Nitroglycerin Adsorption to Polyvinylchloride Seriously Interferes with Its Clinical Use

Abstract

Extemporaneous preparations of intravenous nitroglycerin solutions are currently being used in a number of centers to control intraoperative hypertension (1), severe aortic regurgitation (2), and hypertension in pregnancy during cesarean section (3), and for reduction of myocardial ischemia (4). A satisfactory injectable product may be prepared by using sublingual nitroglycerin tablets (5), nitroglycerin adsorbed onto lactose (6), or directly synthesized nitroglycerin (7). The material is dissolved in normal saline and the solution is sterilized by filtration. With increasing use of intravenous nitroglycerin, a number of reports have been published describing apparent drug instability and binding to various intravenous containers and delivery sets. Several of these reports, however, provide conflicting data. Our center has used nitroglycerin intravenously for approximately 8 years and over this period it has been noted that often the response to the drug seemed to be inappropriate in relation to the dose administered. To determine the cause of this inconsistent dose response, a series of in vitro experiments has been performed in an effort to reproduce the findings of published reports and to relate these to our experiences with this drug. During the course of these investigations we were able to document a clinical case in which nitroglycerin was administered using two different delivery systems and thus compare our in vitro findings to an in vivo situation.