CORRELATION OF MORPHINE-SULFATE IN BLOOD-PLASMA AND SALIVA IN PEDIATRIC-PATIENTS

This study sought to determine whether saliva concentrations of morphi ne correlate with plasma levels of morphine in pediatric patients rece iving morphine analgesia for severe pain, and to evaluate whether the measurement of saliva morphine concentrations would be a useful, nonin vasive, clinical tool to diagnose systemic exposure to morphine. Fifte en pediatric patients were enrolled. for the control group, 18 adult v olunteers were recruited. Patients received continuous morphine drips to ameliorate pain caused by a sickle cell vasoocclusive crisis (range , 10-40 mu g/kg.h). Control subjects were randomized into those receiv ing acetaminophen with either 8 mg (n = 13) or 30 mg (it = 5) of codei ne. All participants fasted at least 2 hours before sample collection. Blood and saliva samples were collected simultaneously. All samples w ere analyzed by radioimmunoassay for morphine. There was no correlatio n between saliva and plasma morphine concentrations in either the pati ents receiving intravenous morphine (r = 0.04, P = 0.89) or in the con trols receiving codeine (r = 0.43, P = 0.08). There was no observed di fference in the mean counts per minute (CPM) for saliva samples in the pH range 3.96 to 8.06. Saliva concentrations of morphine cannot be us ed to predict the plasma concentration of morphine in children or adul ts. However, the concentration of morphine in saliva may be used as a qualitative indicator of systemic exposure to morphine in a subject.