Moxisylyte, also known as thymoxamine, is a drug used in urology for the treatment of erectile dysfunction. It is an α1-adrenergic antagonist. Moxisylyte is also used for the short-term treatment of primary Reynaud's syndrome, a condition where the fingers and toes become discoloured in response to cold or emotional distress. Moxisylyte helps by improving blood circulation to the extremities. It is also used locally in the eye to reverse the mydriasis caused by phenylephrine and other sympathomimetic agents.