Long-term monitoring of the effects of thymoxamine hydrochloride tablets in the management of patients with Raynaud's disease.

Seventeen patients with Raynaud's disease were followed whilst receiving treatment with 40 mg thymoxamine hydrochloride 4-times daily for period ranging between 11 and 19 months. Digital artery patency and blood flow changes, assessed by Doppler ultrasound techniques after different thermal stresses, were monitored regularly as were platelet aggregation to ADP and collagen, platelet adhesion to glass beads, measures of blood coagulation and fibrinolysis, and plasma viscosity. Significant clinical improvement noted at 1 month appeared to improve further at 3 months and was maintained thereafter. Vessel patency rates at 10 degrees C and 21 degrees C improved significantly during treatment and both collagen- induced aggregation and platelet retention were significantly inhibited. These unexpected effects on platelet function are not readily explained by the drug's documented activity as a selective alpha-adrenergic antagonist and they may represent other hitherto unrecognized pharmacological effects which merit further exploration. The study also confirmed the usefulness of Doppler techniques for continuous atraumatic evaluation of digital vessel patency and investigation of therapeutic regimens on intermittent digital artery obstruction in Raynaud's disease.