Employment of Quality by Design Approach via Response Surface Methodology to Optimize and Develop Modified-release Formulation of Hydrochlorothiazide.

BACKGROUND: Heart attack predominantly occurs during the last phase of sleep and early morning hours, causing millions of death worldwide. Hydrochlorothiazide (HCTZ) is a recommended drug for the prevention of heart disease, but its long action (>4 h) dosage form is lacking in the commercial market and development of modified-release formulation may have industrial significance. Regulatory agencies emphasize Quality by Design based approach for product development to entrust quality in the product. OBJECTIVE: The current research aimed to develop a quality product profile of HCTZ modifiedrelease tablets (MRT; ~14 h) by applying Response Surface Methodology using the computational QbD approach. METHODS: Three independent factors were identified by qualitative and quantitative risk assessment. Statistical terms like p-value, lack of fit, the sum of square, R-squared value, model F value, and linear equations were determined. Graphical tools like normal plot of residual, residual vs predicted plot and box cox plot were used to verify the model selection. The graphical relationship among the critical, independent variables was represented using the Contour plot and 3-D surface plot. Design space was identified by designing an overlay plot using response surface design. RESULTS: Excellent correlation was observed between actual and predicted values. Similarity Factor (F2) of reproducible trials was 78 and 79, and content uniformity was 100.9% and 100.4%. Average weight, hardness, thickness, diameter, and friability were within acceptable limits. CONCLUSION: QbD approach, along with a quality risk management tool, provided an efficient and effective paradigm to build quality MRT of HCTZ.

Pharmacokinetics of Hydrochlorothiazide in Children: A Potential Surrogate for Renal Secretion Maturation.

Hydrochlorothiazide (HCTZ) is a thiazide diuretic used in adults and children for the treatment of hypertension and edema. The pharmacokinetic (PK) properties of HCTZ in children are not well characterized, particularly among children with obesity who frequently suffer from hypertension and may, therefore, benefit from HCTZ therapy. HCTZ is excreted in the kidney via organic anion transporters 1 and 3 (OAT1 and OAT3). The ontogeny of OAT1 and OAT3 remain unknown, but HCTZ clearance may serve as a surrogate marker of OAT1 and OAT3 maturation. Population PK modeling was performed in NONMEM, and the model was leveraged to conduct dose-exposure simulations. This study examined 83 plasma samples from 49 participants (69% male) taking enteral HCTZ. The median (range) postnatal age was 6.7 years (0.03-19.5 years), and 17 (34%) participants were obese or morbidly obese. The median (range) dose of HCTZ was 0.654 mg/kg (0.11-1.8 kg) and the median number of doses recorded per participant was 5 (1-8). HCTZ PK was well characterized by a 1-compartment PK model. Body weight and a maturation model based on postmenstrual age were significant covariates for apparent clearance, but the presence of obesity was not. Dosing simulations were performed with a standardized 1mg/kg. Simulated exposure (area under the curve and maximum HCTZ concentrations) decreased with age and was likely due to older children receiving the maximum absolute doses of HCTZ. Further studies with more patients in each age group are required to confirm these PK findings of HCTZ in the children.

Validated LC-MS/MS method for the simultaneous determination of enalapril maleate, nitrendipine, hydrochlorothiazide, and their major metabolites in human plasma.

Hypertension is a major risk factor for atherosclerosis and ischemic heart disease. Most hypertensive patients need a combination of antihypertensive agents to achieve therapeutic goals. A rapid, sensitive, and selective liquid chromatography-tandem mass spectrometric method was developed and validated for simultaneous determination of enalapril maleate (ENA) and its major metabolite enalaprilat (ENAT), nitrendipine (NIT) and its major metabolite dehydronitrendipine (DNIT), and hydrochlorothiazide (HCT) in human plasma using felodipine as an internal standard (IS). The drugs were extracted from plasma using one-step protein precipitation. Chromatographic separation was performed on a Symmetry C18 column, with water and acetonitrile (10:90, v/v) as mobile phase. The detection was carried out using multiple reaction monitoring mode and coupled with electrospray ionization source. Multiple reaction monitoring transitions were m/z 377.1 → 234.1 for ENA, m/z 349.2 → 206.1 for ENAT, m/z 361.2 → 315.1 for NIT, m/z 359 → 331 for DNIT, m/z 295.9 → 205.1 for HCT, and m/z 384.1 → 338 for felodipine (IS). The method was linear over concentration ranges of 1-200, 20-500, 5-200, 2-100, and 5-200 ng/mL for ENA, ENAT, NIT, DNIT, and HCT, respectively, with r2 ≥ 0.99. Method validation was performed according to U.S. Food and Drug Administration guidelines. The validated method showed good sensitivity and selectivity and could be applied for therapeutic drug monitoring and bioequivalence studies.

Pharmacokinetic and pharmacodynamic evaluation of nano-fixed dose combination for hypertension.

OBJECTIVE: The current study was planned to formulate, characterize and evaluate the pharmacokinetics, and pharmacodynamics of a novel 'NanoFDC' comprising hydrochlorothiazide, candesartan (CNDT) and amlodipine. METHODOLOGY: The candidate drugs were loaded in poly(DL-lactide-co-glycolide) by emulsion-diffusion-evaporation method. The formulations were evaluated for their size, morphology, drug loading and in-vitro release individually. Repeat dose pharmacokinetic and pharmacodynamic study of the nano-fixed dose combination (FDC) was done in dexamethasone-induced animal model. RESULTS: The entrapment efficiencies ranged from 44 ±â€Š2.1, 32.2 ±â€Š4 and 40.5 ±â€Š2.6% for amlodipine, hydrochlorothiazide and CNDT, respectively. The nanoparticles ranged in size from 164 to 215 nm. In-vitro release profile of the nanoformulation showed unto 90% release by day 7 in simulated gastric fluid and simulated intestinal fluid, respectively. In pharmacokinetic analysis a sustained-release for 7 days was observed in nano-FDC group. Once weekly oral dosing of nano-FDC of amlodipine, CNDT and hydrochlorothiazide provided adequate antihypertensive effect which was not statistically different from daily dosing of free drugs in dexamethasone-induced animal model. CONCLUSION: Once weekly oral dosing of nano-FDC of amlodipine, CNDT and hydrochlorothiazide provided adequate antihypertensive effect and was not statistically different from daily dosing of free drugs in dexamethasone-induced animal model. This study provides proof of concept of feasibility of once weekly dosing of a nano-FDC comprising three antihypertensive drugs, which can lead to significant improvement in patient adherence to therapy.

Vanillin enhances the passive transport rate and absorption of drugs with moderate oral bioavailability in vitro and in vivo by affecting the membrane structure.

Vanillin is a popular flavoring agent in the food, tobacco, and perfume industries. In this paper, we investigated the effect of vanillin on the transport rates of drugs with different levels of permeability (acyclovir, hydrochlorothiazide, propranolol and carbamazepine) through a Caco-2 cell bidirectional transport experiment. We also explored the underlying mechanism using an in silico technique and fluorescence anisotropy measurements. The influence of vanillin on the pharmacokinetics of drugs whose transport rates were affected by vanillin in vitro was then studied in vivo. Results showed that vanillin (100 µM) increased the cumulative amount of passively transported drugs (2.1-fold of hydrochlorothiazide, 1.49-fold of propranolol, 1.35-fold of acyclovir, and 1.34-fold of carbamazepine) in vitro. Molecular dynamics simulations revealed that vanillin disordered the structure of the lipid bilayer and reduced the energy barrier of drugs across the center of the membrane. The anisotropy of TMA-DPH also decreased in Caco-2 cells after treatment with vanillin (25 and 100 µM) and indicated an increase in membrane fluidity, which was dose-dependent. An oral bioavailability study indicated that vanillin (100 mg kg-1) significantly enhanced the Cmax and AUC0-6 of hydrochlorothiazide by 1.42-fold and 1.28-fold, respectively, and slightly elevated the Cmax of propranolol. In conclusion, vanillin can significantly increase the absorption of drugs with moderate oral bioavailability in vitro and in vivo by loosening the membrane. Thus, the concurrent consumption of drugs with food containing vanillin may result in increased drug plasma concentration and pose potential health risks.

Pharmacokinetic Interaction Among Telmisartan, Amlodipine, and Hydrochlorothiazide After a Single Oral Administration in Healthy Male Subjects.

PURPOSE: Hypertension is a major risk factor for cardiovascular diseases, necessitating hypertension control. Antihypertensive drugs are more potent when administered in combinations of 2 or 3 different classes of drugs. One such therapy includes a combination of an angiotensin receptor blocker, a calcium channel blocker, and a diuretic. The objective of this study was to evaluate the pharmacokinetic interaction among telmisartan, amlodipine, and hydrochlorothiazide. METHODS: A randomized, open-label, 3-period, 6-sequence, 3-treatment, single-dose crossover study was conducted in healthy male subjects. Subjects were randomly assigned to 1 of 6 sequences and one of the following treatments was administered in each period: treatment A, co-administration of one tablet of telmisartan 80 mg and one tablet of amlodipine 10 mg; treatment B, one tablet of hydrochlorothiazide 25 mg alone; and treatment C, co-administration of all 3 investigational products. Serial blood samples were collected up to 144 hours postdose. Plasma drug concentrations were measured by using LC/MS-MS. Pharmacokinetic parameters, including Cmax and AUC0-last, were determined by using noncompartmental analysis. The geometric least squares mean ratios and associated 90% CIs of log-transformed Cmax and AUC0-last for separate administration or co-administration were calculated to evaluate pharmacokinetic interactions. FINDINGS: Twenty-seven subjects completed the study. The geometric least squares mean ratios and 90% CIs of Cmax and AUC0-last were 1.02 (0.85-1.21) and 1.04 (0.97-1.13) for telmisartan; 1.00 (0.95-1.04) and 0.95 (0.91-0.99) for amlodipine; and 0.88 (0.82-0.96) and 0.86 (0.82-0.90) for hydrochlorothiazide, respectively. No serious adverse events were recorded, and all reported adverse events were of mild intensity. IMPLICATIONS: The pharmacokinetic parameters of telmisartan, amlodipine, and hydrochlorothiazide when administered separately or co-administered were compared, and all the parameters met the criteria for pharmacokinetic equivalence. Combination therapy of these 3 drugs had no significant impact on the pharmacokinetic parameters of each drug. (ClinicalTrials.gov Identifier: NCT03889145).

Pharmacogenomics of amlodipine and hydrochlorothiazide therapy and the quest for improved control of hypertension: a mini review.

Blood pressure (BP) is a complex trait that is regulated by multiple physiological pathways and include but is not limited to extracellular fluid volume homeostasis, cardiac contractility, and vascular tone through renal, neural, or endocrine systems. Uncontrolled hypertension (HTN) has been associated with an increased mortality risk. Therefore, understanding the genetics that underpins and influence BP regulation will have a major impact on public health. Moreover, uncontrolled HTN has been linked to inter-individual variation in the drugs' response and this has been associated with an individual's genetics architecture. However, the identification of candidate genes that underpin the genetic basis of HTN remains a major challenge. To date, few variants associated with inter-individual BP regulation have been identified and replicated. Research in this field has accelerated over the past 5 years as a direct result of on-going genome-wide association studies (GWAS) and the progress in the identification of rare gene variants and mutations, epigenetic markers, and the regulatory pathways involved in the pathophysiology of BP. In this review we describe and enhance our current understanding of how genetic variants account for the observed variability in BP response in patients on first-line antihypertensive drugs, amlodipine and hydrochlorothiazide.

Reliable and easy-to-use LC-MS/MS-method for simultaneous determination of the antihypertensives metoprolol, amlodipine, canrenone and hydrochlorothiazide in patients with therapy-refractory arterial hypertension.

BACKGROUND: Therapy-refractory arterial hypertension is defined as a blood pressure (BP) in a subset of patients who fail to achieve BP control despite a three-drug regimen (including a diuretic). Various factors have impact on loss of therapy response. Drug-drug-interactions (DDIs) may cause altered pharmacokinetics (PK) of antihypertensive drugs. Upregulation of activity and expression of cytochrome P450 (CYP) enzymes can result in decreased plasma drug levels. Besides these PK considerations a significant problem could be nonadherence to drug therapy. In this regard Therapeutic Drug Monitoring (TDM) is a useful tool for detecting nonadherence. Therefore a LC-MS/MS-method for determination of Metoprolol (MET), Amlodipine (AML), Canrenone (CAN) and Hydrochlorothiazide (HCT) was developed. METHODS: An UHPLC-MS/MS method was developed and validated for simultaneous determination of MET, AML, CAN and HCT in plasma matrix. Extraction of serum samples consisted of simple protein precipitation using acetonitrile. Stable isotope labeled analogues for each antihypertensive were obtained for internal standardization and quantitative analysis ([2H7]-MET, ([13C6]-AML, [2H4]-CAN, [13C6]-HCT). Calibrators and quality controls were prepared in plasma matrix of normal individuals. Sample preparation: protein precipitation with acetonitrile and addition of internal standard-mix. RESULTS: All analytes were eluted within a runtime of 2.5 min. Linearity experiments were demonstrated in plasma over following concentration ranges: MET: 5-750 µg/l, AML: 1-50 µg/l, CAN: 10-500 µg/l, HCT: 5-500 µg/l (R2 > 0.993). Chromatographic separation was achieved using a C18 column (50 × 2.1 mm, 1.9 µm particle size) and an isocratic elution. LC-MS/MS analyses were performed on a triple quadrupole mass spectrometer using positive and negative electrospray ionization in selected reaction monitoring (SRM) mode. Ion transitions monitored for quantitation were m/z 268.2 → 74.1 for MET, m/z 409.1 → 238.0 for AML, m/z 341.2 → 91.0 for CAN and m/z 296.0 → 205.1 for HCT. For all analytes, inter- and intra-day precision (CV, %) varied between 1.7 and 14.0 and inter- and intra-day accuracy values ranged from -2.5 to 7.1%. The lower limits of detection and quantification were: 0.08 and 0.23; 0.05 and 0.15; 2.82 and 8.54; and 0.02 and 0.05 µg/l for MET, AML, CAN and HCT, respectively. Results of stability experiments were within the required range of +/- 15%. CONCLUSIONS: Although the level of recommendation of TDM of antihypertensive drugs in patients with refractory hypertension is not yet established, the present LC-MS/MS-method can serve as an effective tool for detection of PK-alterations/nonadherence and may help to monitor antihypertensive pharmacotherapy.

Combinação dose fixa de hidroclorotiazida (12, 5 mg) e valsartana (160 mg): Desenvolvimento de metodologia de dissolução in vitro e in silico para avaliar os perfis de dissolução dos produtos comercializados no Brasil e Peru / Fixed dose combination of hydrochlorothiazide (12. 5 mg) and valsartan (160 mg): Development of in vitro and in silico dissolution methodology to evaluate the dissolution profiles of products marketed in Brazil and Peru

Hidroclorothiazida (HTZ) e valsartana (VAL) são fármacos pouco solúveis em meio aquoso e pertencem às classes IV e II do Sistema de Classificação Biofarmacêutica (SCB), respectivamente. O objetivo deste trabalho foi desenvolver um método para avaliar o perfil de dissolução de formas farmacêuticas sólidas de dose fixa combinada contendo HTZ (12,5 mg) e VAL (160 mg) usando ferramentas in silico para avaliar os perfis de dissolução de produtos comercializados no Brasil e Peru. O presente trabalho foi dividido em 4 capítulos. No Capítulo I, foi determinada a solubilidade da HTZ e VAL pelo método shake-flask e potenciométrico, no qual foi possível demonstrar que existe correlação entre ambos os métodos e que HTZ e VAL são solúveis em tampão fosfato pH 6,8. No Capítulo II, um método cromatográfico em HPLC foi desenvolvido com base em Quality by Design (QbD), com auxílio do software Fusion®, no qual foi estabelecido uma zona de confiança dos parâmetros, que garantiu a robustez do método. O Capítulo III descreve o desenvolvimento de um método de dissolução utilizando ferramenta in silico (DDDplus®) na qual foi definido um delineamento experimental do tipo fatorial completo 33 usando como fatores a formulação, utilização de âncora e velocidade de agitação. Para os ensaios de dissolução in vitro, foi proposto um outro delineamento fatorial 3(3-1) com o intuito de obter as constantes de calibração das simulações in silico. Através de uma análise estatística das eficiências de dissolução obtidas nas simulações, foram avaliados os efeitos e as interações entre os fatores. Assim, as condições finais do método de dissolução estabelecidas foram: 900 mL de tampão fosfato pH 6,8 como meio de dissolução, 75 rpm de velocidade de agitação, e utilização de âncora para evitar a flutuação das formulações. O método desenvolvido foi empregado, no contexto do Capítulo IV, para avaliar o perfil de dissolução dos produtos contendo HTZ e VAL comercializados no Brasil e no Peru. Por análise multivariada, a eficiência de dissolução (ED), tempo médio de dissolução (MDT) e as porcentagens de dissolução de 5 até 60 minutos foram utilizadas para agrupar as formulações em grupos distintos. Embora os perfis de dissolução mostrem similaridade entre todas as formulações avaliadas, o produto referência se destacou por apresentar uma maior ED comparado com as outras formulações, devido à maior liberação nos primeiros 5 minutos de ensaio. Concluiu-se que o método proposto, além de garantir a liberação total de HTZ e VAL a partir das formulações, possui adequado poder discriminativo

Hydrochlorothiazide (HTZ) and valsartan (VAL) are poorly soluble drugs in aqueous medium and belong to classes IV and II of the Biopharmaceutical Classification System (BCS), respectively. The objective of this study was to develop a dissolution method to evaluate the dissolution profile of solid pharmaceutical forms of combined dose containing HTZ (12.5 mg) and VAL (160 mg) using in silico tools to evaluate the dissolution profiles of products sold in Brazil and Peru. The present study was divided into four chapters. In Chapter I, the HTZ and VAL solubility were determined by the shake-flask and potentiometric methods, in which it was possible to demonstrate that there is a correlation between both methods and that HTZ and VAL are soluble in pH 6.8 phosphate buffer. In Chapter II, a chromatographic method in HPLC was developed based on Quality by Design (QbD), using the Fusion® software, in which a zone of confidence of the parameters was established, which ensured the robustness of the method. Chapter III presents the development of a dissolution method using in silico (DDDplusTM) as a tool, in which an experimental design of the complete factorial type 33 was defined using as factors: the formulation, use of sinker and agitation speed. For in vitro dissolution assays, another factor design 3(3-1) was proposed to obtain the calibration constants of the in silico simulations. Through a statistical analysis of the dissolution efficiencies obtained in the simulations, the effects and interactions between the factors were evaluated. Thus, the final conditions of the dissolution method established were: 900 mL of pH 6.8 phosphate buffer as a dissolution medium, 75 rpm of stirring speed, and use of sinker to avoid the fluctuation of the formulations. The method developed was used, in the context of Chapter IV, to evaluate the dissolution profile of HTZ and VAL products marketed in Brazil and Peru. By multivariate analysis, the dissolution efficiency (ED), mean dissolution time (MDT) and the dissolution percentages from 5 to 60 minutes were used to group the formulations in different groups. Although the dissolution profiles show a similarity between all the evaluated formulations, the reference product stood out for presenting a higher ED compared to the other formulations, due to the higher release in the first 5 minutes of the test. It was concluded that the proposed method, besides guaranteeing the total release of HTZ and VAL from the formulations, has adequate discriminatory capacity

Vibrational Spectroscopy for Cocrystals Screening. A Comparative Study.

A recurrent problem faced by the pharmaceutical industry when formulating drug products concerns poorly soluble drugs, which, despite having desirable pharmacological activity, present limited bioavailability. Cocrystallization is growing up as a possible approach to tackle this problem. Cocrystals are crystalline materials comprising at least two components, solid at room temperature, and held together by non-covalent bonds. The increasing interest in these compounds is steadily demanding faster, simpler, and more reliable methods for the task of screening new cocrystals. This work aims at comparing the performance of three vibrational spectroscopy techniques (mid infrared, near infrared, and Raman spectroscopy) for cocrystals screening. Presented results are based on hydrochlorothiazide, a poorly soluble drug belonging to class IV of the Biopharmaceutical Classification System. The implemented cocrystal screening procedure tested six coformers (all considered safe for human administration) added according to a drug:coformer ratio of 1:1 and 1:2 and seven solvents with different polarity. The screening method chosen was based on slurry cocrystallization performed by sonication (ultrasound assisted) in a 96-well plate. Results show that all evaluated vibrational spectroscopy techniques provided important information regarding cocrystal formation, including information on the groups involved in the cocrystallization and purity, and can be used for the screening task.

Physiologically Based Pharmacokinetic Modeling of Fimasartan, Amlodipine, and Hydrochlorothiazide for the Investigation of Drug-Drug Interaction Potentials.

PURPOSE: To build a physiologically based pharmacokinetic (PBPK) model for fimasartan, amlodipine, and hydrochlorothiazide, and to investigate the drug-drug interaction (DDI) potentials. METHODS: The PBPK model of each drug was developed using Simcyp software (Version 15.0), based on the information obtained from literature sources and in vitro studies. The predictive performance of the model was assessed by comparing the predicted PK profiles and parameters with the observed data collected from healthy subjects after multiple oral doses of fimasartan, amlodipine, and hydrochlorothiazide. The DDI potentials after co-administration of three drugs were simulated using the final model. RESULTS: The predicted-to-observed ratios of all the pharmacokinetic parameters met the acceptance criterion. The PBPK model predicted no significant DDI when fimasartan was co-administered with amlodipine or hydrochlorothiazide, which is consistent with the observed clinical data. In the simulation of DDI at steady-state after co-administration of three drugs, the model predicted that fimasartan exposure would be increased by ~24.5%, while no changes were expected for the exposures of amlodipine and hydrochlorothiazide. CONCLUSIONS: The developed PBPK model adequately predicted the pharmacokinetics of fimasartan, amlodipine, and hydrochlorothiazide, suggesting that the model can be used to further investigate the DDI potential of each drug.

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.

Challenges in Simultaneous Determination of Hydrochlorothiazide and Ramipril in Human Plasma: Application to a Bioequivalence Study.

An isotope dilution selective and sensitive high-performance liquid chromatography-tandem mass spectrometry (LC-ESI-MS/MS) method has been developed for the simultaneous determination of hydrochlorothiazide (HCTZ) and ramipril in human plasma through a new concept of periodical polarity switching. Extraction of HCTZ, ramipril and their deuterated analogs as internal standards (ISs) was carried out from 150 µL of human plasma by solid-phase extraction method. Chromatographic separation of analytes was performed on Hypurity C18 (150 mm × 4.6 mm, 5 µ) column under gradient conditions with methanol:0.2% (v/v) formic acid in water as the mobile phase. The method was validated over a concentration range of 0.750-300 ng/mL for HCTZ and 0.125-80.0 ng/mL for ramipril. The mean extraction recovery for analytes and ISs were >(86.0%), consistent across all four QC levels. The challenges to evaluate matrix effect and continuous reproducibility of method during long analytical run was studied and resolved. Processed samples, freeze-thaw, long-term and whole blood stability were evaluated for both the analytes. The method was applied to support a bioequivalence study of 25 mg of HCTZ and 5 mg of ramipril tablet formulation in nine healthy Indian subjects. Assay reproducibility was demonstrated by reanalysis of 42 incurred samples.

Saliva versus Plasma Bioequivalence of Valsartan/Hydrochlorothiazide in Humans: Validation of Classes II and IV Drugs of the Salivary Excretion Classification System.

AIM: The aim of this study is to investigate the robustness of using non-invasive saliva instead of plasma for bioequivalence of valsartan and hydrochlorothiazide (HCT) in humans based on Salivary Excretion Classification System (SECS). METHODS: Plasma and resting saliva samples were collected over 24 h after oral administration of single dose 160 mg valsartan and 12.5 mg HCT to 12 healthy male volunteers after 10 h overnight fasting. Plasma and saliva concentrations were determined by validated liquid chromatography-mass spectrometry. WinNonlin program V5.2 was used to determine pharmacokinetic parameters and bioequivalence metrics. Moreover, optimized effective intestinal permeability was estimated using PK-Sim/Mobi program V5.6. RESULTS AND DISCUSSION: Valsartan is SECS class IV drug due of low permeability and high protein binding and hence didn't appear in saliva. However, HCT is SECS class II drug due to low permeability and low protein binding. No significant differences were observed in the pharmacokinetic parameters in both plasma matrix and saliva matrix (P˃0.05). The 90% confidence intervals did not pass in all parameters due to the high intra-subject variability and small sample size used in this study. Saliva to plasma ratios of HCT were low, yet with high correlation coefficient of 0.96-0.98. So saliva can be used as alternative to plasma sample in pharmacokinetic studies and in bioequivalence when adequate sample size is used.

Facile formation of co-amorphous atenolol and hydrochlorothiazide mixtures via cryogenic-milling: Enhanced physical stability, dissolution and pharmacokinetic profile.

The development of poorly water-soluble drugs faces the risk of low bioavailability and therapeutic efficacy. The co-amorphous drug delivery system has recently gained considerable interest because it offers an alternative approach to modify properties of poorly water-soluble drugs. Herein, we developed a co-amorphous system of atenolol (ATE) and poorly water-soluble hydrochlorothiazide (HCT) by means of cryogenic milling. The co-administration of ATE and HCT has been reported to show therapeutic advantages for patients with uncomplicated hypertension. The co-amorphous ATE-HCT sample with 1:1 molar ratio showed excellent physical stability, which could be attributed to the formation of strong molecular interactions between ATE and HCT as evidenced by FT-IR spectra. Compared to the pure crystalline form, amorphous form and physical mixture, HCT in the co-amorphous form exhibited the significantly increased intrinsic dissolution rate, as well as the enhanced bioavailability in the pharmacokinetic study. It was found that the enhanced bioavailability of HCT in the co-amorphous formulation was achieved by the synergistic effect of amorphized HCT and the water-soluble coformer ATE. The present study provides an improved approach to implement the combination therapy of ATE and HCT for potential clinical treatments.

Development and validation of a reversed-phase high-performance liquid chromatographic method with solid-phase extraction for the quantification of hydrochlorothiazide in ex vivo permeation studies.

Hydrochlorothiazide (HCT) is a diuretic used to treat hypertension. In order to study its intestinal permeation behavior applying an ex vivo methodology, a rapid, sensitive and selective reversed-phase liquid chromatography (RP-HPLC) method coupled with UV detection (RP-HPLC UV) was developed for the analysis of HCT in TC199 culture medium used as mucosal and serosal solutions in the everted rat intestinal sac model. Also, analytical procedures for the quantification of HCT by RP-HPLC with UV detection required a sample preparation step by solid-phase extraction. The method was validated in the concentration range of 8.05 × 10-7 to 3.22 × 10-5 m for HCT. Chromatographic parameters, namely carry-over, lower limit of quantification (1.4491 × 10-7 m), limit of detection (3.8325 × 10-8 m), selectivity, inter- and intraday precision and extraction recovery, were determined and found to be adequate for the intended purposes. The validated method was successfully used for permeability assays across rat intestinal epithelium applying the ex vivo everted rat gut sac methodology to study the permeation behavior of HCT.

Development and in vivo evaluation of an innovative "Hydrochlorothiazide-in Cyclodextrins-in Solid Lipid Nanoparticles" formulation with sustained release and enhanced oral bioavailability for potential hypertension treatment in pediatrics.

An innovative pediatric oral formulation of hydrochlorothiazide (HCT) (2mg/mL), endowed with improved bioavailability and sustained release properties and suitable for the hypertension treatment in pediatric patients, was developed by combining the drug-cyclodextrin complexation and the incorporation of the complex into Solid Lipid Nanoparticles (SLN). Precirol®ATO5-based SLN, with two different surfactants (Pluronic®F68 and Tween®80) loaded with the drug as such or as binary system with hydroxypropyl-beta-cyclodextrin (HPßCd) and sulfobutyl-ether-beta-cyclodextrin (SBEßCd) both as physical mixture (P.M.) or coground product (GR), were prepared using the hot high-shear homogenization followed by ultrasonication method. Loading of the drug:HPßCd both as P.M. and GR gave rise to nanoparticle formation, differently from the HCT:SBEßCd ones, with an entrapment efficiency of about 65%. Such SLN formulations showed an improvement of the drug release rate compared both to the drug suspension and to the free drug-loaded SLN. In all cases the SLN containing the GR systems exhibited better performances than the corresponding with P.M. However, the presence of Tween®80 gave rise to the complete drug release after only 150min, without providing a sustained release, whereas Pluronic®F68-based SLN containing GR were able to assure a sustained release over the time achieving more than 75% drug released at the end of the test, maintaining a constant 1.8-fold increase respect to simple drug suspension. Pluronic®F68-based SLN showed a pharmaceutically acceptable stability up to three months. In vivo studies highlighted the effectiveness of such formulations, enabling a concomitant increased diuretic effect and a sustained drug release and, consequently, enhanced HCT oral bioavailability.

Bioequivalence study between a fixed-dose single-pill formulation of nebivolol plus hydrochlorothiazide and separate formulations in healthy subjects using high-performance liquid chromatography coupled to tandem mass spectrometry.

Systemic arterial hypertension is a major risk factor for cerebrovascular disease. Therefore, adequate control of blood pressure is of enormous importance. One of the many fixed-dose single-pill antihypertensive formulations available on the market is the combination of nebivolol and hydrochlorothiazide. The objective of this study was to develop two distinct high-performance liquid chromatography coupled to tandem mass spectrometry methods to simultaneously quantify nebivolol and hydrochlorothiazide in human plasma. The methods were employed in a bioequivalence study, the first assay involving a nebivolol fixed-dose single-pill formulation based on healthy Brazilian volunteers. Nebilet HCT™ (nebivolol 5 mg + hydrochlorothiazide 12.5 mg tablet, manufactured by Menarini) was the test formulation. The reference formulations were Nebilet™ (nebivolol 5 mg tablet, manufactured by Menarini) and Clorana™ (hydrochlorothiazide 25 mg tablet, manufactured by Sanofi). For both analytes, liquid-liquid extraction was employed for sample preparation and the chromatographic run time was 3.5 min. The limits of quantification validated were 0.02 ng/mL for nebivolol and 1 ng/mL for hydrochlorothiazide. Since the 90% CI for Cmax , AUC(0-last) and AUC(0-inf) individual test/reference ratios were within the 80-125% interval indicative of bioequivalence, it was concluded that Nebilet HCT™ is bioequivalent to Nebilet™ and Clorana™.

Self dispersing mixed micelles forming systems for enhanced dissolution and intestinal permeability of hydrochlorothiazide.

Mixed micelles provide promising strategy for enhancing dissolution and permeability of drugs. However, their fluid nature limited the stability of the loaded drug and hindered the development of stable oral dosage form. Accordingly, the objective was to develop solid self dispersing mixed micelle forming systems (MMFS) for enhanced dissolution and intestinal permeability of hydrochlorothiazide. Pseudoternary phase diagrams were constructed using sodium cholate, lecithin with either poloxamer 407 or PEG 4000 to determine the composition of MMFS. Both polymer free and poloxamer or PEG containing MMFS were prepared as homogenous matrices or as solid self dispersing powder. The later was developed by adsorption of MMFS on avicel-aerosil mixture. Differential scanning calorimetry provided an evidence for existence of hydrochlorothiazide as molecular dispersion in the MMFS. Dispersing polymer free, PEG 4000 or poloxamer based MMFS in aqueous medium produced micelles having size values of 119, 52.6 and 28nm, respectively. The zeta potential values were -61.8, -59.5 and -19.5mV for the same systems, respectively. Preparation of solid self dispersing MMFS enhanced the dissolution rate of hydrochlorothiazide. The intestinal absorption of hydrochlorothiazide from its aqueous solution and polymer incorporating mixed micellar systems was monitored using in situ rabbit intestinal perfusion technique. The permeability results showed a clear trend for enhanced membrane transport of the drug after being incorporated into poloxamer containing mixed micellar system. The study thus introduced a versatile easily formulated solid self dispersing system with high potential for solving the dissolution and permeability problems of class IV drugs.

[Controlled diuretic monotherapy in hypertensive patients: Efficiency and metabolic safety]. / Kontroliruemaya monoterapiya diuretikami u bol'nykh arterial'noi gipertoniei: effektivnost' i metabolicheskaya bezopasnost'.

AIM: To evaluate the antihypertensive efficiency and metabolic effects of controlled monotherapy with hydrochlorothiazide (HCT) and indapamide retard (IR) in hypertensive patients. SUBJECTS AND METHODS: The study included 50 patients with Stage II essential hypertension, grades 1-3 blood pressure (BP) elevation, who received 3-month monotherapy with IR (n=25) or HCT (n=25). Changes were determined in BP, blood lipid, glucose, and potassium levels. The efficiency of antihypertensive therapy was evaluated in the entire group and subgroups of patients identified in accordance with the used diuretic and the presence (n=27) or absence (n=23) of therapy at previous stages. RESULTS: A total of 54% of the patients included in the study achieved target BP after 3 months of therapy. The proportion of individuals with normalized BP was comparable in the HCT and IR groups (52 and 56%, respectively) and in previously treated patients and those who used for the first time antihypertensive drugs (51.8 and 56.5%, respectively). Normalization of systolic and diastolic BPs was achieved in 78 and 58% of the patients, respectively. Target BP was achieved in 94,1%, 42,9% and 16,7% of patients with grades 1,2 and 3 hypertension, respectively. IR proved to be metabolically neutral whereas HCT was found to significantly increase the blood levels of triglycerides and glucose by 15.3% (p<0.05) and 12.2% (p<0.05), respectively. CONCLUSION: Controlled diuretic monotherapy allows BP normalization in more than 50% of the hypertensive patients. HCT and IR have similar antihypertensive efficiency. Because of the negative changes observed in lipid and carbohydrate metabolism with the use of relatively small doses of HCT, IR is a preferential alternative in the long-term treatment of hypertensive patients.