Feasibility and acceptance of salivary monitoring of antiepileptic drugs via the US postal service

Salivary and serum levels of phenobarbital, carbamazepine, and phenytoin are closely correlated. Salivary monitoring of antiepileptic drugs has a number of advantages including the potential for home collection if measured levels are unaffected by transit in the mail. Saliva was collected from 60 adult and 42 pediatric patients in the clinic. A control aliquot was immediately frozen, and a second aliquot was packaged and mailed to the laboratory. Patients were also asked to collect another sample at the same time on the following day and mail it to the laboratory. On receipt, all samples were held frozen and analyzed as a single batch by fluorescence polarization immunoassay. The effects of mailing, the duration in transit, and the season were assessed by multivariable, repeated-measures analysis of variance. One hundred two saliva samples were collected in a mean of 2.6 minutes, and the mailed aliquot was received in a mean of 6.4 days. Two children and 3 adults (4.9% of total) preferred blood collection, but the rest preferred saliva collection or had no preference. There was no significant difference between the control sample and the clinic mailed samples for any of the 3 medications. There were no significant effects of the duration in transit or the season on reliability. Transit of saliva samples in the mail does not adversely affect accuracy of antiepileptic drug measurement. Patients prefer and can successful collect saliva samples at home. Home monitoring of salivary antiepileptic drug levels is a cost-effective technique that deserves additional study.