Evaluation of nitroglycerin ointments in the rabbit.

The rate of percutaneous absorption of nitroglycerin from different ointment preparations was studied in the rabbit using an indirect method which suffices bioavailability requirements. Ointment bases of different lipophilic character were compared with a commercially available preparation. Rate of absorption was fastest from the least lipophilic base. A hypothesis is presented regarding the clinical observation that topical use of nitroglycerin may not show enzyme induction as was found in peroral use. According to this hypothesis while achieving therapeutically effective levels the rate of percutaneous absorption should be slow enough not to result in a systemic drug concentration critical to enzyme induction. One experimental preparation (A) resulted in practically identical rate of absorption as obtained with the standard preparation.