior study of olanzapine-induced weight gain. These findings suggest mechanistic involvement of the hypothalamic-pituitary-adrenal axis in the weight and cardiometabolic side effects of antipsychotic medications. Future research should continue to test the potential of glucocorticoid antagonists to alleviate the deleterious side effects associated with use of antipsychotic medications.

Mifepristone treatment of olanzapine-induced weight gain in healthy men.

INTRODUCTION: Antipsychotic medications are associated with significant weight gain, type 2 diabetes mellitus, dyslipidemia, and increased cardiovascular risk. Suggested mechanisms of weight gain from antipsychotic medication include antagonism of histamine and serotonin receptors, and effects on the hypothalamic-pituitary-adrenal axis. The objective of this study was to determine if mifepristone, a glucocorticoid receptor antagonist, could prevent olanzapine-induced weight gain. METHODS: This was a randomized, double-blind trial. Fifty-seven lean, healthy men (body mass index 18-25 kg/m(2)) aged 19-38 years were randomized to olanzapine (7.5 mg) (n=22), olanzapine (7.5 mg) plus mifepristone (600 mg) (n=24), or mifepristone (600 mg) (n=11) daily for 2 weeks in an institutional setting. Subjects were provided food ad libitum to accentuate weight gain. Body weight was measured daily. RESULTS: The mean change in baseline weight was +3.2+/-0.9 kg in subjects receiving olanzapine versus +2.0+/-1.2 kg in those receiving olanzapine plus mifepristone (P<0.0001). Subjects receiving mifepristone alone had a similar degree of weight gain compared to those receiving olanzapine plus mifepristone. The olanzapine group had significant increases in waist circumference when compared with the olanzapine plus mifepristone group (3.7+/-1.3 cm vs. 2.2+/-1.9 cm, respectively; P=0.006). Fasting insulin and triglycerides increased more in the olanzapine group, although differences were not statistically significant. CONCLUSION: Mifepristone was effective in attenuating the increase in weight associated with olanzapine treatment over a 2-week period. Longer-term studies are required to examine the durability and full magnitude of this response.

Cinnamic acid based thiazolidinediones inhibit human P450c17 and 3beta-hydroxysteroid dehydrogenase and improve insulin sensitivity independent of PPARgamma agonist activity.

Thiazolidinediones improve insulin sensitivity in type 2 diabetes mellitus by acting as peroxisome proliferator-associated receptor gamma (PPARgamma) agonists, and decrease circulating androgen concentrations in polycystic ovary syndrome by unknown mechanisms. Some thiazolidinediones directly inhibit the steroidogenic enzymes P450c17 and 3beta-hydroxysteroid dehydrogenase type II (3betaHSDII) by distinct mechanisms. We synthesized five novel thiazolidinediones, CLX-M1 to -M5 by linking a 2,4-thiazolidinedione moiety to a substituted alpha-phenyl cinnamic acid previously shown to have glucose-lowering effects. Using yeast microsomes expressing human P450c17 and 3betaHSDII we found that cinnamic acid methyl esters with a double bond in the thiazolidinedione core structure (M3, M5) were stronger inhibitors of P450c17 than methyl esters with the conventional core (M1, M4). These four compounds inhibited 3betaHSDII equally well, while the free cinnamic acid analog (M2) did not inhibit either enzyme. Thus, the inhibition of P450c17 and 3betaHSDII by these novel thiazolidinediones reveals structure-activity relationships independent of PPARgamma transactivation. PPARgamma transactivation was moderate (M1), weak (M2, M3) or even absent (M4, M5). While the PPARgamma agonist activity of M1 was only 3% of that of rosiglitazone, both increased glucose uptake by 3T3-L1 adipocytes and reduced serum glucose levels in ob/ob and db/db mice to a similar extent. The similar glucose-lowering effects of M1 and rosiglitazone, despite their vast differences in PPARgamma agonist activity, suggests these two actions may occur by separate mechanisms.

A novel peroxisome proliferator-activated gamma (PPAR gamma) agonist, CLX-0921, has potent antihyperglycemic activity with low adipogenic potential.

Agonists of the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR gamma) are pharmacologically active antihyperglycemic agents that act by increasing peripheral tissue sensitivity to insulin. Many of these agonists have antihyperglycemic activity that is directly proportional to their ability to bind and activate PPAR gamma; however, recent data bring this relationship into question. In this report we describe a new PPAR gamma agonist, CLX-0921, that is derived from a natural product. This thiazolidinedione (TZD) has a spectrum of activity that differs from commercially available TZDs. It is a weak activator of PPAR gamma (EC(50) of 0.284 micromol/L) compared to rosiglitazone (EC(50) 0.009 micromol/L). Despite this difference, the drug maintains potent glucose uptake activity in vitro and glucose-lowering activity in vivo that is equipotent to that of rosiglitazone. Moreover, CLX-0921 showed a 10-fold reduction in in vitro adipogenic potential compared to rosiglitazone. CLX-0921 also increases glycogen synthesis, an activity not typically associated with rosiglitazone or pioglitazone. Thus CLX-0921 appears to have a distinct spectrum of activity relative to other TZDs.

Synthesis and structure-activity relationship studies of cinnamic acid-based novel thiazolidinedione antihyperglycemic agents.

A number of 2,4-thiazolidinedione derivatives of -phenyl substituted cinnamic acid were synthesized and studied for their PPAR agonist activity. The E-isomer of cinnamic acid, 11, showed moderate PPAR transactivation. The corresponding Z-isomer, 23, and double bond reduced derivative, 15, were found to be much less potent. Although the E-isomer showed a moderate PPAR gamma transactivation, it demonstrated a strong glucose-lowering effect in a genetic rodent model of diabetes. Results of pharmacokinetic, metabolism and permeability studies are consistent with 11 being an active prodrug with an active metabolite, 14, that has similar glucose lowering and PPAR gamma agonist properties.