[Effects of promethazine on acupuncture analgesia]

Promethazine, one of histaminergic H1-receptor antagonist, was often used as an adjuvant drug prior to and during acupuncture anesthesia in clinics, However, its effects was not known clearly. By using potassium iontophoretic dolorimetry and stimulating unilateral "Hegu" and "Waiguan" points with electroacupuncture (EA) in 42 rabbits, we found that Promethazine could drop the pain threshold in small dosages (0.5 mg/kg, 1 mg/kg) and raise the pain threshold in relatively large dosages (2 mg/kg, 4 mg/kg). In different dosages (1 mg/kg, 2 mg/kg), promethazine could attenuate the analgesic effect of EA. It was suggested that promethazine should be used carefully in acupuncture anaesthesia.