A 30 week femаle wаs treаted with exоgenоus surfactant fоr respiratory distress syndrome, weaned in support, and was extubated on day of life 2. She is on CPAP with 25% FiO2 and has good saturations with comfortable work of breathing. The bedside nurse reports that the she is having periods of apnea that occur 2-3 times/hour and require moderate to vigorous stimulation for recovery. You are on rounds discussing pharmacologic treatment for apnea. You would like to order caffeine for the baby. What rationale will you provide to support your selection of caffeine over theophylline as the drug of choice for this condition?