Looked at retrospectively, we now wonder if the potassium concentrations fell further still in patients 5 and 9. Because blood specimens were not taken after the end of the dosage period, the answer to this question must remain open. Nevertheless, the different patterns in the fall and rise of serum potassium concentrations with time in the other patients did not point to any obvious line of investigation. Continued falls were sometimes seen (for example in patient 13), sometimes there was a return towards normality (patients 1,2,3, and 4), and sometimes the serum potassium concentrations remained reasonably steady after the inhalations were stopped (see Table 5).
Because there were no clinical symptoms that could point to ECG abnormalities or cardiac complaints in connection with the reduction in serum potassium levels, the question whether these reductions were of clinical significance must also remain unanswered. In any case, we felt it justified to conclude that, based on the results of this tolerability study, very high doses of formoterol given by aerosol could be considered just as safe as the equivalent doses of salbutamol.