Comparative evaluation of sublingual long-acting nitrates

Regional differences in the actions of verapamil and isosorbide dinitrate on rabbit and dog vascular smooth muscle

The effects of verapamil and isosorbide dinitrate (ISDN) alone or together on mechanical responses of the rabbit coronary artery and mesenteric vein, and the dog coronary artery have been investigated. Verapamil, in concentrations exceeding 10 nM consistently inhibited and at 10 microM, blocked the contraction evoked by excess concentrations of K in these tissues, but agonist-induced contraction was not modified by the presence or absence of Ca. In concentrations greater than 1 microM, verapamil depolarized the membrane by inhibiting the K-conductance of the membrane. ISDN had little effect on the rabbit coronary artery in concentrations below 10 microM. In contrast, in the rabbit mesenteric vein and dog coronary artery, ISDN in concentrations over 1 microM inhibited the contraction evoked by excess concentrations of K or by agonists. Species differences were apparent in the actions of ISDN on vascular tissues. When verapamil and ISDN were simultaneously applied to the rabbit mesenteric vein and dog coronary artery, the K-induced contraction was markedly inhibited by an amount exceeding that produced by the sum of the contractions evoked by the individual application of both agents. An enhanced vasodilating action induced by simultaneous applications of both agents indicates a possible clinical benefit for anti-anginal treatment.

Actions of isosorbide dinitrate on smooth muscle cells of rabbit vascular tissues

To investigate the mechanism of the anti-anginal actions of isosorbide dinitrate (ISDN), the effects of this agent on smooth muscle cells of intact and skinned preparations of the rabbit mesenteric artery and vein, and of the coronary artery were studied. ISDN (less than 10(-5) M) had no effect on the membrane potential or resistance of smooth muscle cells of the mesenteric artery and vein under resting conditions, nor when the membrane was depolarized by the presence of various concentrations of [K]o or noradrenaline (NA). The amplitude of spike evoked by outward current pulse after pretreatment with 10 mM tetraethylammonium (TEA) in the mesenteric artery was slightly inhibited by application of 10(-5) M ISDN. The K-induced and NA-induced contractions in the mesenteric artery were not affected by 10(-5) M ISDN, while those evoked in the mesenteric vein were inhibited in concentrations above 10(-6) M. The amplitude and facilitation of excitatory junction potentials evoked by perivascular nerve stimulation in the mesenteric artery were not affected by 10(-5) M ISDN. In skinned muscles, the free calcium concentration (pCa)-tension relationships observed in the mesenteric artery and vein were not affected by 10(-5) M ISDN. This agent had no effect on Ca accumulation into and Ca release from the stores in muscle cells of the mesenteric artery and vein, in skinned preparations. In the rabbit coronary artery, the membrane potential, resistance and spike evoked in the presence of 10 mM TEA were not affected by application of 10(-5) M ISDN. The contraction evoked by excess concentrations of [K]o was not affected. The contraction evoked by a low concentration of acetylcholine (3 X 10(-7) M) but by high concentrations (greater than 10(-6) M) was slightly inhibited by 10(-5) M ISDN. A tonic contraction induced in 39 mM [K]o was reduced by 10(-5) M nitroglycerine but not by 10(-5) M ISDN. Thus in rabbit vascular tissues, ISDN mainly acts on the venous system in vitro. The induced vasodilatation may lead to a reduction in the venous return and hence, reduce oxygen consumption in the cardiac muscles. This effect of ISDN may relate to the anti-anginal actions.

Haemodynamic and clinical effects of isosorbide-dinitrate in patients with severe effort angina on beta-blocking treatment

The effect of isosorbide-dinitrate (ISDN) 20 mg 4 times daily against placebo has been tested in 12 patients with stable effort induced angina pectoris receiving prophylactic treatment with metoprolol. ISDN did not decrease the attack rate or nitroglycerine consumption, nor was exercise tolerance increased after it. Left ventricular function, assessed by radionuclide ventriculography, increased in 6 out of 8 patients (p less than 0.1). It is concluded that ISDN has no place in the treatment of haemodynamically intact patients with severe angina pectoris in spite of beta-blocking treatment, but that it may be of value in the treatment of patients with left ventricular failure, including those whose left ventricular failure has been brought about by beta-blocking treatment necessitated by angina pectoris.

Effect of coronary vasodilating drug on myocardial work

The purpose of this paper is to show, by noninvasive measurements, previously undocumented effects on cardiac work of the nitrate coronary vasodilator Pentaerythritol Tetranitrate (Peritrate). The chew-and-swallow 40-mg tablets of this drug were given to 10 patients of type II AHA classification. The Diastolic Time Tension Index/Systolic Time Tension Index Ratio increased significantly from 1.15 (+/- 0.11 SEM) to 1.46 (+/- 0.13), p less than 0.05. The Double Product decreased significantly from 9813 (+/- 606) to 8336 (+/- 497), p less than 0.01. The Triple Product also decreased significantly from 3223 (+/- 235) to 2425 (+/- 206), p less than 0.01. The percent diastole of the R-R interval increased significantly from 65% (+/- 2.44) to 70% (+/- 1.73) p less than 0.05, while no significant change in heart rate occurred (63.2 bts/min to 62.4 bts/min). Correspondingly, there was a decrease of systolic time interval, from 0.33 second (+/- 0.2) to 0.29 second (+/- .01) p less than 0.01. A significant decrease in blood pressure was also noted. Systolic BP dropped from 155 (+/- 8.0) to 134 (+/- 7.2), p less than 0.01. Diastolic BP dropped from 89.2 (+/- 2.8) to 79.2 (+/- 2.2), p less than 0.01. This study shows that Peritrate produced significantly favorable changes in all the cited indicators of cardiac work.

Molsidomine in the treatment of patients with angina pectoris

Molsidomine, a new long-acting vasodilator, was administered intravenously (0.03 mg per kilogram of body weight) to two groups of six patients with stable anginapectoris. In the first group, studied during exercise-induced angina, the drug shortened the duration of pain and reduced electrocardiographically measured ST-segment depression, mean systemic arterial pressure, and mean pulmonary wedge pressure. Cardiac output and heart rate remained unchanged. In the second group, studied during pacing-induced angina, the drug reduced both left ventricular pressures and angiographically estimated ventricular volumes and improved the ejection fraction. In a double-blind crossover comparison with a placebo, molsidomine (2 mg three times daily) reduced the frequency of anginal attacks and the consumption of nitroglycerin tablets in 14 patients. During exercise testing on a treadmill a statistically significant reduction in ST-segment depression lasted for up to six hours. These studies suggest that molsidomine acts like nitroglycerin but its effects last longer. We conclude that molsidomine is effective in preventing the symptoms of angina pectoris. (N Engl J Med 302:1-6, 1980).

Sustained effect of orally administered isosorbide dinitrate on exercise performance of patients with angina pectoris

The efficacy of oral isosorbide dinitrate was evaluated in nine hospitalized patients with chronic angina pectoris and positive maximal bicycle exercise tests. Patients were randomized double-blind to receive either 20 mg of isosorbide dinitrate or placebo on successive days after a control maximal upright bicycle exercise test. On each day hourly exercise tests were performed for 4 hours after drug administration to an end point of fatigue or angina pectoris. Mean systolic blood pressure 4 hours after the administration of isosorbide dinitrate was 25 mm Hg less than the control value (P less than 0.001). The values for resting heart rate and exercise-attained heart rate-blood pressure product were not significantly different from the values after placebo. The duration of exercise was prolonged (P less than 0.025) for at least 3 hours, and less ST depression (P less than 0.01) was observed up to 3 hours after the administration of isosorbide dinitrate compared with control values. The demonstration of sustained imporved exercise performance and previously described hemodynamic effects with the use of higher doses suggests that adequate blood levels of isosorbide dinitrate or mononitrate metabolites may be important for the efficacy of oral organic nitrates.

Effect of sublingual pentrinitrol on exercise tolerance in angina pectoris

The effects of 10 mg sublingual pentrinitrol and placebo on the exercise tolerance of 20 patients with angina pectoris were compared. The ten patients who received pentrinitrol had increases in exercise times and metabolic oxygen equivalents (METs) 15 and 60 minutes after administration, whereas no change occurred in ten comparable patients receiving placebo. Pentrinitrol produced lower preexercise systolic blood pressures and systolic blood pressures at point of angina. An increase in heart rate offset the effect of the reduced systolic blood pressure on double product (systolic blood pressure times heart rate). Sublingual pentrinitrol is an effective antianginal drug for at least 60 minutes.

Nitroglycerin and nitrate esters

The expanding applications of nitroglycerin and nitrate esters--in congestive heart failure, in the reduction of infarct size in myocardial infarction and in the long-term prophylaxis of angina--have enhanced the clinical importance of these drugs. This article reviews some of the significant recent investigations of the nitrates and makes specific recommendations regarding clinical use.

Long-lasting effect of oral molsydomine on exercise performance: a new antianginal agent

This study examines whether the beneficial effects of molsydomine, a recently introduced antianginal agent, on exercise performance of patients with angina pectoris are long lasting. The hemodynamic effects are known to persist for several hours. The effects of molsydomine on the duration of exercise and the time to the onset of ST depression were compared to those of placebo during two hours after oral administration. Molsydomine prolonged the duration of exercise in all eight patients (average 2.8 min, P less than 0.001) and delayed the onset of ST depression (average 2.2 min, P less than 0.001), while the placebo failed to alter these measurements. The increment of the duration of exercise produced by 2 mg of molsydomine in two hours following oral administration was comparable to the increment produced in a few minutes after 0.3 mg of nitroglycerin given sublingually. The results indicate that molsydomine offers prophylasis for angina pectoris that lasts at least two hours after oral administration.

Treatment of angina pectoris. Pharmacologic approaches

The short-acting nitrite sublingual nitroglycerin is the cornerstone of drug treatment of angina pectoris. It is most useful when given two to three minutes before activity that may precipitate an anginal attack. If disabling angina persists despite medical management and there is no contraindication, the beta-adrenergic blocking agent propranolol should be tried before coronary artery surgery is considered. Newer bera-adrenergic blocking agents do not appear to be more effective than propranolol. Digitalis may be beneficial in patients with congestive heart failure or with cardiac arrhythmias responsive to digitalis and in some patients with radiographic evidence of left ventricular enlargement or with nocturnal angina resulting from increased left ventricular end-diastolic volume. If bypass graft surgery is done, medical management must be continued postoperatively.

Effects of isosorbide dinitrate and nitroglycerin on central circulatory dynamics in coronary artery disease

This study compares the effects and duration of the effects of 5 mg. of sublingual (SL) isosorbide dinitrate (ISD), 20 mg. of oral ISD, and 0.4 mg. of SL nitroglycerin (TNG) on central circulatory dynamics. Twenty-seven patients with coronary artery disease were evaluated with radioisotope techniques and determinations made of heart rate (HR), blood pressure (BP), cardiac index (CI), stroke volume index (SVI), left ventricular enddiastolic volume index (LVEDVI), and left ventricular ejection fraction (LVEF). There were significant and equivalent reductions in BP, SVI, LVEDVI, and CI 15 minutes after TNG, 1 hour after SL ISD, and 4 hours after oral ISD in addition to comparative increases in HR and EF by all drugs at these same time intervals. The effects of TNG were gone at 30 minutes while changes in LVEDVI, LVEF, and CI were present 4 hours after SL ISD and persistent changes in LVEDVI and SVI present 6 hours after oral ISD. We conclude that nitrates have significant effects on both preload and afterload and that the duration of effects of sublingual and oral ISD are truly long acting as compared to TNG.

Effect of nitroglycerin ointment on the clinical and hemodynamic response to exercise

The effects of nitroglycerin ointment (15 mg nitroglycerin) on hemodynamics at rest and during exercise were studied in 12 patients with coronary artery disease and exertional angina (angina group) and in 8 patients with normal coronary arteriograms or with nonsignificant arteriographic abnormalities who did not have exertional chest pain (nonangina group). In both groups at rest nitroglycerin ointment induced within 15 minutes a significant decrease in left ventricular end-diastolic pressure that was sustained for at least 60 minutes; systemic arterial pressure also decreased within 15 minutes and continued to decrease during the 60 minutes of observation. By 30 to 60 minutes there were significant decreases in cardiac index, stroke index, left ventricular stroke work index and tension-time index. During exercise performed 60 minutes after receiving nitroglycerin ointment, 10 of the 12 patients in the angina group had no pain, whereas 2 had delayed and less severe symptoms. Hemodynamic observations during this exercise period revealed significant decreases in left ventricular end-diastolic pressure, systemic pressure and tension-time index from values in the initial exercise period; heart rate remained unchanged. These data document the protective effect of nitroglycerin ointment for a period of at least 60 minutes and also suggest that the beneficial effects are related to a reduction in myocardial oxygen requirements.

The effect of isosorbide dinitrate following experimental coronary occlusion

The results of the present investigation indicate that ISDN infusion following experimental coronary occlusion in anesthetized dogs (1) lowers systemic, cardiac, and pulmonary blood pressures; (2) decreases systemic resistance; (3) has no significant effect on cardiac output, heart rate, and stroke volume; (4) decreases serum CPK levels; and (5) has little effect on blood biochemical parameters. These results suggest that ISDN may have a minimal effect on the ischemic heart by means of a slight decrease in peripheral vascular resistance and systemic blood pressure.

Comparative effects of nitroglycerin and isosorbide dinitrate on coronary collateral vessels and ischemic myocardium in dogs

To determine the effect of isosorbide dinitrate or ischemic myocardium, this agent was administered to dogs with well developed coronary collateral vessels 8 to 14 weeks after embolization and subsequent occlusion of the left anterior descending coronary artery. After thoracotomy the left coronary artery was cannulated and perfused with blood from the femoral artery. The distal left anterior descending artery was cannulated to monitor peripheral coronary pressure. Regional contractile force in the normal left circumflex and potentially ischemic left anterior descending regions was measured with isometric strain gauge arches sewn to the epicardium. Moderate decreases in coronary perfusion pressure averaging 27 mm Hg produced selective ischemia in the myocardium beyond the site of occlusion of the left anterior descending artery. Under these conditions the average increase in peripheral coronary pressure produced by intracoronary injection of isosorbide dinitrate was 9.0 mm Hg, whereas contractile force in the ischemic region increased by 30 percent. The contractile force was unchanged in the normal regions. Therefore, isosorbide dinitrate can dilate coronary collateral vessels and improve contractile force in ischemic areas. Intracoronary injection of nitroglycerin had similar effects. The durations of responses to isosorbide dinitrate and nitroglycerin were remarkably similar: 6.4 and 6.7 minutes, respectively. Although isosorbide dinitrate can directly dilate coronary collateral vessels, its effects are not longer lasting than those of nitroglycerin.

Hemodynamic effects of isosorbide dinitrate vs nitroglycerin in patients with unstable angina

The hemodynamic response to nitroglycerin administration, to sublingual or oral administration of isosorbide dinitrate, or to a placebo was evaluated and compared in 37 patients with unstable angina pectoris under resting, pain-free conditions. Patients with congestive heart failure were not included in this study. Serial measurements of mean arterial blood pressure (MAP), pulmonary arterial end-diastolic pressure (PAEDP), cardiac index (CI), and heart rate (HR) were obtained for one hour following nitroglycerin administration and for four hours following sublingual or oral administration of isosorbide dinitrate. Echocardiographic end-diastolic volume (EDV) measurements were obtained for the groups receiving isosorbide dinitrate or placebo. There was a significant (P less than 0.05 or less than 0.1) reduction of the MAP (5 to 10 mm Hg) that persisted for more than four hours following both sublingual and oral administration of isosorbide dinitrate. The changes in the PAEDP, HR, and CI following sublingual or oral administration of isosorbide dinitrate were small and not significant. In the group receiving isosorbide dinitrate sublingually, the EDV was reduced by more than 30 ml below the placebo group (P less than 0.1) for up to four hours. The effects of nitroglycerin administration were similar in magnitude but of much shorter duration (three to four hours for sublingual and oral administration of isosorbide dinitrate vs 15 to 30 minutes for nitroglycerin). These data demonstrate that the duration of the hemodynamic effects of sublingually and orally administered isosorbide dinitrate in patients with unstable angina pectoris and normal resting hemodynamics is 8 to 12 times longer than that of nitroglycerin.

Hemodynamic effects of petrinitrol in man

The hemodynamic effects of petrinitrol, a new antianginal agent, were evaluated in 30 patients during cardiac catheterization. The administration of 5 mg and 10 mg doses, both sublingually and orally, caused significant reductions of systemic arterial pressure, cardiac index, stroke index, and pulmonary arterial pressure that were prominent 15 to 30 minutes after administration of the drug. All but the 5 mg oral dose produced an increment of heart rate. The 10 mg sublingual dose also caused a significant reduction of left ventricular work. Total systemic resistance, and the product of blood pressure and heart rate did not change significantly. It appears that petrinitrol and nitroglycerin have several similar effects upon the cardiovascular system; but in the doses administered, petrinitrol caused changes of greater magnitude and longer duration.

Oral nitroglycerin as a prophylactic antianginal drug: clinical, physiologic, and statistical evidence of efficacy based on a three-phase experimental design

With the use of a three-phase experimental design, the efficacy of oral nitroglycerin has been evaluated in a total of 53 patients with documented angina pectoris due to coronary artery disease. The study were a double-blind, randomized, and cross-over comparison of controlled-release nitroglycerin (2.6 mg. tablets administered three times daily) and an indistinguishable placebo. Sixteen patients recorded anginal symptoms by the diary method over a 6 month trial of randomly sequenced 1 month periods of drug or placebo. In 15 patients, ST segments were monitored with a Holter dynamic electrocardiograph for periods of 10 to 12 hours under normal life style and evaluated by matching activities during periods of drug and placebo. In 22 patients, a multistage treadmill exercise test was conducted to an endpoint of anginal pain. The three phases of the investigation were run in succession; each phase was completed before the next one was begun. Oral nitroglycerin reduced the incidence and severity of anginal attacks by 47.2 and 49.4 per cent, respectively, and decreased the number of sublingual nitroglycerin tablets used by 51.1 per cent in comparison to placebo (p less than 0.001). Eleven of 16 patients (69 per cent) decreased their need for sublingual nitroglycerin by over 50 per cent. Based on a polynomial trend analysis over a period of 8 weeks, no tolerance to the therapeutic effects of the drug was found. With DCG monitoring, drug decreased the ST segment depression from 1.76 mm. on placebo to 1.12 mm, with a significant difference of 0.64 mm. (p less than 0.001). ST segment depression was decreased more than 0.5 mm. by drug in comparison to placebo in 10 of 15 patients (66 per cent). Larger depressions of the ST segment noted with placebo at heart rates greater than 80 beats per minute were prevented by administration of the drug. During treadmill exercise, drug delayed the onset of pain by 83 seconds (64 per cent) over placebo (p less than 0.001) and decreased the duration of pain by 70 seconds (49 per cent) in comparison to placebo (p less than 0.001). Drug did not affect heart rate or systolic blood pressure at rest or after exercise, as well as rate-pressure product for production of angina following exercise (p less than 0.05). There was no side effects reported caused by the drug. The data demonstrate that oral nitroglycerin, given as controlled-release tablets, was absorbed from the gastrointestinal tract in quantities sufficient to provide statistically significant clinical improvement of angina pectoris.

Nitroglycerin treatment following experimental coronary occlusion

The effect of sublingual (0.2 mg.) nitroglycerin (TNG) was studied in anesthetized dogs before and after coronary occlusion. Coronary artery occlusion was accomplished by embolization of the circumflex branch of the left coronary artery. TNG was administered before embolization and again at one minute, one, two, and six hours after embolization. TNG treatment did not significantly increase the number of arrhythmias or deaths compared to untreated animals with coronary occlusion. Hemodynamic and blood biochemical parameters were measured 5 to 15 minutes after TNG treatment. At this time of measurement, blood pressures (AO, LV, LA, PA, RV, RA), cardiac output, pulmonary and systemic resistances, and left ventricle work were not significantly different in the TNG-treated group compared to the animals with coronary occlusion but no TNG treatment. In the first five minutes after TNG administration, aortic pressure is reduced. Blood samples withdrawn five minutes after TNG treatment are not significantly different from the untreated animals in PO2, PCO2, pH, glucose, lactate, pyruvate, free fatty acids, LDH, CPK, and SGOT. It is concluded that TNG is not detrimental to animals with acute coronary occlusion and that TNG has a transient, short-duration effect.

Effects of isosorbide dinitrate on the response to atrial pacing in coronary heart disease

To study the efficacy of isosorbide dinitrate in prevention of myocardial ischemia, 20 patients with angiographically proved coronary artery disease underwent atrial pacing (mean rate 138/min) before (P1), 10 minutes after (P2) and 65 minutes after (P3) sublingual administration of 5 mg of isosorbide dinitrate. The symptomatic, hemodynamic and metabolic responses were evaluated at rest and during each pacing period. Angina occurred in all subjects during P1. Angina did not recur or was less severe in 17 of 19 patients during P2 and in 19 of 20 patients during P3. Resting left ventricular end-diastolic pressure for the group was normal at 11 plus or minus 4 mm Hg (mean plus or minus standard deviation). On interruption of pacing at 4.5 minutes during P1, average end-diastolic pressure during sinus rhythm was abnormal (18 plus or minus 6 mm Hg). After administration of isosorbide dinitrate mean left ventricular end-diastolic pressure was significantly decreased at rest and remained normal when pacing was interrupted during P2 and P3. Brachial arterial pressure, cardiac index, tension-time index, left ventricular stroke work index and maximal rate of rise of left ventricular pressure were all diminished at rest before and during P2 and P3. S-T segment depression was less during P2 and P3 than during P1. Before isosorbide dinitrate was given, resting myocardial lactate extraction was 15 plus or minus 11 percent during P1 lactate extraction decreased to minus2 plus or minus 25 percent. Lactate extraction was significantly greater during P2 and P3 than during P1. This study demonstrates that sublingual administration of 5 mg of isosorbide dinitrate has a significant protective effect against pacing-induced myocardial ischemia at 10 and 65 minutes after administration.