ABSTRACT
The present study was conducted to evaluate clinically and pharmacologically a modified method for protamine sulfate administration during heparin reversal, so as to overcome the systemic hypotension, which commonly occurs as a side effect after protamine infusion. The modified method is as follows: One third of the calculated dose of protamine is given slowly i.v. over 3 minutes and after 3 minutes the remaining two thirds of protamine is given over another 3 minutes. The clinical and pharmacological results of this study showed that, this method of protamine administration has the advantage that it is devoid of any effect of the arterial blood pressure both in humans as well as in experimental animals. In a trail to detect the possible site of action of such vasodepressor effect, which followed protamine administration in heparinized, but not unheparinized animals. The experimental work showed that the hypotension is probably reflex in nature, as it disappeared completely in spinal animals, atropinized animals, animals in which both vagi are excised and in animals in which a ganglion blocker was given