The oculocardiac reflex in adults. A dose response study of glycopyrrolate and atropine.

Ninety adult patients about to undergo strabismus surgery received glycopyrrolate or atropine intramuscularly. Three doses of each anticholinergic were studied. Cardiac rate and rhythm were recorded during halothane anaesthesia. The oculocardiac reflex, defined as a fall of 20% in heart rate during traction of the extraocular muscle was inhibited in a dose-dependent manner by the drugs studied. The potency ratio of glycopyrrolate to atropine according to the oculocardiac reflex was established as 1:2.