I am intrigued by the recent study of Miller et al,1 in which primidone therapy lessened the occurrence of apnea of prematurity that was refractory to theophylline therapy. I wonder, however, if their patients were truly refractory to standard therapy.
The serum levels for theophylline ranged from 33.3 to 70.4 μmol/L in their patients (mean, 51.6 μmol/L). It is possible that some of their patients might have responded to higher therapeutic theophylline levels.2
Ten of their 16 infants were not receiving airway pressure support. It appears that these 10 infants were having many more apneic and bradycardic events than the other six. Since air flow was not monitored, the role of obstructive or mixed apnea cannot be assessed. Nasal continuous positive airway pressure is effective against obstructive and mixed apnea3 and may have helped those 10 infants.
Primidone may indeed be effective therapy for refractory apnea of