Single dose oral H2-antagonists do not affect plasma lidocaine levels in the parturient.

We studied whether a single oral dose of either cimetidine or ranitidine affects the disposition of epidurally administered lidocaine in the parturient. Patients given epidural analgesia for elective caesarean section were randomly pretreated with either cimetidine 400 mg (n = 5), ranitidine 150 mg (n = 7) or no H2 receptor antagonist (n = 5). Following the administration of 400 mg of lidocaine 2% with adrenaline 1:200,000 no difference was found in peak plasma lidocaine levels or area under the plasma concentration/time curve (AUC) between the three groups. A single oral dose of cimetidine or ranitidine does not affect lidocaine disposition in the obstetric patient.