Description: Cilostazol is a quinolinone derivative that functions as a phosphodiesterase 3 (PDE3) inhibitor. It works by inhibiting platelet aggregation (clumping) and by acting as a vasodilator, meaning it widens blood vessels. This dual action helps to improve blood flow.

Indication: The primary indication for Cilostazol is the treatment of symptoms associated with intermittent claudication. This is a condition caused by peripheral artery disease (PAD), where narrowed blood vessels in the legs lead to pain, cramping, or numbness during walking or exercise. Cilostazol is used to reduce these symptoms and increase the patient’s walking distance. It is typically a second-line treatment for patients who have not responded to lifestyle modifications like exercise and smoking cessation.

Mechanism of Action: Cilostazol’s mechanism of action involves inhibiting the enzyme phosphodiesterase III (PDE3). This inhibition prevents the breakdown of cyclic adenosine monophosphate (cAMP) inside cells. The resulting increase in cAMP levels leads to two key effects:

1. Antiplatelet effect: The increased cAMP in platelets inhibits their activation and aggregation, reducing the risk of blood clots.
2. Vasodilatory effect: The increased cAMP in the smooth muscle cells of blood vessels causes them to relax and widen (vasodilation), improving blood flow to the legs.