The effect of calcium channel antagonist administered by iontophoresis on the pain threshold.

Three calcium (Ca) channel antagonists were administered to healthy adult volunteers by iontophoresis alone or in combination with lidocaine to study their effects on the pain threshold. Nicardipine, verapamil or diltiazem administered alone elevated the pain threshold to the same degree as lidocaine. When Ca channel antagonists were administered in combination with lidocaine, the pain threshold elevation was not changed, but the duration of the analgesic action was prolonged when compared with lidocaine alone. These results suggest a role of the calcium channel in the pain control mechanism and the possible clinical application of Ca channel antagonists delivered by iontophoresis in pain management.