Nicardipine and treatment of cerebrovascular diseases with particular reference to hypertension-related disorders

Differential Preincubation Effects of Nicardipine on OATP1B1- and OATP1B3-Mediated Transport in the Presence and Absence of Protein: Implications in Assessing OATP1B1- and OATP1B3-Mediated Drug-Drug Interactions

Impaired transport activity of hepatic OATP1B1 and OATP1B3 due to drug-drug interactions (DDIs) often leads to increased systemic exposure to substrate drugs (e.g., lipid-lowering statins). Since dyslipidemia and hypertension frequently coexist, statins are often concurrently used with antihypertensives, including calcium channel blockers (CCBs). OATP1B1/1B3-related DDIs in humans have been reported for several CCBs. To date, the OATP1B1/1B3-mediated DDI potential of CCB nicardipine has not been assessed. The current study was designed to assess the OATP1B1- and OATP1B3-mediated DDI potential of nicardipine using the R-value model, following the US-FDA guidance. IC50 values of nicardipine against OATP1B1 and OATP1B3 were determined in transporter-overexpressing human embryonic kidney 293 cells using [3H]-estradiol 17β-D-glucuronide and [3H]-cholecystokinin-8 as substrates, respectively, with or without nicardipine-preincubation in protein-free Hanks' Balanced Salt Solution (HBSS) or in fetal bovine serum (FBS)-containing culture medium. Preincubation with nicardipine for 30 min in protein-free HBSS buffer produced lower IC50 and higher R-values for both OATP1B1 and OATP1B3 compared to in FBS-containing medium, yielding IC50 values of 0.98 and 1.63 µM and R-values of 1.4 and 1.3 for OATP1B1 and OATP1B3, respectively. The R-values were higher than the US-FDA cut-off value of 1.1, supporting that nicardipine has the potential to cause OATP1B1/3-mediated DDIs. Current studies provide insight into the consideration of optimal preincubation conditions when assessing the OATP1B1/3-mediated DDIs in vitro.

Effect of concomitant oral administration of ethanol on the pharmacokinetics of nicardipine in rats

Ethanol intake can alter pharmacokinetics by increasing the solubility or enhancing the absorption of concomitant drugs. Here, a selective, sensitive and reproducible high-performance liquid chromatography-tandem mass spectrometry method for the quantitative analysis of nicardipine in rat plasma was developed using simple protein precipitation. The calibration curve was linear over a concentration range of 1-2,000 ng/ml (r²  > 0.998). Accuracy ranged from 93.4 to 112.2% and precision was within 12.1% from three independent analytical batches. Stable conditions for the quantification of nicardipine in rat plasma were established in various conditions, including sample storage and handling. The matrix effect was negligible, and recovery was consistent at three different levels of quality control sample. The method was applied to assessment for the effect of ethanol on the pharmacokinetics of nicardipine in rats. The oral bioavailability of nicardipine was increased from 5.4 to 9.4% in Sprague-Dawley rats by concomitant oral administration of ethanol whereas the half-life was not altered. The findings indicated that concomitant ethanol intake can increase systemic drug exposure by increasing gastrointestinal absorption, especially poorly soluble drugs. This study provides an insight for further investigation of the alteration of the pharmacological effect of poorly soluble drugs owing to ethanol intake.

Effects of Clot Removal by Meticulous Irrigation and Continuous Low-Dose Intravenous Nicardipine on Symptomatic Cerebral Vasospasm in Patients with Aneurysmal Subarachnoid Hemorrhage Treated by Clipping

BACKGROUND

Symptomatic cerebral vasospasm (SCV) is the second most common of morbidity and mortality in aneurysmal subarachnoid hemorrhage (aSAH) after rebleeding. Blood breakdown products are one of the leading causes of vasospasm. We hypothesized that meticulous subarachnoid clot removal in addition to continuous low-dose intravenous nicardipine (CLIN) could reduce the incidence of SCV.

METHODS

SCV was defined as new focal neurologic signs, consciousness deterioration, or both when the cause was believed to be ischemia attributable to vasospasm after other possible causes of worsening were excluded. Initial brain damage was defined as continued consciousness disturbance after clipping without acute hydrocephalus, ischemic lesions, or focal sign before clipping. Poor outcome was defined as a Glasgow Outcome Scale score of 3-5 at 30 days. We compared the variables for 460 aSAH patients with and without SCV, and with and without poor outcome by multivariate analysis.

RESULTS

All patients underwent clipping with meticulous irrigation for clot removal, and SCV was observed in 56 patients (12%). SCV was observed in 2 patients (2.9%) among 70 patients treated with CLIN. There was a higher proportion of patients who were older than 65 years (P = 0.032) and female (P = 0.038), and a lower proportion of patients with CLIN (P = 0.026) among patients with SCV. The outcomes for 109 patients (27%) were poor; age greater than 65 years (P < 0.0001) and initial brain damage (P = 0.008) were related to the poor outcomes.

CONCLUSIONS

The present study showed that meticulous irrigation for clot removal and CLIN might reduce the incidence of SCV in patients with aSAH.

Nicardipine in the treatment of aneurysmal subarachnoid haemorrhage: a meta-analysis of published data

Nicardipine is a dihydropyridine-type Ca(2+) channel blocker with a powerful antihypertensive activity and a unique cerebrovascular profile. Recent studies have examined nicardipine for the treatment of patients with aneurysmal subarachnoid haemorrhage (SAH), but have shown inconsistent results. In the current study, a meta-analysis was performed to assess the clinical effectiveness of nicardipine in the prevention of cerebral vasospasm in patients who had suffered from aneurysmal SAH. Medline, EMBASE, and PubMed databases were searched for the controlled trials evaluating nicardipine for treating SAH after a ruptured aneurysm, without language restrictions. Moreover, a manual search of the bibliographies of relevant articles was also conducted. Two researchers of the present study independently performed the literature search and the data extraction. The meta-analyses were performed using the software RevMan 4.2.10 (provided by the Cochrane Collaboration, Oxford, UK). Five published manuscripts involving 1,154 patients were included in this meta-analysis. Nicardipine infusion reduced the risk of poor outcome (death, vegetative state, or dependency) and mortality, with an odds ratio (OR) of 0.58 [95 % confidence interval (CI) 0.37-0.90] and 0.45 (95 % CI 0.15-1.29), respectively. This meta-analysis suggests that nicardipine therapy reduces the likelihood of poor outcome and mortality in patients after aneurysmal SAH.

A systematic review of nicardipine vs labetalol for the management of hypertensive crises

Hypertensive emergencies are acute elevations in blood pressure (BP) that occur in the presence of progressive end-organ damage. Hypertensive urgencies, defined as elevated BP without acute end-organ damage, can often be treated with oral agents, whereas hypertensive emergencies are best treated with intravenous titratable agents. However, a lack of head-to-head studies has made it difficult to establish which intravenous drug is most effective in treating hypertensive crises. This systematic review presents a synthesis of published studies that compare the antihypertensive agents nicardipine and labetalol in patients experiencing acute hypertensive crises. A MEDLINE search was conducted using the term "labetalol AND nicardipine AND hypertension." Conference abstracts were searched manually. Ultimately, 10 studies were included, encompassing patients with hypertensive crises across an array of indications and practice environments (stroke, the emergency department, critical care, surgery, pediatrics, and pregnancy). The results of this systematic review show comparable efficacy and safety for nicardipine and labetalol, although nicardipine appears to provide more predictable and consistent BP control than labetalol.

Management of hypertensive emergency and urgency

Severe hypertension is a frequent condition among patients presenting to emergency departments. Historically, this has been referred to as a hypertensive crisis. In addition, these hypertensive crises have been further divided into either hypertensive emergencies or urgencies depending on the presence or absence of target organ damage, respectively. The management differs between these crises in both the rapidity of blood pressure correction and the medications used. Hypertensive emergencies must be treated immediately with intravenous antihypertensive medications. However, hypertensive urgencies may be treated with oral antihypertensive agents to reduce the blood pressure to baseline or normal over a period of 24-48 hr. Appropriate identification, evaluation, and treatment of these conditions are of great importance in the emergency department to prevent progression of organ damage and death. The purpose of this article is to provide an overview of the hypertensive crises and their management.

Nicardipine: a hypotensive dihydropyridine-type calcium antagonist with a peculiar cerebrovascular profile

Control of blood pressure protects against the development of cerebrovascular lesions, stroke, and vascular dementia (VaD). Cerebrovascular disease is increasingly recognized as a cause of cognitive impairment and dementia primarily in the elderly. Nicardipine is a dihydropyridine-type calcium channel blocker (CCB) with a peculiar cerebrovascular profile developed approximately 30 years ago. This study has reviewed the main controlled clinical studies investigating the use of nicardipine in pathologies associated with cerebrovascular injury, such as subarachnoid haemorrhage (SAH), acute stroke, and VaD. SAH is a main cerebrovascular indication of CCBs. In this indication, CCBs prevent vasospasm and improve clinical outcomes. Nimodipine represents the CCB more investigated in this indication. Former studies did not demonstrate a clear advantage of nicardipine versus nimodipine in SAH. A more recent approach using implants of nicardipine prolonged-release showed a decreased incidence of vasospasm, delayed ischemic deficits, and improved clinical outcome after severe SAH. Controlled trials have shown the effectiveness of the drug in preventing stroke. Increasing evidence suggests some benefit of some CCBs in VaD or mixed degenerative and vascular dementia. In this setting, nicardipine has been investigated in approximately 6,000 patients, with an improvement of cognitive deterioration in more than 60% of patients treated. The pronounced anti-hypertensive activity of nicardipine and its safety and effectiveness in cognitive domain suggest its reconsideration in the treatment of cognitive impairment of vascular origin as well as for reducing the risk of recurrent stroke in patients at high risk of it.

Effect of Vasoactive Therapy on Cerebral Circulation

Many questions regarding blood pressure management after acute stroke remain unanswered, resulting in an ongoing debate about whether to treat hypertension acutely and how aggressively blood pressure should be lowered. This review discusses normal and altered cerebrophysiology and provides evidence supporting and opposing the active management of blood pressure within the first 24 hours after stroke. Commonly used intravenous antihypertensive agents and their cerebrovascular effects are reviewed, and therapeutic recommendations are given based on the available evidence.

Blood pressure management during acute ischaemic stroke

Control of hypertension is a well-established goal of primary stroke prevention. Management of blood pressure in patients during acute ischaemic stroke, however, is complicated by the need to maintain brain perfusion. Lowering blood pressure in the acute setting may avoid the deleterious effects of high blood pressure but may also lead to cerebral hypoperfusion and worsening of the ischaemic stroke. Little information is available from clinical trials concerning optimal blood pressure management in acute stroke. Current protocols of thrombolytic therapy require strict blood pressure control below certain prescribed limits; however, in most acute stroke patients not treated with thrombolysis, blood pressure reduction is not routinely recommended and guidelines for target blood pressures are difficult to justify. Preliminary studies, in fact, suggest that there may be a role for blood pressure elevation in the treatment of some patients with acute ischaemic stroke.

Bioequivalence study of nicardipine solution versus nicardipine tablets

The bioequivalence of a solution (investigational product) and a tablet (reference product) formulation of the dihydropyridine-type derivative Ca2+ antagonist nicardipine were investigated by measuring plasma levels of the compound after single randomized administration of 20 mg of the two formulations. Drugs were given orally in a single dose to 24 healthy volunteers (12 males and 12 females) at the beginning of the experiment and after a two weeks wash-out. Nicardipine is available in oral and intravenous formulations, the second being used for the short-term treatment of hypertensive crises. Oral formulations of nicardipine most diffused include immediate release (20 or 30 mg, three times a day administration), sustained release (30 mg, 45 mg or 60 mg, twice a day administration) and modified release (80 mg, once a day administration) tablets. A nicardipine solution is available only in Spain, but no published studies on the kinetics of this formulation are available. In the last 15 years, the main efforts were aimed to develop sustained or controlled release formulations of nicardipine to improve patient compliance by reducing the number of doses required each day. However, the use of twice a day or once a day administration of Ca2+ antagonists should be not overemphasized in particular situations like those of possible risk of cerebrovascular and/or coronary steal effect primarily in the elderly. The oral formulation of nicardipine investigated with a bioequivalence range > 70% compared to nicardipine immediate release tablets may represent an additional resource for treating elderly patients with concomitant cerebrovascular or coronary heart disease.

Clinical review: the management of hypertensive crises

Hypertension is an extremely common clinical problem, affecting approximately 50 million people in the USA and approximately 1 billion individuals worldwide. Approximately 1% of these patients will develop acute elevations in blood pressure at some point in their lifetime. A number of terms have been applied to severe hypertension, including hypertensive crises, emergencies, and urgencies. By definition, acute elevations in blood pressure that are associated with end-organ damage are called hypertensive crises. Immediate reduction in blood pressure is required only in patients with acute end-organ damage. This article reviews current concepts, and common misconceptions and pitfalls in the diagnosis and management of patients with acutely elevated blood pressure.

Arterial hypertension and brain damage--evidence from animal models (review)

Hypertension is an important risk factor for cerebrovascular disease including stroke and has also a role in the development of vascular cognitive impairment (VCI) and vascular dementia (VaD). Research on pathophysiology and treatment of hypertensive brain damage may benefit from the availability of animal models. This paper has reviewed the main animal models of hypertension in which brain damage is documented. Spontaneously hypertensive rats (SHR) represent the animal model more largely used. In these rats cerebrovascular changes, brain atrophy, loss of nerve cells in cerebrocortical areas, and glial reaction were documented. Several changes observed in SHR are similar to those found by in vivo imaging studies in essential hypertensives. It is documented that brain gets benefit from lowering abnormally elevated blood pressure and that reduction of hypertension protects brain from stroke and probably reduces the incidence of VaD. The influence of anti-hypertensive treatment on brain structure and function in animal models of hypertension is reviewed. Among classes of drugs investigated, dihydropyridine-type Ca2+ antagonists were those with a most documented protective effect on hypertensive brain damage. Limits and perspectives in the use of animal models for assessing brain damage caused by hypertension and protection from it are discussed.

Quantitative image analysis of choroid and retinal vasculature in SHR: a model of cerebrovascular hypertensive changes?

Retinal and choroids arteries changes were investigated ophthalmoscopically and with morphometric techniques in spontaneously hypertensive rats (SHR) of 26 weeks either untreated (control animals) or treated for 12 weeks equi-hypotensive doses of the Ca2+ antagonist nicardipine or of the non-dihydropyridine type vasodilatator hydralazine. Retinal and choroid arteries hypertensive changes were compared with those affecting pial and intracerebral arteries of frontal lobe. Ophthalmoscopic analysis revealed in control SHR a rarefaction of capillaries and a decrease of their length and area. Treatment with nicardipine and to a lesser extent with hydralazine countered ophthalmoscopic changes noticeable in SHR. Morphometric analysis revealed thickening of the wall and luminal narrowing of retinal, choroids, pial, and intracerebral arteries. Anti-hypertensive treatment decreased thickening of the arterial wall and increased luminal narrowing of different arteries investigated. Nicardipine was more effective than hydralazine in countering arterial hypertensive changes in SHR and displayed a vasodilatory activity on small sized retinal and cerebral arteries, that represent a vascular segment not sensitive to hydralazine. Comparative evaluation of the wall-to-lumen ratio revealed a similar pattern between retinal and intracerebral arteries, but not between other arteries investigated. This suggests that analysis of retinal arteries may be predictive of brain intracerebral arteries changes in hypertension.

Neuronal populations of rat cerebral cortex and hippocampus expressed a higher density of L-type Ca 2+ channel than corresponding cerebral vessels

Dihydropyridine (DHP)-type Ca2+ antagonists block primarily L-type Ca2+ channels and are used in the therapy of hypertension. They were also proposed for the treatment of several central nervous system disorders. In brain, these compounds bind both neuronal and vascular Ca2+ channels, but no studies have evaluated comparatively their density at neuronal and vascular level. This study has analyzed the pharmacological profile and the anatomical localization of L-type Ca2+ channels in rat frontal cortex, hippocampus and in forebrain pial and intracerebral arteries by radioligand binding assay and high resolution light microscope autoradiography. The DHP derivative [3H]nicardipine was used as a radioligand. Binding of [3H]nicardipine was consistent with the labeling of L-type Ca2+ channels. In frontal cortex, the highest density of binding sites was found in nerve cell body region, followed by the neuropil and the wall of intracerebral arteries. In hippocampus, the density of binding sites was higher in the nerve cell body region than in the neuropil of CA1, CA3, and CA4 subfields. In the dentate gyrus, a higher density of silver grains was developed in neuropil than in nerve cell body of granule neurons. With the exception of dentate gyrus, neuronal binding sites were more expressed than vascular binding sites in the hippocampus. In pial arteries [3H]nicardipine binding density decreased concomitant with the reduction of vessel diameter, whereas in intracerebral arteries [3H]nicardipine binding density displayed an opposite pattern. The above findings indicate that in brain the density of neuronal L-type Ca2+ channels was significantly higher than that of vascular ones. This may account for more pronounced neuronal than vascular effects after pharmacological manipulation of cerebral Ca2+ channels.

Occupancy by oral administration of nicardipine of L-type calcium channels in rat brain

The occupancy of L-type Ca2+ channels by treatment with an oral dose of the dihydropyridine-type Ca2+ antagonist nicardipine (sustained-release formulation) was evaluated in membrane preparations of rat frontal cortex and hippocampus using a radioligand binding assay technique, with [3H]-nicardipine as a ligand. Three hours after nicardipine administration, specific binding was decreased by about 15-20%, both in the frontal cortex and hippocampus. This indicates that oral nicardipine occupied approximately 15-20% of L-type Ca2+ channels. A progressive occupancy of Ca2+ channels was observed between six and 12 h after nicardipine administration. Twelve hours after drug administration, approximately 65-70% of Ca2+ channels were occupied. These findings indicate that oral treatment with 3 mg/kg of nicardipine (sustained-release formulation) occupies L-type Ca2+ channels in rat brain by more than 40% from the 6th to the 24th h after drug administration. This suggests that an oral dose of nicardipine (sustained-release formulation) in duces a significant occupancy of L-type Ca2+ channels in rat frontal cortex and hippocampus for about one day. The possible clinico-therapeutic relevance of this observation is discussed.

Role of calcium channels in oxyhemoglobin-induced apoptosis in endothelial cells

OBJECT

Oxyhemoglobin (OxyHb) released from hemolysed erythrocytes has been considered to be responsible for cerebral vasospasm after subarachnoid hemorrhage. The authors previously reported that OxyHb produced apoptosis in cultured vascular endothelial cells. The change in intracellular Ca++ homeostasis was expected to be one of the possible mechanisms of the cytotoxic effects of OxyHb. This study was undertaken to investigate the protective effects of Ca++ channel blockers on OxyHb-induced apoptosis.

METHODS

Cultured bovine coronary artery and brain microvascular endothelial cells (passages 5-9) were used. A cell density study, immunohistochemical staining, and DNA fragmentation analysis were performed to confirm apoptosis. Various concentrations (1-50 microM) of OxyHb were used for 24- to 72-hour incubations with and without Ca++-channel blockers. Oxyhemoglobin produced cytotoxicity leading to cell detachment from the culture dish in time- and concentration-dependent manners. The highest dose (50 microM) of OxyHb produced cell detachment after a 24-hour incubation, and the lower doses (1-10 microM) produced cell detachment after 48 to 72 hours. Immunohistochemical analysis showed that apoptosis occurred in cells that were still attached to the side of the culture dish after 48 to 72 hours of OxyHb treatment (5 microM). The OxyHb (10 microM) produced DNA ladders at 48 to 72 hours. Three Ca++-channel blockers were used to prevent the toxic effect of OxyHb. The voltage-dependent Ca++-channel blocker nicardipine (1 microM), the voltage-independent Ca++-channel blocker econazole (10 microM), and the inorganic Ca++-channel blocker lanthanum (100 microM) all failed to prevent cell detachment or DNA ladders produced by OxyHb. These results were similar in both cell lines.

CONCLUSIONS

Oxyhemoglobin produced apoptotic changes in cultured vascular endothelial cells, and Ca++-channel blockers did not prevent OxyHb-induced apoptosis.

Drug-induced vasodilation in an in vitro and in vivo study: the effects of nicardipine, papaverine, and lidocaine on the rabbit carotid artery

Extreme arterial vasoconstriction (vasospasm) is a common problem encountered in microvascular surgery. An ideal pharmacologic tool able to counteract ischemia during microsurgery should be easy to apply and exert its action both locally and distally in the microcirculation of the flap. We have compared in vitro and in vivo vascular properties of nicardipine, papaverine, and lidocaine in the rabbit carotid artery. In vitro, rings from the rabbit carotid artery (n = 7) were bathed in Krebs-Ringers solution and stretched progressively to an optimal tension of 3.7 to 4.2 g. The specimens were contracted with norepinephrine (1 microM), and a cumulative dose response curve was established. In vivo, microvascular anastomoses were performed bilaterally in the rabbit carotid artery in 35 animals using 9-0 nylon suture and standard microsurgical techniques. During and after the anastomoses, nicardipine (0.1, 0.01 mg topical, or 0.1 mg/hour IV), papaverine (30 mg/cc topical), and lidocaine (2% with and without epinephrine) were applied (blinded) at the anastomotic site in five rabbits each. Heparinized sodium chloride was used as topical irrigation for control and to clean the anastomosis. Blood flow changes were monitored continuously with the transonic Doppler for 30 minutes after the procedure. The systemic blood pressure was also monitored in a group of pilot experiments. A documented decrease in blood flow was noted in all animals after the microvascular anastomosis. Nicardipine and papaverine evoked a concentration-dependent relaxation to precontracted rings to norepinephrine. Nicardipine was greater than papaverine in inducing relaxation. Lidocaine demonstrated a biphasic response with low concentrations potentiating contraction. Systemic nicardipine and papaverine significantly increased the blood flow in the rabbit carotid artery. Topical application of nicardipine and lidocaine did not significantly alter the blood flow; however, the application of nicardipine demonstrates a trend toward increased flow. Lidocaine with epinephrine significantly decreased the blood flow. No drug was found to alter the blood pressure of the animals. Our results demonstrate that nicardipine and papaverine seem to be pharmacologic tools able to increase the blood flow in anastomotic arteries. In contrast, the use of 2% lidocaine as a spasmolytic agent should be re-evaluated, since this substance may act as a partial agonist.

Management of hypertension in acute intracerebral hemorrhage

Hypertension commonly occurs in the acute period following spontaneous intracerebral hemorrhage. Management of this hypertension is controversial. Some advocate lowering blood pressure to reduce the risk of bleeding, edema formation, and systemic hypertensive complications, whereas others advocate allowing blood pressure to run its natural course as a protective measure against cerebral ischemia. This article reviews the pertinent clinical and experimental data regarding these issues and briefly discusses the use of antihypertensive agents commonly administered in this setting.