Thiamin status in furosemide-treated rats.

Rats were treated with furosemide at intraperitoneal doses of 10, 20, and 30 mg kg(-1)day(-1)for 21 days, and some indices of thiamin status (liver, blood and urine thiamin concentrations, erythrocyte transketolase (TK) activity, and thiamin pyrophosphate (TPP) effect, which refers to the increase in TK activity in a deficient haemolysate due to the addition of TPP before incubation) were measured. The results indicated that, at doses of 20 and 30 mg kg(-1)(but not 10 mg kg(-1)), furosemide produced significant effects on these indices suggestive of thiamin deficiency. In another experiment, the effect of thiamin treatment (20 and 100 microg kg(-1)) in rats concomitantly given furosemide (30 mg kg(-1)) was investigated. The high dose of the vitamin was sufficient to overcome the biochemical signs of thiamin deficiency induced by furosemide.