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.