Sensitive GLC-mass spectrometric determination of chlorpheniramine in serum.

A new method was developed for the quantitative analysis of chlorpheniramine in serum using the high sensitivity and selectivity of GLC-mass spectrometry with selected-ion monitoring. Intense fragment ions at m/e 203 and 207 from the drug and a tetradeuterated analog, respectively, are monitored continuously. The deuterated quantitation standard can be prepared by a simple exchange reaction. A linear calibration curve was obtained over the range of 0-160 ng/ml of serum using 85 ng of the standard/ml. The sensitivity limit is 1-2 ng/ml, and each serum extract can be analyzed in less than 2 min. The method was applied to a measure chlorpheniramine concentrations through at least 1.5 biological half-lives.

Pharmacokinetics of intravenous chlorpheniramine in children.

The disposition of chlorpheniramine was examined in seven children, 6-14 years of age, following a 0.1 mg/kg iv dose. Postinjection serum chlorpheniramine levels in each subject declined biexponentially, with the greatest intersubject variability occurring in the initial distribution of the drug. The volume of distribution at steady state ranged from 1.20 to 5.46 liters/kg. The chlorpheniramine serum clearance varied approximately twofold (234-470 ml/hr/kg) and generally decreased with age. The chlorpheniramine elimination half-life in children (mean of 9.6 hr) appeared shorter than that in adults, probably due to higher chlorpheniramine serum clearance in children.