A double-blind, between-patient, placebo controlled trial was carried out to investigate the effects of methylcysteine hydrochloride in patients with chronic obstructive bronchitis. After a 2-week washout period on placebo, 30 patients were allocated at random to treatment for 6 weeks with either methylcysteine (1200 mg daily in Week 1, 800 mg daily in Week 2, then 600 mg daily) or with identical placebo tablets on the same regimen. During the post-treatment period, all patients returned to a single-blind placebo regimen (6 tablets daily) for a further 14 days. Assessments were made at the start, at regular intervals during the trial, and at the end of the post-treatment period, of subjective and objective measures of clinical response, and measurements of pulmonary function and certain physico-chemical properties of sputum. The results showed that methylcysteine increased sputum volume, reduced the viscidity of sputum, and significantly improved the subjective assessments of ease of expectoration and severity and frequency of cough, leading to a definite improvement in the patients' clinical state. No side-effects of clinical significance were reported and no abnormalities were found in any of the haematological, hepatic and renal function tests carried out.

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.