Influence of intravenous acetylsalicylic acid and sodium salicylate on human renal function and lithium clearance.

The influence of intravenous acetylsalicylic acid (ASA; D,L-lysine-mono-acetylsalicylate), equimolar doses of sodium salicylate (SA) and placebo (P) on renal function has been studied in 6 healthy female volunteers, in 150 mmol sodium balance, and in lithium (Li) steady state with a plasma Li between 0.6 and 0.8 mmol/l. Following a bolus injection of 0.5 g ASA, 0.444 g SA or P (50 ml saline) given over 10 min and a subsequent continuous infusion of 1.5 g ASA, 1.332 SA or P (150 ml saline) over 170 min, urine was collected for 3 h as well as 6 plasma samples at 30-min intervals. Plasma ASA levels were between 13.8 and 22.1 micrograms/ml and for SA they were 20.8 to 82.6 microgram/ml during ASA infusion, and between 22.5 and 108.9 microgram/ml for SA during SA infusion. Neither ASA nor SA caused a significant change in urine volume, in the renal clearances of Na, K, free water, osmolality, creatinine, inulin and p-aminohippurate (PAH) or in plasma Li level. Renal Li clearance was slightly reduced by SA, from 37.8 to 29.4 ml/min (p less than 0.05). Since renal prostaglandin (PG) synthesis (urinary PGE2 excretion) was 60.6% suppressed by ASA and was not affected by SA, the decrease in Li clearance cannot be related to inhibition of cyclooxygenase in the kidney.