THE DOSE-RELATED HYPER-AND-HYPOKALEMIC EFFECTS OF SALBUTAMOL AND ITS ARRHYTHMOGENIC POTENTIAL

1 The hypokalaemic effect of salbutamol after more than 30 min of admi nistration has been well described. A hyper-and-hypokalaemic effect fo r adrenaline has been reported, but no such hyperkalaemic effect for s albutamol. 2 The possible hyper-and-hypokalaemic effects of salbutamol with the concomitant potential for pro-arrhythmia were assessed in th e baboon (Papio ursinus). 3 Male and femal baboons were anaesthetized with ketamine (15 mg kg(-1)) and maintained with 6% pentobarbitone as spontaneously breathing animals. Six baboons in each group received ei ther 10, 100 or 500 mu g kg(-1) salbutamol i.v. Lead II of the ECG and femoral i.a. blood pressure were recorded continuously for 10 min. Ar terial blood samples were collected at 0 min and then after 3 and 10 m in of salbutamol administration. 4 All the animals developed sinus tac hycardia (above 200 beats min(-1)) within 30 s of each dose of salbuta mol administration and the high heart rate persisted throughout the ex periment. All the animals were hyperkalaemic after 3 min and hypokalae mic after 10 min for each dose of salbutamol. Left ventricular conduct ion defects were seen in 3 animals during the hyperkalaemic phase. No arrhythmia was seen during the hypokalaemic phase. 5 Salbutamol has a transient hyperkalaemic and a more prolonged hypokalaemic effect in th e baboon. The hypokalaemia could not be associated with arrhythmia alt hough conduction defects were associated with the hyperkalaemia. 6 Sin ce salbutamol is used as a bronchodilator in asthmatic patients and to treat acute hyperkalaemia, it is suggested that caution should be exe rcised when using salbutamol in high doses to treat acute asthma espec ially during the first few minutes of administration. The finding of h yperkalaemia with salbutamol questions its use in the treatment of hyp erkalaemia.