Pentoxifylline exerts its therapeutic effects primarily by improving blood flow and circulation. It works by inhibiting the enzyme phosphodiesterase, which results in increased levels of cyclic adenosine monophosphate (cAMP) within cells. Elevated cAMP levels lead to relaxation of vascular smooth muscle and dilation of blood vessels, thereby improving blood flow to affected areas. Additionally, pentoxifylline reduces the viscosity of blood, making it less likely to form clots and improving the flexibility of red blood cells.