A Randomized Control Trial to Assess the Efficacy of Tadalafil in Raynaud's Phenomenon in Scleroderma

Inclusion Criteria: Male or female subjects between the ages of 18 years and 65 years will be selected for the study if they have a clinical diagnosis of Raynaud's phenomenon secondary to systemic sclerosis (scleroderma) despite being on vasodilator therapy. Raynaud's phenomenon is defined as a history of cold sensitivity associated with colour changes of cyanosis or pallor. Patients with a history of at least 4 attacks per week during two-week pre-trial period even with treatment with other vasodilators will be recruited. Patients fulfilling the diagnostic criteria of scleroderma (as per American College of Rheumatology criteria) or having presence of at least 3 of the 5 features of the CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasias)will be invited to participate in the study. Exclusion Criteria: Patients with: * Symptomatic orthostatic hypotension, * Evidence of current malignancy, * History of sympathectomy, * Upper extremity deep vein thrombosis or lymphedema within 3 months, * Recent surgical procedure requiring general anesthesia, * Acute Myocardial Infarction, unstable angina, strokes and transient ischemic attacks within the past three months, * Smoking, * Use of any investigational drug within 30 days of the study sessions, * Use of medications that might interfere with tadalafil like nitrates and alpha adrenergic blockers that have vasoactive effects, and patients taking potent inhibitors of CYP3A4 such as ritonavir, ketoconazole, and itraconazole, erythromycin, itraconazole, and grapefruit juice, * Patients taking alcohol, * Patients with bleeding disorders * Significant active peptic ulceration, * Current pregnancy, * Current breast-feeding.