A Patient Complains of Pain in His Calf, Buttocks, and Thighs

A patient complains of pain in his calf, buttocks, and thighs after brisk walking or strenuous activity; the pain is relieved when activity is stopped. Pentoxifylline was prescribed to treat this patient's condition. What is the mechanism of action of this drug?

A) Block pain receptor in extremities, increases venous drainage
B) Increases blood flow to the extremities by decreasing blood viscosity.
C) Decreases muscle metabolism, opens more sodium channel, dissolves clots
D) Block pain receptors, blocks nerve conduction in pain fibres