Induction of yawning by low doses of apomorphine (0.1, 0.2 and 0.4 mg) in healthy volunteers

Abstract

SummaryThe dopaminergic agonist apomorphine hydrochloride (0.1, 0.2 and 0.4 mg s.c.) compared to placebo in a double-blind, latin square design induced yawing in population of 8 healthy volunteers. Yawning was the only behavioral effect observed and was not dose-related, as all the 3 doses were equipotent. Yawning was maximum between 10 and 20 min post-injection and did not last longer than 20 min. Compared to the data in the literature, 0.1 mg is the lowest dose described as inducing yawning in man. Further studies using doses lower than 0.1 mg would be required to determine the highest inactive dose in order to use apomorphine-induced yawning as an index of CNS dopaminergic receptor sensitivity.