A simple UHPLC-PDA method with a fast dilute-and-shot sample preparation for the quantification of canrenone and its prodrug spironolactone in human urine samples

Diuretics in Different Samples: Update on the Pretreatment and Analysis Techniques

Diuretics are drugs that promote the excretion of water and electrolytes in the body and produce diuretic effects. Clinically, they are often used in the treatment of edema caused by various reasons and hypertension. In sports, diuretics are banned by the World Anti-Doping Agency (WADA). Therefore, in order to monitor blood drug concentration, identify drug quality and maintain the fairness of sports competition, accurate, rapid, highly selective and sensitive detection methods are essential. This review provides a comprehensive summary of the pretreatment and detection of diuretics in various samples since 2015. Commonly used techniques to extract diuretics include liquid-liquid extraction, liquid-phase microextraction, solid-phase extraction, solid-phase microextraction, among others. Determination methods include methods based on liquid chromatography, fluorescent spectroscopy, electrochemical sensor method, capillary electrophoresis and so on. The advantages and disadvantages of various pretreatment and analytical techniques are elaborated. In addition, future development prospects of these techniques are discussed.

Mineralocorticoid Receptor Antagonist Effect on Aldosterone to Renin Ratio in Patients With Primary Aldosteronism

CONTEXT

Although current international guidelines recommend to avoid mineralocortcoid receptor antagonists in patients undergoing screening test for primary aldosteronism, a recent report suggested that mineralocorticoid receptor antagonist treatment can be continued without significant influence on screening results.

OBJECTIVE

We aimed to evaluate the effect of mineralocorticoid receptor antagonists on the aldosterone to renin ratio in patients with primary aldosteronism.

METHODS

We prospectively enrolled 121 patients with confirmed primary aldosteronism who started mineralocorticoid receptor antagonist (canrenone) treatment. Eighteen patients (11 with unilateral and 7 with bilateral primary aldosteronism) constituted the short-term study cohort and underwent aldosterone, renin, and potassium measurement after 2 and 8 weeks of canrenone therapy. The long-term cohort comprised 102 patients (16 with unilateral and 67 with bilateral primary aldosteronism, and 19 with undetermined subtype) who underwent hormonal and biochemical re-assessment after 2 to 12 months of canrenone therapy.

RESULTS

Renin and potassium levels showed a significant increase, and the aldosterone to renin ratio displayed a significant reduction compared with baseline after both a short- and long-term treatment. These effects were progressively more evident with higher doses of canrenone and after longer periods of treatment. We demonstrated that canrenone exerted a deep impact on the diagnostic accuracy of the screening test for primary aldosteronism: the rate of false negative tests was raised to 16.7%, 38.9%, 54.5%, and 72.5% after 2 weeks, 8 weeks, 2 to 6 months, and 7 to 12 months of mineralocorticoid receptor antagonist treatment, respectively.

CONCLUSION

Mineralocorticoid receptor antagonists should be avoided in patients with hypertension before measurement of renin and aldosterone for screening of primary aldosteronism.

Assessing Adherence to Antihypertensive Medication by Means of Dose-Dependent Reference Plasma Concentration Ranges and Ultra-High Performance Liquid Chromatography-Ion Trap Mass Spectrometry Analysis

Poor adherence to antihypertensive drug therapy is a well-recognized problem and can be assessed by mass spectrometry-based analyses of body fluids. However, contrary statements exist whether drug quantification in blood or qualitative screening in urine is more suitable. The present pilot study aimed to further elucidate the power of blood plasma drug concentrations for adherence monitoring by developing and validating a quantification procedure for nine antihypertensive drugs (amlodipine, bisoprolol, candesartan, canrenone, carvedilol, metoprolol, olmesartan, torasemide, and valsartan) in blood plasma using liquid–liquid extraction and an ultra-high-performance liquid chromatography-ion trap mass spectrometry analysis. The procedure should then be used for an adherence assessment and compared with the results of an established qualitative urine screening. Selectivity, carryover, matrix effect, accuracy, precision, dilution integrity, and stability were successfully validated, except for amlodipine. The applicability was demonstrated by analyzing 19 plasma samples containing 28 antihypertensive drugs and comparing the measured concentrations with calculated dose-dependent reference plasma concentration ranges. The interpretation of plasma concentrations was found to be more sophisticated and time-consuming than that of urine screening results, and adherence could not be assessed in two cases (10%) due to measured plasma concentrations below the lower limit of quantification. However, 14 out of 19 subjects were classified as adherent (75%) and three as nonadherent (15%), in contrast to 19 (100%) that were claimed to be adherent based on the results of the qualitative urine screening. Nevertheless, further data is needed to estimate whether plasma quantification is superior in terms of assessing adherence to antihypertensive medication.

Simple and Fast Determination of Terbinafine in Human Urine by Dilute and Shoot HPLC-DAD Using a Core-Shell Column

BACKGROUND

Terbinafine is an allylamine antifungal that is effective against many fungi, dermatophytes and moulds. Analytical methods are required for the determination of terbinafine in biological fluids to perform therapeutic drug monitoring and pharmacokinetic studies.

OBJECTIVE

The aim of this study was to develop and validate a novel and fast method combining dilute and shoot approach and high-performance liquid chromatography coupled with photodiode array detection for the determination of terbinafine in human urine.

METHODS

Chromatographic parameters including mobile phase composition, pH, flow rate and injection volume were assessed and optimized. The separation of terbinafine and naproxen (internal standard) was achieved within 3 min using a C18 core-shell column (Raptor ARC-18, 100 x 4.6 mm, 2.7 μm) under isocratic conditions. Samples were eluted from the column at the flow rate of 1.4 mL/min using a mobile phase containing 0.2% triethylamine in water (pH 3.4 with formic acid): acetonitrile (45:55, v/v).

RESULTS

The presented technique was linear in the range of 25-2000 ng/mL. Intra- and inter-day reproducibility at four quality control levels (25, 200, 750 and 1500 ng/mL) were less than 7%, with relative errors ranging from -5.40% to 5.91%. The limit of detection was 12.60 ng/mL. The developed method has three main advantages compared to existing methods: simplicity and greenness of sample preparation, use of core-shell column and short analysis time.

CONCLUSION

The results of this study indicate that the combination of dilute and shoot approach and core-shell column can be regarded as an advantageous application for the fast determination of terbinafine in the urine.

Simultaneous determination of canrenone, digoxin and tolvaptan by UHPLC-MS/MS: application in heart failure patients

Aim: Heart failure patients are frequently given comedication of digoxin and diuretics like spironolactone and tolvaptan. A UHPLC-MS/MS assay for determining canrenone (main active metabolite of spironolactone), digoxin and tolvaptan simultaneously should be developed so as to support related drug-drug interaction studies. Results: A UHPLC-MS/MS method for simultaneous determination of these three drugs in human plasma was established and fully verified as per CFDA guidelines. Chromatographic separation was achieved using a 4-min isocratic elution. Mass analyses were performed under positive electrospray ionization mode. The calibration curves were established over 1.0-400.0 ng/ml for canrenone and tolvaptan while over 0.1-40.0 ng/ml for digoxin. Conclusion: The developed method was feasible in detecting concentration and related drug-drug interaction studies.