SESSION TYPE: Critical Care Student/Resident Case Report Posters IIPRESENTED ON: Tuesday, October 23, 2012 at 01:30 PM - 02:30 PM

INTRODUCTION:

Described below is the first report of peri-operative management of a patient with severe pulmonary arterial hypertension (PAH) on oral treprostinil.

CASE PRESENTATION:

68-year-old woman with long-standing, diet-pill associated PAH. She was initially diagnosed in 2004 after a 2 year history of progressive dyspnea and fluid retention; initial right heart catheterization shown in table 1. She was started on sildenafil, furosemide, aldactone, digoxin and warfarin. In 02/2008, ambrisentan was started (table 1). On 03/2008, the patient enrolled in the FREEDOM C study of oral treprostinil. She did well during the initial 16 week randomized placebo controlled portion of the study. She entered the long-term open label extension on 08/2008. In 2011 a routine colonoscopy found 3 polyps, two removed during the procedure. The third, however, located at the apendicial orifice required laparascopic surgery. She was admitted for transition to IV treprostinil in order to avoid discontinuation of the study medication during periods of NPO and the post-operative period. Figure 2 shows the strategy used in the initial PO to IV transition. The patient was monitored with a CVP and central venous oximetry per protocol for PAH patients. The patient underwent a limited right colectomy. After normalization of her arterial CO2, the patient was successfully extubated. The patient was maintained on IV treprostinil at 35ng/kg/min on day of surgery. The following morning, she tolerated a diet and transitioned to oral treprostinil (figure 2). She was discharged home in a stable condition, 30 hours after the completion of her partial colectomy. Daily phone calls and a 1 week post-discharge office visit confirmed that the patient was doing well without any prostanoid excess or PAH symptoms.

DISCUSSION:

Oral treprostinil has been shown to improve six-minute walk distance in a 12-week study in treatment naive patients. Two studies in patients receiving background PAH therapy were negative. The abrupt discontinuation of Prostanoid therapy has in the past resulted in acute decline and death. If oral treprostinil is approved, we anticipate the need for IV treprostinil while patients are unable to take oral medication. For maximal absorption, oral treprostinil must be taken with food. The ability to rapidly and safely switch routes between oral and parenteral treprostinil will allow clinicians to prevent acute decompensation during such periods.

CONCLUSIONS:

Until there is greater experience with the use of oral treprostinil during periods of NPO, we strongly recommend that PAH patients be admitted and managed by physicians familiar with parenteral prostanoid therapy.1) UT-15C Treprostinil Diethanolamine Sustained Release Tablets (Oral Treprostinil)2) FREEDOM-C: Oral Treprostinil in Combination With an Endothelin Receptor Antagonist (ERA) and/or a Phosphodiesterase-5 (PDE-5) Inhibitor for the Treatment of Pulmonary Arterial Hypertension (PAH), United Therapeutics, 2012DISCLOSURE: Jeremy Feldman: Consultant fee, speaker bureau, advisory committee, etc.: United Therapeutics, Consultant fee, speaker bureau, advisory committee, etc.: Gilead SciencesThe following authors have nothing to disclose: Andres Borja Alvarez, Samer IbrahimOral treprostinil is being studied for use in pulmonary arterial hypertension.St Joseph's Hospital and Medical Center, Phoenix, AZ.

The ErbB2 receptor is a proto-oncogene associated with a poor prognosis in breast cancer. Trastuzumab, a humanized anti-ErbB2 antibody currently in clinical use, has proven to be an essential tool in the immunotherapy of breast carcinoma. Additionally, ErbB2 is involved in the growth and survival pathway of adult cardiomyocytes which accounts for the trastuzumab-induced cardiotoxicity. Moreover, in metastatic breast cancer patients treated with trastuzumab, endomyocardial biopsy documented focal vacuolar changes, pleomorphic mitochondria, myocardial cell hypertrophy, and mild interstitial fibrosis on electron microscopy without accompanying light microscopic abnormalities, a finding consistent with a reversible pattern of cardiac injury. On the other hand, aldosterone and mineralocorticoid receptor (MR) researches have experienced a revival after the discovery that aldosterone and MR are not only involved in the electrolyte and volume balance but also in the pathophysiological processes of the reno-cardiovascular system. Aldosterone has both genomic and nongenotropic effects on epidermal growth factor receptor (EGFR) expression. Genomic effect induces genomic up-regulation of the EGFR protein expression via EGFR promoter, whereas nongenotropic effect leads to the EGFR transactivation resulting in persistent pathophysiological effects including formation of extracellular matrix and myocardial hypertrophy. Spironolactone, an aldosterone receptor antagonist, is known to ameliorate the cardiac damage. The underlying mechanism for the genomic interactions seem to be the stimulation of the EGFR promoter by aldosterone-bound MR, which then dose-dependently enhances the EGFR protein levels, which may be successively inhibited by spironolactone. By the light of these findings, we hypothesize that spironolactone may ameliorate trastuzumab-induced cardiotoxicity via inhibition of transactivation of the EGFR by aldosterone and reversing myocardial hypertrophy. This issue warrants further studies.

Fast-release nano- and microfibres of lipophilic spironolactone were prepared in a continuous manner by electrostatic spinning, in which the application of polyvinylpyrrolidone K90 as matrix polymer enabled formation of solid solutions. However, instead of the anticipated immediate drug release, temporary precipitation was observed. The polyvinylpyrrolidone web gelled immediately after wetting, hindering drug diffusion and aiding the crystallisation of the solvated amorphous spironolactone. These local supersaturations could be successfully avoided by using hydroxypropyl-β-cyclodextrin. The dependence of fibre diameter and dissolution speed on the complexing agent-polymer ratio was also studied. A small addition of hydroxypropyl-β-cyclodextrin proved enough for a dramatic release rate enhancement even in the case of high drug loaded formulations. Transmission Raman spectroscopy, differential scanning calorimetry and X-ray powder diffraction showed that the drug was totally amorphised during processing in all formulations. Polymer-free hydroxypropyl-β-cyclodextrin fibres containing spironolactone were also electrospun from an ethanolic solution, which is a new way of dissolution improvement in the case of poorly water-soluble drugs. This novel approach ensured nearly total drug release in a minute, making the system a suitable age-appropriate orally dissolving formulation.

The mechanisms by which aldosterone increases Na(+), K(+) ATPase and sodium channel activity in cortical collecting duct and distal nephron have been extensively studied. Recent investigations demonstrate that aldosterone increases Na-H exchanger-3 (NHE-3) activity, bicarbonate transport, and H(+) ATPase in proximal tubules. However, the role of aldosterone in regulation of Na(+), K(+) ATPase in proximal tubules is unknown. We hypothesize that aldosterone increases Na(+), K(+) ATPase activity in proximal tubules through activation of the mineralocorticoid receptor (MR). Immunohistochemistry of kidney sections from human, rat, and mouse kidneys revealed that the MR is expressed in the cytosol of tubules staining positively for lotus tetragonolobus agglutinin and type IIa sodium-phosphate cotransporter (NpT2a), confirming proximal tubule localization. Adrenalectomy in Sprague Dawley rats decreased expression of MR, ENaC α, Na(+), K(+) ATPase α1, and NHE-1 in all tubules, while supplementation with aldosterone restored expression of above proteins. In human kidney proximal tubule (HKC11) cells, treatment with aldosterone resulted in translocation of MR to the nucleus and phosphorylation of SGK-1. Treatment with aldosterone also increased Na(+), K(+) ATPase-mediated (86)Rb uptake and expression of Na(+), K(+) ATPase α1 subunits in HKC11 cells. The effects of aldosterone on Na(+), K(+) ATPase-mediated (86)Rb uptake were prevented by spironolactone, a competitive inhibitor of aldosterone for the MR, and partially by mifepristone, a glucocorticoid receptor (GR) inhibitor. These results suggest that aldosterone regulates Na(+), K(+) ATPase in renal proximal tubule cells through an MR-dependent mechanism.

OBJECTIVE:

Elevated plasma aldosterone concentrations in patients have been linked to a spectrum of cardiovascular diseases. Mineralocorticoid receptor antagonists provide additional benefits in patients with heart failure. However, whether aldosterone and the mineralocorticoid receptor are involved in aortic aneurysm is unknown. APPROACH AND

RESULTS:

We report that administration of deoxycorticosterone acetate (DOCA) and salt or aldosterone and salt, but not DOCA or salt alone, to C57BL/6 male mice induced abdominal and thoracic aortic aneurysm formation and rupture in an age-dependent manner. DOCA and salt- or aldosterone and salt-induced aortic aneurysm mimicked human aortic aneurysm with respect to elastin degradation, inflammatory cell infiltration, smooth muscle cell degeneration and apoptosis, and oxidative stress. Aortic aneurysm formation did not correlate with the increase in blood pressure induced by DOCA and salt. Systemic administration of the angiotensin-converting enzyme inhibitor, enalapril, or angiotensin type 1 receptor antagonist, losartan, did not affect DOCA and salt-induced aortic aneurysm. In contrast, the mineralocorticoid receptor antagonists, spironolactone or eplerenone, significantly attenuated DOCA and salt- or aldosterone and salt-induced aortic aneurysm.

CONCLUSIONS:

The current study describes a novel aortic aneurysm animal model induced by mineralocorticoid receptor agonist and high salt, and reveals a previously unrecognized but potentially significant role of aldosterone in the pathogenesis of aortic aneurysm. These findings imply that mineralocorticoid receptor antagonists may be effective in the treatment of some aortic aneurysms.

A change in the function or expression of hepatic drug transporters may have significant effect on the efficacy or safety of orally administered drugs. Although a number of clinical drug-drug interactions associated with hepatic transport proteins have been reported, in practice it is not always straightforward to discriminate other pathways (e.g. drug metabolism) from being involved in these interactions. The present study was designed to assess the interactions between organic anion transporting polypeptide (Oatp) substrates (pravastatin or repaglinide) and inhibitors (spironolactone or diphenhydramine) in vivo in rats. The mechanisms behind the interactions were then investigated using in vitro tools (isolated hepatocytes and rat liver microsomes). The results showed a significant increase in the systemic exposures of pravastatin (2.5-fold increase in AUC) and repaglinide (1.8-fold increase in AUC) after co-administration of spironolactone to rats. Diphenhydramine increased the AUC of repaglinide by 1.4-fold. The in vivo interactions observed in rats between Oatp substrates and inhibitors may a priori be classified as transport-mediated drug-drug interactions. However, mechanistic studies performed in vitro using both isolated rat hepatocytes and rat liver microsomes showed that the interaction between pravastatin and spironolactone may be solely linked to the inhibition of pravastatin uptake in liver. On the contrary, the inhibition of cytochrome P450 seemed to be the reason for the interactions observed between repaglinide and spironolactone. Although the function and structure of transport proteins may vary between rats and humans, the approach used in the present study can be applied to humans and help to understand the role of drug transport and drug metabolism in a given drug-drug interaction. This is important to predict and mitigate the risk of drug-drug interactions for a candidate drug in pre-clinical development, it is also important for the optimal design of drug-drug interactions studies in the clinic.

Background:

Previous experimental studies from our laboratory have demonstrated that aldosterone plays a central role in renal ischemic processes. This study was designed to evaluate the effect of mineralocorticoid receptor blockade in renal transplant recipients from living donors.

Methods:

20 adult kidney transplant recipients from living donors were included in a double-blind, randomized, placebo-controlled clinical pilot study that compared spironolactone and placebo. Placebo or spironolactone (25 mg) was administered 1 day before and 3 days posttransplantation. Renal function and urinary kidney injury molecule-1, interleukin-18, and heat shock protein 72 as well as urinary hydrogen peroxide (H2O2) levels were quantified.

Results:

No significant differences were seen between the groups studied regarding age, gender, indication for kidney transplantation, residual renal function, renal replacement therapy, or warm and cold ischemia periods. In contrast, spironolactone administration significantly reduced the oxidative stress assessed by the urinary H2O2 excretion, in spite of no differences in renal function or reduction in tubular injury biomarkers.

Conclusions:

The findings of this exploratory study strongly suggest that aldosterone promotes oxidative stress and that the administration of spironolactone reduces the production of urinary H2O2 as a result of lesser formation of surrogate reactive oxygen species secondary to the ischemia-reperfusion phenomenon.

Abstract The aim of this study was to develop a nanostructured lipid carriers (NLC) formulation containing spironolactone (SPN-NLCs), and to investigate its potential for the oral delivery of poorly water-soluble compounds. SPN-NLCs were orally administered to rabbits and the pharmacokinetics of spironolactone and its metabolites was evaluated. As reference formulation, we administered syrup. Spironolactone was only detected in a few plasma samples; hence, metabolite levels were employed for the pharmacokinetic analysis. The absolute bioavailability of 7α-TMS was significantly higher with the syrup than those obtained with the SPN-NLCs (0.7 versus 0.4, p < 0.05). However, no significant differences were observed in the bioavailability of canrenone, revealing a different canrenone/7α-TMS ratio depending on the administered formulation. Orally administered (99m)Tc-radiolabeled SPN-NLCs were mainly detected in the small intestine. These results suggest the retention of the nanocarriers in the underlying epithelium and further uptake by the epithelial cells.

The effect of a salt-based diet on the coronary responsiveness in aged hypertensive rats (SHR) still is unclear. We investigated the effects of high salt intake on the relaxation properties of coronary arteries of aged SHRs. Male SHR (32week-old) received drinking water (SHR) or 1% NaCl solution (SHR-Salt) for 8weeks. Isolated coronary segments were subjected to concentration-response curves to acetylcholine (ACh) in the presence or absence of L-NAME (100μM), enalaprilate (10μM), losartan (10μM), and spironolactone (100μM). Salt intake did not increase blood pressure in old SHRs, but caused ventricular hypertrophy. The endothelium-dependent relaxation in SHRs was lower than in Wistar rats. However, salt intake did not add further impairment. Both enalaprilate and losartan reduced the vasodilator response in coronary arteries from Wistar, but did not affect SHR-salt rats. Conversely, losartan attenuated the impaired ACh relaxation observed in SHR. Spironolactone reduced the relaxation induced by ACh in coronary arteries from Wistar rats but not in SHR. The renin-angiotensin-aldosterone system participates in the impaired coronary relaxation in aged SHR, but does not partake in this deleterious effect under increased salt intake, indicating that age could differentiate the effects of high sodium intake in coronary arteries of SHR.

Mesangial cells (MCs) play a crucial role in maintaining structure and function of glomerular tufts, providing structural support for capillary loops and modulating glomerular filtration by their contractility. MCs apoptosis occurs in experimental diabetic nephropathy, and this correlates with worsening albuminuria. Accumulating evidence suggests that mineralocorticoid receptor (MR) blockade effectively reduces proteinuria in diabetic nephropathy; however, it is rarely known whether spironolactone (SPI), a nonspecific MR antagonist, inhibits apoptosis in MCs under hyperglycaemic conditions. The objectives of this study are to determine the relationship between SPI and apoptosis, and investigate the cell signalling pathway by which SPI inhibits apoptosis. Rat MCs were treated with 30 mM D-glucose and 10(-8), 10(-7) or 10(-6) M aldosterone (ALD) for 24 h. In some experiments, MCs were pretreated with 10(-7) M SPI or 10 mM LiCl for 1 h. Apoptosis was evaluated by cell nucleus staining and flow cytometric analyses, and caspase-3 activity was assayed. Gene and protein expression were quantified using quantitative real-time PCR and Western blotting, respectively. SPI directly inhibited high glucose and ALD-induced MCs apoptosis in a caspase-dependent manner. Importantly, SPI inhibited MCs apoptosis via the Wnt signalling pathway. SPI promoted activation of the Wnt signalling pathway in MCs, leading to upregulation of Wnt4 and Wnt5a mRNA expression, decreased GSK-3β protein expression and increased β-catenin protein expression. As a conclusion, this study suggests that SPI may inhibit apoptosis in MCs during hyperglycaemic conditions via the Wnt signalling pathway. Blockade of the ALD system may represent a novel therapeutic strategy to prevent MCs injury under hyperglycaemic conditions.