Failure of alkaline diuresis to enhance diflunisal elimination.

1 The effects of alkaline diuresis on the elimination of a single oral dose of 750 mg diflunisal were studied in six healthy male volunteers. 2 The plasma concentrations and half-life of diflunisal were not reduced by alkaline diuresis. 3 The 72 h urinary recovery of unchanged diflunisal was more than doubled with alkaline diuresis, but even so, only 5-7% of the administered dose was excreted unchanged. 4 With alkaline diuresis there was a significant increase in the mean renal clearance of diflunisal from 0.27 to 0.46 ml/min, but there was no significant correlation between the renal clearance of diflunisal and urine flow or pH. 5 However, there was a significant increase in the overall mean renal clearance of diflunisal from 0.22 ml/min over the period 0-24 h to 0.73 ml/min from 48-72 h. 6 Forced alkaline diuresis is unlikely to be of value in diflunisal poisoning.