I'm an 82 yr. old pretty healthy femaie, prediabetic. I had some pains which felt from my heart a while ago, took the 2nd Nitro in 5 min. as instructed, not feeling pain now but had strong shakiness and my teeth trembled for quite a while. Was this caused from the Nitro? That has left me now, but I'm just cold (I'm in FL not the N.). Medicine I took about 1/2 hr before was 150 mg Irbesartain, .5 Lorazepam and Silica plus for hair/nails. First time I ever took the Silica with the other meds.