Antihypertensive effects of CS-905, a novel dihydropyridine Ca++ channel blocker

Therapeutic Usefulness of a Novel Calcium Channel Blocker Azelnidipine in the Treatment of Hypertension: A Narrative Review

The prevalence of hypertension and comorbidities such as metabolic syndrome, diabetes mellitus, and chronic kidney disease in India is alarmingly high. Amlodipine, an older-generation calcium channel blocker (CCB), is currently the gold standard for hypertension management in India. However, it has several disadvantages, including reflex tachycardia and pedal edema. Therefore, an effective antihypertensive agent that does not cause these adverse effects and provides end-organ protection is required for the holistic management of hypertension in the country. Azelnidipine is a new-generation CCB that has recently been approved for the treatment of hypertension in India. This review provides an overview of the utility of azelnidipine for hypertension control, including comparisons with traditional CCBs such as amlodipine. It discusses the key antihypertensive effects of azelnidipine as well as its advantages in the prevention of tachycardia and associated complications. In addition, this review highlights the extensive cardio- and renoprotective activities of azelnidipine, including its effects on systolic and diastolic function and urinary albumin excretion. Overall, this substantial body of evidence supports the use of azelnidipine for the treatment of hypertension, especially in India. It suggests that the adoption of azelnidipine as the new gold standard CCB could help India battle its hypertension epidemic.

The renaissance of strained 1-azabicyclo[1.1.0]butanes as useful reagents for the synthesis of functionalized azetidines

Since their discovery in the late 1960s, 1-azabicyclo[1.1.0]butanes have demonstrated to be interesting precursors of azetidines, because of the peculiar reactivity of the C3–N bond that allows double functionalization in the 1,3 positions.

Limonin alleviates macro- and micro-vascular complications of metabolic syndrome in rats: A comparative study with azelnidipine

BACKGROUND

Hypertension is a serious component of metabolic syndrome (MetS).

HYPOTHESIS

This research investigates the potential protective effect of limonin against MetS-associated hypertension in comparison with azelnidipine, a common calcium channel blocker.

STUDY DESIGN

MetS was induced in rats by 10% fructose in water and 3% salt in diet over a 16-week period. Limonin (50 mg/kg) and azelnidipine (5 mg/kg) were administered daily in the last four weeks METHODS: Non-invasive blood pressure (BP) was recorded in conscious animals. Concentration-response curves for phenylephrine (PE) and acetylcholine (ACh) were analysed in thoracic aorta (macrovessels) and kidney microvessels. Blood glucose level, serum insulin level, advanced glycation end products (AGEs), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA) and transforming growth factor-β1 (TGF-β1) were determined.

RESULTS

Limonin alleviated elevations in systolic and diastolic BP associated with MetS similar to levels associated with azelnidipine. Limonin prevented the MetS induced exaggerated macro- and micro-vascular contractility to PE and the impaired dilatation to ACh. However, in vitro incubation with limonin partially alleviated the deteriorated vascular reactivity of aorta isolated from MetS animals or AGEs injured aorta. Limonin did not have direct relaxant effect on the isolated vessel. On the other hand, limonin reduced the elevated serum levels of AGEs, TNF-α and MDA. Limonin suppressed the vascular fibrosis through reducing the elevated serum level of TGF-β1 and excessive aortic collagen deposition. Limonin decreased the elevated HOMA-IR in MetS animals.

CONCLUSION

Limonin offsets the hypertensive and vascular impairment associated with MetS via attenuation of inflammation and fibrosis. Its impact is comparable to that of azelnidipine.

Predicted Biological Activity of Purchasable Chemical Space

Whereas 400 million distinct compounds are now purchasable within the span of a few weeks, the biological activities of most are unknown. To facilitate access to new chemistry for biology, we have combined the Similarity Ensemble Approach (SEA) with the maximum Tanimoto similarity to the nearest bioactive to predict activity for every commercially available molecule in ZINC. This method, which we label SEA+TC, outperforms both SEA and a naïve-Bayesian classifier via predictive performance on a 5-fold cross-validation of ChEMBL’s bioactivity data set (version 21). Using this method, predictions for over 40% of compounds (>160 million) have either high significance (pSEA ≥ 40), high similarity (ECFP4MaxTc ≥ 0.4), or both, for one or more of 1382 targets well described by ligands in the literature. Using a further 1347 less-well-described targets, we predict activities for an additional 11 million compounds. To gauge whether these predictions are sensible, we investigate 75 predictions for 50 drugs lacking a binding affinity annotation in ChEMBL. The 535 million predictions for over 171 million compounds at 2629 targets are linked to purchasing information and evidence to support each prediction and are freely available via https://zinc15.docking.org and https://files.docking.org.

Asymmetric Synthesis of 2-Substituted Azetidin-3-ones via Metalated SAMP/RAMP Hydrazones

2-Substituted azetidin-3-ones can be prepared in good yields and enantioselectivities (up to 85% ee) by a one-pot procedure involving the metalation of the SAMP/RAMP hydrazones of N-Boc-azetidin-3-one, reaction with a wide range of electrophiles, including alkyl, allyl, and benzyl halides and carbonyl compounds, followed by hydrolysis using oxalic acid.

Validated Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Azelnidipine and Olmesartan in Their Combined Dosage Form

A simple, rapid, and highly selective RP-HPLC method was developed for the simultaneous determination of Azelnidipine (AZL) and Olmesartan (OLM) drug substances in the fixed dosage strength of 16 mg and 20 mg, respectively. Effective chromatographic separation was achieved using a Hypersil GOLD C18 column (150 mm × 4.6 mm internal diameter, 5 µm particle size) with a mobile phase composed of methanol, acetonitrile, and water in the ratio of 40:40:20 (by volume). The mobile phase was pumped using a gradient HPLC system at a flow rate of 0.5 mL/min, and quantification of the analytes was based on measuring their peak areas at 260 nm. The retention times for Azelnidipine and Olmesartan were about 8.56 and 3.04 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. Calibration curves were linear in the ranges of 2–48 μg/mL for Azelnidipine and 2.5–60 μg/mL for Olmesartan with correlation coefficients >0.990. The proposed method proved to be selective and stability-indicating by the resolution of the two analytes from the forced degradation (hydrolysis, oxidation, and photolysis) products. The validated HPLC method was successfully applied to the analysis of AZL and OLM in their combined dosage form.

Clinical use of azelnidipine in the treatment of hypertension in Chinese patients

Background

Hypertension is the most common chronic disease and the calcium channel antagonist is the most popularly used antihypertensive drug in Chinese patients. Azelnidipine is a third generation and long-acting dihydropyridine calcium channel antagonist. A series of research has demonstrated that azelnidipine produced an effective antihypertensive effect in patients with essential hypertension. Now it is need to summarize clinical use of azelnidipine in the treatment of hypertension in Chinese patients.

Methods

Relevant literature was identified by performing searches in PubMed and CNKI (China National Knowledge Infrastructure), covering the period from January 2003 (the year azelnidipine was launched) to July 2014. We included studies that described pharmacology of azelnidipine, especially the pharmacokinetics, clinical efficacy, and safety and tolerability of azelnidipine in a Chinese population. The full text of each article was strictly reviewed, and data interpretation was performed.

Results

In Chinese healthy volunteers, a single-dose oral administration of azelnidipine 8–16 mg had a peak plasma concentration of 1.66–23.06 ng/mL and time to peak plasma concentration was 2.6–4.0 hours and the area under the plasma concentration versus time curve from time 0 hour to 96 hours was 17.9–429 ng/mL·h and elimination half-life was 16.0–28.0 hours. A number of clinical trials have demonstrated that azelnidipine produced a significant reduction in blood pressure in Chinese patients with mild-to-moderate hypertension, which was similar to that of other effective antihypertensive drugs such as amlodipine, zofenopril, and nifedipine. In addition to its antihypertensive effect, azelnidipine had other cardiovascular protective effects as well, like anti-oxidative action, decreasing heart rate, and improving systolic and diastolic function. Azelnidipine was generally well tolerated in Chinese patients and no severe adverse events were observed.

Conclusion

Azelnidipine is effective and safe in the treatment of hypertension in Chinese patients.

Azelnidipine inhibits cultured rat aortic smooth muscle cell death induced by cyclic mechanical stretch

Acute aortic dissection is the most common life-threatening vascular disease, with sudden onset of severe pain and a high fatality rate. Clarifying the detailed mechanism for aortic dissection is of great significance for establishing effective pharmacotherapy for this high mortality disease. In the present study, we evaluated the influence of biomechanical stretch, which mimics an acute rise in blood pressure using an experimental apparatus of stretching loads in vitro, on rat aortic smooth muscle cell (RASMC) death. Then, we examined the effects of azelnidipine and mitogen-activated protein kinase inhibitors on mechanical stretch-induced RASMC death. The major findings of the present study are as follows: (1) cyclic mechanical stretch on RASMC caused cell death in a time-dependent manner up to 4 h; (2) cyclic mechanical stretch on RASMC induced c-Jun N-terminal kinase (JNK) and p38 activation with peaks at 10 min; (3) azelnidipine inhibited RASMC death in a concentration-dependent manner as well as inhibited JNK and p38 activation by mechanical stretch; and (4) SP600125 (a JNK inhibitor) and SB203580 (a p38 inhibitor) protected against stretch-induced RASMC death; (5) Antioxidants, diphenylene iodonium and tempol failed to inhibit stretch-induced RASMC death. On the basis of the above findings, we propose a possible mechanism where an acute rise in blood pressure increases biomechanical stress on the arterial walls, which induces RASMC death, and thus, may lead to aortic dissection. Azelnidipine may be used as a pharmacotherapeutic agent for prevention of aortic dissection independent of its blood pressure lowering effect.

Study of sustained blood pressure-lowering effect of azelnidipine guided by self-measured morning and evening home blood pressure: subgroup analysis of the At-HOME study

BACKGROUND

Morning hypertension is a risk factor for cardiovascular and cerebrovascular events, and consequently diagnosis and control of morning hypertension are considered very important. We previously reported the results of the Azelnidipine Treatment for Hypertension Open-label Monitoring in the Early morning (At-HOME) Study, which indicated that azelnidipine effectively controlled morning hypertension.

OBJECTIVES

The objective of this At-HOME subgroup analysis was to evaluate the sustained blood pressure (BP)-lowering effect of azelnidipine, using mean morning and evening systolic BP [ME average] and morning systolic BP minus evening systolic BP (ME difference).

METHODS

We analyzed the self-measured home BP data (measured in the morning and at bedtime) from this 16-week prospective observational study to clarify the effect of morning dosing of azelnidipine (mean [± standard deviation] maximum dose 14.3 ± 3.6 mg/day). A subgroup of patients from the At-HOME Study who had an evening home BP measurement within 28 days prior to the baseline date were used for efficacy analysis (n = 2,546; mean age, 65.1 years; female, 53.6 %).

RESULTS

Home systolic BP/diastolic BP levels in the morning and evening were significantly lowered (p < 0.0001) by -19.4 ± 17.1/-10.3 ± 10.6 and -16.9 ± 17.0/-9.4 ± 10.6 mmHg, respectively. Home pulse rates in the morning and evening were also significantly lowered (p < 0.0001) by -3.5 ± 7.8 and -3.5 ± 7.3 beats/min, respectively. At baseline, patients whose ME average was ≥135 mmHg and whose ME difference was ≥15 mmHg (defined as morning-predominant hypertension) accounted for 20.4 % of the study population. However, at the end of the study, the number of such patients was significantly reduced to 7.9 % (p < 0.0001). Patients whose ME average was ≥135 mmHg and whose ME difference was <15 mmHg (defined as sustained hypertension) accounted for 71.1 % of the study population at baseline. This was reduced significantly to 42.8 % at the end of the study (p < 0.0001). ME average decreased significantly from 153.8 ± 15.5 mmHg to 135.6 ± 11.9 mmHg, and ME difference also decreased significantly from 6.7 ± 13.1 mmHg to 4.7 ± 10.8 mmHg (both p < 0.0001).

CONCLUSION

These results suggest that azelnidipine improved morning hypertension with its sustained BP-lowering effect.

Inhibitory effects of azelnidipine tablets on morning hypertension

Background

Morning hypertension is a risk factor for cardiovascular and cerebrovascular events. Furthermore, it is a useful measure for definitive diagnosis of hypertension, and patients who self-assess their own blood pressure (BP) in the morning tend to exhibit better compliance with antihypertensive medication than those who do not.

Objective

The objective of this analysis was to determine the BP- and pulse rate-lowering effects of azelnidipine, a long-acting dihydropyridine calcium antagonist administered once daily in the morning.

Methods

We conducted the Azelnidipine Treatment for Hypertension Open-label Monitoring in the Early morning (At-HOME) Study by surveying patients who were taking azelnidipine. According to the study protocol, high systolic BP (SBP) was defined as ≥135 mmHg when measured at home in the morning and ≥140 mmHg when measured at the clinic during the day. A total of 5,433 hypertensive patients, who were registered at 1,011 medical institutions across Japan, were enrolled in the study. Data obtained from 4,852 of these patients (mean age, 64.8 years; female, 52.9 %; previous medication with other antihypertensive agents used concomitantly with the present study agent, 45.5 %) were used for efficacy analysis.

Results

At baseline, the subjects’ mean [± standard deviation] SBP/diastolic BP values at home in the morning, at the clinic during the day, and at home in the evening were 156.9 ± 16.4/89.7 ± 12.0, 157.5 ± 18.7/89.1 ± 13.3, and 150.2 ± 17.6/85.6 ± 12.2 mmHg, respectively. The mean pulse rates were 72.7 ± 10.7, 74.9 ± 11.2, and 72.5 ± 9.6 beats/min, respectively. Patients whose BP was defined as high accounted for 83.4 % of the study population, whereas 9.9 % had ‘masked’ hypertension, defined as SBP of ≥135 mmHg at home in the morning and <140 mmHg at the clinic. However, from 4 weeks after initiation of azelnidipine treatment till the end of the study at week 16, all three daily BP determinations were significantly (p < 0.0001) lowered, and pulse rates at home in the morning, at the clinic, and at home in the evening were similarly and significantly reduced (by −3.7 ± 8.0, −3.5 ± 9.5, and −3.5 ± 7.3 beats/min, respectively). Whereas achievement of home SBP of <135 mmHg in the morning was noted in only 6.6 % of patients before the start of azelnidipine treatment, this was noted in 43.3 % after 16 weeks. Meanwhile, achievement of clinic SBP of <140 mmHg was increased from 12.9 % of patients to 56.1 % of patients at the same timepoints. After azelnidipine treatment, 32.2 % of patients had well-controlled hypertension in both the home and clinic settings. Adverse drug reactions occurred in 2.92 % of patients (154/5,265). All adverse drug reactions were as expected for the calcium antagonist class of agents.

Conclusion

These data suggest that azelnidipine controlled morning hypertension well. Furthermore, azelnidipine reduced pulse rates significantly.

Electronic supplementary material

The online version of this article (doi:10.1007/s40268-013-0006-8) contains supplementary material, which is available to authorized users.

Azelnidipine prevents cardiac dysfunction in streptozotocin-diabetic rats by reducing intracellular calcium accumulation, oxidative stress and apoptosis

BACKGROUND

Numerous evidences suggest that diabetic heart is characterized by compromised ventricular contraction and prolonged relaxation attributable to multiple causative factors including calcium accumulation, oxidative stress and apoptosis. Therapeutic interventions to prevent calcium accumulation and oxidative stress could be therefore helpful in improving the cardiac function under diabetic condition.

METHODS

This study was designed to examine the effect of long-acting calcium channel blocker (CCB), Azelnidipine (AZL) on contractile dysfunction, intracellular calcium (Ca2+) cycling proteins, stress-activated signaling molecules and apoptosis on cardiomyocytes in diabetes. Adult male Wistar rats were made diabetic by a single intraperitoneal (IP) injection of streptozotocin (STZ). Contractile functions were traced from live diabetic rats to isolated individual cardiomyocytes including peak shortening (PS), time-to-PS (TPS), time-to-relengthening (TR90), maximal velocity of shortening/relengthening (± dL/dt) and intracellular Ca2+ fluorescence.

RESULTS

Diabetic heart showed significantly depressed PS, ± dL/dt, prolonged TPS, TR90 and intracellular Ca2+ clearing and showed an elevated resting intracellular Ca2+. AZL itself exhibited little effect on myocyte mechanics but it significantly alleviated STZ-induced myocyte contractile dysfunction. Diabetes increased the levels of superoxide, enhanced expression of the cardiac damage markers like troponin I, p67phox NADPH oxidase subunit, restored the levels of the mitochondrial superoxide dismutase (Mn-SOD), calcium regulatory proteins RyR2 and SERCA2a, and suppressed the levels of the anti-apoptotic Bcl-2 protein. All of these STZ-induced alterations were reconciled by AZL treatment.

CONCLUSION

Collectively, the data suggest beneficial effect of AZL in diabetic cardiomyopathy via altering intracellular Ca2+ handling proteins and preventing apoptosis by its antioxidant property.

Long-term normalization of blood pressure in SHR and 1-kidney 1-clip rats by synthetic precursor of stable PAF analogue without systemic effects in normotensive rats

This study characterized the actions of the newly synthesized PAF precursor 1-hexadecyl-2-alkylcarbamoyl-glycerol (HAG) on blood pressure (BP) in male spontaneously hypertensive rats (SHR), SHR-stroke prone (SHRSP) and Wistar rats with 1-kidney 1-clip (1K1C) renovascular hypertension used as experimental models of human primary and secondary hypertension. Systolic blood pressure (SBP) in the tail artery and mean arterial pressure (MAP) in the abdominal aorta were measured by tail plethysmography and invasive pressure transducer, respectively. Intravenous treatment with 1mg/kg HAG in SHR resulted in a rapid decline of MAP from 151±4 to 127±4mmHg in 50min (p<0.001) that was maintained for 24h after injection (128±5mmHg, p<0.01). We also observed a profound hypotensive effect of HAG in SHRSP but not in normotensive Wistar rats. In 1K1C rats, the magnitude of the BP decline evoked by HAG was correlated with MAP measured before drug administration (R=0.74, p<0.005). In 1K1C rats with SBP>140mmHg, 5mg/kg/48h HAG, given orally for 14 days, decreased SBP by 20-30mmHg without an increase in the death rate and other adverse effects. Thus, our results show that intravenous and oral administration of HAG led to a long-lasting reduction of BP in experimental models of primary and secondary hypertension. In contrast to PAF and its derivatives, the hypotensive action of HAG was preserved for 24h after a single administration, was absent in normotensive animals, and was not accompanied by visible side-effects, at least during 2 weeks of treatment.

Azelnidipine, a long-acting calcium channel blocker, could control hypertension without decreasing cerebral blood flow in post-ischemic stroke patients. A 123I-IMP SPECT follow-up study

Azelnidipine, a long-acting calcium channel blocker, is highly lipid soluble and selective for the vascular wall, and is expected to have an increasing effect on cerebral blood flow (CBF). The aim of this study is to investigate its safety and efficacy in stroke patients in the chronic stage as far as CBF is concerned using N-isopropyl-p-(123)I-iodo amphetamine ((123)I-IMP) single-photon emission computed tomography (SPECT). The patients were orally administered 8 or 16 mg of azelnidipine. Regional CBF was evaluated by (123)I-IMP SPECT using three-dimensional stereotactic region-of-interest (ROI) template (3D-SRT), a technique using anatomical standardization and ROI template consisting of 636 ROIs for the whole brain. Mean hemispheric CBF was defined as the mean value of the corpus callosum, and the precentral, central, parietal, angular and temporal gyri. Mean hemispheric and regional CBF after 1, 3 and 6 months were analyzed using a one-way repeated-measures analysis of variance. Ten post-ischemic stroke patients with hypertension were enrolled between October 2005 and October 2007, and all of them were well controlled with normal blood pressure (before: 172.3+/-16.6/88.4+/-14.0 mm Hg; 6 months: 128.7+/-15.9/70.9+/-10.1 mm Hg). No vascular events were observed during the study period. The mean hemispheric CBF was maintained during the study period (before: 46.0+/-9.7 ml per 100 g per min; 6 months: 49.3+/-11.1 ml per 100 g per min). The regional CBF was also maintained. In the chronic stage of ischemic stroke, azelnidipine could safely decrease systemic blood pressure without decreasing CBF.

Prevention of vascular injury by combination of an AT1 receptor blocker, olmesartan, with various calcium antagonists

BACKGROUND

A combination of different types of antihypertensive drugs is widely used for the treatment of hypertension. We examined the inhibitory effects of a combination of an AT(1) receptor blocker (ARB), olmesartan, with various calcium channel blockers (CCBs) on inflammatory vascular remodeling.

METHODS

Inflammatory vascular remodeling was induced by polyethylene-cuff placement around the femoral artery of C57BL/6J mice at 10 weeks of age. Olmesartan (0.5 mg/kg/day) was administered intraperitoneally using an osmotic minipump. CCBs (nifedipine 1.0 mg/kg/day, amlodipine 0.1 mg/kg/day, azelnidipine 0.1 mg/kg/day), and hydrochlorothiazide (HCTZ 0.5 mg/kg/day) were administered orally.

RESULTS

In the injured artery, superoxide anion production and expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits p47(phox) and Rac-1 were markedly increased, together with expression of monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor (TNF)-alpha. Administration of a single drug alone at each concentration did not significantly inhibit these changes in the injured artery. However, a combination of olmesartan with various CCBs inhibited neointimal formation as well as oxidative stress and inflammatory markers in the injured artery. Moreover, among these CCBs, inhibition of these markers by olmesartan with azelnidipine was stronger than that caused by a combination with other CCBs. On the other hand, a combination of subeffective doses of olmesartan and HCTZ did not significantly affect vascular changes after cuff placement.

CONCLUSIONS

These results suggest that the combination of ARB with CCB synergistically inhibits vascular remodeling and that the inhibitory actions of ARB on vascular remodeling may vary depending on the combined CCB.

Calcium channel blocker, azelnidipine, reduces lipid hydroperoxides in patients with type 2 diabetes independent of blood pressure

Anti-hypertensive agents with antioxidative effects are potentially useful for diabetic patients with hypertension to prevent the onset and progression of their complication. While dihydropyridine-type calcium antagonists are among the frequently used anti-hypertensive drugs, azelnidipine, a novel calcium antagonist, has been reported to have a unique anti-oxidative effect in vitro and in animals. In this study, we measured lipid hydroperoxides in human sample using diphenyl-1-pyrenylphosphine for the first time, and used the value of lipid hydroperoxides as an index of oxidative stress. Then, we compared the antioxidative properties of azelnidipine and amlodipine, a frequently used calcium antagonist in hypertensive diabetic patients. Administration of vitamin C and E for 8 weeks significantly reduced lipid hydroperoxides in erythrocyte membrane in normal subjects. In hypertensive diabetic patients, azelnidipine treatment for 12 weeks induced a more significant fall in erythrocyte lipid hydroperoxide level than amlodipine, though blood pressure during each treatment was comparable. Our data confirm the usefulness of lipid hydroperoxides in erythrocyte membrane as a marker of oxidative stress in vivo, and indicate that azelnidipine has a unique antioxidative property in human.

Effects of Calcium Channel Blocker Azelnidipine on Experimental Abdominal Aortic Aneurysms

PURPOSE

Azelnidipine has recently been recognized in vascular remodeling. However, the effects of azelnidipine on aneurysmal disease have not yet been studied. The aim of this study was to evaluate whether azelnidipine can inhibit a further expansion of aneurysmal disease.

METHODS

Experimental abdominal aortic aneurysms (AAAs) were created in a rat model by perfusing elastase. The rats in the first group received no treatment (n=10). In the second group (n=10) azelnidipine (2 mg/kg) was administered to the animals from 3 days before perfusion. The aortic diameter (AD) was measured at the time of initial surgery and death on postoperative day 14. The production of matrix metalloproteinases (MMP)-2 and -9 was analyzed by gelatin zymography.

RESULTS

The aortic diameter was smaller in the azelnidipine group than in the control (7.875+/-1.454 vs 10.745+/-0.551 mm, P<0.01). the active MMP-2 and MMP-9 levels decreased in the azelnidipine group. Hematoxylin-eosin and elastin staining revealed fewer changes in the inflammatory infiltrate and degradation of elastin in the azelnidipine group.

CONCLUSION

Azelnidipine reduced the expansion of experimental AAAs. Azelnidipine therefore appears to influence the inflammatory oxidative response seen in AAAs while also decreasing the MMP-2 and MMP-9 levels. In addition, azelnidipine inhibited aortic dilatation.

The long-acting Ca2+-channel blocker azelnidipine prevents left ventricular remodeling after myocardial infarction

Long-acting Ca(2+)-channel blockers have been reported to be effective in treating ischemic heart disease. However, their effects on cardiac remodeling after myocardial infarction (MI) are still unclear. We performed this study to examine the effect of azelnidipine on left ventricular (LV) remodeling, including systolic and diastolic dysfunction, in rats with MI. MI was induced by ligation of the left anterior descending artery. The rats were then separated into 3 groups: a sham-operated group (n = 9), untreated MI group (n = 10), and azelnidipine-treated MI group (n = 10). Four weeks after MI, hemodynamic measurements and Doppler echocardiographic assessment were performed. LV weight and LV end-diastolic dimension were significantly higher in the untreated MI group than in the sham-operated group. Azelnidipine significantly prevented the increases in these parameters. Azelnidipine also improved the ejection fraction (42 +/- 3%, P<0.05) and the E wave to A wave ratio (3.2 +/- 0.5, P<0.05), compared with the untreated MI group (31 +/- 3% and 5.3 +/- 0.8, respectively). In conclusion, azelnidipine can prevent LV remodeling and improve systolic and diastolic function after MI. Administration of long-acting Ca(2+)-channel blockers after MI is an effective strategy for treating MI.

Azelnidipine inhibits H2O2-induced cell death in neonatal rat cardiomyocytes

PURPOSE

Oxidative stress plays an important role in the pathogenesis of cardiovascular diseases. Azelnidipine is a novel dihydropyridine calcium channel blocker. Several studies have demonstrated that some dihydropyridine calcium channel blockers have antioxidant effects. We evaluated the antioxidant effects of azelnidipine compared to another dihyropyridine calcium channel blocker, nifedipine, in neonatal rat cardiomyocytes.

MATERIALS AND METHODS

We examined effects of azelnidipine and nifedipine on the H(2)O(2)-induced mitogen-activated protein kinase (MAPK) activity and cell death in neonatal rat cardiomyocytes.

RESULTS

Extracellular signal-regulated protein kinases (ERK), p38 MAPK and c-Jun NH(2)-terminal kinases (JNK) were activated by H(2)O(2) stimulation. Azelnidipine and nifedipine did not affect the H(2)O(2)-induced activation of ERK and p38 MAPK. In contrast, azelnidipine, but not nifedipine, inhibited the H(2)O(2)-induced JNK activation. The numbers of viable cell were significantly decreased by H(2)O(2) treatments (65.8 +/- 4.11% of control, P < 0.0001). Azelnidipine, but not nifedipine, inhibited the H(2)O(2)-induced cell death (azelnidipine: 76.0 +/- 4.66% of control, P < 0.05; nifedipine: 70.7 +/- 4.01% of control, P = 0.32).

CONCLUSION

Azelnidipine inhibited the H(2)O(2)-induced JNK activation and cardiac cell death. Azelnidipine may have cardioprotective effects against oxidative stress.

Long-acting calcium channel blocker, azelnidipine, increases endothelial nitric oxide synthase in the brain and inhibits sympathetic nerve activity

Nitric oxide (NO) in the central nervous system inhibits sympathetic nerve activity, thereby decreasing blood pressure. It is unknown, however, whether orally administered antihypertensive treatment alters NO synthase (NOS) expression, particularly in the brain, and how changes in NOS expression affects sympathetic nerve activity. Azelnidipine, a recently developed long-acting dihydropyridine calcium channel blocker, does not cause baroreflex-induced tachycardia. The aim of the present study was to determine whether antihypertensive treatment with azelnidipine alters endothelial NOS (eNOS), neuronal NOS (nNOS), or inducible NOS (iNOS) expression in the brain, and how changes in NOS affect sympathetic nerve activity. Azelnidipine (20 mg/kg/day) or hydralazine (20 mg/kg/day) was orally administered for 30 days in stroke-prone spontaneously hypertensive rats (SHRSP). Blood pressure and heart rate were measured by the tail cuff method. Urinary norepinephrine excretion was measured as a marker of sympathetic nerve activity. Western blot analysis was performed to examine eNOS, nNOS, or iNOS expression levels in the brain (cortex, cerebellum, hypothalamus, and the brain stem), heart, and aorta. The extent of blood pressure reduction was similar between the two groups. Heart rate increased in the hydralazine-treated group but did not change in the azelnidipine-treated group. Urinary norepinephrine excretion was significantly increased only in the hydralazine-treated group. Treatment with azelnidipine significantly increased eNOS expression levels in the brain, heart, and aorta, but did not alter nNOS or iNOS expression levels. Treatment with hydralazine did not change any of the NOS expression levels. These results suggest that antihypertensive treatment with azelnidipine attenuates reflex-induced sympathetic activation and enhances eNOS expression levels in the brain as well as in the heart and aorta.

The actions of azelnidipine, a dihydropyridine-derivative Ca antagonist, on voltage-dependent Ba2+ currents in guinea-pig vascular smooth muscle

BACKGROUND AND PURPOSE

Although azelnidipine is used clinically to treat hypertension its effects on its target cells, Ca2+ channels, in smooth muscle have not been elucidated. Therefore, its effects on spontaneous contractions and voltage-dependent L-type Ca2+ channels were investigated in guinea-pig portal vein.

EXPERIMENTAL APPROACH

The inhibitory potency of azelnidipine on spontaneous contractions in guinea-pig portal vein was compared with those of other dihydropyridine (DHP)-derived Ca antagonists (amlodipine and nifedipine) by recording tension. Also its effects on voltage-dependent nifedipine-sensitive inward Ba2+ currents (IBa) in smooth muscle cells dispersed from guinea-pig portal vein were investigated by use of a conventional whole-cell patch-clamp technique.

KEY RESULTS

Spontaneous contractions in guinea-pig portal vein were reduced by all of the Ca antagonists (azelnidipine, Ki = 153 nM; amlodipine, Ki = 16 nM; nifedipine, Ki = 7 nM). In the whole-cell experiments, azelnidipine inhibited the peak amplitude of IBa in a concentration- and voltage-dependent manner (-60 mV, Ki = 282 nM; -90 mV, Ki = 2 microM) and shifted the steady-state inactivation curve of IBa to the left at -90 mV by 16 mV. The inhibitory effects of azelnidipine on IBa persisted after 7 min washout at -60 mV. In contrast, IBa gradually recovered after being inhibited by amlodipine, but did not return to control levels. Both azelnidipine and amlodipine caused a resting block of IBa at -90 mV. Only nifedipine appeared to interact competitively with S(-)-Bay K 8644.

CONCLUSIONS AND IMPLICATIONS

These results suggest that azelnidipine induces long-lasting vascular relaxation by inhibiting voltage-dependent L-type Ca2+ channels in vascular smooth muscle.

Comparative effects of azelnidipine and other Ca2+-channel blockers on the induction of inducible nitric oxide synthase in vascular smooth muscle cells

Overproduction of nitric oxide by inducible nitric oxide synthase contributes to the progression of cardiovascular disease. We investigated the effects of azelnidipine and other Ca2+-channel blockers on nitric oxide production by cultured aortic smooth muscle cells isolated from Wistar rats and human umbilical vein endothelial cells (HUVECs), using the Griess reaction and oxyhemoglobin method. Release of lactic dehydrogenase (LDH) was measured to evaluate cell damage, and immunohistochemistry was performed to examine the expression of inducible nitric oxide synthase and nitrotyrosine protein. Azelnidipine and other Ca2+-channel blockers inhibited the release of nitric oxide induced by lipopolysaccharide plus interferon-gamma. Azelnidipine inhibited it most potently among the Ca2+-channel blockers tested (azelnidipine, amlodipine, nifedipine, diltiazem, verapamil, and nicardipine) at a concentration of 10 microM. Longer stimulation with these agents induced the expression of inducible nitric oxide synthase and nitrotyrosine, with an increase of lactic dehydrogenase release, whereas azelnidipine suppressed these changes. In human umbilical vein endothelial cells, azelnidipine enhanced basal nitric oxide production by endothelial nitric oxide synthase. In conclusion, azelnidipine potently inhibited the induction of inducible nitric oxide synthase and then nitric oxide production in vascular smooth muscle cells, while enhancing constitutive nitric oxide production by endothelial cells. Azelnidipine may inhibit nitrotyrosine expression and cell damage caused by overproduction of nitric oxide, suggesting a mechanism for its cardiovascular protective effect.

New Generation Calcium Channel Blockers in Hypertensive Treatment

During a couple of decades, a number of antihypertensive drugs have been developed, and the choice of hypertension treatment has been expanded. Among antihypertensive drugs, calcium channel blockers, which inhibit L-type voltage-gated calcium channels, are potent vasodilators, and have been used as a first- or second-line drug. Dihydropyridine-class calcium channel blockers are categorized into three generations according to the length of activity, and long-acting calcium channel blockers cause less activation of sympathetic nervous system, and are reported to offer beneficial action compared with short-action agents. Furthermore, novel types of calcium channel blockers have been developed that possess the blocking action on other calcium channel subtypes (T- and N-type), and exert agent-specific action apart from their class effects, such as the effects on heart rate and renin/aldosterone release. These additional benefits conferred by T/N-type calcium channel blockade are anticipated to provide organ protective actions in the treatment of hypertension, in addition to the blood pressure-lowering effect of L-type calcium channel blockade. In conclusion, novel calcium channel blockers with sustained activity and T/N-type calcium channel blocking action could provide more beneficial effects than classical blockers, and may expand the clinical utility of these agents.

Effects of calcium channel blockade on angiotensin II-induced peritubular ischemia in rats

Recent studies have indicated that derangement of peritubular capillary (PTC) circulation with consequent tubulointerstitial hypoxia plays a pivotal role in the pathogenesis of renal injury. The present study was performed to determine whether azelnidipine, a new dihydropyridine calcium channel blocker, attenuates angiotensin II (AngII)-induced peritubular ischemia in anesthetized rats. The superficial PTCs were visualized directly using an intravital fluorescence videomicroscope system, and the PTC blood flow was evaluated by analyzing the velocity of fluorescein isothiocyanate-labeled erythrocytes. Intravenous infusion of AngII (50 ng/kg/min, 10 min) significantly increased mean arterial pressure (MAP) and renal vascular resistance (RVR) (by 35 +/- 3% and 110 +/- 32%, respectively), and decreased total renal blood flow (RBF) and PTC erythrocyte velocity (by -34 +/- 4 and -37 +/- 1%, respectively). Treatment with azelnidipine (5 microg/kg/min i.v., 10 min) had no effect on basal MAP, RBF, RVR, or PTC erythrocyte velocity. However, azelnidipine markedly attenuated the AngII-induced increases in MAP (7 +/- 3%) and RVR (40 +/- 4%) and decreases in RBF (-24 +/- 1%) and PTC erythrocyte velocity (-22 +/- 1%). Similar attenuation in the AngII-induced responses of MAP, RBF, RVR, and PTC erythrocyte velocity were observed in rats treated with a higher dose of azelnidipine (20 microg/kg/min i.v., 10 min), which significantly decreased basal MAP and RVR and increased RBF and PTC erythrocyte velocity. These data suggest that calcium channel blockade attenuates AngII-induced peritubular ischemia, which may be involved in its beneficial effects on renal injury.

Additive beneficial effects of the combination of a calcium channel blocker and an angiotensin blocker on a hypertensive rat-heart failure model

The present study was undertaken to examine the effects of a calcium channel blocker, azelnidipine (1 mg/kg/day), an angiotensin converting enzyme (ACE) inhibitor, temocapril (10 mg/kg/day), an angiotensin II type 1 (AT1) receptor blocker (ARB), olmesartan (5 mg/kg/day), and their combination on Dahl salt-sensitive rats (DS rats) developing heart failure with preserved systolic function. DS rats were fed a high-salt diet (8% NaCl) from 7 weeks of age and progressively developed hypertension. Although monotherapy with azelnidipine lowered the blood pressure of DS rats to a greater extent than monotherapy with temocapril or olmesartan, the three drugs had similar effects on cardiac hypertrophy, cardiac fibrosis, the expressions of brain natriuretic peptide, transforming growth factor-beta1, collagen I, collagen III and monocyte chemoattractant protein-1 mRNA (as estimated by Northern blot analysis), and cardiac diastolic dysfunction (as estimated by echocardiography). These results show that ACE and AT1 receptor, as well as hypertension, are involved in the development of heart failure with preserved systolic function in DS rats. The combination of azelnidipine with olmesartan or temocapril produced no additive hypotensive effect in DS rats and no additive effect on cardiac hypertrophy or gene expressions. However, the combination therapy prolonged the survival rate of DS rats more than azelnidipine (p <0.01) or temocapril alone (p <0.05), and this additive beneficial effect by the combination therapy was associated with a greater reduction of cardiac fibrosis, urinary albumin excretion and serum creatinine. Our results thus showed that the combination of a calcium channel blocker with an ARB or an ACE inhibitor had additive preventive effects on a rat model of hypertensive heart failure with preserved systolic function. Thus, combination therapy with these agents seems to be a useful therapeutic strategy for the prevention of hypertensive heart failure.

Effects of a New Calcium Channel Blocker, Azelnidipine, on Systemic Hemodynamics and Renal Sympathetic Nerve Activity in Spontaneously Hypertensive Rats

Antihypertensive treatment with dihydropyridine calcium channel blockers elicits sympathetic nerve activation, which may contribute to cardiovascular events. However, recent clinical studies showed that treatment with azelnidipine, a new dihydropyridine calcium channel blocker, significantly reduced blood pressure in hypertensive patients while either maintaining or actually decreasing heart rate (HR). In this study, we examined the effects of azelnidipine and amlodipine on systemic hemodynamics and renal sympathetic nerve activity (RSNA) in anesthetized spontaneously hypertensive rats (SHR). We also examined the effects of these agents on baroreflex functions by infusing phenylephrine (30 microg/kg/min, i.v.) and sodium nitroprusside (10 microg/kg/min, i.v.) into azelnidipine- or amlodipine-treated SHR. Fifty min after administration of azelnidipine (10 microg/kg/min for 10 min, i.v.), mean arterial pressure (MAP) significantly decreased from 153+/-5 to 122+/-5 mmHg; however, HR and integrated RSNA did not change significantly (from 352+/-9 to 353+/-10 beats/ min and 115+/-5% of baseline, respectively). Infusion of amlodipine (50 microg/kg/min for 10 min) elicited similar effects on MAP (from 152+/-5 to 120+/-4 mmHg). However, amlodipine significantly increased HR (from 351+/-9 to 375+/-11 beats/min) and integrated RSNA (165+/-5% of baseline). Analyses of baroreflex function curves revealed that azelnidipine-treated rats showed a smaller baroreflex function than amlodipine-treated rats (p<0.05). These data suggest that azelnidipine possesses sympathoinhibitory effects, which may be one reason why it had less pronounced effects on HR in hypertensive patients.

Azelnidipine

Azelnidipine is a new dihydropyridine calcium channel antagonist with selectivity for L-type calcium channels that has recently been approved in Japan for the treatment of patients with hypertension. Results from clinical trials showed that, in 95 patients with mild-to-moderate hypertension, long-term treatment with azelnidipine effectively controls blood pressure (BP). The mean reduction from baseline in sitting systolic/diastolic BP after 1 year of treatment was 27.8/16.6 mm Hg. Among 172 patients with uncontrolled hypertension receiving non-calcium channel antagonist antihypertensive agents, the addition of azelnidipine therapy significantly reduced mean BP in a noncomparative, 1-year study (a reduction from 165.7/95.4 mm Hg at baseline to 138.2/79.9 mm Hg at study end). The antihypertensive efficacy of azelnidipine in patients with mild-to-moderate hypertension was shown to be similar to that of amlodipine or nitrendipine in randomised, double-blind studies. Azelnidipine and amlodipine controlled 24-hour BP to a similar extent. Azelnidipine is generally well tolerated; vasodilator adverse events such as as headache and hot facial flushes account for most of the adverse events. Its use is not associated with reflex tachycardia.

Biliary excretion of azelnidipine, a calcium antagonist, in rats

BACKGROUND AND AIMS

Azelnidipine (CS-905) is a novel dihydropyridine calcium antagonist that is known to be excreted in feces. To examine the mechanism of biliary excretion of azelnidipine, the authors studied its biliary excretion in Eisai hyperbilirubinuria rats (EHBR), multidrug resistance protein (Mrp)2-deficient rats, and the effect of cholephilic compounds on the biliary excretion of azelnidipine in rats.

METHODS

Radiolabeled azelnidipine was intravenously administered to EHBR and control rats, and the biliary excretion of radiolabeled metabolites was studied. Furthermore, the effect of sulfobromophthalein, taurocholate and vinblastine on the biliary excretion of azelnidipine metabolites was also studied in control rats.

RESULTS

The biliary excretion of azelnidipine metabolites was delayed in EHBR. The biliary excretion of azelnidipine metabolites was inhibited by sulfobromophthalein and vinblastine, but was not inhibited by taurocholate or phenothiazine pretreatment.

CONCLUSION

These findings suggest that the metabolites of azelnidipine are excreted into the bile partly by Mrp2 and P-glycoprotein.

Antioxidant Effect of a New Calcium Antagonist, Azelnidipine, in Cultured Human Arterial Endothelial Cells

Azelnidipine is a novel dihydropyridine-type calcium antagonist with long-acting anti-hypertensive action and a low reported incidence of tachycardia. We aimed to evaluate its antioxidant activity in cultured human arterial endothelial cells under oxidative stress. Endothelial cells were exposed to 1 mM H2O2 and treated with 100 μM α-tocopherol, 1 nM, 10 nM or 100 nM azelnidipine, 100 nM nifedipine or 100 nM amlodipine. After 3 h, the cell number and level of lipid peroxidation were evaluated by measuring the total protein and 8-iso-PGF2α concentrations, respectively. The total protein concentration was similar with each treatment. Inhibition of 8-iso-PGF2α was greatest with 10 nM azelnidipine (compared with the other drugs); the difference between 10 nM and 100 nM azelnidipine was not significant. We conclude that azelnidipine has a potent antioxidative effect that could be of significant clinical benefit when combined with its long-lasting anti-hypertensive action and low incidence of tachycardia.

Pharmacological profiles and clinical effects of azelnidipine, a long-acting calcium channel blocker

Azelnidipine (Calblock) is a newly developed dihydropyridine-type calcium antagonist for the treatment of hypertension. In hypertensive animals, a single oral administration of azelnidipine caused a slowly developed and long-lasting hypotensive effect with a little reflex tachycardia. The extent of tachycardia was less with azelnidipine than with other agents of the same class. Long-term administrations of azelnidipine produced a stable antihypertensive effect with a slight decrease in heart rate. The hypotensive effect was preceded by an increase in plasma drug concentration and it persisted even after plasma drug concentration declined to very low levels. In the isolated arteries, the calcium blocking action developed gradually after treatment with azelnidipine and survived for a long period of time after the drug was removed from the bathing solution. These data suggest that the high affinity to vascular tissue contributes to the long-lasting hypotensive effects of this agent. The results from clinical studies in hypertensive patients indicated that once daily administration of azelnidipine achieved stable, 24-h control of blood pressure with no change or a slight decrease in heart rate. Clinical studies also showed a low incidence of adverse events such as headache, facial flush, dizziness, and palpitations. These characteristics make azelnidipine a new generation calcium antagonist that can be used for the treatment of hypertension.

Azelnidipine and amlodipine: a comparison of their pharmacokinetics and effects on ambulatory blood pressure

We objected: 1) To compare the effects of azelnidipine and amlodipine on 24-h blood pressure; 2) To monitor the plasma concentration vs. the time profile in order to assess the association between pharmacokinetics and hypotensive activity after administration of either drug for 6 weeks. Blood pressure and pulse rate were measured by 24-h monitoring with a portable automatic monitor in a randomized double-blind study of 46 patients with essential hypertension. Azelnidipine 16 mg (23 patients) or amlodipine 5 mg (23 patients) was administered once daily for 6 weeks. Pharmacokinetics were analyzed after the last dose was taken. Both drugs showed similar effects on the office blood pressure and pulse rate. During 24-h monitoring, both drugs caused a decrease in systolic blood pressure of 13 mmHg and had a similar hypotensive profile during the daytime period (07:00-21:30). The pulse rate decreased by 2 beats/min in the azelnidipine group, whereas it significantly increased by 4 beats/min in the amlodipine group. Similar trends in the blood pressure and pulse rate were observed during the nighttime (22:00-6:30) and over 24 h. Excessive blood pressure reduction during the nighttime was not seen in either group. The pharmacokinetic results indicated that the plasma half-life (t1/2) of amlodipine was 38.5 +/- 19.8 h and that of azelnidipine was 8.68 +/- 1.33 h. Despite this difference in pharmacokinetics, the hypotensive effects of amlodipine and azelnidipine were similar throughout the 24-h administration period.

Combination therapy with an angiotensin-converting enzyme (ACE) inhibitor and a calcium antagonist: beyond the renoprotective effects of ACE inhibitor monotherapy in a spontaneous hypertensive rat with renal ablation

To assess the renal benefits of combined angiotensin-converting enzyme inhibition and calcium antagonism, we studied the antihypertensive and renoprotective effects of temocapril (TMP) alone or in combination with azelnidipine (AZN) in a spontaneously hypertensive rat (SHR) remnant kidney model of chronic renal failure. Male 5/6-nephrectomized SHR/Izumo rats were randomly assigned to receive vehicle (control group), TMP (TMP group; 10 mg x kg(-1) x day(-1)), AZN (AZN group; 3 mg x kg(-1) x day(-1)), or both (TMP+AZN group) orally for 12 weeks. Systolic blood pressure (SBP) and urinary excretion of albumin (UalbV) were measured every 2 weeks. At the end of the experiment, serum creatinine (Scr), heart weight (HW), and blood urea nitrogen (BUN) levels were measured and the remnant kidneys were examined to determine the index of glomerular sclerosis (IGS). SBP and UalbV in the control group increased progressively throughout the experimental period. TMP, AZN, and TMP+AZN blocked the development of hypertension. TMP+AZN did not enhance the antihypertensive effects of either TMP or AZN used singly. TMP, AZN, and TMP+AZN all significantly decreased the UalbV, Scr, BUN, and HW/body weight (BW) ratio. The level of UalbV and the HW/BW ratio in the TMP+AZN group were significantly lower than those in the TMP and AZN groups, and the level of Scr in the TMP+AZN group was significantly lower than that in the TMP group. TMP, AZN, and TMP+AZN all significantly protected against an increase in the IGS. The IGS in the TMP+AZN group was significantly lower than that in the TMP and AZN groups. These results indicate that both TMP and AZN have antihypertensive and renoprotective effects in this model. They also suggest that simultaneous administration of TMP and AZN provides greater renoprotective effects than TMP alone.

Effects of azelnidipine, a dihydropyridine calcium antagonist, on myocardial stunning in dogs

Effects of azelnidipine, a dihydropyridine derivative, on stunned myocardium were examined in anesthetized open-chest dogs. The left anterior descending (LAD) coronary artery was ligated for 20 min and then released for 60 min. Dimethyl sulfoxide (DMSO), the solvent of azelnidipine, or azelnidipine (0.03, 0.1 or 0.3 mg/kg) was injected i.v. 20 min before ligation. Segment shortening was determined by sonomicrometry. The levels of high-energy phosphate were measured in 60-min reperfused hearts. Azelnidipine at 0.1 and 0.3 mg/kg significantly decreased diastolic blood pressure and increased % segment shortening. The increase in % segment shortening due to azelnidipine appeared to be abolished by propranolol and atropine pretreatment. Ischemia significantly decreased % segment shortening in all groups. The % segment shortening that had been decreased by ischemia recovered during reperfusion, but did not reach its preischemic level in each group. In the 0.1 and 0.3 mg/kg of azelnidipine-treated dogs, a significant enhancement of % segment shortening recovery during reperfusion was observed, as compared with that in the DMSO-treated dogs. Azelnidipine did not affect the high-energy phosphate levels in 60-min reperfused hearts. In conclusion, azelnidipine improved the contractile dysfunction in stunned myocardium, without any preservation of high-energy phosphate.

Evaluation of the long-lasting antihypertensive action of 7-O-ethylfangchinoline

The antihypertensive effect of 7-O-ethylfangchinoline (TJN-220) was analyzed in an experimental model of hypertensive rats under the conscious condition. Single oral administration of TJN-220 (25 and 50 mg/kg) produced a progressive and long-lasting fall of mean blood pressure in spontaneously hypertensive rats (SHRs), deoxycorticosterone acetate (DOCA)-salt hypertensive rats and renal hypertensive rats until 72 hr after the drug administration, but affected neither the heart rate in these hypertensive rats nor the hemodynamic parameters in normotensive rats. In SHRs implanted with a telemetry transmitter, TJN-220 (50 mg/kg, p.o.) produced falls of systolic and diastolic blood pressures and diminished the difference in blood pressure between the dark period and the light period for 3 days, particularly by suppressing the increasing phase of blood pressure during the dark period without influencing heart rate or locomotor activity. On the other hand, nicardipine (10 mg/kg, p.o.) produced a transient fall of blood pressure associated with a tachycardia during the light period on the first day alone. Clonidine (0.3 mg/kg, p.o.) diminished the increasing phases of blood pressure and heart rate during the dark period on the first day alone. Thus, the antihypertensive action of TJN-220 was much longer than those of nicardipine and clonidine. The present results suggest that TJN-220 may have potential for use as a beneficial antihypertensive drug.

Stimulatory effects of HSR-803 on ileal motor activity

Stimulatory effects of HSR-803 on intestinal motor activity in vitro were studied in guinea pig ileum. HSR-803 (1 x 10(-6)-1 x 10(-4) M) increased the amplitude of longitudinal muscle contractions and increased the frequency of peristalsis in isolated segments of guinea pig ileum. The stimulatory effect in amplitude and not frequency was abolished by 1 x 10(-6) M atropine. In the Magnus method with ileal segments, HSR-803 (1 x 10(-7) - 1 x 10(-4) M) produced contractions concentration-dependently, which were inhibited by atropine (1 x 10(-8) and 3 x 10(-8) M) and 3 x 10(-7) M tetrodotoxin (TTX). In the [3H]-quinuclidinyl benzilate (QNB) binding experiment with ileal smooth muscle, HSR-803 had low affinity for acetylcholine (ACh) receptors (pKi = 4.47 +/- 0.04). In addition, HSR-803 failed to increase the spontaneous release and the electrical stimulation-induced [3H]ACh release in ileal smooth muscle. On the other hand, HSR-803 (1 x 10(-5) M) enhanced contractions induced by ACh, but had no effect on contractions induced by carbachol, which is not hydrolyzed by acetylcholinesterase (AChE). In conclusion, HSR-803 stimulated ileal motor activity. However, HSR-803 had low affinity for ACh receptors and had no influence on ACh release. It is likely that HSR-803 stimulated motor activity mainly due to prevention of ACh hydrolysis.

Studies on the hypotensive mechanisms of NZ-105, a new dihydropyridine derivative, in rats and rabbits

1. Intravenous administration of NZ-105 caused a slow-onset and long-lasting hypotension in anesthetized SHR. 2. Centrally administered NZ-105 (0.04 mg/kg) slightly decreased blood pressure. 3. The hypotension of NZ-105 (0.1 mg/kg, i.v.) was not affected by atropine, propranolol, diphenhydramine plus cimetidine, aminophylline or indomethacin. 4. In ganglion-blocked rats, NZ-105 (0.003-0.3 mg/kg, i.v.) inhibited the pressor response to several hypertensive agents to a similar degree. 5. In pithed SHR, NZ-105 (0.03 mg/kg, i.v.) showed the same degree of hypotensive action as in non-treated SHR. 6. NZ-105 did not inhibit reflex responses to tilting in conscious rabbits. 7. Thus NZ-105 exerts its hypotensive action through the mechanisms of peripheral origin.

Hemodynamic changes following long-term administration of CS-905, a novel dihydropyridine calcium blocker, in conscious SHR

To investigate the central and regional hemodynamics after long-term administration of CS-905, a novel calcium blocker, we administered the agent (1 and 3 mg/kg/day) for 15 weeks in spontaneously hypertensive rats. At the end of the dosing period, hemodynamic changes were examined using the radioactive microsphere technique. CS-905 produced a sustained dose-dependent antihypertensive effect without inducing tolerance during the 15-week dosing period and prevented cardiac hypertrophy. The agent increased cardiac output, decreased blood pressure and thus decreased total peripheral resistance in a dose-related manner. Regional blood flows measured by the microsphere technique were increased in the kidney and brain despite the lowered blood pressure. There was no organ where regional blood flow was decreased. These changes after chronic treatment with CS-905 would be beneficial in the long-term therapy of hypertension.