Lipid Emulsion Inhibits Amlodipine-Induced Nitric Oxide-Mediated Vasodilation in Isolated Rat Aorta.

This study aimed to examine the effect of lipid emulsion on the vasodilation induced by a toxic dose of amlodipine in isolated rat aorta and elucidate its mechanism, with a particular focus on nitric oxide. The effects of endothelial denudation, NW-nitro-L-arginvine methyl ester (L-NAME), methylene blue, lipid emulsion, and linolenic acid on the amlodipine-induced vasodilation and amlodipine-induced cyclic guanosine monophosphate (cGMP) production were examined. Furthermore, the effects of lipid emulsion, amlodipine, and PP2, either alone or combined, on endothelial nitric oxide synthase (eNOS), caveolin-1, and Src-kinase phosphorylation were examined. Amlodipine-induced vasodilation was higher in endothelium-intact aorta than in endothelium-denuded aorta. L-NAME, methylene blue, lipid emulsion, and linolenic acid inhibited amlodipine-induced vasodilation and amlodipine-induced cGMP production in the endothelium-intact aorta. Lipid emulsion reversed the increased stimulatory eNOS (Ser1177) phosphorylation and decreased inhibitory eNOS (Thr495) phosphorylation induced via amlodipine. PP2 inhibited stimulatory eNOS, caveolin-1, and Src-kinase phosphorylation induced via amlodipine. Lipid emulsion inhibited amlodipine-induced endothelial intracellular calcium increase. These results suggest that lipid emulsion attenuated the vasodilation induced via amlodipine through inhibiting nitric oxide release in isolated rat aorta, which seems to be mediated via reversal of stimulatory eNOS (Ser1177) phosphorylation and inhibitory eNOS (Thr495) dephosphorylation, which are also induced via amlodipine.

Refractory Shock from Amlodipine Overdose Overcomed with Hyperinsulinemia.

Intoxication from calcium channel blockers exhibits almost 50% mortality rates. Amlodipine is a long-acting dihydropyridine and inappropriate dosage poses a great threat for profound vasodilation, hypotension, and refractory vasopressor-resistant shock. A 72-year-old woman with unremarkable medical history presented to the emergency department due to amlodipine overdose after a suicide attempt attributed to COVID-19 pandemic severe anxiety disorder. Vital signs at presentation: heart rate 82 beats/ min, arterial pressure 72/55 mmHg, and oxygen saturation 98%. Resuscitation was initiated with intravenous infusion of normal saline 0,9%, noradrenaline, and calcium chloride, while activated charcoal was orally administrated; however, blood pressure remained at 70/45 mmHg. Abruptly, she experienced acute pulmonary edema and was finally intubated. We commenced high-dose insulin infusion with Dextrose 10% infusion to maintain euglycemic hyperinsulinemia. Hemodynamic improvement occurred after 30 min, systolic blood pressure raised to 95 mmHg, and decongestion was achieved with intravenous furosemide. Insulin effect was dose-dependent and patient's hemodynamic status improved after insulin uptitration. Eight days later, the patient was weaned from the mechanical ventilation and she was successfully discharged after 14 days. High-dose intravenous infusion of insulin up to 10 units/kg per hour appears as an inotropic agent possibly through alterations in myocardial metabolism of fatty acids and augmentation of insulin secretion and uptake. This regimen possibly exhibits additional vasotropic properties. We conclude that euglycemic hyperinsulinemia is a potentially advantageous treatment in CCB toxicity.

Lipid emulsion attenuates extrinsic apoptosis induced by amlodipine toxicity in rat cardiomyoblasts.

Amlodipine-induced toxicity has detrimental effects on cardiac cells. The aim of this study was to examine the effect of lipid emulsion on decreased H9c2 rat cardiomyoblast viability induced by amlodipine toxicity. The effects of amlodipine, lipid emulsion, LY 294002, and glibenclamide, either alone or in combination, on cell viability and count, apoptosis, and expression of cleaved caspase-3 and -8, and Bax were examined. LY 294002 and glibenclamide partially reversed lipid emulsion-mediated attenuation of decreased cell viability and count induced by amlodipine. Amlodipine increased caspase-3 and -8 expression, but it did not alter Bax expression. LY 294002 and glibenclamide reversed lipid emulsion-mediated inhibition of cleaved caspase-3 and -8 expression induced by amlodipine. Lipid emulsion inhibited early and late apoptosis induced by amlodipine. LY 294002 and glibenclamide inhibited lipid emulsion-mediated inhibition of late apoptosis induced by amlodipine, but they did not significantly alter lipid emulsion-mediated inhibition of early apoptosis induced by amlodipine. Lipid emulsion decreased amlodipine-induced TUNEL-positive cells. These results suggest that lipid emulsion inhibits late apoptosis induced by amlodipine at toxic dose via the activation of phosphoinositide-3 kinase and ATP-sensitive potassium channels in the extrinsic apoptotic pathway.

Lipid emulsion inhibits the vasodilation induced by a toxic dose of amlodipine in isolated rat aortae.

The goal of this study was to examine the effect of lipid emulsion on the vasodilation induced in isolated endothelium-denuded rat aortae by a toxic dose of amlodipine. We examined the effects of lipid emulsion and verapamil on amlodipine-induced vasodilation. We also examined the effects of a mixture of lipid emulsion and amlodipine, as well as the centrifuged aqueous extract (CAE) obtained by ultracentrifuging such a mixture and then removing the upper lipid layer, on amlodipine-induced vasodilation. The effect of lipid emulsion on the amlodipine concentration was examined. Lipid emulsion attenuated amlodipine-induced vasodilation in isolated aortae. Both CAE and lipid emulsion containing amlodipine inhibited amlodipine-induced vasodilation. However, there was no significant difference in amlodipine-induced vasodilation between aortae treated with CAE and those treated with lipid emulsion containing amlodipine. Verapamil inhibited amlodipine-induced vasodilation. Lipid emulsion decreased the concentration of amlodipine. Lipid emulsion attenuated the vasodilation induced by a toxic amlodipine dose in NaF-precontracted aortae. The data show that lipid emulsion inhibited the vasodilation induced by a toxic amlodipine dose in isolated rat aortae by reducing the concentration of amlodipine. Amlodipine-induced vasodilation seems to be mediated mainly by blockade of L-type calcium channels and partially by inhibition of the Rho-kinase pathway.

Comparative effectiveness of methylene blue versus intravenous lipid emulsion in a rodent model of amlodipine toxicity.

Context: Calcium channel blocker (CCB) poisonings are the leading cause of death from cardiovascular medication-related overdoses. Current treatments (calcium salts, vasopressors, inotropes) are often insufficient. Intravenous lipid emulsion (ILE) and methylene blue (MB) show promise in treating CCB overdoses unresponsive to conventional therapy. Objective: To compare the effectiveness of MB versus ILE in a rodent model of amlodipine (AML) poisoning with survival as the primary outcome and hemodynamic parameters as secondary outcomes. Materials and methods: Sixty-four adult male albino rats were anesthetized and cannulated for non-invasive hemodynamic measurement. Rats received amlodipine intraperitoneally (42 mg/kg). We then divided the rats into four groups: AML only without antidote, AML followed by ILE (24.8 mL/kg over 10 min), AML followed by normal saline (an equivalent volume of ILE), and AML followed by IV MB (2 mg/kg over 5 min). They received study treatments at 5, 30, and 60 minutes from the start of the protocol and with observation for 2 hours. Results: Survival time in ILE group was greater than in the control and NS groups. Differences between ILE and MB and between MB and NS were not significant. Hemodynamic parameters significantly increased in ILE group compared to the MB group at the 30, 60 and 120 min assessments but not after induction of AML poisoning and at 5 min assessment. Conclusions: Survival was greatest in rats treated with ILE. Both MB and NS had little effect on survival when compared to control animals. Both ILE and MB improved hemodynamics.

Effects of amlodipine and valsartan on glibenclamide-treated streptozotocin-induced diabetic rats.

Diabetes mellitus (DM) is a spectrum of metabolic disorders, arising from pathologic mechanisms, resulting in hyperglycaemia. Diabetes and hypertension frequently occur together and are leading risk factors for cardiovascular complications. This study examined the effects of amlodipine and valsartan on glibenclamide-treated streptozotocin-induced diabetic rats. Male albino rats (200-350 g) were fasted overnight and DM was induced by a single dose 40 mg/kg of streptozotocin (i.p.). After 48 h, DM was confirmed (blood sugar ≥200 mg/dl) and the animals were grouped into normal rats with no drug treatment, untreated diabetic animals and groups treated with glibenclamide, glibenclamide plus amlodipine, and glibenclamide plus valsartan. After six weeks treatment, animals were sacrificed under chloroform anaesthesia. Kidney, liver, lung, heart and blood were collected for histology, haematological and biochemical analyses. Untreated diabetic rats had 100% mortality before 6 weeks but addition of valsartan to glibenclamide improved survival rate (71.4% compared with 57.4% in glibenclamide-treated) and blood glucose control but this was not so with glibenclamide plus amlodipine-treated group with 50% survival rate. Treatment ameliorated pathologic changes and there was histologic evidence of organ protection among the various treatment groups when compared with the untreated diabetic group. Addition of valsartan to glibenclamide improved treatment outcome compared to when glibenclamide was used alone but this was not so with the addition of amlodipine to glibenclamide.

Evaluation system for arrhythmogenic potential of drugs using human-induced pluripotent stem cell-derived cardiomyocytes and gene expression analysis.

In recent years, human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) have been widely used to develop evaluation systems for drug cardiotoxicity, including the arrhythmia caused by QT prolongation. To accurately assess the arrhythmogenic potential of drugs, associated with QT prolongation, we developed an evaluation system using hiPS-CMs and gene expression analysis. hiPS-CMs were treated with 8 arrhythmogenic and 17 non-arrhythmogenic drugs at several concentrations for 24 hr to comprehensively analyze gene expression. The results showed that 19 genes were upregulated in the arrhythmogenic drug-treated cells compared with their expression levels in the non-treated and non-arrhythmogenic drug-treated cells. The arrhythmogenic risks of the drugs were evaluated by scoring gene expression levels. The results indicated that arrhythmogenic risks could be inferred when cells were treated at a concentration 100 times higher than the maximum blood concentration of the drug. Thus, we succeeded in developing a system for evaluation of the arrhythmogenic potential of drugs using gene expression analysis.

Steroidogenesis in amlodipine treated purified Leydig cells.

Drugs have been shown to adversely affect male fertility and recently anti-hypertensive drugs were added to the list. The anti-fertility effects of amlodipine, a calcium channel blocker, are well-illustrated in in vivo experiments but lack an in vitro proof. The present study was designed to experimentally elucidate the effects of amlodipine on Leydig cell steroidogenesis and intracellular calcium in vitro. Leydig cells of Sprague-Dawley rats were isolated and purified by Percoll. Cells were incubated for 3h with/without amlodipine in the presence/absence of LH, dbcAMP, Pregnenolone and 25-Hydroxycholesterol. Cytosolic calcium was measured in purified Leydig cells by fluorometric technique. The results showed significantly reduced (P<0.05) steroidogenesis and intracellular calcium in amlodipine exposed rats. The site of amlodipine induced steroidogenic inhibition seems to be prior to the formation of Pregnenolone at the level of StAR protein.

Adverse effects of the amlodipine on bone healing of the mandibular fracture: an experimental study in rats.

BACKGROUND: Calcium channel blockers are effective antihypertensive agents, but they may affect many metabolic processes, including bone metabolism. PURPOSE: The aim of this study was to evaluate by radiographic, histologic, and biochemical analyses the effects of amlodipine on bone healing of a defect simulating a fracture in mandibular ramus of rats. METHODS: Fifty male Wistar rats were submitted to the same unilateral surgical procedure simulating a mandibular fracture. Experimental group received oral doses of amlodipine 0.04 mg/rat/day starting 12 days before procedure, while control group received water. Animals were sacrificed at 1, 7, 14, 30, and 90 days postoperatively. Numerical values were submitted to statistical analyses. RESULTS: Radiographic analysis showed larger radiolucent area into bone defect to the experimental group at the periods of 14 (p = 0.016), 30 (p = 0.009), and 90 (p = 0.028) days. In the histological analysis, the experimental group had a slight delay in the chronology of the repair process. In the histomorphometric analysis, the experimental group presented significant lowering of newly formed bone volume at 7 and 14 days periods (p = 0.049). There was a significant decrease of alkaline phosphatase levels in experimental group in the initial periods (p = 0.049). CONCLUSIONS: It was concluded that chronic use of amlodipine compromised bone neoformation in the repairing process of surgical defect in the mandibular ramus of rats, but no precluded occurrence of fracture consolidation.

The calcium channel blocker amlodipine exerts its anti-proliferative action via p21(Waf1/Cip1) gene activation.

Proliferation of vascular smooth muscle cells (VSMC) contributes to the progression of atherosclerotic plaques. Calcium channel blockers have been shown to reduce VSMC proliferation, but the underlying molecular mechanism remains unclear. p21(Waf1/Cip1) is a potent inhibitor of cell cycle progression. Here, we demonstrate that amlodipine (10(-6) to 10(-8) M) activates de novo synthesis of p21(Waf1/Cip1) in vitro. We show that amlodipine-dependent activation of p21(Waf1/Cip1) involves the action of the glucocorticoid receptor (GR) and C/EBP-alpha. The underlying pathway apparently involves the action of mitogen-activated protein kinase or protein kinase C, but not of extracellular signal-related kinase or changes of intracellular calcium. Amlodipine-induced p21(Waf1/Cip1) promoter activity and expression were abrogated by C/EBP-alpha antisense oligonucleotide or by the GR antagonist RU486. Amlodipine-dependent inhibition of cell proliferation was partially reversed by RU486 at 10(-8) M (58%+/-29%), antisense oligonucleotides targeting C/EBP-alpha (91%+/-26%), or antisense mRNAs targeting p21(Waf1/Cip1) (96%+/-32%, n=6); scrambled antisense oligonucleotides or those directed against C/EBP-beta were ineffective. The data suggest that the anti-proliferative action of amlodipine is achieved by induction of the p21 (Waf1/Cip1) gene, which may explain beneficial covert effects of this widely used cardiovascular therapeutic drug beyond a more limited role as a vascular relaxant.

Amlodipine 2.5 mg once daily in older hypertensives: a Brazilian multi-centre study.

OBJECTIVES: The use of low-dose amlodipine has not yet been well established in the elderly. This study therefore aimed to evaluate the efficacy and tolerability of low-dose amlodipine in elderly patients with Joint National Committee VI stage I or II hypertension. PATIENTS AND METHODS: Sixty-five hypertensive individuals (aged 66.3 +/- 5.3 years) received amlodipine 2.5 mg per day for 12 weeks before and after two periods of 4 weeks of placebo. At weeks 0, 12 and 16, patients were submitted to office, 24 h ambulatory blood pressure monitoring and home blood pressure measurement. RESULTS: Office systolic and diastolic blood pressure showed decreases at weeks 8 (153 +/- 17, 90 +/- 9 mmHg) and 12 (152 +/- 16, 90 +/- 9 mmHg) compared with weeks 0 (164 +/- 16, 99 +/- 6 mmHg) and 16 (162 +/- 19, 95 +/- 9 mmHg). During ambulatory monitoring, a decrease was observed in the average 24 h systolic and diastolic pressure at week 12 (143 +/- 13, 86 +/- 7 mmHg) compared with weeks 0 (155 +/- 15, 93 +/- 6 mmHg) and 16 (152 +/- 16, 92 +/- 8 mmHg). A daytime and night-time reduction in systolic and diastolic pressure was observed on home blood pressure monitoring at week 12 (146 +/- 16/88 +/- 8, 144 +/- 16/93 +/- 8 mmHg) compared with weeks 0 (159 +/- 17/94 +/- 8, 161 +/- 19/93 +/- 8 mmHg) and 16 (153 +/- 16/93 +/- 8, 154 +/- 17/92 +/- 8 mmHg). Adverse reactions were infrequent. CONCLUSIONS: Amlodipine at a dose of 2.5 mg per day showed efficacy and good tolerability in elderly hypertensives.

Efficacy and tolerability of the combination valsartan/hydrochlorothiazide compared with amlodipine in a mild-to-moderately hypertensive Brazilian population.

Most hypertensive patients need more than one drug to reach recommended blood-pressure targets. We investigated the effects on 24-h ambulatory blood pressure (ABP) of the angiotensin-receptor blocker, valsartan, in combination with hydrochlorothiazide (HCTZ), compared with the calcium-channel blocker amlodipine in a Brazilian population in a multicentre, double-blind, double-dummy, parallel group, controlled study in 373 patients with essential hypertension. After a 2-week washout period, patients with a mean sitting systolic blood pressure (SBP) of 160-190 mmHg were randomized to receive either valsartan 160 mg o.d., or amlodipine 5 mg o.d. for 2 weeks and subsequently force-titrated to valsartan 160 mg/HCTZ 25 mg o.d. or amlodipine 10 mg o.d. This regimen was continued until the end of the study at week 8. The primary efficacy parameter was the change from baseline to week 8 in mean 24-h SBP. Secondary endpoints were change in mean 24-h diastolic blood pressure (DBP), tolerability and safety of treatments. Valsartan/HCTZ achieved a mean reduction in systolic ABP of -19.1 +/- 11.3 mmHg compared with -20.7 +/- 12.0 mmHg with amlodipine (p = 0.324 for the comparison) and in diastolic ABP by -11.1 +/- 7.4 mmHg vs -11.6 +/- 7.2 mmHg by amlodipine (p = 0.853 for the comparison). The valsartan/HCTZ group exhibited markedly lower rates of adverse events and discontinuations than the amlodipine group. Peripheral oedemas were far more frequent with amlodipine than with valsartan/ HCTZ (1.6% with valsartan/HCTZ; 16.8% with amlodipine). Thus, the valsartan 160 mg/HCTZ 25 mg combination appears to be as efficacious as amlodipine 10 mg in this patient population but better tolerated.

Nebivolol vs amlodipine as first-line treatment of essential arterial hypertension in the elderly.

The antihypertensive efficacy of nebivolol and amlodipine and their tolerability were compared in a multicentre, randomized, active-controlled, double-blind parallel-group trial in elderly patients with mild to moderate essential arterial hypertension. One hundred and eighty-four subjects aged > or = 65 years were screened. After a run-in phase of 4 weeks, only 168 of these were randomized with either nebivolol 2.5-5 mg daily (n = 81) or amlodipine 5-10 mg daily (n = 87) over a period of 12 weeks. The response rate to treatment and the changes of sitting diastolic blood pressure (BP) at week 12 were similar between the two groups. A lower sitting systolic BP (SBP) was detected with amlodipine at week 4 (p < 0.05) and at week 8 (p < 0.05). Standing BP showed no changes between the two groups; only SBP was lower with amlodipine at week 8 (p < 0.05). Heart rate was lower at all treatment visits with nebivolol (p < 0.001). The incidence of adverse events was no different between the two groups; however the incidence of headache and ankle oedema was significantly higher with amlodipine (p < 0.05). In elderly subjects with essential hypertension, the antihypertensive efficacy of nebivolol and amlodipine was similar. Both drugs were well tolerated, although amlodipine was accompanied by higher incidence of drug-related adverse events.