Drugs We have previously administered intra-arterial NAC without complication. Assuming a forearm blood flow of 50 ml/min, an infusion of 25 mg/min would be expected to achieve a local concentration ~500 mg/l, similar to peak concentrations reached during the standard 20-hour intravenous NAC protocol used on the hospital wards. We intend to use a range of 6 incremental doses at 10 min intervals to include this concentration: 1 mg/min, 5 mg/min, 10 mg/min, 50 mg/min, 100 mg/min, and 200 mg/min. The total infusion rate will be maintained 1 ml/min.