The relationship of cerebrospinal fluid and plasma theophylline concentrations in children and adolescents taking theophylline.

Ten ambulatory subjects with asthma experienced a seizure while they were receiving oral theophylline preparations and were evaluated prospectively according to a set protocol. The protocol included a lumbar puncture that permitted the simultaneous determination of plasma and cerebrospinal fluid (CSF) theophylline concentrations. A constant relationship was observed between the plasma theophylline concentration and that of the CSF. It was found that the theophylline concentrations in these two biologic fluids could be characterized by the regression equation y = 0.41 X + 0.7 where y is the CSF theophylline concentration and X is the plasma theophylline concentration. Two infants with hydrocephalus treated by ventriculoperitoneal shunt were also simultaneously evaluated for plasma and CSF theophylline concentrations. These infants demonstrated greater than expected entry of theophylline into the CSF. Some central nervous system abnormalities may be characterized by increased theophylline entry into the CSF.