By the use of thermocouple and clinical data, methyldopa was evaluated as a therapeutic agent in 42 patients with Raynaud's phenomenon. The administration of 1 to 2 gm daily of methyldopa was frequently effective in (1) preventing episodes of Raynaud's phenomenon during both experimental cold exposure and normal wintertime exposure; (2) improving the blood supply to the digital skin during cold exposure; (3) increasing the rate of rewarming of digits after cold exposure; and (4) relieving chronic pain in the fingers, which occurred at ambient temperatures above 25 C. The response of Raynaud's phenomenon to methyldopa depended most significantly on the relative contribution, in a given digit, of (1) spasm and (2) organic obstruction of digital vessels, respectively, to the development of ischemia. Only if spasm predominated could one anticipate a good response.
Varadi DP, Lawrence AM. Suppression of Raynaud's Phenomenon by Methyldopa. Arch Intern Med. 1969;124(1):13–18. doi:10.1001/archinte.1969.00300170015003