Losartan

Exploring Hypertension: The Role of AT1 Receptors, Sartans, and Lipid Bilayers

The rational design of AT1 receptor antagonists represents a pivotal approach in the development of therapeutic agents targeting cardiovascular pathophysiology. Sartans, a class of compounds engineered to inhibit the binding and activation of Angiotensin II on the AT1 receptor, have demonstrated significant clinical efficacy. This review explores the multifaceted role of sartans in mitigating hypertension and related complications. We highlight the integration of crystallography, computational simulations, and NMR spectroscopy to elucidate sartan-AT1 receptor interactions, providing a foundation for the next-generation antagonist design. The review also delves into the challenges posed by the high lipophilicity and suboptimal bioavailability of sartans, emphasizing advancements in nanotechnology and novel drug delivery systems. Additionally, we discuss the impact of lipid bilayers on the AT1 receptor conformation and drug binding, underscoring the importance of the lipidic environment in receptor-drug interactions. We suggest that optimizing drug design to account for these factors could enhance the therapeutic potential of AT1 receptor antagonists, paving the way for improved cardiovascular health outcomes.

Molecular mechanism of cognitive impairment associated with Parkinson's disease: A stroke perspective

Parkinson's disease (PD) is a common neurological illness that causes several motor and non-motor symptoms, most characteristically limb tremors and bradykinesia. PD is a slowly worsening disease that arises due to progressive neurodegeneration of specific areas of the brain, especially the substantia nigra of the midbrain. Even though PD has continuously been linked to a higher mortality risk in numerous epidemiologic studies, there have been significant discoveries regarding the connection between PD and stroke. The incidence of strokes such as cerebral infarction and hemorrhage is substantially associated with the development of PD. Moreover, cognitive impairments, primarily dementia, have been associated with stroke and PD. However, the underlying molecular mechanism of this phenomenon is still obscure. This concise review focuses on the relationship between stroke and PD, emphasizing the molecular mechanism of cognition deficit and memory loss evident in PD and stroke. Furthermore, we are also highlighting some potential drug molecules that can target both PD and stroke.

Design and Evaluation of Losartan Potassium Effervescent Floating Matrix Tablets: In Vivo X-ray Imaging and Pharmacokinetic Studies in Albino Rabbits

Losartan potassium (LP) is an angiotensin receptor blocker used to treat hypertension. At higher pH, it shows poor aqueous solubility, which leads to poor bioavailability and lowers its therapeutic effectiveness. The main aim of this research was to develop a direct compressed effervescent floating matrix tablet (EFMT) of LP using hydroxyl propyl methylcellulose 90SH 15,000 (HPMC-90SH 15,000), karaya gum (KG), and an effervescent agent, such as sodium bicarbonate (SB). Therefore, an EFMT has been developed to prolong the stomach residence time (GRT) of a drug to several hours and improve its bioavailability in the stomach region. The blended powder was evaluated for pre-compression characteristics, followed by post-compression characteristics, in vitro floating, water uptake studies, and in vitro studies. The optimized formulation of EFMT was investigated for in vivo buoyancy by X-ray imaging and pharmacokinetic studies in Albino rabbits. The results revealed that the parameters of pre- and post-compression were within the USP limits. All tablets showed good floating capabilities (short floating lag time <1 min and floated for >24 h), good swelling characteristics, and controlled release for over 24 h. The Fourier-transform infrared (FTIR) and differential scanning calorimetry (DSC) spectra showed drug-polymer compatibility. The optimized formulation F3 (HPMC-90SH 15,000-KG) exhibited non-Fickian diffusion and showed 100% drug release at the end of 24 h. In addition, with the optimized formulation F3, we observed that the EFMT floated continuously in the rabbit's stomach area; thus, the GRT could be extended to more than 12 h. The pharmacokinetic profiling in Albino rabbits revealed that the relative bioavailability of the optimized LP-EFMT was enhanced compared to an oral solution of LP. We conclude that this a potential method for improving the oral bioavailability of LP to treat hypertension effectively.

Coronavirus pandemic: treatment and future prevention

The rapid spread of SARS-CoV-2 leading to the COVID-19 pandemic with more than 400,000 deaths worldwide and the global economy shut down has substantially accelerated the research and development of novel and efficient COVID-19 antiviral drugs and vaccines. In the short term, antiviral and other drugs have been subjected to repurposing against COVID-19 demonstrating some success, but some excessively hasty conclusions drawn from significantly suboptimal clinical evaluations have provided false hope. On the other hand, more than 300 potential therapies and at least 150 vaccine studies are in progress at various stages of preclinical or clinical research. The aim here is to provide a timely update of the development, which, due to the intense activities, moves forward with unprecedented speed.

Coronavirus Pandemic-Therapy and Vaccines

The current coronavirus COVID-19 pandemic, which originated in Wuhan, China, has raised significant social, psychological and economic concerns in addition to direct medical issues. The rapid spread of severe acute respiratory syndrome-coronavirus (SARS-CoV)-2 to almost every country on the globe and the failure to contain the infections have contributed to fear and panic worldwide. The lack of available and efficient antiviral drugs or vaccines has further worsened the situation. For these reasons, it cannot be overstated that an accelerated effort for the development of novel drugs and vaccines is needed. In this context, novel approaches in both gene therapy and vaccine development are essential. Previous experience from SARS- and MERS-coronavirus vaccine and drug development projects have targeted glycoprotein epitopes, monoclonal antibodies, angiotensin receptor blockers and gene silencing technologies, which may be useful for COVID-19 too. Moreover, existing antivirals used for other types of viral infections have been considered as urgent action is necessary. This review aims at providing a background of coronavirus genetics and biology, examples of therapeutic and vaccine strategies taken and potential innovative novel approaches in progress.

Online extraction of antihypertensive drugs and their metabolites from untreated human serum samples using restricted access carbon nanotubes in a column switching liquid chromatography system

A novel analytical method was developed to determine 5 antihypertensive drugs of different pharmacological classes (angiotensin-converting enzyme inhibitors, calcium channel blockers, α-2 adrenergic receptor agonists, angiotensin II receptor blockers, and aldosterone receptor antagonists) and some of their metabolites in human serum. The untreated samples were directly analyzed in a column switching system using an extraction column packed with restricted access carbon nanotubes (RACNTs) in an ultra-high performance liquid chromatography coupled to a mass spectrometer (UHPLC-MS/MS). The RACNTs column was able to exclude approximately 100% of proteins from the samples in 2.0min, maintaining the same performance for about 300 analytical cycles. The method was validated in accordance with Food and Drug Administration (FDA) guidelines, being linear for all the determined analytes in their respective analytical ranges (coefficients of determination higher than 0.99) with limits of detection (LODs) and quantification (LOQs) ranging from 0.09 to 10.85μgL^-1 and from 0.30 to 36.17μgL^-1, respectively. High recovery values (88-112%) were obtained as well as suitable results for inter and intra-assay accuracy and precision. The method provided an analytical frequency of 5 samples per hour, including the sample preparation and separation/detection steps. The validated method was successfully used to analyze human serum samples of patients undergoing treatment with antihypertensive drugs, being useful for pharmacometabolomic, pharmacogenomic, and pharmacokinetic studies.

Angiotensin-II mediates nonmuscle myosin II activation and expression and contributes to human keloid disease progression

Aberrant fibroblast migration in response to fibrogenic peptides plays a significant role in keloid pathogenesis. Angiotensin II (Ang II) is an octapeptide hormone recently implicated as a mediator of organ fibrosis and cutaneous repair. Ang II promotes cell migration but its role in keloid fibroblast phenotypic behavior has not been studied. We investigated Ang II signaling in keloid fibroblast behavior as a potential mechanism of disease. Primary human keloid fibroblasts were stimulated to migrate in the presence of Ang II and Ang II receptor 1 (AT₁), Ang II receptor 2 (AT₂) or nonmuscle myosin II (NMM II) antagonists. Keloid and the surrounding normal dermis were immunostained for NMM IIA, NMM IIB, AT₂ and AT₁ expression. Primary human keloid fibroblasts were stimulated to migrate with Ang II and the increased migration was inhibited by the AT₁ antagonist EMD66684, but not the AT₂ antagonist PD123319. Inhibition of the promigratory motor protein NMM II by addition of the specific NMM II antagonist blebbistatin inhibited Ang II-stimulated migration. Ang II stimulation of NMM II protein expression was prevented by AT₁ blockade but not by AT₂ antagonists. Immunostaining demonstrated increased NMM IIA, NMM IIB and AT₁ expression in keloid fibroblasts compared with scant staining in normal surrounding dermis. AT₂ immunostaining was absent in keloid and normal human dermal fibroblasts. These results indicate that Ang II mediates keloid fibroblast migration and possibly pathogenesis through AT₁ activation and upregulation of NMM II.

Reciprocal regulation of transcription factors and PLC isozyme gene expression in adult cardiomyocytes

By employing a pharmacological approach, we have shown that phospholipase C (PLC) activity is involved in the regulation of gene expression of transcription factors such as c-Fos and c-Jun in cardiomyocytes in response to norepinephrine (NE). However, there is no information available regarding the identity of specific PLC isozymes involved in the regulation of c-Fos and c-Jun or on the involvement of these transcription factors in PLC isozyme gene expression in adult cardiomyocytes. In this study, transfection of cardiomyocytes with PLC isozyme specific siRNA was found to prevent the NE-mediated increases in the corresponding PLC isozyme gene expression, protein content and activity. Unlike PLC gamma(1) gene, silencing of PLC beta(1), beta(3) and delta(1) genes with si RNA prevented the increases in c-Fos and c-Jun gene expression in response to NE. On the other hand, transfection with c-Jun si RNA suppressed the NE-induced increase in c-Jun as well as PLC beta(1), beta(3) and delta(1) gene expression, but had no effect on PLC gamma(1) gene expression. Although transfection of cardiomyocytes with c-Fos si RNA prevented NE-induced expression of c-Fos, PLC beta(1) and PLC beta(3) genes, it did not affect the increases in PLC delta(1) and PLC gamma(1) gene expression. Silencing of either c-Fos or c-Jun also depressed the NE-mediated increases in PLC beta(1), beta(3) and gamma(1) protein content and activity in an isozyme specific manner. Furthermore, silencing of all PLC isozymes as well as of c-Fos and c-Jun resulted in prevention of the NE-mediated increase in atrial natriuretic factor gene expression. These findings, by employing gene silencing techniques, demonstrate that there occurs a reciprocal regulation of transcription factors and specific PLC isozyme gene expression in cardiomyocytes.

Efficacy and safety of losartan 100 mg or losartan 100 mg plus hydrochlorothiazide 25 mg in the treatment of patients with essential arterial hypertension and CV risk factors: observational, prospective study in primary care

BACKGROUND

Patients with high cardiovascular risk are prevalent in ambulatory care. To achieve adequate blood pressure control, such patients require higher drug doses and/or combination therapy. We aimed to assess the efficacy and safety of losartan 100 mg as monotherapy or in fixed-dose combination with hydrochlorothiazide 25 mg.

DESIGN AND METHODS

Multicentre, prospective, open observational study over 13 weeks in patients with essential hypertension, whose blood pressure was not adequately controlled despite pretreatment. Main outcome parameters were the systolic (SBP) and diastolic (DBP) blood pressure reduction, the rate of normalized patients at study end compared to baseline, and the number and type of adverse events (AEs).

RESULTS

Of the 7702 documented patients, 53.1% (N = 4088) were men, with a mean age of 63.5 +/- 10.7 years. Comorbidities were frequent (diabetes mellitus in 57.4% [N = 4418], coronary heart disease in 30.3% [N = 2330], left ventricular hypertrophy in 28.2% [N = 2172], heart failure in 14.0% [N = 1079], and peripheral arterial disease in 9.0% [N = 690]). Patients received losartan 100 mg in 45.7% (N = 3521), losartan/HCTZ in 53.8% (N = 4143); additional antihypertensive drugs were given in 45.5% (N = 3505). Physicians reported somewhat lower target values than those stipulated by the guidelines (irrespective of age, gender, and concomitant diseases except for diabetes). Mean SBP/DBP decreased from a baseline value of 158/93 mmHg by 24/12 mmHg at study end. The BP lowering effect was similar in subgroups by treatment or comorbidity, respectively, however target attainment rates were substantially higher in non-diabetic patients. Metabolic and renal parameters (fasting glucose, HbA(1c), serum creatinine and albumin in urine) showed trends for improvement. Tolerability was very good, as only 0.43% (N = 33) experienced an AE (in 0.31% [N = 24] serious AEs), and 0.08% (N = 6) discontinued therapy due to reasons related to study drug.

CONCLUSION

In high-risk patients, treatment with losartan 100 mg or losartan/HCTZ 100/25 mg was effective and well tolerated, irrespective of comorbidity. These findings from a real-life setting are in line with those from randomized controlled trials.

Regulation of c-Fos and c-Jun gene expression by phospholipase C activity in adult cardiomyocytes

This study was undertaken to determine whether gene expression for transcriptional factors such as c-Fos and c-Jun is regulated by phospholipase C (PLC) activity. Norepinephrine (NE) increased PLC beta(1), beta(3), gamma(1), and delta(1) isozyme gene expression, protein contents and their activities in adult rat cardiomyocytes. Increases in PLC beta(1), beta(3), gamma(1), and delta(1) activities and gene expression in response to NE were prevented by prazosin, an alpha(1)-adrenoceptor (AR) antagonist. Furthermore, mRNA levels for c-Fos and c-Jun, unlike other transcriptional factors, were increased by both NE and phenylephrine, a specific alpha(1)-AR agonist. Increases in c-Fos and c-Jun gene expression due to NE were attenuated by both prazosin and a PLC inhibitor, U73122. Activation of protein kinase C (PKC) with phorbol myristate acetate increased c-Fos and c-Jun mRNA, whereas inhibition of PKC with bisindolylmaleimide as well as inhibition of extracellular signal-regulated kinases (ERK) 1/2 with PD98059 abolished the NE-induced increase in c-Fos and c-Jun gene expression. Reduction of c-Jun phosphorylation by SP600125, an inhibitor of JNK activity, was associated with an attenuation of the NE-induced increases in PLC gene expression. It is suggested that c-Fos and c-Jun gene expression is regulated by PLC in adult cardiomyocytes through a PKC- and ERK1/2-dependent pathway.

Losartan and its interaction with copper(II): Biological effects

Losartan, the potassium salt of 2-n-butyl-4-chloro-5-hydroxymethyl-1-[(2'-(1H-tetrazol-5-yl)biphenyl-4-yl)methyl]imidazol, is an efficient antihypertensive drug. The vibrational FTIR and Raman spectra of Losartan (its anionic and protonated forms) are discussed. In addition, the copper(II) complex of Losartan was obtained and characterized as a microcrystalline powder. The metal center is bound to the ligand through the nitrogen atoms of the tetrazolate moiety as determined by vibrational spectroscopy. The compound is a dimer with the metal centers in a tetragonal distorted environment but the presence of a monomeric impurity has been determined by EPR spectroscopy. The antioxidant properties of the complex (superoxide dismutase mimetic activity) and its effect on the proliferation and morphology of two osteoblast-like cells in culture are reported. The new compound exerted more toxic effects on tumoral cells than the copper(II) ion and Losartan.

Impact of losartan on stroke risk in hypertensive patients in primary care

BACKGROUND AND OBJECTIVE

While a number of conditions and risk factors that increase stroke risk have been identified, arterial hypertension is the most consistent and powerful predictor. The angiotensin II type 1 receptor antagonist (angio-tensin receptor blocker [ARB]) losartan has been shown in the LIFE (Losartan Intervention for Endpoint Reduction in Hypertension) study to decrease stroke risk in hypertensive patients to a substantially greater extent than conventional therapy. We aimed to assess the impact of the blood pressure-lowering effect of losartan therapy on stroke risk in hypertensive patients in primary care.

METHODS

A total of 2977 primary-care practices throughout Germany included 22 499 consecutive unselected patients with a confirmed diagnosis of hypertension in an open-label, prospective, observational study. In addition to demographics, known risk factors for stroke were documented on standardised questionnaires. The 10-year predicted risk of first stroke was calculated according to the Framingham Stroke Risk Score at baseline and after a mean of 94 +/- 24 days of losartan (+/- hydrochlorothiazide [HCTZ]) therapy.

RESULTS

The mean patient age was 64.1 +/- 10.6 years, and 52.4% were males. Mean systolic/diastolic blood pressure decreased from 160 +/- 15/93 +/- 9 mm Hg at baseline by -21 +/- 14/-11 +/- 9 mm Hg. Besides hypertension, 84.9% of patients had other co-morbidities, of which the most frequent were hypercholesterolaemia (53.0%), diabetes mellitus (36.1%), coronary heart disease (31.1%) and left ventricular hypertrophy (24.2%). The average predicted 10-year stroke risk was 28.0 +/- 21.9% at baseline, and 22.1 +/- 19.5% at study end (relative risk reduction 24 +/- 16%, p<0.05). In subgroups of patients with diabetes or nephropathy, similar effects were noted. Drug-related adverse events were reported in 18 patients; all of these were non-serious.

CONCLUSION

Because of the high prevalence of co-morbidities and risk factors, the hypertensive patient population observed in this study presented with a high 10-year stroke risk. Treatment with losartan (+/- HCTZ) was well tolerated and led to a substantial decrease in blood pressure and associated stroke risk.

Drug therapy for the secondary prevention of stroke in hypertensive patients: current issues and options

Hypertension is the major risk factor for ischaemic and haemorrhagic clinical strokes as well as for silent brain infarcts with a continuous association between both systolic and diastolic blood pressures. Epidemiological data highlight the increasing burden to come over the next decades. Without any doubt, antihypertensive treatment is the most important therapy to reduce the risk of stroke by approximately 30-40%. International guidelines recommend antihypertensive treatment for primary prevention with evidence level A. Recurrent strokes or transient ischaemic attack (TIA) are an important practical, clinical and economic problem, and have a major impact on the development of vascular dementia. All stroke patients and patients with TIA have to be regarded as very high-risk patients. Hypertension increases the risk of recurrent strokes. Only limited data directly address the role of blood pressure treatment among individuals with stroke or TIA. There is a general lack of definitive data regarding when to start antihypertensive treatment in the initial phase, and treatment of hypertension in the acute period after stroke is still under debate. Experimental and clinical data suggest that reducing the activity of the renin-angiotensin aldosterone system (RAAS) may have beneficial effects beyond the lowering of blood pressure. There is increasing evidence of cerebroprotective effects for medication influencing the RAAS, such as angiotensin receptor antagonists or ACE inhibitors. The MOSES study showed for the first time superiority of an angiotensin receptor antagonist compared with a calcium channel antagonist in antihypertensive treatment for secondary stroke prevention. Optimal blood pressure range in secondary prevention seems to be 120-140/80-90 mm Hg, but questions about a J- or U-shaped curve are still not answered sufficiently. The effects of additional antihypertensive treatment in the evening for stroke patients with 'non-dipping' blood pressure need to be investigated.Currently, the most important goal in primary and secondary prevention of stroke is a strict normotensive blood pressure control. Antihypertensive treatment is recommended for both prevention of recurrent stroke and prevention of other vascular events in individuals who have had an ischaemic stroke or TIA (class I, level of evidence A). Many open questions remain and funding of stroke research needs to be increased in the near future.