Background and objective: The aim was to compare the effects of two different priming doses and priming intervals with the standard intubating dose of rocuronium on the onset time and intubation conditions.

Methods: After induction of anaesthesia, 75 patients were randomly assigned to one of five groups. Patients in Group 1 received a priming dose of rocuronium 0.06 mg kg−1 followed 2 min later by rocuronium 0.54 mg kg−1, Group 2 received a priming dose of 0.10 mg kg−1 followed 2 min later by a rocuronium injection of 0.50 mg kg−1. Group 3 was given a priming dose of 0.06 mg kg−1 followed 3 min later by administration 0.54 mg kg−1, where Group 4 received a priming dose of 0.10 mg kg−1 followed 3 min later by injection of 0.50 mg kg−1. Group 5 received a placebo injection followed 3 min later by rocuronium 0.60 mg kg−1.

Results: Priming with a 3 min priming interval shortened the onset time of rocuronium irrespective of the dosage of (P < 0.001). Clinical duration of action was significantly longer after priming in Group 4 than in Group 5. Clinically acceptable intubation conditions were obtained in all patients.

Conclusions: Priming with a 3 min priming interval was effective when rapid tracheal intubation with rocuronium was necessary. However, priming with rocuronium should be used carefully with special attention given to the possibility of hypoxia and aspiration of gastric contents in awake patients.