Prolonged benefit of nitroglycerin ointment on exercise tolerance in patients with angina pectoris

Nitroglycerin ointment effective for seven hours in severe angina pectoris

The efficacy and tolerability of nitroglycerin (NTG) ointment were studied in 80 male patients with severe angina pectoris. Two symptom-limited exercise tests were performed on successive days after application of an ointment containing 15 mg NTG or a placebo (P) ointment. The patients were assigned to 4 groups. The study was conducted in a double-blind, cross-over manner. The total amount of work performed was higher in all groups on NTG (46-70%) compared to P ointment. The difference was statistically significant (p less than 0.001) at all points of time from 0.5 to 7 hours. The ST segment depression in ECG at the end of the exercise test was slightly greater on P than on NTG, but the difference was statistically significant only in the 3-hour group (p less than 0.01). The frequencies of headache and dizziness were 35% and 16%, respectively, on NTG. Eight patients (10%) reported that headache was severe enough to prevent regular use of NTG ointment. NTG ointment is effective, has a long duration of action and is relatively well tolerated by patients with severe angina pectoris.

Ointments and transdermal nitroglycerin patches for stable angina pectoris

Nitroglycerin (NTG) ointment is used for the prophylaxis against angina pectoris, but there are no data to support its effectiveness during long-term therapy. Continuous, once-daily application of isosorbide dinitrate cream produces tolerance with complete loss of efficacy within 1 week. Nitroglycerin patches are very popular and continuous once-daily application is still claimed by some investigators to provide 24 hour antiischemic and antianginal efficacy. This claim is based on data from postmarketing studies in a very large number of patients and placebo-controlled studies in smaller groups of patients from Italy, Yugoslavia, Greece, and Germany. In contrast, studies from the United States, Canada, England, and some centers in Germany have failed to show superiority of patches over placebo during continuous therapy. This controversy was addressed by the NTG cooperative study group, in which a total of 562 patients who were responders to sublingual nitroglycerin were studied. Patients received either placebo or NTG patches delivering low (15-30 mg/24 hr), moderate (45-60 mg/24 hr), or large (75 and 105 mg/24 hr) amounts of NTG. Four hours after the initial application, NTG patches increased exercise duration compared to placebo, but this beneficial effect had disappeared by 24 hours. Furthermore, after 8 weeks of continuous therapy, none of the NTG patches were superior to placebo, whether patients were or were not taking concomitant beta-blockers. Therefore, current opinion is that continuous therapy with NTG patches produces pharmacologic tolerance and is ineffective.(ABSTRACT TRUNCATED AT 250 WORDS)

Controlled-release isosorbide dinitrate pellets. Part II: In vivo studies

Isosorbide dinitrate (ISDN) capsules containing 20.0 and 40.0 mg of the drug (reported earlier in Part I of this series) were evaluated in vivo in eight healthy volunteers in a double-blind study with marketed sustained-release preparations containing 20.0 and 40.0 mg of ISDN. The results were normalized by administering placebo and four conventional ISDN tablets, each containing 5.0 mg of ISDN, to the same group of volunteers in a separate study. The blood pressure of the volunteers was monitored for 8 h. The results indicate that the capsules prepared in the laboratory with the new formulation gave controlled release when compared with the respective marketed SR product.

Simultaneous pharmacodynamic modeling of the non-steady-state effects of three oral doses of 1,3-glyceryl dinitrate upon blood pressure in healthy volunteers

The organic nitrate 1,3-glyceryl dinitrate (1,3-GDN) is one of the primary dinitrate metabolites of the antianginal agent nitroglycerin (GTN). Investigational New Drug Approval was sought to administer oral solution doses of 1,3-GDN to a small number (n = 3) of healthy volunteers; each subject receiving three doses at 1.2, 2.4, and 3.6 mg. With volunteers confined to a semirecumbent posture for the duration of each treatment (4-hr period postdose), diastolic blood pressure (DBP) was recorded and plasma samples collected for 1,3-GDN concentration analysis. Appreciable concentration-related decreases in DBP were observed, with maximal decreases from predose baseline values approximating 11 to 25 mm Hg. For each subject parametric pharmacodynamic modeling was performed with simultaneous analysis utilizing the DBP vs. time data from all three doses; an inhibitory Emax pharmacodynamic model was adopted. The temporal relationship between plasma 1,3-GDN concentrations and DBP displayed rapid equilibration. For subjects 1, 2 and 3, respectively, Emax was predicted as 12.9, 23.4, and 29.7 mm Hg, representing 21.5, 31.6, and 39.5% decreases in DBP from predose baseline values; plasma concentrations at half Emax (C50) were 2.75, 2.43, and 5.93 micrograms/L. Utilizing pharmacokinetic-pharmacodynamic modeling, 1,3-GDN plasma concentrations appear to relate to a systemic "effect measure" that is mechanistically representative of the therapeutic actions of organic nitrates as peripheral vasodilators. The establishment of a GDN plasma concentration-effect relationship together with the relatively high plasma levels of GDN achieved following GTN dosing supports the hypothesis that the GDNs contribute significantly to the hemodynamic effect observed with GTN.

The effect of nitroglycerin ointment on exercise-induced angina: a multicenter trial

The efficacy of nitroglycerin ointment was determined by treadmill exercise testing through a randomized, double-blind crossover trial with placebo in 22 patients with chronic stable exertional angina. On different days, 3 cm of nitroglycerin ointment (NGO, 18 mg) and placebo ointment were applied over the epigastric region, followed by the exercise test 1 hour later. The maximal exercise time was 459 +/- 124 seconds after application of placebo and 510 +/- 113 seconds after application of NGO, and the exercise time to 1 mm of ST-segment depression was significantly extended to 297 +/- 110 seconds after placebo and 366 +/- 134 seconds after NGO (p less than 0.01, p less than 0.001, respectively). ST-segment depression at the endpoint of exercise was significantly reduced from 2.4 +/- 1.2 mm to 1.5 +/- 0.7 mm after application of NGO (p less than 0.01). There was no difference in rate-pressure product at the endpoint of exercise between placebo and NGO. Adverse reactions were elicited in 5 of 22 patients. The results of this present study suggest that NGO is effective in the treatment of exertional angina.

Nitrates

Nitroglycerin and the long-acting nitrates are playing an increasingly important role in cardiovascular medicine. These agents are recommended in all of the various anginal syndromes and are as effective as the beta-blockers and calcium channel antagonists. There is a definite place for nitrate therapy in treating the complications of acute myocardial infarction. These drugs are also highly effective as unloading therapy in congestive heart failure. The mechanisms of action of the nitrates are reviewed in this article. Information is provided regarding nitrate efficacy in all the major clinical syndromes in which these drugs are used. Finally, appropriate dosing strategies are suggested that should eliminate the potential problem of nitrate tolerance.

Tolerance to organic nitrates in ischemic heart disease

The development of tolerance to organic nitrates in patients with ischemic heart disease is reviewed, with particular interest in alterations to both the hemodynamic and antiischemic effects over time. The article primarily focuses on how tolerance is defined, what biochemical mechanisms are involved when this condition occurs, which agents have been associated with the development of tolerance, and what can be done to prevent or reverse the condition in patients taking nitrates for ischemic heart disease. From a historical perspective, tolerance to organic nitrates has been a recognized phenomenon since the last century. The role that blood-level determinations and nitroglycerin pharmacokinetics have in the development of tolerance is discussed, and an extensive overview of currently marketed organic nitrate preparations and a few others available only through approved investigational protocols is presented. The role of cross-tolerance is discussed as is the role that nitrate-free intervals play in partially or completely reversing the effects of tolerance during chronic nitrate therapy. Additionally, a discussion of which specific nitrate formulation are least likely to have tolerance associated with their use is included, such as short-acting nitrate formulations with the exception of the intravenous dosage form. Finally, buccal nitroglycerin is presented as another new formulation that appears to be associated with minimal tolerance in studies already completed.

Effect of a new transdermal therapeutic system containing nitroglycerin on exercise capacity in patients with angina pectoris

In a double-blind, within-patient, randomized, placebo-controlled, acute study, the effects at rest and on exercise capacity of two doses of a new transdermal therapeutic system (TTS), releasing respectively 10 and 20 mg of nitroglycerin (NTG) over 24 hours, were assessed in 15 outpatients with stable exercise-induced angina pectoris. A symptom-limited exercise test was performed 4 and 24 hours after the application of each system. In comparison with placebo, both TTS-NTG doses induced a statistically significant (p less than 0.01) increase in total duration of exercise, in exercise duration to 1 mm ST segment depression, in maximal workload and in total work performed, at both 4 and 24 hours after dosing. Furthermore, both TTS-NTG doses induced a significant rise in the pressure-rate product, both 4 and 24 hours after dosing (p less than 0.01 and p less than 0.05, respectively). No statistical difference was found between the two doses of active drug in any of the above-mentioned evaluation parameters. The only unpleasant side effect was the typical nitrate headache, which occurred in 11 of 15 patients. In conclusion, a single application of TTS-NTG, 20 cm2 or 40 cm2, may improve exercise capacity over a 24-hour period in patients with stable exercise angina due to atherosclerotic heart disease.

Cutaneous administration of nitroglycerin: a review

Chronic administration of nitroglycerin may have important therapeutic effects in patients with angina, acute myocardial infarction, congestive heart failure and peripheral vascular disease. Because of unpredictable oral absorption and short duration of action, topical preparations provide an alternative mode of administration. New controlled release transdermal preparations appear to produce constant plasma nitroglycerin concentrations of 0.2-0.3 ng/ml that persist for up to 24 hours. Additional clinical trials of the therapeutic response to this drug form are necessary, particularly in regard to the relative hemodynamic efficacy and side-effect profile of sustained vs. fluctuating plasma nitroglycerin concentrations.

Sustained anti-anginal action of glyceryl trinitrate cream

1 In an acute study, 45 min following topical application of 9.2 mg of nitroglycerin (GTN) cream, exercise time increased by 100s (P < 0.005) and this increase persisted for 270 min. Systolic blood pressure showed a progressive fall.

2 In the second study 1 h following application of 9.2 mg GTN cream, a significant reduction in left ventricular diastolic dimension was seen.

3 In a subsequent chronic randomised double blind study, exercise time increased by 47 s (P < 0.05) at 6 h, following 3 weeks continual use.

4 An increased dose for a further 3 weeks produced no further increase in exercise time; however, a significant decrease in left ventricular end diastolic dimension was seen.

5 No evidence of pharmacological tolerance was seen, as patients continued to show a maximal response to sublingual nitroglycerin during the course of the study.

The transdermal administration of nitrates: an overview

Nitroglycerin has been the mainstay of the medical management of angina pectoris for over 100 years. The long-held clinical impression of the efficacy of nitroglycerin has now been clearly documented in controlled clinical trials designed to evaluate objective response to antianginal agents. Advances in scientific methodology and improved experimental design have contributed to continuing interest in nitrates. Newer uses of nitroglycerin and other nitrates in congestive heart failure and acute myocardial infarction are the result of a developing understanding of the pharmacology of nitrates.

The clinical use of transdermal delivery devices with nitroglycerin

Eleven patients entered a double-blind, cross-over study that compared the influence of a new transdermal preparation of nitroglycerin (Nitrodisc: MDD-NG, Searle Limited) on exercise performance with the influence of placebo. Eight patients have completed the study. All patients had severe stable angina, and ten had angiographically proven, severe, three-vessel coro nary disease (including two patients with left main stem disease). Ejection fraction varied between 0.31 and 0.74. No patient received beta-blocking drugs or calcium antagonists at the time of entry into the study.

All patients initially underwent a series of maximal treadmill exercise tests according to a modified Bruce Protocol. After a base-line exercise test, the active device was titrated to the point of efficacy or until side effects occurred. In stage 2 the patients were randomly allocated to an active or placebo group during the course of which further exercise tests were performed at two hours and 26 hours after the application of the device. In stage 3 the patients' regimens were crossed-over after one day's rest to the treatment they had not received in the first treatment period. Further exercise tests were performed at two hours and 26 hours after application of the preparation. Three days after the last 26-hour test, a further exercise test was run to determine the stability of the base-line.

Three patients were removed from the study: two as a result of the appear ance of unstable angina requiring urgent coronary surgery; the third patient died from non-cardiac causes during the titration stage of the study. The mean duration of exercise at the pre-study exercise test was 11.9 minutes. Two hours after the application of MDD-NG, the mean duration of exercise increased to 14.4 minutes compared with 11.3 minutes with placebo ( P<.05). This effect was maintained at 26 hours with a mean duration of exercise of 14.1 minutes with MDD-NG compared with 11.8 minutes with placebo (P< .05). This repre sents a 30% increase in exercise capacity from base-line at two hours and 25% at 26 hours for the active drug. Exercise times to anginal threshhold associated with 1.5 mm of ST segment depression were increased by 38% at two hours after the application of MDD-NG when compared with control and was 44% at 26 hours after the application. These differences were statistically significant (P<.05). Changes in the double product of heart rate and systolic blood pressure at peak exercise were not significantly different between control, active drug, or placebo. Changes in the consumption of oral nitroglycerin were assessed during the titration phase on the active drug. From the fourth day onward the consumption of nitroglycerin was reduced by 63%. Side effects, including headache and blurring of vision, occurred in two patients; these responded readily to a reduction in dosage.

It is concluded from these preliminary data that MDD-NG significantly increases exercise capacity in patients with stable angina and that this effect is maintained during a 24-hour period using a single-dose application.

The effect of glyceryl trinitrate ointment on heart rate--corrected systolic time intervals in angina pectoris

1 Individual systolic time intervals (STI) v heart rate regression equations were determined using small doses of intravenous atropine in seven patients with angina pectoris. 2 Regression lines of the form LVET = A + B.HR and QS2 = C + D.HR were calculated. There was no significant correlation between PEP and HR. The values of parameters A C and D were significantly different from a group of previously studied normal volunteers. 3 STI changes were recorded for 5 h after the application of GTN or placebo ointment. The active drug caused shortening of LVET and QS2 with the peak effect occurring between 105 and 180 min. After 180 min neither LVET nor QS2 were significantly shortened. There was no significant effect on PEP or heart rate.

Treatment of vasospastic angina pectoris at rest with nitroglycerin ointment: a short-term controlled study in the coronary care unit

The effectiveness of nitroglycerin ointment in vasospastic angina pectoris at rest was evaluated in 10 patients selected for study. The study was performed after a 24 hour control period, and a randomized single-blind crossover experimental design was followed. Two percent nitroglycerin ointment (15 mg) or placebo ointment was administered every 6 hours for a period of 48 hours each; the first treatment period was followed by a second in which each preparation was used for a 24 hour period. All patients were hospitalized in the coronary care unit; an objective evaluation was carried out using a multichannel electrocardiographic recording to assure recognition of the painless ischemic episodes. Coronary angiography showed critical stenosis of one or two vessels in 9 of the 10 patients; spasm was demonstrated in 3. Results of the ergonovine test were positive in nine of nine patients. Nitroglycerin ointment produced a significant reduction in the mean daily number of episodes during the first (12.5 +/- 3.9 versus 0.5 +/- 0.4, p less than 0.02) as well as the second treatment period (10.6 +/- 3.8 versus 0.6 +/- 0.4, p less than 0.02). These results demonstrate that nitroglycerin ointment provides effective, long-lasting protection against angina due to coronary spasm.

Glyceryl trinitrate ointment in angina pectoris

Skin absorption of glyceryl trinitrate (GTN) has been recognized for a long time. The effect of GTN and a placebo ointment in prevention of chest pain has been assessed and compared by studying the exercise capacity in 17 patients with angina pectoris. The placebo cream was ineffective but the GTN ointment was found to have beneficial effect in relief of pain in 16 cases. This was established by the patients' capacity to exercise on a bicycle ergometer without chest pain. The beneficial effect was sustained for up to 3 hr in 12 patients. This preparation appears to act as a long-acting nitrate and may be valuable for patients in whom beta-blocking agents are ineffective or contra-indicated, and surgery is not feasible.