Dermal anaesthesia: comparison of EMLA cream with iontophoretic local anaesthesia.

We have compared the efficacy of two non-invasive methods of transdermal anaesthesia: application of EMLA cream and iontophoresis of 5% lignocaine with adrenaline 1:50,000 in six healthy subjects. We tested depth of tissue penetration (pinprick) and effect on pain evoked by i.v. injection. After iontophoresis, pain on i.v. injection was abolished in five of six volunteers, whereas EMLA had no effect. We conclude that local anaesthetics penetrate deeply enough to numb both veins and skin with iontophoresis only.