We hypothesize that urine levels might be reliable to assess the therapeutic range of caffeine.Objectives
We correlated plasma and urinary levels of caffeine in preterm infants treated with this drug for apnea of prematurity.Methods
Infants (n=56) were given a loading dose of caffeine citrate (10 mg/kg, per os) and 24 h later a maintenance dose (2 mg/kg, per os, once a day). Plasma and urinary levels of caffeine were determined 24 h after the loading dose (before administration of the maintenance dose) and then weekly.Results
Plasma and urinary levels correlate at all examined ages: 29 weeks (r = 0.92, P<0.001), 30 weeks (r = 0.97, P<0.001), 31 weeks (r = 0.82, P<0.001), 32 weeks (r = 0.92, P<0.001), 33 weeks (r = 0.87, P<0.001), 34 weeks (r = 0.81, P<0.001).Conclusion
Urinary levels of caffeine might be a useful means to assess therapeutic ranges.