Pharmacokinetics of theophylline in neonates.

Theophylline is a safe, effective drug for the treatment of apnea of prematurity. The pharmacokinetics of theophylline have been studied extensively in preterm neonates. There is some inter-infant variability, but generally, compared to children and adults, prolonged half-life values and low clearance rates have been found: the apparent volume of distribution is larger and protein binding of the drug is decreased. A unique pattern of metabolism involving methylation to caffeine has been identified. Theophylline maintenance dose requirements are much lower in neonates than in children. When therapy is begun, a useful guide is to give a loading dose of 5 mg/kg anhydrous theophylline followed by maintenance doses of 2 mg/kg every 12 hr. In many infants, this will suffice to prevent apnea without producing signs of toxicity. After commencement of therapy, doses must be individualized for each infant on the basis of serum theophylline concentration monitoring and monitoring for apnea. Evidence of theophylline toxicity in neonates may be subtle, and only scanty data are available regarding possible long-term effects of chronic theophylline treatment of neonates.