Successive ratio subtraction as a novel manipulation of ratio spectra for quantitative determination of a mixture of furosemide, spironolactone and canrenone

Furosemide and spironolactone are commonly prescribed antihypertensive drugs. Canrenone is the main degradation product and main metabolite of spironolactone. Ratio subtraction and extended ratio subtraction spectrophotometric methods were previously applied for quantitation of only binary mixtures. An extension of the above mentioned methods; successive ratio subtraction, is introduced in the presented work for quantitative determination of ternary mixtures exemplified by furosemide, spironolactone and canrenone. Manipulating the ratio spectra of the ternary mixture allowed their determination at 273.6nm, 285nm and 240nm and in the concentration ranges of (2-16μgmL^-1), (4-32μgmL^-1) and (1-18μgmL^-1) for furosemide, spironolactone and canrenone, respectively. Method specificity was ensured by the application to laboratory prepared mixtures. The introduced method was ensured to be accurate and precise. Validation of the developed method was done with respect to ICH guidelines and its validity was further ensured by the application to the pharmaceutical formulation. Statistical comparison between the obtained results and those obtained from the reported HPLC method was achieved concerning student's t-test and F ratio test where no significant difference was observed.

Electrospray ionization tandem mass spectrometric analysis of ent-6,7-seco-kaurane diterpenoids from the Isodon species

Electrospray ionization tandem mass spectrometry (ESI-MS(n)) using an ion trap instrument and accurate mass measurement on a quadrupole time-of-flight (Q-TOF) mass spectrometer has aided the structural characterization and differentiation of the enmein and spiro-lactone types of ent-6,7-seco-kaurane diterpenoids from Isodon species. The mass spectral fragmentation data from both techniques was compared to obtain the mass spectrometric fragmentation pathways of the ent-6,7-seco-kaurane diterpenoids with high confidence. The analysis revealed that losses of CH(2)O and CO(2) are the predominant process for the enmein type of ent-kauranes in negative ion mode, and the loss of CO(2) is typical for the spiro-lactone type in positive ion mode. In addition, compounds of the spiro-lactone type with a conserved core structure but different substituent groups, such as acetyl, hydroxyl, and aldehyde moiety, resulted in diagnostic product ions by means of successive losses of AcOH, H(2)O, and CO, respectively. The fragmentation knowledge will facilitate the analysis and identification of the ent-6,7-seco-kauranes in future plant research.

An Improved High-Performance Liquid Chromatography Assay for Spironolactone Analysis

This study prepared an extemporaneously formulated liquid suspension dosage form (5 mg/ml) from commercially available 25 mg tablets. Stability-indicating HPLC assay procedures were established and utilized to analyze the concentration of the drug. The method proved to be a simple model since it does not contain a buffer system. The mobile phase used was the same as that suggested by the manufacturer for the storage of the column. Therefore, the solvent system saves analytical processing time, since it does not require a change in the mobile phase before or after the analysis. The analytical method has been shown to be stability-indicating. The results have shown that there is no interference from any of the degradation products obtained from stressing spironolactone by heat and extremes in pH or with the internal standard, hydrocortisone 21-acetate.

A new enzyme-linked chemiluminescent immunosorbent digoxin assay is virtually free from interference of spironolactone, potassium canrenoate, and their common metabolite canrenone

Spironolactone and potassium canrenoate (aldosterone antagonist diuretics) are sometimes used in conjunction with digoxin for patient management. Spironolactone, potassium canrenoate, and their common metabolite canrenone interfere with serum digoxin measurement using various immunoassays. Recently a new enzyme-linked chemiluminescent immunosorbent digoxin assay (ECLIA-Digoxin) became commercially available for application on the ADVIA IMS 800i modular system (Bayer HealthCare, Tarrytown, NY). We investigated the potential interference of spironolactone and related compounds in this assay by comparing the results with the fluorescence polarization immunoassay (FPIA), which is known to have significant cross-reactivity with these compounds as well as a turbidimetric assay for digoxin with no known cross-reactivity with spironolactone and related compounds. Aliquots of drug free serum were supplemented with therapeutic and above therapeutic concentrations of spironolactone, canrenone, and potassium canrenoate, and apparent digoxin concentrations were measured. No apparent digoxin concentration was observed using the ECLIA-Digoxin or turbidimetric assay. When serum pools prepared from patients receiving digoxin were further supplemented with these compounds, we observed no significant change in digoxin concentrations in the presence of these compounds with the ECLIA-Digoxin. We conclude that this assay is virtually free from interferences from spironolactone, potassium canrenoate and their common metabolite canrenone.

[Simultaneous determination of inhibitive components in anti-acne cosmetics by reversed-phase high performance liquid chromatography]

The inhibitive components in anti-acne cosmetics including spironolactone, benzoyl peroxide, and tretinoin were simultaneously determined by reversed-phase high performance liquid chromatography (RP-HPLC). The cosmetics were extracted with methanol by microwave and analyzed by high performance liquid chromatography. The HPLC conditions were as follows: Kromasil C18 column (4.6 mm i. d. x 250 mm, 5 microm), methanol and phosphate buffer as mobile phase with gradient elution at a flow rate of 1.0 mL/min, UV detection at 265 nm. Three components were separated completely within 11 min. The calibration curves of the three compounds were linear (nu > 0.999 9) between 1 and 200 mg/L. The average recoveries were from 88.2% to 106.7% with relative standard deviations lower than 3. 1%. The detection limits (S/N = 3) were 0.101 mmicrog for spironolactone, 0.100 microg for benzoyl peroxide, and 0. 107 microg for tretinoin. The method is simple and rapid with high accuracy, and suitable for the determination of the 3 inhibitive components in anti-acne cosmetics.

Ratio spectra derivative spectrophotometry for the determination of furosemide and spironolactone in a capsule formulation

The determination of furosemide and spironolactone in a capsule formulation has been investigated using techniques such as Vierordt's method and derivative spectroscopy dA/d lambda and d2A/d lambda2 applying the zero-crossing technique following reported methods. In our hands, using standard mixtures, these methods gave unreliable results. We have therefore investigated the use of ratio spectra derivative spectrophotometry for this determination. The technique of ratio spectra derivative spectrophotometry was developed in 1990, and has recently been used for a number of analyses of co-formulated products. The method was applied to the analysis of standard mixtures of the two drugs and the combined contents of 20 capsules resulting in values (mean +/- standard deviation) of 102.1 +/- 1.9% and 101.4 +/- 4.0% of the stated content for furosemide and spironolactone, respectively. Similarly, the analysis of individual capsules resulted in values of 101.5 +/- 1.6% and 102.2 +/- 1.4% of the stated content for furosemide and spironolactone, respectively.

Continuous wavelet transformation applied to the simultaneous quantitative analysis of two-component mixtures

In this paper we developed a graphical method based on Haar (HA) and Mexican (MEX) one-dimensional continuous wavelet transforms and we applied it to a mixture of hydrochlorothiazide (HCT) and spironolactone (SP) in the presence of strongly overlapping signals. Keeping in mind to obtain an appropriately transformed spectrum, we tested several values of the scaling parameter a and the point number of the analysed spectrum in the concentration range of 2-22 microg/ml for both active compounds. The optimal values of the scale parameters and the corresponding frequencies were found to be a = 32 and 0.031 for HA and a = 30 and 0.008 for MEX corresponding to 400 points. HA and MEX methods based on a zero crossing technique were applied to the analysed signal and their regression lines at the selected points were obtained. The validation of the above methods was carried out by analysing different synthetic mixtures containing HCT and SP. MATLAB 6.5 software was used for one-dimensional wavelet analysis and the basic concepts about wavelet method were briefly explained. The method developed in this paper is rapid, easy to apply, inexpensive and is suitable for analysing the overlapping signals of compounds in their mixtures without any chemical pre-treatment.

Spectophotometric quantitative resolution of hydrochlorothiazide and spironolactone in tablets by chemometric analysis methods

Spectrophotometric simultaneous determination of hydrochlorothiazide and spironolactone in tablets was performed by classical least-squares (CLS), inverse least-squares (ILS), principal component regression (PCR) and partial least-squares (PLS). The methods of the chemometric analysis do not require sample pretreatment procedure. A training set of 25 standard mixture containing both drugs was prepared in the concentration range of 2-20 mug/ml according to mixture design. The multivarate calibrations were obtained by measuring the zero-order and first-derivative absorbances at 15 points from 220 to 290 nm using the training set. The validation of the multivariate methods was realised by analysing the synthetic mixtures of hydrochlorothiazide and spironolactone. The result obtained on the synthetic mixture and tablets were statistically compared by the one-way ANOVA test. The chemometrics analysis methods were satisfactorily applied to the simultaneous determination of hydrochlorothiazide and spironolactone in the pharmaceutical tablet formulation.

[Simultaneous analysis of four diuretic drugs by HPLC and its application to health food supplements advertising weight reduction]

A high-performance liquid chromatographic (HPLC) method for the simultaneous analysis of triamterene, trichlormethiazide, furosemide and spironolactone is presented for application in the examination of health food supplements advertising weight reduction and in the analysis of pharmaceuticals. The HPLC assay was performed under gradient conditions using a Wakosil ODS 5C18 column (5 microns, 150 x 4.6 mm i.d.). The mobile phase consisted of a gradient program with a mixture of water and acetonitrile containing 0.1% triethylamine adjusted with phosphoric acid to pH 3.0: from 0 to 6 min, 15% acetonitrile; from 6 to 20 min, linear gradient from 15 to 50% acetonitrile; and from 20 to 40 min, 50% acetonitrile. The column effluent was monitored from 0 to 20 min at 260 nm and from 20 to 40 min at 235 nm. The calibration curves of the four drugs showed good linearity and the correlation coefficients were better than 0.999 in all cases. The lower limits of detection were approximately 40 ng for each drug. Commercially available health food supplements and pharmaceuticals were analyzed after extraction with a mixture of methanol and acetic acid (99:1). The procedure described here is suitable for the screening of four diuretic drugs in adulterated supplements and for the quality control of pharmaceuticals with minimal sample preparation.

Simultaneous determination of chlorthalidone and spironolactone with univariate and multivariate calibration: wavelength range selection

Chlorthalidone and spironolactone were determined simultaneously with the aid of univariate and multivariate calibration methods. Univariate calibration was performed by the zero-crossing and derivative ratio spectrum methods. Extensive spectral overlap and the scarcity of wavelengths in derivative spectra allowing one analyte to be distinguished and quantitated in the presence of the other gave rise to poor results that called for multivariate calibration. Partial least-squares regression was used in combination with a suitable method for selecting the optimum wavelength range and number of factors for analysis. The ensuing method was applied to simultaneous determination of chlorthalidone and spironolactone in a commercially available pharmaceutical preparation. The results were validated by high-performance liquid chromatography.

A micellar liquid chromatographic procedure for the determination of amiloride, bendroflumethiazide, chlorthalidone, spironolactone and triamterene in pharmaceuticals

A procedure for the determination of amiloride, bendroflumethiazide, chlorthalidone, spironolactone and triamterene in pharmaceutical preparations (tablets) by micellar liquid chromatography, using a 0.07 M SDS-0.5% pentanol mobile phase, is proposed. Recoveries were found in the 100-108% range, with relative standard deviations of 0.4-3.1%. Elution of the most retained diuretics occurred in less than 18 min (at a 1 ml min-1 flow rate). The change in the values of the solute-micelle binding constants and the partition coefficients of the diuretics between the stationary phase and water, upon addition of pentanol, was also studied.

Utility of Fourier transform-Raman and Fourier transform-infrared diffuse reflectance spectroscopy for differentiation of polymorphic spironolactone samples

Thirteen bulk pharmaceutical preparations of spironolactone were examined by Fourier transform (FT)-Raman spectroscopy and by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) for residual solvents (including the hydrolysis product, thioacetic acid), the presence of enolic tautomeric forms, and evidence for different polymorphic forms. One sample (L) only was found to contain solvent residue (benzene). No evidence for the possible existence of enolic tautomers in the solid state was found. From these specimens, four different representative polymorphic samples (A, B, C, and D) were selected on the basis of their DRIFTS patterns in the 3600-3200-cm-1 region. Samples K and L were considered to represent mixtures of two or more of the above representative types. Similar differentiation of the samples was made on the basis of their Raman spectra over the frequency range 1800-400 cm-1. The various fundamental stretching frequencies for the C = O and C = C bonds have been assigned, and these assignments, in turn, were used to account for all the bands in the 3600-3200-cm-1 region as overtone and combination frequencies of the fundamentals. The Raman lines at 637 and 655 cm-1 were assigned to the two C-S stretching modes of the thioacetyl moiety.

HPLC-photolysis-electrochemical detection in pharmaceutical analysis: application to the determination of spironolactone and hydrochlorothiazide in tablets

To extend the applicability of electrochemical detection in pharmaceutical analysis, an on-line postcolumn photochemical reactor is used to produce electroactive photoderivatives of selected cardiovascular drugs. This system is applied to the analysis of dosage forms containing spironolactone in both single-component formulation and in combination with hydrochlorothiazide. The pH of the mobile phase and irradiation time within the reactor are optimized to produce maximum amperometric response. Spironolactone, hydrochlorothiazide, and 4-amino-6-chloro-1,3-benzenedisulfonamide, the synthetic precursor and hydrolysis product of hydrochlorothiazide, are separated by reversed-phase chromatography on a 5-microns cyano bonded phase column within nine minutes by using a methanol-phosphate buffer mobile phase. Minimum detectable levels are in the low ng range.

A case of testosterone-secreting adrenal cortical adenoma with spironolactone body-like inclusion

Testosterone-secreting adrenal adenoma is rare. We recently experienced a 17-year-old pubertal girl who showed signs of virilization and a high serum level of testosterone. The excised adrenal gland showed a 3.5 x 3 x 3-cm cortical adenoma. Light and electron microscopic findings together with the high serum level and high tumor tissue contents of testosterone and dehydroepiandrosterone (DHA) indicated that the tumor was a testosterone-secreting adrenal cortical adenoma. This appears to be a rather rare tumor from a review of the literature. Interestingly, in this case, the cytoplasm of the tumor cells contained structures resembling spironolactone bodies. From the results of enzyme histochemistry, the steroidogenetic pathways in this tumor were speculated.

Stability of extemporaneously compounded spironolactone suspensions

The short-term stability of spironolactone in liquid formulations prepared from spironolactone tablets was studied at three temperatures. Suspensions of spironolactone at concentrations of 2.5, 5.0, and 10.0 mg/mL were prepared by grinding film-coated tablets to a fine powder, adding Purified Water, USP, triturating the mixture to form a fine paste, adding Cherry Syrup, NF, and homogenizing the suspension. Drug concentrations were immediately measured by a stability-indicating high-performance liquid chromatographic (HPLC) method. Samples were stored in amber glass prescription bottles at 5 and 30 degrees C in controlled environmental cabinets and at ambient room temperature (20 to 24 degrees C) under intense fluorescent light. After two and four weeks of storage the bottles were shaken, and samples were removed and assayed by HPLC. There was no appreciable loss of spironolactone from the cherry syrup formulations stored for two weeks under the conditions studied. Degradation was less than 5% for samples stored for four weeks. Color and odor of the samples did not change appreciably, and counts of bacteria and fungi remained within acceptable limits. Extemporaneously prepared suspensions of spironolactone in Cherry Syrup, NF, are stable for four weeks under the conditions studied.

Oxidative metabolism of spironolactone: evidence for the involvement of electrophilic thiosteroid species in drug-mediated destruction of rat hepatic cytochrome P450

In a preliminary paper [Decker et al. (1986) Biochem. Biophys. Res. Commun. 136, 1162] we have shown that the antimineralocorticoid spironolactone (SPL) preferentially inactivates dexamethasone (DEX) inducible rat hepatic cytochrome P450p isozymes in a suicidal manner. These findings are now confirmed, and the kinetic characteristics of such a process are detailed. In an effort to elucidate the mechanism of SPL-mediated inactivation of cytochrome P450, we have examined the metabolism of SPL in vitro. Incubation of [14C]SPL and NADPH with liver microsomes prepared from DEX-pretreated rats results in the formation of several polar metabolites separable by HPLC with UV detection. This process is found to be dependent on NADPH, O2, SPL, and enzyme concentration, as well as temperature. Furthermore, metabolite formation was significantly attenuated by P450 inhibitors CO and n-octylamine. Mass spectral analysis (thermospray LC/MS, FAB/MS, and FAB/MS/MS) of the two most prominent polar metabolites indicated that these compounds had molecular weights that corresponded to the sulfinic and sulfonic acid derivatives of deacetyl-SPL (SPL-SH). These findings document the formation of previously unreported polar metabolites of SPL by rat liver microsomes enriched in cytochrome P450p and implicate a role for this isozyme in the oxidation of the thiol moiety of deacetyl-SPL. The detection of such metabolites also implicates a catalytic trajectory that includes the thiyl radical and/or sulfenic acid species as a plausible protagonist in drug-mediated inactivation of cytochrome P450p.

Glucocorticoid-suppressible hyperaldosteronism. Ultrastructural observation of a case

A 56-year-old woman presented with intracranial hemorrhage. Laboratory examinations revealed severe hypertension, hypokalemia, elevated aldosterone excretion, and suppressed plasma renin activity. Left adrenocortical tumor was suspected and adrenalectomy was performed. The laboratory data after operation, however, showed no significant difference from the preoperative data. On the basis of further examinations, dexamethasone was administered and returned blood pressure to normal, and also normalized serum potassium, plasma aldosterone, and renin activity. The patient's illness was diagnosed as glucocorticoid-suppressible hyperaldosteronism. Light microscopically, the zona glomerulosa was hypertrophic and the outer zona fasciculata decreased in lipid droplets and was centrifugally arranged in small alveoli. Electronmicroscopically, the cells of the outer zona fasciculata had several lipid droplets and well-developed sER. Mitochondria were round to oval with lamellar or lamellovesicular cristae. These findings were evidence of hyperfunction. The cytoplasm of the cells also contained spironolactone bodies. Therefore, it is assumed that the aldosterone, which induced the disorder, was produced mainly in the outer zona fasciculata.

Colorimetric analysis of some diuretic drugs: hydrochlorothiazide and spironolactone

Two convenient spectrophotometric methods were developed for the determination of hydrochlorothiazide and spironolactone. A specific colour reaction for the determination of hydrochlorothiazide is reported. One method is based on the reaction of hydrochlorothiazide with n-butylamine and cobaltous chloride in anhydrous methanol. A blue-violet colour is produced and is measured at 570 nm. A highly selective colorimetric method was adopted for the analysis of spironolactone by reacting with isoniazid forming a coloured hydrazone derivative and subsequent measurement of the coloured product at 405 nm.

Factors affecting the frequency of occurrence of spironolactone bodies in aldosteronomas and non-tumorous cortex

Histological sections taken from aldosterone-producing-adenomas and from non-tumorous adrenal cortex of 18 patients treated for primary aldosteronism by unilateral adrenalectomy were examined for spironolactone inclusion bodies. Typical inclusions were found in 10 of the 13 patients who received spironolactone up to within 24 h of surgery. They were present in the tumours of 7 patients, and their frequency correlated positively with the percentage of glomerulosa type cells in the tumours. In tumours containing 50% or more glomerulosa-type cells, their frequency correlated negatively with duration of treatment. They were present in the non-tumorous cortex of 4 of these 7 patients, and in the cortex of 3 others whose tumours did not contain them. In the cortex, they were found only in glomerulosa cells, and their presence appeared unrelated to dosage or duration of treatment. No spironolactone inclusion bodies were seen in either the tumour of the non-tumorous cortex of 3 patients who had discontinued spironolactone 19 to 97 d before surgery, or of 2 patients who had never received spironolactone.

Spironolactone bodies. An immunoperoxidase study with biochemical correlation

The present immunoperoxidase study attempted to localize aldosterone and cortisol in formalin-fixed paraffin-embedded adrenal glands or tumors. Apparently, steroid substances are solubilized during routine tissue processing, and the cytoplasm of adrenal cortical cells is not stained by either antialdosterone or anticortisol antibodies. However, spironolactone bodies react positively with antialdosterone antibody. The presence of aldosterone in the concentric laminations of spironolactone bodies supports the concept that spironolactone bodies are not artifacts. Furthermore, the fact that aldosterone does survive in spironolactone bodies suggests that it is bound in some unusual form. The spironolactone bodies are probably derived from endoplasmic reticulum, and the membranes of endoplasmic reticulum are considered capable of storing steroids. It is likely that during the formation of spironolactone bodies are probably derived from endoplasmic reticulum, and the membranes of endoplasmic reticulum are considered capable of storing steroids. It is likely that during the formation of spironolactone bodies, aldosterone or a few cortisol-like substances are trapped in these laminated concentric bodies.

[Analysis of active principles in pharmaceutical dosage forms by high pressure liquid chromatography - spironolactone and hydrochlorothiazide]

A method for the quantitative analysis of spironolactone and hydrochlorothiazide in pharmaceutical products by high pressure liquid chromatography is described. The method is highly reproducible and overcomes every preliminary treatments of the sample.

Electron impact and chemical ionization mass spectrometry of steroidal spirolactones

Electron impact and chemical ionization mass spectra are reported for several steroidal spirolactones and their TMS ethers. The electron impact spectra were characterized generally by low abundance molecular ions and large numbers of fragment ions. Methane chemical ionization spectra exhibited high intensity [M+H]+ and/or [M+H-H2O]+ or [M+H-TMSOH]+ ions with few other fragment ions. Ammonia chemical ionization spectra had intense [M+H]+ and/or [M+NH4]+ ions with a few fragment ions generally formed by loss of H2O or TMSOH from these parent ions. Ammonia chemical ionization gave intense parent ions even for polyhydroxy compounds and their TMS ethers in contrast to methane chemical ionization. The results of this study suggest that a combination of electron impact with ammonia chemical ionization mass spectrometry would offer the best techniques for detection and identification of these compounds in biological fluids.

Stability-indicating methods for quantitative determination of spironolactone using high-pressure liquid chromatography and blue tetrazolium reaction

Stability-indicating methods for the quantitative determination of spironolactone were developed. The methods are based on high-pressure liquid chromatography and a reaction with blue tetrazolium. Both methods are accurate, precise, and sensitive and gave excellent results with commercial tablets, including those containing hydrochlorothiazide in addition to spironolactone, The blue tetrazolium method cannot be used in the presence of high concentrations of either polyethylene glycols or water. Spironolactone decomposition in water or polyethylene glycol appears to follow pseudo-first-order kinetics. The decomposition constant at 65 degrees was 0.0253/day in water versus 0.115/day in polyethylene glycol ointment base USP.

Species differences in the metabolism and disposition of spironolactone

The absorption, excretion and metabolism of [22-14C]spironolactone was compared in Charles River rats, beagle dogs and rhesus monkeys. The drug was administered at the fixed dose of 5 mg/kg po and iv. From the po/iv ratios of the areas under the plasma radioactivity-time curves, the gastrointestinal absorption of the drug was estimated to be 82% in the rat, 62% in the dog, and 103% in the monkey. The absolute bioavailability of a pharmacologically active metabolite, canrenone, was 57% in the dog and 48% in the monkey. Spironolactone was extensively metabolized in all three species and differences existed in the composition of the metabolites in their plasma, urine, and feces. The amount of radioactivity that was excreted in the urine and feces of all three species was similar after either po or iv administration of the drug. The cumulative average excretion of radioactivity in the urine as percentage of the po dose in 6 days was 4.69% in the rat (N = 5), 18.5% in the dog (N = 3), and 46.0% in the monkey (N = 3). In the feces, the corresponding excretion values were 74.2, 69.3 and 40.1%, respectively. Canrenone excretion in the urine constituted 0.65% of the po dose in the rat, 0.82% in the dog, and 5.86% in the monkey, whereas the excretion of total fluorogenic metabolites constituted 1.1, 1.9, and 12.1% respectively. Comparison of animal data with those published for humans indicated that the disposition and metabolism of spironolactone in the rhesus monkey, rather than those in the rat or the dog, was closest to that in man.

Fine structure and morphogenesis of spironolactone bodies in the zona glomerulosa of the human adrenal cortex

Numerous spironolactone bodies have been detected in the zona glomerulosa cells of the adrenal cortex of a 36-year-old spironolactone-treated woman whose non-tumorous right adrenal gland was removed surgically because of primary hyperaldosteronism. Electron microscopy revealed spherical laminated whorls which consisted of a central core composed of an amorphous electron-dense material surrounded by numerous smooth-walled concentric membranes. Continuous with and deriving from the endoplasmic reticulum, they were present in viable cells and were not associated with ultrastructural features indicating cellular injury. Cytoplasmic inclusions similar to spironolactone bodies can be detected in other organs after the administration of various compounds. Thus, they can be regarded as neither specific to spironolactone treatment nor exclusively inducible in the zona glomerulosa of the adrenal cortex.