Nitro is concentrated and a med (isosorbide a nitrate) is effective with no side effects for me.

Information from pharmacy when I purchased nitro...it is to be used when there is angina and can cause severe headaches. Effective for 12 or so minutes.

Subsequently to nitro (sublingual), I began taking Isosorbide (nitrate) tablet. It is a slow release med to be taken to PREVENT angina. No help during the event of angina.

What is the advantage of waiting for angina and then take nitro? I know in advance (i.e. going to health center) and I take isosorbide and no angina with heavy exercise. For a short period prior, I took nitro for angina during exercise and it is/was effective as well...no problem. For me the slow release of a nitrates with isorbide tablets cause no side effects so that isn't an issue. The difference it seems is nitro is more appropriate for unstable angina, but that doesn't rule out a slow acting nitrate couldn't be effective for unstable angina as well...:confused: I don't have unstable angina so there is no personal frame of reference.