NeurogesX has finished enrolling 400 patients in a Phase III clinical trial of Transacin, a pain drug delivered by skin patch.

The company is studying the use of the drug against pain that follows healing of shingles. That pain, which affects about 20 percent of patients who get the disease, can last for years. Transacin, the company hopes, will provide a better treatment than opioids used now, which can cause drowsiness since they act on the central nervous system. The dermal patch will deliver the drug to the skin, where the pain originates.