Alkalinisation of prilocaine for intravenous regional anaesthesia. Suitability for clinical use. Eighty unpremedicated patients undergoing day-case hand surgery under intravenous regional anaesthesia were randomly allocated to receive, in a double-blind study, either 40 ml 0.75% prilocaine hydrochloride, with 5 ml 8.4% sodium bicarbonate or 5 ml 0.9% saline. The alkalinised group had significantly less pain on injection (p = 0.0045), during surgery (p = 0.0074) and 5 minutes after the tourniquet was deflated (p = 0.0027). The time elapsed between insertion of the block and commencement of surgery was not affected. 