In the recipe of ointment containing nitroglycerin, a physician prescribes the nitroglycerin as "Willong 7.5 mg". These are long-release gelules: The nitroglycerin is processed in granules.

Indeed, I would not use these tablets as a starting base for the required amount of nitroglycerin, because of the fact that they should be finely rubbed.

There are two solutions:

1. either you can use the alcoholic nitroglycerin solution as in the cited example from the question box;
2. or, after consulting your physician, replace the nitroglycerin with Isosorbidenitate, which is available as a powder. An example of an ointment or cream based on Isosorbide was published for some time in the Folia Pharmacotherapeutica.