Comparison of transdermal nitrate and isosorbide dinitrate in chronic stable angina

Bayesian analyses of two-treatment crossover studies

This review covers Bayesian analyses of two-treatment crossover studies. The main emphasis is placed on the analysis of continuous data although we also consider dichotomous responses. Studies discussed include (1) the simple two-period, two-treatment crossover, (2) the two-period crossover with one baseline measurement, (3) the two-period crossover with two baselines and (4) the extra-period design with two treatment sequences.

Extending a Bayesian analysis of the two-period crossover to allow for baseline measurements

In the context of a two-period crossover study with baseline measurements a graphical method is developed for displaying the dependence of posterior inferences concerning the treatment effect on unavoidable prior beliefs about the 'correct' model. The method is a generalization of the approach developed by Grieve for the corresponding case without baselines.

Placebo effect of nitrate monotherapy for myocardial ischemia

Nitrate monotherapy was assessed by treadmill exercise stress testing in 18 patients with significant but relatively asymptomatic myocardial ischemia who were receiving no other antianginal therapy. In addition, prolonged ambulatory electrocardiographic monitoring was performed in 7 patients with demonstrable ischemia during baseline monitoring. After baseline assessment, 5 treatment periods were used in a random order (each of 1 week duration), incorporating 2 dose levels of transdermal nitrate (10 and 20 mg/24 hours) and isosorbide dinitrate (ISDN) (30 and 60 mg/day in divided doses) with a 10-hour nitrate-free interval every 24 hours, as well as a placebo period using a double-blind technique. All treatment periods (including placebo) showed a significant (p < 0.01) 45 to 69% prolongation in the time to 1 mm ST depression during exercise. Paired baseline times of 231 +/- 28 and 233 +/- 30 seconds increased to 367 +/- 37 seconds with 30 mg/day of ISDN, 393 +/- 37 seconds with 60 mg/day of ISDN, 381 +/- 31 seconds with 10 mg/day of transdermal nitrate, and 372 +/- 33 seconds with 20 mg/day of transdermal nitrate. The value for placebo was 342 +/- 29 seconds, which was not significantly different from active treatment (p > 0.1). Some patients appeared to individually respond to > or = 1 nitrate preparation significantly more than to placebo, but this appeared to be unpredictable and largely independent of dosage level and route of administration. There was a qualitatively similar but statistically insignificant reduction in total ischemic time during ambulatory monitoring.(ABSTRACT TRUNCATED AT 250 WORDS)

Transdermal nitroglycerin (glyceryl trinitrate). A review of its pharmacology and therapeutic use

Nitroglycerin (glyceryl trinitrate) has been used for many years via the sublingual route for treating acute anginal attacks. In recent years transdermal delivery of nitroglycerin has gained popularity for prophylaxis against angina. However, nitrate tolerance appears to be a therapeutic problem with all long-acting nitrates regardless of delivery mechanism, and it occurs in most patients with stable angina treated with continuous 24-hour application of nitroglycerin patches. Since continuous 24-hour plasma concentrations of nitroglycerin do not appear to be desirable, alternative approaches to therapy are needed. A simple method to minimise tolerance with transdermal nitroglycerin patches is to remove the patch at bedtime and reapply a new patch in the morning. Such intermittent therapy allows a patch-free period during the night, when most patients experience few angina attacks, but optimises nitrate sensitivity during the daytime. However, the place of intermittent nitroglycerin patch therapy in the treatment of stable angina needs clarification with further study, particularly comparisons with other long-acting forms of nitrates. There are insufficient data to recommend the use of transdermal nitroglycerin patches in the treatment of patients with unstable angina or congestive heart failure. In conclusion, transdermal nitroglycerin patches offer a convenient and cosmetically acceptable dosage form which has potential use in stable angina if administered as an intermittent regimen providing a patch-free period each night.

Nitrate tolerance. A review of the evidence

Organic nitrates are well established in the treatment of a wide variety of cardiovascular disorders, most notably angina pectoris and congestive heart failure. However, attenuation of, or tolerance to, haemodynamic and anti-ischaemic effects may occur with all long-acting nitrate formulations. In the majority of patients continuous administration of long acting nitrates tends to promote the development of attenuation, while intermittent administration avoids it. Likewise, higher-doses appear to induce attenuation to a greater degree than lower doses. Attenuation of haemodynamic effects and exercise tolerance in heart failure patients, and of clinical end-points in angina patients, appears to be less than attenuation of exercise testing end-points in angina patients. While the use of intermittent therapy avoids the development of attenuation, it may expose the patient to an as yet undefined risk of silent and/or symptomatic anginal episodes occurring during the nitrate-free interval. Likewise, the role of concomitant therapy in avoiding this potential risk remains to be defined. Means of avoiding attenuation may include the coadministration of sulfhydryl donors such as N-acetylcysteine. Alternatively, angiotension-converting enzyme (ACE) inhibitors such as captopril may block renin-angiotensin system-induced reflex sympathetic stimulation. Attenuation may occur to a greater or lesser degree in individual patients. The proportion of attenuators vs non-attenuators remains to be defined, as does a means of identifying such patients prospectively by clinical and/or laboratory parameters. Conflicting results among smaller studies may reflect variable proportions of attenuators vs non-attenuators. However, conflicting results among larger studies may reflect differences in patient selection criteria, such as selecting patients with positive and reproducible stress tests and little in the way of spontaneously occurring angina versus selecting patients with positive but variable stress tests and frequent episodes of spontaneously induced angina. The former group may reflect pure fixed coronary artery disease with little in the way of vasospasm, or change in vasomotor tone, while the latter group may reflect greater variability in vasomotor tone and/or more in the way of plaque instability. The clinical efficacy of long acting nitrates might therefore be expected to be greatest in those patients with larger numbers of spontaneously occurring angina episodes. Recent data suggest that nitrates may have important direct effects on coronary vessels including dilating eccentric coronary stenoses, dilating intercoronary collateral channels and having greater dilating effects on more diseased segments as opposed to less diseased coronary segments.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparative clinical trial of the tolerability, patient acceptability and efficacy of two transdermal glyceryl trinitrate patches ('Deponit' 5 and 'Transiderm-Nitro' 5) in patients with angina pectoris

A randomized two-period crossover trial was carried out to compare the efficacy, tolerability and patient acceptability of two transdermal ('patch') formulations of glyceryl trinitrate. 'Deponit' 5 and 'Transiderm-Nitro' 5, both designed to deliver 5 mg glyceryl trinitrate in 24 hours. All patients were treated for 4 weeks with each of the formulations, changed once per day. Forty-seven patients entered the trial and all completed both phases of treatment. Both drugs resulted in highly significant mean reductions in angina attack frequency, the reduction being significantly greater with 'Deponit'. Similarly, mean sublingual glyceryl trinitrate consumption was also reduced; again, the greater reduction with 'Deponit' was significant. In terms of effectiveness, 'Deponit' was preferred to 'Transiderm-Nitro' by 19 patients, whilst only 5 patients preferred 'Transiderm-Nitro' (p less than 0.01). In terms of ease of application, comfort, appearance and adhesion (assessed in relation to daytime, night-time, washing, bathing and exercising), there were no appreciable or significant differences between patients' assessments of the two forms. Neither treatment had any appreciable effect on heart rate or blood pressure. Both formulations were very well tolerated, with very few reported side-effects.

Comparison of nitroglycerin-TTS and long-acting nitroglycerin tablets in the treatment of angina pectoris: a double-blind controlled study

A cohort of 99 patients with severe, stable angina pectoris participated in a 26-week double-blind, between-patient trial of a transdermal therapeutic system (TTS) Nitroglycerin-TTS 5 mg/24 h and long-acting nitroglycerin tablets, 10.4 mg daily. The variables registered included daily sublingual nitroglycerin requirement, daily anginal attack rate, exercise test performance with ECG recordings, and a subjective patient evaluation on a visual analogue scale. There were no significant differences in the efficacy of the treatment between the two groups. Nor could we find any difference in the efficacy between the initial single-blind placebo treatment and the active nitroglycerin treatments.