Plasma Trough Concentrations of Antihypertensive Drugs for the Assessment of Treatment Adherence: A Meta-Analysis.

Biochemical drug screening by liquid chromatography-tandem mass spectrometry in plasma is an accurate method for the quantification of plasma concentrations of antihypertensive medications in patients with hypertension. Trough concentrations could possibly be used as drug-specific cutoff values in the biochemical assessment of (non-)adherence. We performed a literature review and meta-analysis of pharmacokinetic studies to determine plasma trough concentrations of amlodipine, hydrochlorothiazide, and valsartan. PubMed was searched for pharmacokinetic studies up to September 2020. Eligible studies reported steady-state mean trough concentration and their variance. Pooled trough concentrations were estimated using a three-level random effects meta-analytic model. Moderator analyses were performed to explore sources of heterogeneity. One thousand three hundred eighteen potentially relevant articles were identified of which 45 were eligible for inclusion. The pooled mean trough concentration was 9.2 ng/mL (95% CI, 7.5-10.8) for amlodipine, 41.0 ng/mL (95% CI, 17.4-64.7) for hydrochlorothiazide, and 352.9 ng/mL (95% CI, 243.5-462.3) for valsartan. Substantial heterogeneity was present for all 3 pooled estimates. Moderator analyses identified dosage as a significant moderator for the pooled trough concentration of amlodipine (ß1=0.9; P<0.05), mean age, and mean body weight for the mean trough concentration of hydrochlorothiazide (ß1=2.2, P<0.05, respectively, ß1=-4.0, P<0.05) and no significant moderators for valsartan. Plasma trough concentrations of amlodipine, hydrochlorothiazide, and valsartan, measured with liquid chromatography-tandem mass spectrometry, are highly heterogeneous over the different studies. Use of the pooled trough concentration as a cutoff in the biochemical assessment of adherence can result in inaccurate diagnosis of (non-)adherence, which may seriously harm the patient-physician relationship, and is therefore not recommended.

Assessment of adherence to diuretics and ß-blockers by serum drug monitoring in comparison to urine analysis.

Purpose: Toxicological screenings for identifying antihypertensive drugs proved to be a useful tool for assessing adherence. However, misinterpretation may occur in case of highly metabolised drugs with low renal excretion, as well as for drugs with a prolonged detectability. The aim of the present study was to compare a recently developed therapeutic drug monitoring (TDM) method based on serum concentrations to an urine drug detection method for assessing adherence in outpatients.Materials and methods: Corresponding urine and blood samples were obtained at the same time from 26 outpatients without supervised medication. Urine and serum analyses were performed using established high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodologies. Adherence was assumed if drugs were detectable in urine or if serum concentrations were above individually calculated lower dose-related concentrations (DRC) or literature-based therapeutic reference ranges (TRR) used as cut-off, respectively.Results: The identification of analytes in urine as well as the quantitative serum assay were performed for atenolol (n = 6 patients), bisoprolol (n = 8), nebivolol (n = 6), canrenone (n = 6, metabolite of spironolactone), hydrochlorothiazide (n = 12) and furosemide (n = 2). On the basis of drug detectability in urine, adherence was assumed in 88% of prescriptions. In 81% (DRC) and 50% (TRR) of the serum analyses the cut-off value was exceeded, which confirms patients' adherence in a lower number. Differences in adherence rates were found in five patients, mainly for ß-blockers.Conclusion: This study suggests that assessment of adherence can be performed more precisely on the basis of serum drug concentrations with individually calculated lower DRC than by using the TRR or qualitative urinalysis.

Comparing PyroMark Q24 Pyrosequencing and MALDI-TOF MS for Identification of CYP2D6*10.

BACKGROUND: CYP2D6*10 is mainly responsible for the large pharmacokinetic variability of routinely administered metoprolol in middle-aged and elderly Asian patients. Utilizing an efficient method for identifying the CYP2D6*10 genotypes is clinically important for evaluating the pharmacokinetic effect of administration of metoprolol. This study attempted to evaluate the effectiveness of the two methods used to detect the rs1065852 and rs1135840 SNPs of the CYP2D6*10 gene. METHODS: Blood samples were processed for the collection of genomic DNA from 198 subjects across Chinese population, and detection of CYP2D6*10 (rs1065852 and rs1135840) was performed using the PyroMark Q24 pyrose-quencing and matrix-assisted laser desorption/ionization time-of-flight mass-spectrometry (MALDI-TOF MS). The discordant results were further validated with Sanger sequencing. We eventually attempted to assess some features of these two methods including reliability, rapidness, being appropriate, and cost-effectiveness. RESULTS: Genotyping of rs1065852 and rs1135840 detected by MALDI-TOF MS were concordant with those identified by PyroMark Q24 pyrosequencing in all 198 (100%) individuals. The hands-on-time and the turnaround time were shorter in the PyroMark Q24 pyrosequencing method than in the MALDI-TOF MS method for SNP of CYP2D6*10. In terms of being cost-effective and high-throughput, the MALDI-TOF MS method outperformed the PyroMark Q24 pyrosequencing method. CONCLUSIONS: CYP2D6*10 genotypes detected by PyroMark Q24 pyrosequencing and MALDI-TOF-MS showed that both methods were reliable, rapid, appropriate, and cost-effective methods. These methods are valuable for clinical applications.

Screening of cardiovascular agents in plasma with LC-MS/MS: A valuable tool for objective drug adherence assessment.

Adherence to cardiovascular preventive agents is important to prevent short and long term cardiovascular events. Recently, qualitatively compound screening using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has gained interest for drug adherence assessment in patients at high risk of cardiovascular events. Therefore, we developed and tested an assay including 52 compounds and metabolites, covering over 95% of the antihypertensive and antithrombotic agents available worldwide. Trichloroacetic acid was used as simple and fast method for protein precipitation. The assay was validated for lower limit of quantification (LLOQ), linearity, stability for freeze/thaw, room temperature, autosampler and matrix effects. The LLOQ for each compound was targeted under the population trough concentration (PTC) as reported in literature to assure high sensitivity for adherence detection. This was accomplished for 50 of 52 compounds with a LLOQ equal or lower compared to the PTC. Linearity was confirmed for all compounds (r2 > 0.995), except for acetylsalicylic acid (r2 = 0.991). For room temperature stability, 12 compounds showed degradation over 20% after 20 h. 3 compounds suffer from matrix effect with recoveries < 50%. After analytical validation, blood samples from 91 patients with difficult-to-treat hypertension were analyzed. Patients were unaware of adherence assessment. Adherence varied largely per agent and per concentration ratio (CR) (ratio of the detected concentration with LC-MS/MS and the PTC) cut-off value. Additionally, stratification by adherence group showed that the percentage of patients classified as non-adherent increased from 6.6% for qualitative analysis (pos/neg) to 19.8% for a CR cut-off of 0.5. The data imply that using the CR cut off values has a significant and relevant effect on patient adherence classification.

The Assessment of Serum Drug Levels to Diagnose Non-Adherence in Stable Chronic Heart Failure Patients.

BACKGROUND: The aim of our study was to evaluate the prevalence of drug non-adherence in stable chronic heart failure (CHF) patients using serum drug levels (SDL) assessment. METHODS: CHF patients were prospectively enrolled during scheduled outpatient visit. Except standard procedures an unanticipated blood sampling for the SDL assessment was obtained. Analysis was focused on the prescribed heart failure and antihypertensive medication and was performed by liquid chromatography coupled with mass spectrometry. The patient was labelled as non-adherent if at least one of drugs assessed was not found in the serum. In the first half of patients multiple SDL have been evaluated during the follow-up. RESULTS: Eighty one patients were enrolled. The non-adherence was proven in twenty of them (25%). In the subgroup of thirty eight patients with multiple SDL evaluation the non-adherence raised significantly with increasing number of visits assessed together (21% for single visit, 29% for two of three visits assessed together and 34% for all three visits evaluated together, all p < 0.001). CONCLUSION: The non-adherence was proven in significant part of stable CHF patients using SDL assessment. This method seems to be reliable and effective and should be a part of clinical assessment in selected patients with CHF.

Quantification of Hydrochlorothiazide and Ramipril/Ramiprilate in Blood Serum and Cerebrospinal Fluid: A Pharmacokinetic Assessment of Central Nervous System Adverse Effects.

BACKGROUND: A drug must reach the central nervous system (CNS) in order to directly cause CNS adverse effects (AEs). Our current study addressed the pharmacokinetic (PK) background of the assumption that CNS concentrations of hydrochlorothiazide (HCT) and ramiprilate may directly cause CNS AEs such as headache and drowsiness. METHODS: In neurological patients, paired serum and cerebrospinal fluid (CSF) samples were withdrawn simultaneously. Some of them were treated with HCT (n = 15, daily chronic doses 7.5-25 mg) or ramipril (n = 9, 2.5-10 mg). Total concentrations of HCT and ramiprilate were quantified in these samples. To this end, sensitive liquid chromatography/tandem mass spectrometry methods were developed. RESULTS: CSF reached 4.1% (interquartile ranges 2.5-5%) of total serum concentrations for HCT and 2.3% (1.7-5.7%) for ramiprilate, corresponding to about 11.3% and 5.5% of respective unbound serum concentrations. CONCLUSION: The PK/Pharmacodynamic characteristics of HCT and ramiprilate in the CNS are unknown. However, since the CSF levels of these agents, both free and bound, were much lower than the corresponding concentrations in serum, it is unlikely that the observed CNS AEs are mediated primarily via direct effects in the brain.

Usability of Functional MRI in Clinical Studies for Fast and Reliable Assessment of Renal Perfusion and Quantification of Hemodynamic Effects on the Kidney.

The purpose of this study was to evaluate contrast-media-free arterial spin labeling, a technique of functional magnetic resonance imaging (MRI), for assessment of kidney perfusion in a clinical study. We examined renal perfusion by arterial spin labeling in 15 healthy adults using a clinical 1.5-T MRI system, twice under baseline conditions and 60 minutes after a single oral dose of 50 mg captopril. Data evaluation included assessment of interstudy and interrater reproducibility in addition to the pharmacological effect of captopril on kidney perfusion and a sample size calculation for potential application of the technique in pharmacological intervention studies. Interstudy reproducibility of cortical and medullary kidney perfusion was excellent (intraclass correlation coefficients 0.77 and 0.83, respectively). Interrater reproducibility was excellent in the cortex and good in the medulla (intraclass correlation coefficients 0.97 and 0.66, respectively). Ingestion of 50 mg captopril was associated with an 11% drop of systolic blood pressure and a rise in kidney perfusion by 22% in the cortex (369 ± 48 vs 452 ± 56 mL/[min·100 g], P < .001) and 26% in the medulla (157 ± 39 to 198 ± 45 ml/[min·100 g]; P < .01). Statistical power analysis revealed that a small sample size of only 6 participants is needed in a clinical trial to capture an equal change in kidney perfusion to the one induced by 50 mg captopril with a statistical power of 82% and an α error of 0.05. In conclusion, funtional MRI with arterial spin labeling is a reliable method for quantification of kidney perfusion and for fast assessment of pharmacologically induced renal perfusion changes, allowing low case numbers.

Assessment of a Potential Pharmacokinetic Interaction between Nebivolol and Bupropion in Healthy Volunteers.

BACKGROUND/AIMS: The study aimed at investigating the effects of multiple-dose bupropion (potent inhibitor of CYP2D6) on the pharmacokinetics (PKs) of single-dose nebivolol (CYP2D6 substrate) and to evaluate the clinical relevance of this potential drug interaction. METHODS: This open-label, nonrandomized clinical study had a 2-period design: during period 1 (reference), a single dose of 5 mg nebivolol was administered, while during period 2 (test), 5 mg nebivolol + 300 mg bupropion were ingested concomitantly, after a pretreatment regimen with bupropion (7 days). The PK parameters of nebivolol and its active metabolite were analyzed by noncompartmental modeling, while the pharmacodynamic (PD) parameters (blood pressure and heart rate) were assessed at rest. RESULTS: Bupropion plus nebivolol increased the mean peak plasma concentrations (Cmax) of nebivolol (1.67 ± 0.69 vs. 3.80 ± 1.70 ng/ml) and its active metabolite (0.68 ± 0.22 vs. 1.13 ± 0.38 ng/ml) compared to nebivolol alone. After bupropion pretreatment, the exposure to nebivolol was increased by 7.2-fold for the parent drug and 4-fold for the hydroxylated active metabolite. The difference between the PD parameters measured during the 2 periods was not significant. CONCLUSION: The study concluded that bupropion influenced the PKs of nebivolol in healthy volunteers, but a clinical relevance was not established. However, this latter aspect requires further investigation.

Assessment of adherence to treatment in patients with resistant hypertension using toxicological serum analysis. A subgroup evaluation of the RESIST-POL study.

INTRODUCTION: Nonadherence to antihypertensive therapy is one of the main causes of resistant hypertension. OBJECTIVES: The aim of our study was to evaluate adherence to therapy in patients with resistant hypertension by determining serum antihypertensive drug levels with the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS). PATIENTS AND METHODS: The study included 36 patients with primary resistant hypertension selected from the RESIST-POL study (23 men and 13 women; mean age, 52.5 ±9.1 years; range, 22-67 years; mean number of antihypertensive drugs, 5.3 ±1.4), who met all 3 inclusion criteria: use of ≥4 antihypertensive drugs; average daytime ambulatory systolic blood pressure ≥140 mmHg; one of the clinical features suggesting nonadherence. All patients had their serum drug levels assessed using LC-MS/MS. Patients in whom the serum level of at least 1 drug was below the limit of quantification for the method used were regarded as nonadherent. RESULTS: Of all study patients, nonadherence was observed in 31 patients (86.1%), and none of the prescribed drugs was detected (complete nonadherence) in 5 patients (13.9%). In 26 patients (72.2%), at least 1 of the prescribed drugs could not be detected (partial nonadherence). CONCLUSIONS: In our study, we documented a surprisingly low adherence to antihypertensive treatment in patients with resistant hypertension. Our results suggest that, particularly in those patients, the analysis of serum antihypertensive drug levels using LC-MS/MS might allow to avoid a comprehensive and costly diagnostic work-up including biochemical and imaging studies.

Pharmacokinetic drug-drug interaction assessment between LCZ696, an angiotensin receptor neprilysin inhibitor, and hydrochlorothiazide, amlodipine, or carvedilol.

LCZ696 is a first-in-class angiotensin receptor neprilysin inhibitor in development for treatments of hypertension and heart failure indications. In 3 separate studies, pharmacokinetic drug-drug interactions (DDIs) potential was assessed when LCZ696 was coadministered with hydrochlorothiazide (HCTZ), amlodipine, or carvedilol. The studies used a open-label, single-sequence, 3-period, crossover design in healthy subjects. Blood samples were collected to determine the pharmacokinetic parameters of LCZ696 analytes (AHU377, LBQ657, and valsartan), HCTZ, amlodipine, or carvedilol (R[+]- and S[-]-carvedilol) for statistical analysis. When coadministered LCZ696 with HCTZ, the 90% CIs of the geometric mean ratios of AUCtau,ss of HCTZ and that of LBQ657 were within a 0.80-1.25 interval, whereas HCTZ Cmax,ss decreased by 26%, LBQ657 Cmax,ss increased by 19%, and the AUCtau,ss and Cmax,ss of valsartan increased by 14% and 16%, respectively. Pharmacokinetics of amlodipine, R(+)- and S(-)-carvedilol, or LBQ657 were not altered after coadministration of LCZ696 with amlodipine or carvedilol. Coadministration of LCZ696 400 mg once daily (qd) with HCTZ 25 mg qd, amlodipine 10 mg qd, or carvedilol 25 mg twice a day (bid) had no clinically relevant pharmacokinetic drug-drug interactions. LCZ696, HCTZ, amlodipine, and carvedilol were safe and well tolerated when given alone or concomitantly in the investigated studies.

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.

Development and validation of a simple and sensitive HPLC-UV method for the determination of captopril in human plasma using a new derivatizing reagent 2-naphthyl propiolate.

In this study, a simple, sensitive and reliable HPLC-UV method applying rapid sample preparation technique for the determination of captopril in human plasma was developed and validated. The method is based on pre-column derivatization of captopril and 2-propene-1-thiol (internal standard) with a new reagent 2-naphthyl propiolate. Sample clean-up, derivatization and extraction were carried out in two steps, totally less than 30min. The extracts were chromatographed on a C18 column (5µm, 150mm×4.6mmi.d.). The mobile phase consisted of methanol (75%, v/v) and phosphate buffer (25%, pH=8, 0.01M). UV detection was performed at 290nm. To obtain the best reaction yield, the factors that could influence the derivatization process, including the concentration of derivatization reagent, pH of sample solution and temperature were investigated in detail and optimized using Box-Behnken response surface methodology. Under optimized conditions the average extraction recovery of captopril and internal standard were >86%. The achieved lower limit of quantification (LLOQ) was 3ng/mL; the assay exhibited a linear dynamic range of 3-2000ng/mL with correlation coefficient (r(2)) of ≥0.99. The precision was satisfactory in the whole calibration range with RSD of 5.9-12.4% (accuracy: from 97.5% to 93.6%) and of 6.4-12.8% (accuracy: from 97.3% to 95.2%) for intra- and inter-assay, respectively. The method stability was confirmed in a series of experiments including: freeze-thaw, short- and long-term stability testing. Lastly, the developed method was successfully applied to the bioequivalence study of captopril administrated as a single oral dose (50mg) to 12 healthy male volunteers.

Enhanced transdermal delivery of an anti-hypertensive agent via nanoethosomes: statistical optimization, characterization and pharmacokinetic assessment.

The aim of the current investigation is to develop and statistically optimize nanoethosomes for transdermal valsartan delivery. Box-Behnken experimental design was applied for optimization of nanoethosomes. The Independent variables were phospholipids 90G (X(1)), ethanol (X(2)), valsartan (X(3)) and sonication time (X(4)) while entrapment efficiency (Y(1)), vesicle size (Y(2)) and flux (Y(3)) were the dependent variables. The optimized formulation obtained was then tested in rats for an in vivo pharmacokinetic study. Results indicate that the nanoethosomes of valsartan provides better flux, reasonable entrapment efficiency, more effectiveness for transdermal delivery as compared to rigid liposomes. Optimized nanoethosomal formulation with mean particle size is 103 ± 5.0 nm showed 89.34 ± 2.54% entrapment efficiency and achieved mean transdermal flux 801.36 ± 21.45 µg/cm(2)/h. Nanoethosomes proved significantly superior in terms of, amount of drug permeated in the skin, with an enhancement ratio of 43.38 ± 1.37 when compared to rigid liposomes. Confocal laser scanning microscopy revealed an enhanced permeation of Rhodamine-Red loaded nanoethosomes to the deeper layers of the skin as compared to conventional liposomes. In vivo pharmacokinetic study of nanoethosomal transdermal therapeutic system showed a significant increase in bioavailability (3.03 times) compared with oral suspension of valsartan. Our results suggest that nanoethosomes are an efficient carrier for transdermal delivery of valsartan.

Rapid and sensitive liquid chromatography/tandem mass spectrometry method for simultaneous determination of enalapril and its major metabolite enalaprilat, in human plasma: application to a bioequivalence study.

A rapid and most sensitive method for simultaneous determination of enalapril (ENP) and its metabolite, enalaprilat (ENPT), in human plasma using ESI-LC-MS/MS (electrospray ionization liquid chromatography tandem mass spectrometry) positive ion multiple reactions monitoring (MRM) mode, was developed and validated. The procedure involves a simple solid-phase extraction (SPE) followed by evaporation of the sample. Chromatographic separation was carried out on a Hypurity C(18) column (50 mm × 4.6 mm, 5 µm) with an isocratic mobile phase and a total run time of 2.0 min only. The MRM of ENP and ENPT is 377.10 → 234.20 and 349.20 → 206.10 respectively. The standard calibration curves showed excellent linearity within the range of 0.064 to 431.806 ng/mL for ENA and 0.064 to 431.720 ng/mL for ENPT (r ≥ 0.990). This is the only method which can quantitate upto 0.064 ng/mL for both ENP and ENPT in a single run with the shortest analysis time. In matrix effect experiment, this method shows a % CV (% coefficients of variation) of less than 5, which means that the proposed method is free from any kind of irregular ionization process. This method was successfully applied to a pharmacokinetic study after oral administration of enalapril maleate 20 mg tablet in Indian healthy male volunteers.

Assessment of the drug-drug interactions between fimasartan and hydrochlorothiazide in healthy volunteers.

AIM: Fimasartan is a selective angiotensin II receptor blocker. Hydrochlorothiazide (HCTZ), which is used to treat hypertension and edematous conditions, is coadministered with many antihypertensive agents. METHODS: An open-label, randomized, multiple-dosing, 2-arm, 1-sequence, 2-period study was conducted to assess the effects of fimasartan (240 mg) on HCTZ (25 mg) or vice versa in 18 and 14 healthy male volunteers, respectively. During each drug administration period, drugs were given once daily for 7 days, with a 7-day washout period between the 2 administration periods. RESULTS: The respective geometric mean ratios of fimasartan for AUC τ,ss and C max,ss with HCTZ were 1.30 [90% confidence interval (CI), 0.84-2.01] and 1.17 (90% CI, 0.93-1.47) compared with fimasartan alone. The respective geometric mean ratios of HCTZ for AUC τ,ss and C max,ss with fimasartan were 0.94 (90% CI, 0.84-1.04) and 0.88 (90% CI, 0.80-0.97) compared with HCTZ alone. Plasma renin activity indicated no significant differences between fimasartan monotherapy and coadministered treatment. CONCLUSIONS: Fimasartan administered alone or in combination with HCTZ was well tolerated at the described dosages. Coadministration of fimasartan increased the urinary excretion of HCTZ and urine volume, but these observations are unlikely to have any clinical relevance.

Development and validation of a highly sensitive and robust LC-ESI-MS/MS method for simultaneous quantitation of simvastatin acid, amlodipine and valsartan in human plasma: application to a clinical pharmacokinetic study.

A high-throughput, simple, highly sensitive and specific LC-MS/MS method has been developed for simultaneous estimation of simvastatin acid (SA), amlodipine (AD) and valsartan (VS) with 500 microL of human plasma using deuterated simvastatin acid as an internal standard (IS). The API-4000 LC-MS/MS was operated under the multiple reaction-monitoring mode (MRM) using electrospray ionization. The assay procedure involved precipitation of SA, AD, VS and IS from plasma with acetonitrile. The total run time was 2.8 min and the elution of SA, AD, VS and IS occurred at 1.81, 1.12, 1.14 and 1.81 min, respectively; this was achieved with a mobile phase consisting of 0.02 M ammonium formate (pH 4.5):acetonitrile (20:80, v/v) at a flow rate of 0.50 mL/min on an X-Terra C18 column. A linear response function was established for the range of concentrations 0.5-50 ng/mL (r > 0.994) for VS and 0.2-50 ng/mL (r > 0.996) for SA and AD. The method validation parameters for all three analytes met the acceptance as per FDA guidelines. This novel method has been applied to human pharmacokinetic study.

Treatment of hypertension and diabetes mellitus in patients with chronic kidney disease: a review.

Hypertension and diabetes mellitus are the two leading causes of chronic kidney disease (CKD). The purpose of this paper is to provide an overview of the present pharmacologic and adverse events involved in the treatment of hypertension and diabetes mellitus in patients with CKD. Proper management of hypertension and diabetes mellitus, a common co-morbidity associated with CKD, would slow the progression of kidney disease and reduce healthcare expenditures. Awareness of potential side effects due to the medications or renal insufficiency could prevent unnecessary harm to the patient and provide cost-containment. Active involvement of all healthcare team members can reduce progression of CKD and improve quality of life outcomes in CKD patients.

Quantification of trandolapril and its metabolite trandolaprilat in human plasma by liquid chromatography/tandem mass spectrometry using solid-phase extraction.

A sensitive high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (MS/MS) method was developed and validated for the simultaneous quantification of trandolapril and its metabolite trandolaprilat in human plasma using ramipril as an internal standard. Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M-H]- ions, m/z 429/168 for trandolapril, m/z 401/168 for trandolaprilat and m/z 415/166 for the internal standard. The method exhibited a linear dynamic range of 20-10,000 pg/mL for both trandolapril and trandolaprilat in human plasma. The lower limit of quantification was 20 pg/mL for both trandolapril and its metabolite. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.0 min for each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies.

Comparative pharmacokinetics of two tablet formulations of Losartan: bioequivalence assessment.

The pharmacokinetic profiles of two brands of losartan 50 mg tablets were compared in 24 healthy adult volunteers after a single oral dose in a randomized cross-over study. The study was conducted at the ACDIMA Center for Bioequivalence & Pharmaceutical Studies, Amman, Jordan. The reference (Cozaar, MSD, The Netherlands) and test (Blosart, Julphar, UAE) products were administered to fasting volunteers. Blood samples were collected at specified time intervals, and the plasma separated and analysed for losartan and its active metabolite (losartan carboxylic acid) using a validated HPLC method with fluorescence detection. Pharmacokinetic parameters AUC(0-t), AUC(0-alpha), C(max), T(max), T(1/2), elimination rate constant, MRT, Cl/F and Vss/F were determined from plasma concentration-time profiles of both formulations and found to be in good agreement with reported values. Three parameters (AUC(0-t), AUC(0-alpha), and C(max)) were compared statistically to evaluate the bioequivalence between the two brands, using statistical modules recommended by the FDA. Analysis of variance (ANOVA) did not show any significant difference between the two formulations and 90% confidence intervals fell within the acceptable range (80%-125%) for bioequivalence. Based on these statistical inferences it was concluded that the two formulations exhibited comparable pharmacokinetic profiles and that Julphar's Blosart is bioequivalent to Cozaar of MSD, The Netherlands.

Quantitative determination of BMS186716, a thiol compound, in dog plasma by high-performance liquid chromatography-positive ion electrospray mass spectrometry after formation of the methyl acrylate adduct.

As it is extremely unstable in blood, the thiol compound BMS186716 was stabilized by the addition of methyl acrylate (MA) to blood samples. The blood samples were then kept in ice for 10-15 min for completion of the Michael addition reaction to occur between the thiol group of BMS186716 and MA, after which the plasma was separated by centrifugation under refrigeration. For sample analysis, the standard and quality control samples were prepared by spiking blank plasma with the BMS186716-MA adduct. After addition of the internal standard, BMS 188035-MA, each sample was acidified with HCI and then extracted with methyl tert.-butyl ether. Each reconstituted extract was injected into a high-performance liquid chromatography-positive ion electrospray ionization mass spectrometric system. The electrospray condition was chosen to enhance the [M+NH4]+ signal at the expense of the [M+H]+ signal. Monitoring the [M+NH4]+ signal, a lower limit of quantitation of 2.5 ng/ml was achieved, with 0.5 ml plasma. We have thus shown that a sulfhydryl compound (BMS186716) in blood can successfully be stabilized by reacting it with MA and that the adduct produced is adequately stable in blood and plasma to allow the development of a rugged quantitative bioanalytical method.