[The effect of iontophoresis with several Ca channel blockers for PHN patients]

We performed iontophoresis with Ca channel blockers for healthy adult volunteers. In this clinical study, we used iontophoresis with Ca channel blockers. Ten out patients with PHN treated at our pain clinic were treated with iontophoresis. They were randomly assigned to one of the following four treatments: (1) 5 ml of 4% lidocaine HCl, (2) 2 mg of nicardipine HCl + 5 ml of distilled water, (3) 2 mg of verapamil HCl + 5 ml of distilled water, and (4) 2 mg of diltiazem HCl + 5 ml distilled water. Iontophoresis was performed using the above four drugs on the positive pole. Using a VAS, each patient was evaluated concerning the analgesic effect. The pain before treatment (10 points) was used as the base line. Compared with the scores before treatment, VAS scores decreased significantly after iontophoresis in all four groups. In the lidocaine group, a significant decrease in VAS scores occurred immediately after iontophoresis and lasted up to 24 hours, reaching the nadir at 2 hours. In the nicardipine group, the decrease occurred immediately after iontophoresis and lasted up to one day, reaching the nadir at four hours. In the verapamil group, the decrease started 1 hour after iontophoresis and lasted up to 48 hours, reaching the nadir at 8 hours. In diltiazem group, the decrease started 1 hour after iontophoresis and lasted up to 48 hours, reaching the nadir at 4 hours. Iontophoresis with Ca channel blockers produced a prolonged analgesic effect in PHN patients. Previously we had observed the same effect in adult volunteers. Therefore, we believe that this therapy will be clinically useful.