Respiration paralysing and circulatory effects of a new non-depolarizing relaxant, pipecurium bromide, in anaesthetized dogs.

The effect of a new sterane-structure, non-depolarizing muscle relaxant 2 beta,16 beta-bis(4'-dimethyl-1'-piperazino)-3 alpha,17 beta-diacetoxy-5 alpha-androstane dibromide (pipecurium bromide, RGH-1106, Arduan) was studied in 42 mongrel dogs under general anaesthesia (ether, halothane, methoxyflurane, thiobutobarbital, hydroxydione and dehydrobenzperidol-fentanyl (NLA II). Onset and duration of action and the presence of circulatory side effects were examined. It was found that the mean onset of respiration paralysing action was 156.1 s and apnea lasted for 38 min. In the thiobutobarbital group apnea lasted for 74 min. Arterial systolic blood pressure and central venous pressure did not change, but the heart rate was mildly decreased by pipecurium bromide. ECG intervals (PQ, QT and TP) did not change considerably, and the variations ran parallel with the prolongation of RR intervals due to the decrease of heart rate. Pipercurium bromide is a non-depolarizing muscle relaxant of medium duration, without any significant circulatory effects. Its duration of action was prolonged in the presence of thiobutobarbital, indicating a drug interaction between the two preparations.