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January 1981

Theophylline Pharmacokinetics

Author Affiliations

526-B Shoup Ave W Twin Falls, ID 83301
Room 311A Skaggs Hall University of Utah Salt Lake City, UT 84112
Department of Pediatrics University of Louisville School of Medicine Suite 211 Ten Thousand Building 10000 Shellyville Rd Louisville, KY 40223

Am J Dis Child. 1981;135(1):82-83. doi:10.1001/archpedi.1981.02130250068025

Sir.—Although our article is not cited by Simons et al (Journal 1980;134:39-41), we first reported the phenomenon of biphasic theophylline elimination in 1978.1 Although our case involved an older child (7 months), the elimination curves are surprisingly similar. It should be noted that our patient did not receive phenobarbital. As a result, we speculate that phenobarbital has nothing to do with the shorter half-life reported in the second phase. If case 1 of Simons et al had been followed up long enough, it is likely that a similar phenomenon could have been observed. In our case report, the time at which the kinetic change took place was approximately the same. There were no caffeine metabolites present in our patient, and we attribute this to the age differential. The ratio of CSF theophylline to serum theophylline is approximately the same level in both their case and our case. We