Measurement of Equilibrium Angiotensin II in the Diagnosis of Primary Aldosteronism.

BACKGROUND: Many medications (including most antihypertensives) and physiological factors affect the aldosterone/renin ratio (ARR) when screening for primary aldosteronism (PA). We sought to validate a novel equilibrium angiotensin II (eqAngII) assay and compare correlations between the aldosterone/angiotensin II ratio (AA2R) and the current ARR under conditions affecting the renin-angiotensin system. METHODS: Among 78 patients recruited, PA was excluded in 22 and confirmed in 56 by fludrocortisone suppression testing (FST). Peripheral levels of eqAngII, plasma renin activity (PRA) and direct renin concentration (DRC) were measured. RESULTS: EqAngII showed good consistency with DRC and PRA independent of PA diagnosis, posture, and fludrocortisone administration. EqAngII showed close (P < 0.01) correlations with DRC (r = 0.691) and PRA (r = 0.754) during FST. DRC and PRA were below their assays' functional sensitivity in 43.9% and 15.1%, respectively, of the total 312 samples compared with only 7.4% for eqAngII (P < 0.01). Bland-Altman analysis revealed an overestimation of PRA and DRC compared with eqAngII in a subset of samples with low renin levels. The AA2R showed not only consistent changes with the ARR but also close (P < 0.01) correlations with the ARR, whether renin was measured by DRC (r = 0.878) or PRA (r = 0.880). CONCLUSIONS: Dynamic changes of eqAngII and the AA2R show good consistency and close correlations with renin and the ARR. The eqAngII assay shows better sensitivity than DRC and PRA assays, especially at low concentrations. Whether the AA2R can reduce the impact of some factors that influence the diagnostic power of the ARR warrants further study.

Aerosolization, Drug Permeation and Cellular Interaction of Dry Powder Pulmonary Formulations of Corticosteroids with Hydroxypropyl-ß-Cyclodextrin as a Solubilizer.

PURPOSE: The purpose of this study was to assess the feasibility of hydroxypropyl-ß-cyclodextrin as a solubilizer for the corticosteroids prednisolone and fludrocortisone acetate in dry powder inhalation formulations. METHODS: The dry particles were simultaneously produced and coated with nanosized L-leucine crystals using an aerosol flow reactor method. The aerosolization performances of carrier-free powders were studied using Easyhaler® and Twister™ at 2 and 4 kPa pressure drops over the inhalers. Drug permeation properties of the formulations were tested across a Calu-3 cell monolayer. Toxicity and reactive oxygen species induction were tested against Calu-3 and A549 cell lines. RESULTS: The hydroxypropyl-ß-cyclodextrin in the powders promoted the dissolution of fludrocortisone the most, followed by that of prednisolone. Fine particle fractions were 52-70% from emitted doses which showed good repeatability with a coefficient variation of 0.9-0.17. In addition, hydroxypropyl-ß-cyclodextrin enhanced the permeation of the corticosteroids. The powders showed no statistically significant toxicity nor reactive oxygen species induction in the tested cell lines. CONCLUSIONS: This study demonstrated the preparation and function of fine powder formulations which combine improved dissolution of poorly soluble drugs with good aerosolization performance. These results are expected to promote particle engineering as a way to develop new types of therapeutic pulmonary powders.

Dilution of semi-solid creams: influence of various production parameters on rheological properties and skin penetration.

UNLABELLED: In order to customise treatment for patients, topical formulations are often diluted with drug-free cream bases to adjust the drug dose and thereby the formulations' activity to the patients' needs. However, the process of dilution influences properties of the formulations. Stability can be reduced as well as the microbial stability and most importantly, efficacy and skin penetration behaviour can be severely and unpredictably changed. The present study investigates the effects of production parameters on creams, namely incorporation of an API (active pharmaceutical ingredients) into an OW cream with prior mixing with propylene glycol or without and subsequent automated or manual dilution of the resulting creams with three different cream bases. Effects were measured by influence on microscopic appearance, measurement of chemical stability, skin penetration and rheological behaviour. RESULT: suggest strong influence of the cream bases used for dilution of the formulations. Mixture of equal amounts of the employed OW and WO cream proved unfavourable due to inferior penetration behaviour and less appealing microscopic and macroscopic appearance. Prior mixing with PG was of negligible importance for the characteristics of the dilutions, however, the type of API and manner of dilution had an influence on the viscosity of the formulations.

Mutual amplification of corticosteroids and angiotensin systems in human vascular smooth muscle cells and carotid atheroma.

UNLABELLED: The involvement of the renin-angiotensin-aldosterone system (RAAS) and cortisol in increased cardiovascular risk is well known. If numerous relationships between RAAS and corticosteroids have been described, their interactions within the arterial wall, especially during the transdifferentiation of vascular smooth muscle cells (VSMCs) and the atheroma formation, are not established. Here, we clarified the relationships between mRNA levels of corticosteroid and angiotensin system components using cortisol, fludrocortisone, and angiotensin II treatments of cultured VSMCs maintained in a contractile phenotype or induced to a lipid storing phenotype. We then determined the quantitative relationships between the mRNA content of these components measured with reverse transcription polymerase chain reaction (RT-PCR), in the atheroma plaque and nearby macroscopically intact tissue (MIT) from 27 human carotid endarterectomy samples. In both VSMC phenotypes, cortisol markedly increased both angiotensinogen (AGT) and AT1-receptor (AT1R) mRNA levels. These effects of cortisol were mediated via glucocorticoid receptor-α (GRα) without any illicit activation of the mineralocorticoid receptor (MR). Angiotensin II increased GRα, 11ßHSD1, CYP11B1, as well as CYP11B2 mRNAs and decreased AT1R in contractile VSMC; only GRα and CYP11B2 were increased in lipid storing VSMCs, while MR and AGT mRNAs decreased. In endarterectomy specimens, positive correlations between mRNA levels of AGT and aldosterone synthase or 11ßHSD1 in MIT and of AT1R and MR in atheroma were detected. The arterial tissue angiotensin system is a target for local glucocorticoids and arterial glucocorticoids for angiotensin II. Both systems appear activated in lipid storing VSMCs and strongly correlated in vivo, and their mutual amplification may contribute to the development of atheroma. KEY MESSAGE: Cortisol increases angiotensin II signaling in VSMCs via GRα. Angiotensin II stimulates cortisol signaling through increased GRα and 11ß-HSD1. Corticoid and angiotensin receptors are strongly correlated in the arterial wall. These correlations are maintained at different stages of atheroma development. An auto-amplification loop between angiotensin and cortisol signaling favors atherogenesis.

Human plasma quantification of fludrocortisone using liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry after low-dosage administration.

BACKGROUND: Fludrocortisone acetate is given at very low dosage (50 µg) to patients suffering from septic shock with controversial clinical results. However, it is not clear if absorption is effective in these patients. METHODS: An analytical method based upon liquid chromatography coupled to triple quadrupole spectrometry detection with atmospheric pressure chemical ionization interface has been developed for the identification and quantification of fludrocortisone, the active molecule circulating in human plasma. A solid phase extraction of plasma was used after addition of fludrocortisone-D2 as internal standard. Compounds were separated on a C18 column with a gradient of methanol-formate buffer. The ion transitions used to monitor analytes were m/z 381→239 and m/z 381→181 for fludrocortisone and m/z 383→239 and m/z 383→181 for fludrocortisone-D2. RESULTS: Retention times were 4.0 min for both compounds. Calibration curves were linear for fludrocortisone in the 0.1-25 ng/ml range. The limits of detection and quantification were 0.05 ng/ml and 0.1 ng/ml, respectively. The intra- and inter-assay precisions were lower than 10.9% and the recovery was 101.8%. A slight matrix effect by about 10% was observed. Application of the method to a patient in septic shock treated with one 50-µg dose of fludrocortisone acetate has shown a maximal plasma concentration of 0.36 ng/ml obtained after 2h. CONCLUSION: This method allows fludrocortisone pharmacokinetic/pharmacodynamic studies when given at low dosage in an intensive care unit in case of adrenal insufficiency during a septic shock.

Effect of γ-cyclodextrin on the in vitro skin permeation of a steroidal drug from nanoemulsions: impact of experimental setup.

Numerous reports on the enhancement effect of cyclodextrins (CDs) on the skin permeation of dermally applied drugs exist, the majority of which is based on in vitro diffusion cell studies. The specific experimental setup of such studies may skew the obtained results, which is rarely discussed in the context of CD studies. Thus, the aim of this work was to conduct a systematic in vitro investigation of the permeation enhancement potential of γ-CD on a steroidal drug from a nanoemulsion. The role of critical diffusion cell parameters such as the dose of application, occlusive conditions, the nature of the receptor medium and the skin thickness were investigated. The results showed that significantly enhanced skin permeation rates of fludrocortisone acetate were indeed caused by 1% (w/w) of γ-CD at both finite and infinite dose conditions. At 0.5% (w/w) of γ-CD, significant enhancement was only achieved at infinite dose application. Additional in vitro tape stripping experiments confirmed these tendencies, but the observed effects did not reach statistical significance. It may be concluded that the full permeation enhancement potential of the CD as observed in the Franz-cell setup can only be realised at infinite dose conditions while preserving the formulation structure.

Development of sucrose stearate-based nanoemulsions and optimisation through γ-cyclodextrin.

Nanoemulsions aimed at dermal drug delivery are usually stabilised by natural lecithins. However, lecithin has a high tendency towards self-aggregation and is prone to chemical degradation. Therefore, the aim of this study was to develop nanoemulsions with improved structure and long-term stability by employing a natural sucrose ester mixture as sole surfactant. A thorough comparison between the novel sucrose stearate-based nanoemulsions and corresponding lecithin-based nanoemulsions revealed that the sucrose ester is superior in terms of emulsifying efficiency, droplet formation as well as physical and chemical stability. The novel formulations exhibited a remarkably homogeneous structure in cryo TEM investigations, as opposed to the variable structure observed for lecithin-based systems. The in vitro skin permeation rates of lipophilic drugs from sucrose stearate nanoemulsions were comparable to those obtained with their lecithin-based counterparts. Furthermore, it was observed that addition of γ-cyclodextrin led to enhanced skin permeation of the steroidal drug fludrocortisone acetate from 9.99±0.46 to 55.10±3.67 µg cm(-2) after 24 h in the case of sucrose stearate-based systems and from 9.98±0.64 to 98.62±24.89 µg cm(-2) after 24 h in the case of lecithin-based systems. This enhancement effect was significantly stronger in formulations based on lecithin (P<0.05), which indicates that synergistic mechanisms between the surfactant and the cyclodextrin are involved. Cryo TEM images suggest that the cyclodextrin is incorporated into the interfacial film, which might alter drug release rates and improve the droplet microstructure.

Lecithin based nanoemulsions: A comparative study of the influence of non-ionic surfactants and the cationic phytosphingosine on physicochemical behaviour and skin permeation.

Charged drug delivery systems are interesting candidates for the delivery of drugs through skin. In the present study, it was possible to create negatively and positively charged oil/water nanoemulsions by using sucrose laureate and polysorbate 80 as non-ionic surfactants. The positively charged nanoemulsions were generated by adding cationic phytosphingosine (PS). The relationship between the physicochemical properties of the nanoemulsions was shown by particle size and zeta potential measurements. These properties were dependent on the type of non-ionic surfactant and the concentration of PS. Furthermore the cationic PS had a positive impact on the skin permeation rates (flux) of the incorporated model drugs fludrocortisone acetate and flumethasone pivalate. An enhancement factor between 1.1 and 1.5 was obtained in relation to the control. The interaction of pre-impregnated porcine skin with positively and negatively charged nanoemulsions was confirmed by DSC analysis. The generated DSC-curves showed a slight difference in the phase transition temperature assigned to the characteristic lipid transition. However, it was not possible to assign the effect to one of the ingredients in the multicomponent system.

Effect of selected fluorinated drugs in a "ringing" gel on rheological behaviour and skin permeation.

The purpose of the present study was to investigate the influence of different drugs exhibiting different solubility on the viscoelastic properties and on the skin diffusion profile of a ringing gel. In a preliminary rheology study with the placebo gel predominating elastic properties were confirmed and a temperature influence was indicated. Fluconazole, fludrocortisone-acetate, flumethasone-pivalate, flutamide and flufenamic-acid each 1% (w/w) were incorporated into the preparation and oscillatory measurements were performed at temperatures of 25, 28, 32 and 37 degrees C. In all drug containing formulations a high elastic G' value predominated the viscous G'' value. The highest G' value could be obtained with the incorporated flumethasone-pivalate. Additionally in almost all cases the G' values decreased with increasing temperature compared to the placebo gel. Additionally in vitro standard diffusion experiments using Franz-type cells and porcine skin were performed. Following rank order of the cumulative drug release after 48 h was obtained: fluconazole>flufenamic-acid>flumethasone-pivalate>flutamide>fludrocortisone-acetate. Furthermore an excellent chemical stability of all incorporated drugs was confirmed over 10 weeks.

[The effect of fluorine substituent on radiochemical stability of some steroid and azole derivatives]. / Wplyw podstawnika fluorowego na trwalosc radiochemiczna niektórych leków pochodnych steroidów i azoli.

Radiochemical stability of three fluorine containing therapeutic substances: dexamethasone, fludrocortisone acetate (steroid derivatives) and fluconazole (azole derivative) has been studied. The compounds in the solid phase were exposed to ionising radiation in the form of electron beam using doses of 20-400 kGy. The inital and irradiated compounds were subjected to comparative analyses by organoleptic, spectrophotometric (UV and IR) and chromatographic (TLC and HPLC) methods. For all compounds studied the irradiation was found to lead to a decrease in the active substance content (HPLC), appearance of radiolysis products (TLC), changes in the physical and chemical properties such as colour (fluconazole), formation of agglomerates (dexamethasone), decrease (dexamethasone, fludrocortisone acetate) or increase in UV absorption (fluconazole). The two steroid derivatives were found resistant to ionising radiation at doses of 25-50 kGy and can be sterilised by radiation, whereas fluconazole was too sensitive to electron beam irradiation and should be sterilised by other methods. The results were compared with those of earlier studies on radiation sterilisation of other steroid derivatives. An interesting conclusion is that the presence of the fluorine atom in the molecule of fludrocortisone acetate has no significant effect on its radiochemical stability when compared with that of hydrocortisone acetate--the analogue without fluorine.

Automated coupling of capillary-HPLC to matrix-assisted laser desorption/ionization mass spectrometry for the analysis of small molecules utilizing a reactive matrix.

This study describes the application of a novel, reactive matrix for the mass spectral analysis of steroids by capillary-high performance liquid chromatography (capillary-HPLC) coupled to matrix-assisted laser desorption/ionization (MALDI). The mass spectral analysis of steroids was accomplished after fully automated peak deposition of chromatographic peaks onto MALDI targets. The seven corticosteroids used as test compounds were: triamcinolone, prednisone, cortisone, fludrocortisone, dexamethasone, deoxycorticosterone, and budesonide. They were separated using a PepMap C(18) (3 microm particle size, 100 A pore width) column at five different concentration levels of 25, 15, 7.5, 2.5 and 1 ng/microL, and the peaks were detected at a wavelength of 237 nm. The column effluent was mixed with 2,4-dinitrophenylhydrazine (DNPH) directly following the UV detector. The chromatographic peaks were then deposited onto the MALDI target with a robotic micro-fraction collector triggered by the UV detector signals. A special hydrophobic surface coating allowed the deposition of up to 4 microL (up to 90 % of the chromatographic peak volume) onto one sample spot. The compounds were then identified by MALDI mass spectrometry. Depending on the nature of the analyte, radical cations ([M](+.)) and sodium adduct ions ([M+Na](+)) of the steroids as well as protonated steroid-dinitrophenylhydrazone derivatives ([M(D)+H](+)) were detected in positive ion mode. The detection limits were between 0.5 and 15 ng injected with capillary-HPLC-MALDI-TOF-MS and between 0.3 and 3 ng on target with MALDI-TOF when deposited manually.

Stability of fludrocortisone acetate solutions prepared from tablets and powder.

To assess the stability of fludrocortisone acetate oral solutions prepared from tablets and powder at three temperatures over a 60-days period. Solutions of fludrocortisone acetate 40 microg/ml were prepared from commercially available 0.05-mg tablets and powder in ethanol 17% v/v. They stored in an amber glass prescription bottles at +4, +23 and +40 degrees C shielded from light. The concentrations of fludrocortisone acetate were determined in duplicate by high-performance liquid chromatography at 0, 1, 7, 14, 30, 50 and 60 days. The initial and final pH of solutions were compared. The recovery of fludrocortisone acetate from tablets was determined. The times (t(90)) needed for fludrocortisone acetate to fall to 90% of it's initial concentration were calculated by a linear regression analysis to allow the determination of the expired dates. The recovery of fludrocortisone acetate from tablets was 78 +/- 3%. The t(90) expressed with 95% confidence limits were 2 +/- 1 and 22 +/- 3 days for the solutions prepared from tablets and stored at +23 and +4 degrees C, respectively, whereas t(90) were 11 +/- 2 days and at least 60 days for the solutions prepared with the powder and stored at +23 and +4 degrees C, respectively. No color or odour changes were observed during the study period. The initial pH of the solutions prepared from tablets and powder were 7.7 and 6.9, respectively. No change of pH values was observed at the end of the 60 days. Significant degradation of fludrocortisone acetate occurred in formulations stored at +23 degrees C. Fludrocortisone acetate 40 microg/ml solutions prepared from tablets and powder were stable 19 days and at least 60 days, respectively, when stored at +4 degrees C. The solution prepared from powder is the best in term of stability and final concentration which is independent on the fludrocortisone acetate recovery.

Structural basis for the glucocorticoid response in a mutant human androgen receptor (AR(ccr)) derived from an androgen-independent prostate cancer.

The crystal structure of a mutant androgen receptor (AR) ligand-binding domain (LBD) in complex with the agonist 9alpha-fluorocortisol has been determined at 1.95 A resolution. This mutant AR contains two mutations (L701H and T877A) and was previously reported as a high-affinity cortisol/cortisone responsive AR (AR(ccr)) isolated from the androgen-independent human prostate cancer cell lines MDA PCa 2a and 2b (Zhao et al. Nature Med. 2000, 6, 703-6). The three-dimensional structure of the AR(ccr) LBD complexed with 9alpha-fluorocortisol shows the typical conformation of an agonist-bound nuclear receptor in which helix 12 is precisely positioned as a "lid" for the ligand-binding pocket. Binding of 9alpha-fluorocortisol to the AR(ccr) involves favorable hydrogen bond patterns on the C17 and C21 substituents of the ligand due to the mutations at 701 and 877 in the AR(ccr). Our studies provide the first structural explanation for the glucocorticoid activation of AR(ccr), which is important for the development of new therapeutic treatments for androgen-independent prostate cancer.

[Synthetic mineralocorticoid, clinical application of fludrocortisone acetate (Florinef)].

Fludrocortisone acetate (Florinef), a 9 alpha-fluorinated derivative of hydrocortisone, has strong mineralocorticoid activity. From the calculated values in a tracer study, the divided dose regimen is recommended. Florinef has been widely used in the treatment of salt-wasting congenital adrenal hyperplasia (CAH). A tentative guideline for the treatment of salt-wasting CAH was described and its usefulness was discussed.

Dissolution of fludrocortisone from phospholipid coprecipitates.

The physical properties and dissolution behavior of phospholipid coprecipitates of fludrocortisone acetate (FA) prepared from ethyl acetate, as well as the effect of added polymer, have been determined. The fraction dissolved after 90 min and the initial dissolution rate (IDR) of coprecipitates containing dimyristoyl phosphatidylcholine (DMPC) (4:1, w/w; FA:DMPC) were 77% and 3.5-fold greater than for FA at pH 2.0 and 37 degrees C. The mechanisms of dissolution were similar to those previously established for griseofulvin, but no aging occurred over 4 months at room temperature in a desiccator. The addition of 0.01 mol% of dextran (MW = 2 million) or 0.1 mol% of poly(lactic acid) reduced the fraction of FA dissolved in 90 min by 15% and reduced the IDR by 35%. The addition of poly(vinylpyrrolidone) (PVP) resulted in a minimum of dissolution efficiency at 1 mol% of PVP 10 (MW = 10,000) or PVP 24 (MW = 24,000) and at 0.1 mol% PVP 40 (MW = 40,000). Only PVP 24 influenced the melting point and heat of fusion of the coprecipitates (determined by differential thermal analysis). Coprecipitate dissolution was reasonably described by either second-order or Weibull distribution kinetic models. These results support the application of high drug-containing solid dispersions using phospholipids to increase the dissolution behavior of poorly water-soluble drug solvates and the possibility of modifying drug release by the incorporation of small amounts of polymers.