Efficacy of sustained-release buccal nitroglycerin in patients with angina pectoris. New and long-acting therapy demonstrated by exercise

Buccal versus intravenous nitroglycerin in unstable angina pectoris

The clinical syndrome of unstable angina includes patients with the first onset of angina, change in a previous stable pattern or the development of chest pain at rest. Administration of intravenous nitroglycerin is established therapy in unstable angina. Buccal nitroglycerin has been introduced as an alternative means of administering nitroglycerin, which provides relief of anginal pain within 2 to 3 min and a sustained effect for 3 to 5 h. Twenty-nine patients admitted to the coronary care unit due to unstable angina were randomized to receive treatment with nitroglycerin i.v. for 24 h or buccal nitroglycerin every 4 h. Therapy was titrated according to haemodynamic effects. The mean dose of buccal nitroglycerin was 4.42 mg versus 0.45 micrograms.kg-1.min-1 in the intravenous group. The efficacy of treatment was similar in the two groups. Buccal nitroglycerin appeared to cause fewer adverse effects, especially less haemodynamic intolerance and headache, although the differences were not significant. Repeated administration of buccal nitroglycerin appears to be a safe and well tolerated alternative to high-dose i.v. nitroglycerin treatment in unstable angina pectoris.

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.

New nitrate delivery systems: buccal nitroglycerin

BN, a new nitrate formulation, has recently been made available. The main advantages of this medication is the combination of prompt onset of action, comparable to that of sublingual NTG, and sustained activity that persists for many hours. The tablet remains pharmacologically effective as long as it remains in the buccal pouch. A variety of studies indicate that BN is well tolerated by patients, acts promptly to provide protection against anginal pain, and has sustained efficacy that persists for 2 to 6 hours. Clinical investigations using serial treadmill testing in patients with angina demonstrate clinical effectiveness and bioactivity of BN beginning within minutes and lasting over 4 hours. The potential advantages of this preparation are discussed, and the formulation is compared to other available longacting nitrates. BN is an effective new addition to the nitrate armamentarium.