Novel approach to adherence assessment based on parent drug and metabolite pharmacokinetics: pilot study with spironolactone.

AIM: The aim of this study was to evaluate adherence to spironolactone in a group of unselected patients with arterial hypertension by analysis of measured serum spironolactone and canrenone concentrations according to a proposed two-step decision scheme based on pharmacokinetic considerations. MATERIALS AND METHODS: Simulation of serum concentration-time profiles of spironolactone and canrenone based on population pharmacokinetic parameters described in literature and a body weight-normalized spironolactone dose / canrenone level nomogram derived from a group of adherent patients with conservatively treated primary hyperaldosteronism, were used to create a two-step decision scheme. 71 outpatients treated with spironolactone for resistant hypertension with spironolactone and canrenone serum concentrations measured between 2018 and 2021 were analyzed according to the proposed scheme. We compared our proposed methodology to the standard approach for adherence testing. RESULTS: With the most sensitive traditional approach to adherence assessment through detectable serum concentrations of spironolactone and/or canrenone, 9 (12.7%) non-adherent patients were identified. With our two-step assessment of adherence, we were able to identify 18 (25.4%) non-adherent patients. CONCLUSION: Consideration of the pharmacokinetic properties of parental drug and its metabolite led to improved sensitivity in non-adherence detection in patients with arterial hypertension. This approach enables better interpretation of measured spironolactone and canrenone serum concentrations and should be used in clinical practice.

Adherence and blood pressure control in patients with primary aldosteronism.

PURPOSE: The aim of our study was to evaluate the adherence to mineralocorticoid receptor (MR) antagonists and other antihypertensive therapy and blood pressure control in conservatively treated patients with primary aldosteronism (PA). MATERIALS AND METHODS: Conservatively treated subjects with previously confirmed PA (n-50, 64.5 ± 9 years of age, 24% women) were investigated via our outpatient hypertension clinic. All subjects underwent regular examinations in our clinic. In addition to basic laboratory and clinical parameters, 24 h ambulatory blood pressure monitoring (ABPM) (Spacelabs) was evaluated. Unplanned blood sampling for assessment of serum antihypertensive drug concentrations by the means of liquid chromatography-mass spectrometry was performed in all patients. In case of spironolactone, its active metabolite canrenone was also evaluated. Total non-compliance was then defined as the absence of all measured antihypertensive drugs. Partial non-compliance was calculated as the absence of serum levels of at least one, but not all antihypertensive drugs prescribed. RESULTS: Good blood pressure control was detected (mean 24 h systolic/diastolic BP 130 ± 12/77 ± 9 mmHg). The average number of antihypertensive drugs was 3.9 ± 1.5. All subjects were treated by MR antagonists. 44% of patients received spironolactone (average daily dose 45 ± 20 mg) and in the remaining 56% of subjects eplerenone was administered (average daily dose 80 ± 30 mg) due to spironolactone side effects. Assessment of antihypertensive drug concentrations revealed full adherence in 80% of all subjects, partial nonadherence was noted in the remaining 20% of subjects. MR antagonist levels were detected in almost all subjects (49 out of 50). CONCLUSIONS: Good blood pressure control and adherence to therapy were detected in conservatively treated patients with PA. Eplerenone had to be used quite often as male subjects did not tolerate dose escalation due to spironolactone side effects.

SNPs within CHRNA5-A3-B4 and CYP2A6/B6, nicotine metabolite concentrations and nicotine dependence treatment success in smokers.

AIM: Plasma values of nicotine and its metabolites are highly variable, and this variability has a strong genetic influence. In our study, we analysed the impact of common polymorphisms associated with smoking on the plasma values of nicotine, nicotine metabolites and their ratios and investigated the potential effect of these polymorphisms and nicotine metabolite ratios on the successful treatment of tobacco dependence. METHODS: Five variants (rs16969968, rs6474412, rs578776, rs4105144 and rs3733829) were genotyped in a group of highly dependent adult smokers (n=103). All smokers underwent intensive treatment for tobacco dependence; 33 smokers were still abstinent at the 12-month follow-up. RESULTS: The rs4105144 (CYP2A6, P<0.005) and rs3733829 (EGLN2, P<0.05) variants were significantly associated with plasma concentrations of 3OH-cotinine and with 3OH-cotinine: cotinine ratios. Similarly, the unweighted gene score was a significant (P<0.05) predictor of both cotinine:nicotine and 3OH-cotinine:cotinine ratios. No associations between the analysed polymorphisms or nicotine metabolite ratios and nicotine abstinence rate were observed. CONCLUSION: Although CYP2A6 and EGLN2 polymorphisms were associated with nicotine metabolism ratios, neither these polymorphisms nor the ratios were associated with abstinence rates.

Antitubercular nanocarrier monotherapy: Study of In Vivo efficacy and pharmacokinetics for rifampicin.

Tuberculosis represents a major global health problem for which improved approaches are needed to shorten the course of treatment and to combat the emergence of resistant strains. The development of effective and safe nanobead-based interventions can be particularly relevant for increasing the concentrations of antitubercular agents within the infected site and reducing the concentrations in the general circulation, thereby avoiding off-target toxic effects. In this work, rifampicin, a first-line antitubercular agent, was encapsulated into biocompatible and biodegradable polyester-based nanoparticles. In a well-established BALB/c mouse model of pulmonary tuberculosis, the nanoparticles provided improved pharmacokinetics and pharmacodynamics. The nanoparticles were well tolerated and much more efficient than an equivalent amount of free rifampicin.

Biochemical Screening for Nonadherence Is Associated With Blood Pressure Reduction and Improvement in Adherence.

We hypothesized that screening for nonadherence to antihypertensive treatment using liquid chromatography-tandem mass spectrometry-based biochemical analysis of urine/serum has therapeutic applications in nonadherent hypertensive patients. A retrospective analysis of hypertensive patients attending specialist tertiary care centers was conducted in 2 European countries (United Kingdom and Czech Republic). Nonadherence to antihypertensive treatment was diagnosed using biochemical analysis of urine (United Kingdom) or serum (Czech Republic). These results were subsequently discussed with each patient, and data on follow-up clinic blood pressure (BP) measurements were collected from clinical files. Of 238 UK patients who underwent biochemical urine analysis, 73 were nonadherent to antihypertensive treatment. Their initial urinary adherence ratio (the ratio of detected to prescribed antihypertensive medications) increased from 0.33 (0-0.67) to 1 (0.67-1) between the first and the last clinic appointments. The observed increase in the urinary adherence ratio in initially nonadherent UK patients was associated with the improved BP control; by the last clinic appointment, systolic and diastolic BPs were ≈19.5 and 7.5 mm Hg lower than at baseline (P=0.001 and 0.009, respectively). These findings were further corroborated in 93 nonadherent hypertensive patients from Czech Republic-their average systolic and diastolic BPs dropped by ≈32.6 and 17.4 mm Hg, respectively (P<0.001), on appointments after the biochemical analysis. Our data show that nonadherent hypertensive patients respond to liquid chromatography-tandem mass spectrometry-based biochemical analysis with improved adherence and significant BP drop. Such repeated biochemical analyses should be considered as a therapeutic approach in nonadherent hypertensive patients.

Adherence with perindopril therapy: a pilot study using therapeutic drug monitoring of perindoprilat and an evaluation of the clearance estimation.

Background Although measurement of drug serum levels is an objective direct method for testing compliance, it can be distorted by "white-coat compliance" or by variations in drug elimination. Objective The aim of this prospective study was to evaluate the prevalence of noncompliance with perindopril therapy in adult out-patients using pharmacokinetic simulations. The additional aim was to compare the predictive performance of two glomerular filtration rate markers-creatinine and cystatin C. Setting Department of Cardiology, Tomas Bata Regional Hospital in Zlín, Czech Republic. Method Perindoprilat pharmacokinetic models individualized according to patient characteristics were compared with measured perindoprilat serum concentrations to document compliance. Linear regression was used to evaluate the relations between perindoprilat clearance and glomerular filtration rate estimated using creatinine and cystatin C. Main outcome measure Assessment of non-compliance with medication using drug concentration measurements reinforced with therapeutic drug monitoring. Results Non-detectable perindoprilat levels were observed in 26.1% of patients. Another 21.7% were classified as non-compliant based on therapeutic drug monitoring pharmacokinetic simulations. Volume of distribution, clearance and half-life median value (interquarti°range) for perindoprilat were 408.3 (360.4-456.8) L, 10.1 (4.9-17.0) L h-1 and 24.7 (19.4-62.7) h, respectively. Linear regression models showed tight relationship between cystatin C and perindoprilat clearance. Conclusions Assessment of adherence with medication reinforced with therapeutic drug monitoring and pharmacokinetic simulations is proposed as an optimal method reducing disadvantages of simple drug concentration measurements. Cystatin C proves to be better surrogate marker for perindoprilat elimination than creatinine.

Risk Factors for Nonadherence to Antihypertensive Treatment.

Nonadherence to antihypertensive treatment is a critical contributor to suboptimal blood pressure control. There are limited and heterogeneous data on the risk factors for nonadherence because few studies used objective-direct diagnostic methods. We used high-performance liquid chromatography-tandem mass spectrometry of urine and serum to detect nonadherence and explored its association with the main demographic- and therapy-related factors in 1348 patients with hypertension from 2 European countries. The rates of nonadherence to antihypertensive treatment were 41.6% and 31.5% in the UK and Czech populations, respectively. Nonadherence was inversely related to age and male sex. Each increase in the number of antihypertensive medications led to 85% and 77% increase in nonadherence (P<0.001) in the UK and Czech populations, respectively. The odds of nonadherence to diuretics were the highest among 5 classes of antihypertensive medications (P≤0.005 in both populations). The predictive model for nonadherence, including age, sex, diuretics, and the number of prescribed antihypertensives, showed area under the curves of 0.758 and 0.710 in the UK and Czech populations, respectively. The area under the curves for the UK model tested on the Czech data and for the Czech model tested on UK data were calculated at 0.708 and 0.756, respectively. We demonstrate that the number and class of prescribed antihypertensives are modifiable risk factors for biochemically confirmed nonadherence to blood pressure-lowering therapy. Further development of discriminatory models incorporating these parameters might prove clinically useful in assessment of nonadherence in countries where biochemical analysis is unavailable.

Precise assessment of noncompliance with the antihypertensive therapy in patients with resistant hypertension using toxicological serum analysis.

BACKGROUND: The aim of our study was to assess the prevalence of pseudo-resistance caused by noncompliance with treatment among patients with severe resistant hypertension and to analyze the contributing factors. METHOD: Three hundred and thirty-nine patients (195 men) with resistant essential hypertension were studied. The first group consisted of 176 patients admitted for hospitalization for exclusion of a secondary cause to our hypertension centre (103 men); the second one consisted of 163 out-patients (92 men) investigated for the first time in an out-patient hypertension clinic. Unplanned blood sampling for assessment of serum antihypertensive drug concentrations by means of liquid chromatography-mass spectrometry was performed in all patients. RESULTS: Our main finding is a surprisingly low compliance with drug treatment in out-patients with resistant hypertension (23% partially noncompliant and 24% totally noncompliant - in total, 47% prevalence of noncompliance). Eighty-one percent of hospitalized patients were positive, in 10% the results were partially positive and in 9% of the patients, the drugs were all negative. The compliance among hospitalized patients was probably better due to lower numbers of prescribed drugs and expected thorough investigation. More frequently, noncompliance was found in nonworking (potential purpose-built behaviour), younger and less well educated patients. The most frequent noncompliance was to doxazosine, spironolactone and hydrochlorothiazide. We have observed a surprisingly low compliance with treatment among out-patients with severe hypertension. CONCLUSION: We conclude that the evaluation of antihypertensive drugs concentrations is a useful and precise method for assessment of noncompliance in patients with resistant hypertension. This evaluation is useful before starting the diagnostic work-up of secondary forms of hypertension and before assignment patients into protocols with new therapy modalities such as renal denervation.

Determination of doxazosin and verapamil in human serum by fast LC-MS/MS: application to document non-compliance of patients.

A rapid and sensitive method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for simultaneous determination of doxazosin and verapamil in human serum has been developed. Trimipramine-d3 as an isotopic labelled internal standard was used for quantification. Serum samples were prepared by simple liquid-liquid extraction with mixture of tert butyl methyl ether and ethyl acetate (1:1, v:v). The analytes and internal standard were separated on C18 column using an isocratic elution with 5 mM ammonium formate with 0.02% formic acid and 0.02% formic acid in acetonitrile (55:45, v:v) at a flow rate of 1.1 mL/min. Positive TurboIonSpray mass spectrometry was used with multiple reaction monitoring of the transitions at: m/z 455.3→165.2 and 150.2 for verapamil, m/z 452.2→344.4 and 247.4 for doxazosin, m/z 298.2→103.1 for trimipramine-d3. Linearity was achieved between 1 and 500 ng/mL (R² ≥ 0.997) for both analytes. An extensive pre-study method validation was carried out in accordance with FDA guidelines. This assay was successfully applied to determine the serum concentrations of doxazosin and verapamil in suspect non-compliance patients.

Development of a fast LC-MS/MS method for quantification of rilmenidine in human serum: elucidation of fragmentation pathways by HRMS.

Rilmenidine is an alpha 2 adrenoreceptor agonist used in the treatment of mild and moderate hypertension. In this study, a fast and accurate liquid chromatographic method with tandem mass spectrometric detection has been validated in order to assure quantification of rilmenidine in human serum. The fragmentation pathway of protonated rilmenidine was studied using high-resolution mass spectrometry (HRMS). This study compared selectivity, linearity, accuracy, precision, extraction efficiency, matrix effect and sensitivity using common liquid-liquid extraction (LLE) and solid-phase extraction (SPE) procedures. The limit of quantitation for both extraction techniques was 0.1 ng/ml. Several differences between the LLE and SPE have been observed in terms of linearity, accuracy, precision and matrix effect. Additionally, the advantages of SPE included less manual work load and increased recovery of rilmenidine in human serum to approximately 80% (LLE, 57%). The developed method involving SPE was found to be accurate (relative error (RE) < 5%), reproducible (relative standard deviation, RSD < 7%), robust and suitable for quantitative analysis of rilmenidine in serum samples obtained from patients under antihypertensive treatment.

Screening and semiquantitative analysis of drugs and drugs of abuse in human serum samples using gas chromatography-mass spectrometry.

OBJECTIVES: The purpose of this study is to develop the gas chromatographic-mass spectrometric method (GC-MS) for screening and semiquantification of drugs and drugs of abuse in human serum. METHOD: GC-MS method after liquid-liquid extraction (LLE) and derivatization with N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA) is presented for screening as well as identification and semiquantification of the most frequently used drugs and drugs of abuse in human serum. RESULTS: Bovine serum spiked with ephedrine (EPHE), 3,4-methylenedioxymethamphetamine (MDMA), guaifenesin (GUAIF), tramadol (TRAM), phenobarbital (PHENO), amitriptyline (AMITR), cocaine (COCA), mirtazapine (MIRTA), dothiepin (DOTH), citalopram (CITAL), clomipramine (CLOMI), bromazepam (BMZPM), diazepam (DZPM), codeine (COD), morphine (MORPH), levomepromazine (LEVO), zolpidem (ZOLP), clozapine (CLOZP), alprazolam (ALPZM) was used for the recovery and repeatability study and for preparation of calibration curves of individual compounds or their TMS derivatives. Recoveries were tested on concentration levels 0.05, 0.1 and 0.5 microg/mL (n=6) and established in range 72.0-98.0%. Repeatabilities expressed as relative standard deviations (RSDs) measured at concentration levels 0.05, 0.1 and 0.5 microg/ mL (n=6) were lower than 10.0%. The calibration curves for analytes or their TMS derivatives were linear in concentration range 0.025-2.000 microg/mL (except of EPHE 2TMS, MDMA TMS, MORPH 2TMS, BMZPM TMS, ALPZM) with correlation coefficients exceeding 0.99. The limit of quantification (LOQ) for analytes used for evaluation study was 0.025 microg/mL (except analytes mentioned above). CONCLUSIONS: The GC-MS method presented here is allowing screening, identification and semiquantification of the most commonly encountered drugs and drugs of abuse in human serum and can be successfully applied to analysis of real samples from clinical and forensic toxicology cases.

Simultaneous determination of amphetamines and amphetamine-derived designer drugs in human urine by GC-MS.

OBJECTIVES: The purpose of this study is to evaluate the gas chromatographicmass spectrometric method (GC-MS) for assay of stimulants of amphetamine type: amphetamine (AMP), methamphetamine (MAMP), ephedrine (EPH), norephedrine (NOREPH), and the amphetamine-derived designer drugs 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA, ecstasy), 3,4-methylenedioxy-N-ethylamphetamine (MDEA) and N-methyl-benzodioxolylbutanamine (MBDB) in urine. These drugs are often encountered in forensic and clinical toxicological analysis. METHODS: GC-MS method after mixed-mode solid-phase extraction (SPE) and derivatization with heptafluorobutyric anhydride (HFBA) is presented for quick and reliable screening as well as identification and quantification of amphetamines and amphetamine derived designer drugs in urine. RESULTS: The measurement of calibration dependence allowed to determine the extent of linearity in the concentration range from 10 to 2,000 ng/ml for all amphetamines except AMP and for all amphetamine-derived designer drugs with correlation coefficients exceeding 0.98. Detection limits were established at 5 ng/ml and quantification limits at 10 ng/ml for all analytes, except AMP. LOD for AMP was established at 20 ng/ml and LOQ at 50 ng/ml. Extraction efficiency for all analytes at concentration levels 50 and 500 ng/ml (n=6) was established in the range 60-99%. Repeatability was measured at concentration levels 50 and 500 ng/ml (n=6), relative standard deviations (RSDs) were under 10% for all analytes. CONCLUSIONS: The GC-MS method after mix-mode solid-phase extraction and derivatization with heptafluorobutyric anhydride is presented for screening followed by identification and quantification of AMP, MAMP, EPH, NOREPH, MDA, MDMA, MDEA, and MBDB. The applicability of the GC-MS method was proven by analyzing authentic urine samples.