Rapid, sensitive high-performance liquid chromatographic method for the quantification of promethazine in human serum with electrochemical detection.

A method of analysis has been developed to quantify promethazine in human serum with a sensitivity that was suitable for bioavailability studies following a 50.0-mg rectal dose. The limit of quantification from 1.0 ml of serum for promethazine using electrochemical detection was 0.200 ng/ml. At this concentration, the total coefficient of variation obtained from seven replicates over the course of three days of validation was 7.53%. The amount of serum required, the ease of sample preparation and the precision of the method at the limit of quantification demonstrated an improvement over previous assays. A validation study was completed that included an evaluation of recovery, ruggedness, linearity of response, accuracy, precision, sensitivity, stability and selectivity. The method was then used to determine promethazine serum levels in a 36-subject bioavailability study following a 50.0-mg suppository dose.