[Electroplethysmographic study of nitroglycerin microcapsule preparation at two concentrations: 2.5 and 7.5 mg...

In a double-blind, cross-over study involving 15 subjects (10 healthy volunteers and 5 patients with chronic coronary disease) the authors have compared the activity of two nitroglycerin microcapsule preparations containing 2.5 and 7.5 mg respectively. The hemodynamic effects were assessed by electroplethysmography, which is based on variations of impedance in the precordial area. The method records plethysmographic changes in the aorta and measures parameters exploring ventricular stroke. Both concentrations were found to be active. The effects lasted about 1 to 3 hours with the 2.5 mg preparation and more than 4 hours with the 7.5 mg preparation. The response to the 7.5 mg dose was approximately 50% greater than that to the 2.5 mg dose. These findings were supported by the occurence of headaches of six hours duration in 3 out of the 10 healthy subjects.