Abstract: AIM: To investigate the safety and tolerance of phentolamine mesylate in Chinese healthy male volunteers. METHODS: The trial protocol was designed according to the Good Clinical Practice (GCP) of the State Drug Administration of China (SDA).Thirty-six healthy volunteers in 18 -50 years old were chosen and randomized to 6 dose groups, including 10, 20, 30, 40, 50 and 60mg (n =6).Some indices were examined, including clinical symptoms, vital signs, routine blood tests, routine urine tests, hepatic functions, renal functions, blood electrolytes, electrocardiogram, and electroencephalogram. RESULTS: After single oral doses of 10 -60 mg, the vital signs, the clinical symptoms, and the values of laboratory tests were in the normal range. However, some slight adverse reactions were related to the drug, such as face flushing, nosal obstruction, dizziness, and pulse increased after administration.Penile erection was found in 9 volunteers 20 -30 min after administration. CONCLUSION: The single dose of 60 mg domestic phentolamine mesylate was safe and tolerable in 36 Chinese healthy male volunteers.

Key words: phentolamine mesylate, tolerance, healthy volunteers