Efficacy Study of PDE-5 Inhibitor and Calcium Channel Inhibitor for the Treatment of Secondary Raynaud Phenomenon

The prevalence of Raynaud phenomenon (RP), a reversible vaso-constriction with skin discoloration, is 5-10% in general population. Often conventional measures such as warming up or minimizing exposure to cold are not enough and many patients require treatment with a vasodilator therapy. A recent study showed a good efficacy and safety profile of sildenafil, a selective inhibitor of cGMP specific phosphodiesterase type 5 (PDE5) in RP. Here, the investigators aim to examine the efficacy and safety of Udenafil, a newer PDE5 inhibitor, as compared to amlodipine, a well known calcium channel blocker, in the treatment of secondary RP in Korean patients.