Effects of the calcium antagonist, isradipine, and nifedipine on resting and exercise haemodynamics and the neurohumoral system in patients with stable chronic angina

In a randomized double-blind study, the haemodynamic and anti-ischaemic effects of the new dihydropyridine calcium channel blocker isradipine (5 mg and 10 mg thrice daily (t.i.d.) were investigated over 1 week in nine patients with coronary artery disease and chronic effort angina and compared with nifedipine (20 mg t.i.d.) and placebo. In standardized exercise stress tests and exercise radionuclide ventriculography, haemodynamics improved under medication compared with placebo: resting end-diastolic and end-systolic volume index decreased on isradipine 5 mg, 10 mg and on nifedipine, and ejection fraction at rest increased with all medications. Resting mean arterial pressure was reduced compared with placebo accompanied by a decrease in systemic vascular resistance (P less than 0.05) and systolic wall tension (P less than 0.05). Cumulative ST-segment depression was significantly reduced by all three medications (-48%, -23%, -36%), while the increase in work capacity was insignificant. No significant change was found for either heart rate, double product, cardiac index, or stroke work index. Resting plasma levels of noradrenaline, adrenaline and renin activity increased with all three medications (except adrenaline at isradipine 5 mg). Isradipine has favourable effects comparable with those of nifedipine in patients with chronic stable angina and can be safely administered in these patients.     

DHEA和nifedipine对大鼠低氧性肺动脉高压的治疗作用比较

目的 对慢性缺氧3周大鼠静脉注射钾通道开放剂脱氢表雄甾酮(DHEA)和钙通道阻断剂nifedipine,以对照研究它们对大鼠慢性低氧性肺动脉高压的治疗作用。方法 60只大鼠随机分为2组,每组30只,均给予缺氧3周。Ⅰ组再分为3个小组(A1,A2,A3),分别按100mg/kg,150mg/kg和200mg/kg给予DHEA,Ⅱ组再分为3个小组(B1,B2,B3),按100mg,/kg,150mg/kg和200mg,/kg给予nifedipine。大鼠3周低氧后,行右心插管于给药前后分别测定2组大鼠的肺动脉平均压(mPAP)、体动脉平均压(mSAP)。结果 2组大鼠在缺氧3周后肺劝脉压均明显增高,Ⅰ组静脉给予DHEA可见A1,A2,A3组大鼠mPAP明显降低,呈剂量依赖性变化,但平均体动脉压变化不明显;Ⅱ组给予nifedipine后,可见B1,B2,B3组大鼠伴随mSAP明显降低,大鼠mPAP呈剂量依赖性降低。结论 钾通道活性的改变在HPH发病机制中起着十分重要的作用,钾通道开放剂DHEA可有效治疗HPH,且DHEA对体循环的影响相对较小。     

Clinical assessment of gingival hyperplasia in patients treated with nifedipine

Abstract Gingival hyperplasia caused by the use of nifedipine has been extensively reported. In this paper, the gingiva of 18 patients suffering from cardiopathy and treated with nifedipine were compared with those of 10 patients with cardiac disorders who had not been treated with calcium antagonists and with a no-treatment group of 12 patients. Nifedipine produced gingival hyperplasia although patients who had not been treated with calcium antagonists also had mild hyperplasia. Hyperplasia first appeared in the interproximal areas, an observation which may be important for early detection. There was a direct correlation between the degree of hyperplasia and the bacterial plaque score. When we studied the influence of administration time and dose of nifedipine with the degree of hyperplasia, no statistically significant differences were found.     

尼群地平(NT)和硝苯吡啶(NF)对离体豚鼠工作心脏的作用

连续记录的豚鼠离体工作心脏100min,50min内各项指标(AF、CF、LVP、dp/dtmax、ASP和HR等)值较稳定和可靠。其后有自然衰竭趋势,-dp/dtmax最先减慢,提示心脏的自然衰竭与心室舒张功能受损有关。0.1-100nMN T和0.001—10nM有负性肌力和降低心泵的作用,且呈剂量依赖关系。NT和NF抑制AF的ID_(50),分别为15.2nM和1.03nM;+dp/dtmax的ID_(50),分别为52.4nM和3.3nM;-dp/dtmax的ID_(50),分别为56.3nM和1.6nM,两者相差15倍以上,差异显著,提示NT对心脏的抑制作用比NF弱得多。     

缓释型硝苯地平与氨氯地平的降压作用比较

目的：比较缓释型硝苯地平与氨氯地平的动态降压作用。方法：１７例中、轻度原发性高血压病人（男性８例，女性９例，年龄４３±ｓ６ａ）８例予缓释型硝苯地平２０ｍｇ，ｐｏ，ｑｄ，９例予氨氯地平５～１０ｍｇ，ｐｏ，ｑｄ，×４ｗｋ。服药前、后做２４ｈ动态血压测定及踏车运动激发试验（ｎ＝１６）。结果：２药均有效地降低２４ｈ平均血压，但降压谷／峰（Ｔ／Ｐ）比值，收缩压（ＳＢＰ）Ｔ／Ｐ比值缓释硝苯地平组高于氨氯地平组，分别为８７％与７４％；舒张压（ＤＢＰ）Ｔ／Ｐ比值氨氯地平组高于缓释硝苯地平组，分别为８１％与６２％；运动激发下，服氨氯地平后ＤＢＰ仍能显著下降（Ｐ＜０．０１）及心率减慢（Ｐ＜０．０５）。结论：氨氯地平降２４ｈＤＢＰ的平稳性及对运动的耐受性均较缓释硝苯地平好。     

Site-specific variations in metabolism by human fibroblasts exposed to nifedipine in vitro

Nifedipine induces overgrowth of gingival tissues in some patients. However, other collagenous tissues in their body do not overgrow. The purpose of this study was to compare effects of serial dilutions of nifedipine on the in vitro metabolism of fibroblasts derived from normal gingiva. nifedipine-induced hyper-plastic gingiva. knee capsular ligament, and dermis. The data suggested that nifedipine affects the metabolism of fibroblasts derived not only from gingiva. but also from other connective tissues. Thus, nifedipine-responder cells are present in tissues other than gingiva. There was an inverse relationship between in vivo tissue levels of IL-1-beta and in vitro responsiveness to nifedipine of fibroblasts derived from that tissue. Nifedipine-induced overgrowth of connective tissues, other than gingiva, probably does not occur either because of the relatively slow rate of collagenous protein synthesis by resident fibroblasts or because of alterations in collagen deposition/resorption within susceptible tissues produced by nifedipine on collagenase synthesis.     

Inhibited neutrophil functions in patients treated with nifedipine but not with verapamil or diltiazem

Neutrophil functions were studied in patients receiving calcium channel blockers: nifedipine, diltiazem or verapamil. Neutrophils from patients treated with nifedipine showed a significantly lower superoxide generation stimulated by phorbol myristate acetate (PMA) (50 ng mL⁻¹), opsonized zymosan (1 mg mL⁻¹) or formyl-methionyl-leucyl-phenylalanine (FMLP) (10⁻⁷  m ), whereas superoxide generation by neutrophils of patients receiving diltiazem or verapamil showed only a slight and insignificant reduction compared with controls. Similarly, chemotaxis towards 10⁻⁷  m FMLP and phagocytosis were significantly lower in patients receiving nifedipine compared with controls and were only slightly reduced in patients receiving diltiazem or verapamil. Nifedipine was the most efficient drug in inhibiting the rise in intracellular calcium ion concentration ([Ca²⁺]_i) when added in vitro and in neutrophils of patients receiving this drug, whereas verapamil had no significant effect. The correlation between the inhibitory effect of nifedipine on neutrophil function and the elevation of [Ca²⁺]_i suggests that nifedipine inhibits neutrophil functions through its effect on [Ca²⁺]_i. However, it is not the sole mechanism as superoxide generation induced by PMA, an agent that does not induce a rise in [Ca²⁺]_i, is also inhibited. The unique effect of nifedipine in reducing neutrophil functions in vivo suggests its clinical implications concerning response to acute ischaemic myocardial events.     

Controversies concerning calcium antagonists

Summary The paper discusses the controversial attitude regarding the safety of calcium channel blockers (CCBs), especially of the dihydropyridine nifedipine, induced through several meta-analyses of studies with CCBs by Dr. Furberg et al.; as a result, a detrimental effect of CCBs, especially during acute myocardial infarction, has been claimed. Several independent re-analyses of the 16 studies, all performed in the 1980s and mainly using the short-acting nifedipine capsule, did not confirm Furberg's results and showed an insignificant mortality difference between patients on CCBs versus those on control. Nevertheless, new safety studies applying long-acting CCBs (half-lives of 1 or more days) combined with efficacy assessments are necessary, both in hypertension as well as coronary artery disease, to finally clear up this important question.     

Administration of slow-release nifedipine does not affect lactate threshold,hormone release during exercise,and quality of life in normal subjects

Summary In a double-blind crossover study of 10 normal healthy subjects, we examined the effects of slow-release nifedipine (nifedipine-SR, 10 mg b.i.d) administration on exercise capacity, hormone levels during exercise, and quality of life (QOL) after a 2-week treatment. Two exercise tests, a progressive exercise test and a constant work-rate exercise test, were performed. Maximal oxygen uptake (\.VO₂max) and blood lactate concentration were measured during the progressive exercise test and the exercise intensity corresponding to half lactate threshold (LT), LT, and 4 mmol/l of lactate concentration was determined. Subjects underwent 20 minutes of constant work-rate exercise at each work load, and blood lactate, plasma epinephrine, plasma norepinephrine, plasma renin activity, plasma aldosterone, atrial natriuretic peptide, plasma β-endorphin, and met-enkephalin were measured. Taking nifedipine-SR had no effect on the responses of blood pressure, heart rate, VO₂max, maximal work load, and LT compared to taking placebo. Blood lactate, plasma catecholamine, plasma renin activity, aldosterone, atrial natriuretic peptide, and β-endorphin levels increased during exercise, and there was no difference between nifedipine-SR and placebo. Met-enkephalin did not increase with either treatment. In the QOL questionnaires, no differences were noted between the two treatments. These findings suggest nifedipine-SR to be a potentially useful drug in view of the lack of effect on exercise capacity, hormone release, and QOL.