Atropine pharmacokinetics and pharmacodynamics following endotracheal versus endobronchial administration in dogs.

Emergency endotracheal and endobronchial drug administration provide an effective alternative for intravenous drug delivery during cardiopulmonary resuscitation. The purpose of the present study was to determine the immediate pharmacokinetic and pharmacodynamic properties of atropine following administration by either of these routes. Atropine (0.02 mg/kg) was given to seven anaesthetized mongrel dogs. Each dog was studied twice: once when atropine was injected into the endotracheal tube, and on another day when atropine was given via a flexible catheter wedged into a peripheral bronchus. Plasma atropine concentrations and blood gases were measured during 60 min following drug administration. Both routes of atropine administration differed significantly in three measures: the maximal atropine concentration (Cmax) was significantly higher with the endobronchial administration 40.0 +/- 7.8 ng/ml compared to 23.9 +/- 5 ng/ml endotracheally (P = 0.008); atropine's elimination (t1/2beta) half-life was significantly longer with the endobronchial route (39.3 +/- 5.2 min vs. 28.0 +/- 7.9 min; P = 0.05); Endobronchial administration resulted in an increase of 16% in heart rate, beginning immediately after drug delivery and peaking after 5 min. Other pharmacokinetic parameters were not significantly different. We conclude that endobronchial administration of atropine has a clear advantage over the endotracheal route.