ABSTRACT
Simultaneous saliva and plasma theophylline levels in 12 chronic asthmatic children were measured by high pressure liquid chromatography following administration of a theophylline preparation. In five subjects, simultaneous plasma and salivary theophylline were measured one week later. A strongly positive correlation between plasma and salivary theophylline levels was found at all time periods tested. There was no substantial difference in the plasma-saliva theophylline ratio determined one week later. A predicted plasma level was compared with the observed value. The proportionality of predicted to observed plasma theophylline levels using either the entire study group mean plasma-saliva ratio or each individual's ratio was approximately 1.00 with 9% variability. When a previously reported plasma-saliva theophylline ratio was used for comparison, the predicted plasma theophylline was 15% above the observed plasma level.
Subject(s)
Saliva/metabolism , Theophylline/blood , Theophylline/metabolism , Adolescent , Asthma/blood , Asthma/drug therapy , Child , Chromatography, Liquid , Chronic Disease , Humans , Saliva/analysis , Theophylline/therapeutic useABSTRACT
We describe a micro-scale method for determining serum theophylline. The chromatography system includes a muBondapack C18 column and acetonitrile, 70 ml/liter of sodium acetate buffer (10 mmol/liter, ph 4.0) as the mobile phase. Test serum or plasma, 30 mul, is mixed with an equal quantity of a solution containing the internal standard, beta-hydroxyethyltheophylline in acetonitrile/sodium acetate buffer (20 mmol/liter, pH 4.0), 7/43 by vol. After the precipitate is removed by centrifugation, the mixture is chromatographed and the amount of theophylline calculated from the ratio between peak heights for theophylline and the internal standard. Advantages include easy sample preparation, involving only addition of internal standard and centrifugation before injection, long column life, and the suitability of the internal standard, which is adjusted to a peak height equivalent to 20 mg of theophylline per liter for easy computation of results.