Dose Response Study of a Topical Gel for the Treatment of Raynaud's Phenomenon

The Purpose of this clinical study is to determine, in a controlled fashion, the response to two dosage strengths of a topical gel formulation of Nitroglycerin, MQX-503, in the determination of changes in finger blood flow and skin temperature in the fingers of patients with moderate to severe primary Raynaud's phenomenon and with Raynaud's phenomenon secondary to autoimmune diseases, such as scleroderma. The dosage strength response in the treatment of the symptoms (pain, tingling, numbness) will also be monitored.