The vasodilator effects of clevidipine on human internal mammary artery

The Current Role of Clevidipine in the Management of Hypertension

Acute hypertension, which may damage blood vessels, causes irreversible organ damage to the vasculature, central nervous system, kidney, and heart. Clevidipine, the first third-generation calcium channel antagonist approved by the Food and Drug Administration (FDA) in the past 20 years, is an ultra-short-acting calcium channel blocker that inhibits L-type calcium channels with high clearance and low distribution, can be rapidly metabolized into the corresponding inactive acid, and is rapidly hydrolyzed into inactive metabolites by esterase in arterial blood. Clevidipine is the same as nicardipine in that the main physiological effect is vasodilation and the main target is the arterial system, which has a limited effect on capacitor vessels. Unlike nitroglycerin, clevidipine has a limited effect on preload. In contrast to other direct-acting vasodilators, clevidipine has an ultra-short half-life due to metabolism by nonspecific blood and tissue esterases. Clevidipine trials conducted in adult populations have proven that it can rapidly control blood pressure in cardiac surgery situations and that adverse reactions to clevidipine are similar to those with other antihypertensive agents. In recent years, clinical trials have shown that clevidipine has excellent blood pressure-lowering capability in patients with acute neurological injury (hemorrhage, stroke, and subarachnoid and acute intracerebral hemorrhage), those  undergoing coronary artery bypass graft or spinal surgery, and in those with cerebral aneurysm/pheochromocytoma, acute heart failure, acute aortic syndromes, or renal insufficiency with severe hypertension, and it is equivalent to commonly used blood pressure-lowering medicines such as nicardipine or nitroglycerin. However, there is a lack of large-scale clinical trial data on the efficacy and safety of clevidipine in children during the perioperative period.

Urapidil, but not dihydropyridine calcium channel inhibitors, preserves the hypoxic pulmonary vasoconstriction: an experimental study in pig arteries

Hypoxic pulmonary vasoconstriction (HPV) is a protective mechanism maintaining blood oxygenation by redirecting blood flow from poorly ventilated to well-ventilated areas in the lung. Such a beneficial effect is blunted by antihypertensive treatment with dihydropyridine calcium channel inhibitors. The aim of the present study was to evaluate the effect of urapidil, an antihypertensive agent acting as an α₁ adrenergic antagonist and a partial 5-HT_1A agonist, on HPV in porcine proximal and distal pulmonary artery rings, and to characterize underlying mechanisms. Rings from proximal and distal porcine pulmonary artery were suspended in organ chambers and aerated with a 95% O₂ + 5% CO₂ gas mixture. HPV was induced by changing the gas to a 95% N₂ + 5% CO₂ mixture following a low level of pre-contraction with U46619. Hypoxia induced a contractile response in both proximal and distal pulmonary artery rings. This effect is observed in the presence of a functional endothelium and is inhibited by a soluble guanylyl cyclase inhibitor (ODQ), a NO scavenger (carboxy-PTIO), and by catalase in proximal pulmonary artery rings. The endothelium-dependent HPV is prevented by nicardipine and clevidipine but remained unaffected by urapidil in both proximal and distal pulmonary artery rings. These findings indicate that urapidil, in contrast to nicardipine and clevidipine, preserves the hypoxia-triggered vasoconstriction in isolated pulmonary arteries. They further indicate the involvement of the NO-guanylyl cyclase pathway and H₂ O₂ in HPV. Further research is warranted to determine the potential clinical relevance of the preserved hypoxia-induced pulmonary vasoconstriction by urapidil.

High affinity complexes of pannexin channels and L-type calcium channel splice-variants in human lung: Possible role in clevidipine-induced dyspnea relief in acute heart failure

Clevidipine, a dihydropyridine (DHP) analogue, lowers blood pressure (BP) by inhibiting l-type calcium channels (Ca_V1.2; gene CACNA1C) predominantly located in vascular smooth muscle (VSM). However, clinical observations suggest that clevidipine acts by a more complex mechanism. Clevidipine more potently reduces pulmonary vascular resistance (PVR) than systemic vascular resistance and its spectrum of effects on PVR are not shared by other DHPs. Clevidipine has potent spasmolytic effects in peripheral arteries at doses that are sub-clinical for BP lowering and, in hypertensive acute heart failure, clevidipine, but not other DHPs, provides dyspnea relief, partially independent of BP reduction. These observations suggest that a molecular variation in Ca_V1.2 may exist which confers unique pharmacology to different DHPs. We sequenced CACNA1C transcripts from human lungs and measured their affinity for clevidipine. Human lung tissue contains CACNA1C mRNA with many different splice variations. Ca_V1.2 channels with a specific combination of variable exons showed higher affinity for clevidipine, well below the concentration associated with BP reduction. Co-expression with pannexin 1 further increased the clevidipine affinity for this Ca_V1.2 splice variant. A high-affinity splice variant of Ca_V1.2 in combination with pannexin 1 could underlie the selective effects of clevidipine on pulmonary arterial pressure and on dyspnea.

Research in Context

Clevidipine lowers blood pressure by inhibiting calcium channels in vascular smooth muscle. In patients with acute heart failure, clevidipine was shown to relieve breathing problems. This was only partially related to the blood pressure lowering actions of clevidipine and not conferred by another calcium channel inhibitor. We here found calcium channel variants in human lung that are more selectively inhibited by clevidipine, especially when associated with pannexin channels. This study gives a possible mechanism for clevidipine's relief of breathing problems and supports future clinical trials testing the role of clevidipine in the treatment of acute heart failure.

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CaV1.2 splice variants are found in human lung that have increased affinity for clevidipine.

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Co-expression of CaV1.2 splice variant with Pannexin 1 further increases affinity for clevidipine but not for nicardipine.

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Study supports future clinical trials testing the role of clevidipine in the treatment of acute hypertensive heart failure.

Intravenous clevidipine for management of hypertension

Hypertension remains one of the most prevalent diseases affecting our society, and its complications lead the list of causes of mortality all over the world. Most efforts to control the disease are unsuccessful, failing in at least two-thirds of affected patients, despite the availability of multiple drugs for its treatment. The limited number of medications available for aggressive management of hypertensive crises has intensified the search for novel drugs that can achieve a rapid decrease in blood pressure without increasing the possible complications. Clevidipine is a novel, vasculoselective, dihydropyridine calcium channel blocker characterized by a very fast onset and offset of action. Metabolism of clevidipine does not occur in the liver or kidneys, and thus there are no restrictions to using clevidipine in patients with hepatic or renal dysfunction. This agent has been widely used to reduce blood pressure when oral therapy is not appropriate, and its use in the perioperative setting has been shown to be beneficial. This manuscript reviews the key characteristics of clevidipine and its role in the management of acute hypertension.

Comparison of relaxation responses to multiple vasodilators in TxA(2)-analog and endothelin-1-precontracted pulmonary arteries

BACKGROUND

Peri-operative pulmonary hypertension can lead to right ventricular dysfunction and to an increase in morbidity and mortality. Altered function of the pulmonary vascular endothelium and vasoconstriction play a crucial role in the development of elevated pulmonary vascular resistance. Because pulmonary artery vasoreactivity is dependent on many factors including the constricting agent that precipitated the event therefore the aim of the current study was to investigate the effectiveness of different classes of vasodilator agents to reverse endothelin-1 (ET-1) or thromboxane A(2) (TxA(2))-induced vasoconstriction in porcine pulmonary artery (PA) in vitro.

METHODS

Relaxation responses to vasodilatory drugs were studied in PA precontracted with ET-1 (1 x 10(-8) M) or TxA(2) analog (U46619, 1 x 10(-8) M). All vasodilating drugs were added in a cumulative fashion and isometric tension measurements were obtained using an organ chamber technique.

RESULTS

In both groups relaxation responses to the vasodilators were dose dependent. When ET-1 was used as a constrictor nitroglycerin and milrinone caused nearly complete (80-100%) relaxation, whereas other agents were of limited effectiveness (40-50%). On the other hand, in the vessels constricted with U46619, olprinone, indomethacin, prostaglandin E(1) (PGE(1)), nitroglycerin, milrinone and clevidipine induced complete (90-110%) vasodilatation but brain natriuretic peptide (BNP), L-arginine, and isoproterenol relaxed the vessels maximally by 45-60%.

CONCLUSIONS

Nitroglycerin and milrinone are very effective in reversing ET-1 and U46619-induced pulmonary vasoconstriction in vitro. The effectiveness of other drugs studied was dependent on the type of constrictor used. BNP, L-arginine and isoproterenol were shown to have minimal vasodilatory effects in porcine PA.

Coronary and systemic hemodynamic effects of clevidipine, an ultra-short-acting calcium antagonist, for treatment of hypertension after coronary artery surgery

BACKGROUND

The aim was to evaluate the use of clevidipine, a new vascular selective, ultra-short-acting calcium antagonist for blood pressure control after coronary artery bypass grafting (CABG).

METHODS

The effects of clevidipine on central hemodynamics, myocardial blood flow and metabolism were studied at two different phases after CABG. In phase 1 (n=13), the hypertensive phase, the effects of clevidipine were compared to those of sodium nitroprusside (SNP) when used to control postoperative hypertension. In phase 2 (n=9), the normotensive phase, a clevidipine dose-response relationship was established.

RESULTS

At a target mean arterial pressure (MAP) of 75 mmHg, systemic vascular resistance (SVR) and heart rate (HR) were lower, preload, stroke volume (SV) and pulmonary vascular resistance (PVR) were higher, while there were no differences in myocardial lactate metabolism or oxygen extraction with clevidipine compared to SNP. In the normotensive phase, clevidipine induced a dose-dependent decrease in MAP (-19%), SVR (-27%) and PVR (-15%), accompanied by an increase in SV (10%), but no reflex increase in HR or changes in cardiac preload. Clevidipine caused a direct coronary vasodilation, as indicated by a decrease in myocardial oxygen extraction from 54% to 45%. Myocardial lactate metabolism was unaffected by clevidipine. The blood clearance of clevidipine was 0.05 l x min(-1) x kg(-1), the volume of distribution at steady state was 0.08 l x kg(-1) and the initial and terminal half-lives were <1 min and 4 min, respectively.

CONCLUSIONS

Clevidipine rapidly reduced MAP and induced a systemic, pulmonary and coronary vasodilation with no effect on venous capacitance vessels or HR. Clevidipine caused no adverse effects on myocardial lactate metabolism. Clevidipine thus appears suitable to control blood pressure after CABG.