Comparison of antianginal efficacies and exercise hemodynamic effects of nifedipine and diltiazem in stable angina pectoris

Advancements in pharmacotherapy for angina

INTRODUCTION

Angina pectoris is the most prevalent symptomatic manifestation of ischemic heart disease, frequently leads to a poor quality of life, and is a major cause of medical resource consumption. Since the early descriptions of nitrite and nitrate in the 19th century, there has been considerable advancement in the pharmacologic management of angina. Areas covered: Management of chronic angina is often challenging for clinicians. Despite introduction of several pharmacological agents in last few decades, a significant proportion of patients continue to experience symptoms (i.e., refractory angina) with subsequent disability. For the purpose of this review, we searched PubMed and Cochrane databases from inception to August 2016 for the most clinically relevant publications that guide current practice in angina therapy and its development. In this article, we briefly review the pathophysiology of angina and mechanism-based classification of current therapy. This is followed by evidence-based insight into the traditional and novel pharmacotherapeutic agents, highlighting their clinical usefulness. Expert opinion: Considering the wide array of available therapies with different mechanism efficacy and limiting factors, a personalized approach is essential, particularly for patients with refractory angina. Ongoing research with novel pharmacologic modalities is likely to provide new options for management of angina.

Safety of nifedipine in angina pectoris: a meta-analysis

-Our objective was to compare cardiovascular event rates in patients with stable angina receiving nifedipine as monotherapy or combination therapy and in active drug controls. A MEDLARS search of published articles from 1966 to 1995 in English, French, German, Italian, or Spanish, supplemented by a manual search of bibliographies, identified 60 randomized controlled trials that met protocol criteria. Blinded articles were extracted by 2 physicians. The pooled risks of death, withdrawal, and cardiovascular event were computed and expressed as odds ratios (ORs) for all nifedipine formulations and relative to same study control drug regimens. Thirty cardiovascular events were reported in 2635 nifedipine exposures (1.14%) and 19 events in 2655 other active drug exposures (0.72%). Unadjusted ORs for nifedipine versus controls were 1.40 (95% CI, 0.56 to 3.49) for major events (death, nonfatal myocardial infarction, stroke, revascularization procedure), 1.75 (95% CI, 0.83 to 3.67) for increased angina, and 1.61 (95% CI, 0.91 to 2.87) for all events (major events plus increased angina). Episodes of increased angina were more frequent on immediate-release nifedipine (OR, 4.19 [95% CI, 1.41 to 12.49]) and on nifedipine monotherapy (OR, 2.61 [95% CI, 1.30 to 5.26]). The OR for immediate-release nifedipine was significantly higher than that for sustained-release/extended-release nifedipine (P=0.001), and the OR for nifedipine monotherapy was higher than that for nifedipine combination therapy (P=0.03). Increased risks of cardiovascular events in patients with stable angina on nifedipine were due primarily to more episodes of increased angina, confined to the immediate-release formulation and to nifedipine monotherapy.

Nifedipine gastrointestinal therapeutic system (GITS). A review of its pharmacodynamic and pharmacokinetic properties and therapeutic efficacy in hypertension and angina pectoris

Nifedipine 'gastrointestinal therapeutic system' (GITS) is a recently developed formulation that slowly releases the drug into the intestinal tract over a 24-hour period. When administered once daily, it is of similar efficacy to sustained release formulations of felodipine, verapamil, and diltiazem and at least as effective as standard formulations of lisinopril and enalapril, and long-acting propranolol and atenolol in the treatment of patients with mild to moderate essential hypertension. Substitution of nifedipine GITS for conventional formulations of nifedipine, diltiazem or verapamil, maintained adequate control of anginal symptoms in patients with stable angina pectoris. Nifedipine GITS appears to maintain quality of life and is apparently better tolerated than those formulations of nifedipine which require 2 or 3 times daily administration in both elderly and younger patients. In addition, it has minimal effect on lipid and glucose metabolism and reverses left ventricular hypertrophy, and is thus suitable for treatment of the majority of patients with mild to moderate hypertension or angina pectoris.

Autonomic dysreflexia in a rat model spinal cord injury and the effect of pharmacologic agents

The object of this study was to develop a spinal cord injury (SCI) rat model for autonomic dysreflexia (AD), assessing the effect of alpha-adrenergic and calcium channel blockade and to determine the relationship of detrusor-external sphincter dyssynergia (DESD) to the development of AD. A laminectomy was performed in male rats at the T4 or T10 level and a controlled 50 g cm blunt SCI was induced using an impounder. Four weeks after injury, changes in arterial blood pressure and heart rate were monitored while simultaneous cystometry (CMG) and pelvic floor electromography (EMG) were performed in vivo in sham (control) and spinal cord injured rats. The effects of terazosin (0.1 mg/kg), diltiazem (0.5 mg/kg), and oxybutynin chloride (0.1 mg/kg) on hemodynamic changes were assessed independently. Both T4 and T10 SCI rat displayed evidence of DESD (enhanced pelvic floor EMG activity at cystometric capacity) while control rats did not. Only T4 injured rats exhibited evidence of AD, with mean blood pressure elevations from 82.9 +/- 13.6 to 93.9 +/- 11.3 mm Hg (P < 0.01) and a mean heart rate decrease from 332.2 +/- 56.5 to 311.1 +/- 54.5 beats/min (P = 0.02) at cystometric capacity. The intravenous administration of terazosin or diltiazem abolished the AD response during CMG. The administration of oxybutynin exhibited the ability to increase bladder capacity and improve compliance in all 3 groups but did not blunt AD. The rat model of SCI effectively reproduced hemodynamic changes consistent with the AD complex in T4 level SCI but not T10 level SCI animals, despite incomplete lesions. Blockade with either an alpha-1 or a calcium channel antagonist effectively ablated the AD response to bladder distention. Anticholinergic agents had no effect on AD. DESD frequently accompanies autonomic dysreflexia, although the development of AD is not a prerequisite for DESD.

Comparison of nifedipine gastrointestinal therapeutic system and atenolol on antianginal efficacies and exercise hemodynamic responses in stable angina pectoris

A gastrointestinal therapeutic system (GITS) of nifedipine has been developed to provide a once-daily dosing, and predictable, relatively constant plasma concentrations. This study compared the antianginal efficacy of nifedipine GITS with a once-a-day beta-receptor blocker, atenolol. Seventeen patients with documented coronary artery disease and stable stress-induced angina pectoris were studied during a 2-week, single-blind, placebo baseline phase and a 12-week randomized, double-blind, active drug crossover efficacy phase, using the bicycle exercise test and ambulatory electrocardiographic recordings. Patients exercised significantly longer with nifedipine GITS (883 +/- 47 seconds) and atenolol (908 +/- 44 seconds) than with placebo (794 +/- 41 seconds). Nifedipine GITS reduced systolic blood pressure at all stages of exercise compared with placebo but, because heart rate tended to increase more during nifedipine therapy, there was no difference in rate-pressure products between the placebo and nifedipine GITS periods. In contrast, atenolol reduced heart rate, systolic blood pressure and rate-pressure product during exercise compared with placebo. Whereas left ventricular ejection fractions (by radionuclide angiocardiography) increased with exercise, the maximal increase was smaller with atenolol than with placebo and nifedipine. The net increase in left ventricular ejection fraction at the end of exercise was greater with nifedipine than with placebo or atenolol. Ambulatory electrocardiograms showed only a small number of ischemic events. Neither nifedipine GITS nor atenolol reduced the number of ischemic events or total duration of ST-segment deviations significantly. It is concluded that nifedipine GITS is as effective an antianginal agent as atenolol, but the hemodynamic effects of the 2 agents differ.(ABSTRACT TRUNCATED AT 250 WORDS)

Ischemia in collateral-dependent myocardium: effects of nifedipine and diltiazem in man

It has recently been shown that ischemia in collateral-dependent myocardium may develop at a very variable threshold in anginal patients; accordingly, the aim of this study was to assess whether nifedipine and diltiazem can increase blood flow to collateralized myocardium in man. Nine patients with complete coronary occlusion filled by collaterals, with no other coronary stenosis, normal left ventricular function, and reproducibly positive exercise tests were studied. They underwent exercise tests off therapy and after acute randomized administration of nifedipine (10 mg sublingually), diltiazem (120 mg orally), and nitroglycerin (0.5 mg sublingually), the latter a drug known to increase blood flow to collateralized myocardium. Following nifedipine, time to 1 mm ST segment depression increased significantly (from 430 +/- 176 to 576 +/- 205 seconds, p < 0.01), while heart rate and rate-pressure product remained unchanged (115 +/- 16 vs 121 +/- 17 beats/min and 199 +/- 29 vs 204 +/- 44 beats/min.mm Hg.10(2), respectively, p = NS for both). Similarly, diltiazem significantly increased time to ischemic threshold from baseline to 638 +/- 125 seconds (p < 0.01), but did not change heart rate and rate-pressure product at 1 mm ST segment depression. Submaximal rate-pressure products were significantly lowered by both nifedipine and diltiazem. Nitroglycerin not only significantly improved time to ischemic threshold (from baseline to 666 +/- 76 seconds, p < 0.01), but also increased heart rate (from baseline to 137 +/- 16 beats/min, p < 0.01) and rate-pressure product (from baseline to 242 +/- 48 beats/min.mm Hg.10(2), p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

A dose-response study of clentiazem, a chloro-derivative of diltiazem, in patients with stable angina. CAMCAT Study Group

OBJECTIVES

The efficacy and safety of clentiazem were assessed in 199 patients with stable angina in a dose-ranging, placebo-controlled, double-blind, parallel design study.

BACKGROUND

To date, this is the first large efficacy and safety study of clentiazem in patients with stable angina.

METHODS

After washout and a 1-week placebo run-in period, patients received 20, 40, 80 or 120 mg/day of clentiazem tablets or placebo as a twice-daily dosage for 1 week of treatment after 1 week of dose titration. A symptom-limited exercise tolerance test was performed 4 and 12 h after dosing at the end of treatment and results were compared with baseline measurements.

RESULTS

At 4 h after dosing, improvement of exercise duration from baseline value was significantly greater with clentiazem at doses of 40 mg/day (63 +/- 11 s), 80 mg/day (99 +/- 10 s) and 120 mg/day (70 +/- 11 s) than with placebo (34 +/- 10 s). Moreover, clentiazem (80 and 120 mg/day) increased the time to onset of angina and to > or = 1 mm of ST segment depression significantly more than did placebo. At submaximal exercise, clentiazem (40, 80 and 120 mg/day) decreased rate-pressure product, mainly as a result of a decrease in heart rate. At 12 h after dosing, improvement of exercise duration from baseline was significantly greater with clentiazem in doses of 80 mg/day (77 +/- 9 s) and 120 mg/day (70 +/- 10 s) than with placebo (42 +/- 9 s). The incidence of treatment-related adverse events with placebo (27%) and clentiazem (29%) was similar. The most frequently reported treatment-related adverse events with clentiazem were asthenia, headache (both 7.9%), first-degree atrioventricular block and dizziness (both 4.4%).

CONCLUSIONS

The results of this short-term study suggest that clentiazem given twice daily in doses of 80 or 120 mg/day is safe and effective monotherapy in the treatment of stable angina.

Sustained release nifedipine formulations. An appraisal of their current uses and prospective roles in the treatment of hypertension, ischaemic heart disease and peripheral vascular disorders

Nifedipine antagonises influx of calcium through cell membrane slow channels, and sustained release formulations of the calcium channel blocker have been shown to be effective in the treatment of mild to moderate hypertension and both stable and variant angina pectoris. Preliminary findings also indicate that these formulations are effective in the treatment of Raynaud's phenomenon and hypertension in pregnancy, and that they reduce the frequency of ischaemic episodes in some patients with silent myocardial ischaemia. The exact mechanism of action of nifedipine in all of these disorders has not been defined. However, its potent peripheral and coronary arterial dilator properties, together with improvements in oxygen supply/demand, are of particular importance. A major goal of sustained release therapy is to permit reductions in the frequency of nifedipine administration, preferably to once daily, and thus improve patient compliance. Two new once-daily formulations--the nifedipine gastrointestinal therapeutic system (GITS) and a fixed combination capsule comprising sustained release nifedipine 20 mg and atenolol 50 mg--have exhibited marked antihypertensive efficacy. The GITS preparation has also been used effectively in the treatment of stable angina pectoris, and both formulations appear to be well tolerated. Sustained release nifedipine formulations are generally better tolerated than their conventionally formulated counterparts, particularly with regard to reflex tachycardia. Adverse effects seem to be dose related, are mainly associated with the drug's potent vasodilatory action, and include headache, flushing and dizziness. Generally, these effects are mild to moderate in severity and transient, usually diminishing with continued treatment. Thus, sustained release nifedipine formulations are useful and established cardiovascular therapeutic agents which have demonstrable efficacy in various forms of angina, mild to moderate hypertension and Raynaud's phenomenon. Further, promising results shown by the nifedipine GITS formulation, with its advantage of once daily administration suggest that it is likely to become one of the preferred nifedipine formulations for the treatment of hypertension and the various forms of angina.

Individualized antianginal therapy guided by systemic arterial pressure

All antianginal drugs except nitrates are also first-line antihypertensive drugs. Their antianginal efficacy has not been evaluated in relation to pretreatment blood pressure. They may aggravate ischemia due to excessive reduction in blood pressure. Until the results of direct comparative studies are available, it is advisable to start treatment of angina pectoris in normotensive and hypotensive patients with other drugs that do not primarily decrease blood pressure. Nitrates are a reasonable choice.