title: The antidotal action of thiosulfate following acute nitroprusside infusion in dogs.
abstract: The authors previously demonstrated in dogs that a bolus dose of sodium thiosulfate maintained enhanced cyanide metabolism throughout a 1-h infusion of sodium nitroprusside (SNP). To further test this antidotal action, a bolus dose of thiosulfate (150 mg . kg-1) was given to eight dogs at the end of a 60-min near-lethal infusion of nitroprusside (3 mg . kg-1). Within 2 min of the antidote, mean plasma thiocyanate levels (70.3 mumol . l-1) were significantly higher than those of seven control dogs given nitroprusside only (45.9 mumol . l-1, P = 0.002) and plateaued at 153.8 mumol . l-1 within 60 min, while the control values only reached 79.1 mumol . l-1 (P less than 0.001). Although differences between plasma cyanide levels in the two groups only attained significance 1 h after administering the antidote (0.8 vs. 2.74 mumol . l-1, P = 0.03), red blood cell cyanide concentrations were significantly lower in the antidote group within 5 min (166 vs. 225 mumol . l-1, P = 0.004) and remained so throughout the 2-h observation period. Compared with the controls, there was an impressive reduction in mean half-lives of plasma cyanide (25.1 vs. 74.1 min) and red blood cell cyanide (22.4 vs. 203.6 min). Similarly, peak cyanide levels occurred much sooner following the antidote (mean times: plasma cyanide 2.9 vs. 5.9 min; red blood cell cyanide 0.25 vs. 11 min).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.forename: C J
authors.initials: CJ
authors.lastname: Vesey
authors.forename: J R
authors.initials: JR
authors.lastname: Krapez
authors.forename: J G
authors.initials: JG
authors.lastname: Varley
authors.forename: P V
authors.initials: PV
authors.lastname: Cole
mesh_terms: D000137:Acid-Base Imbalance / Q000097:blood / Q000139:chemically induced / Q000517:prevention & control; D000818:Animals; D000931:Antidotes; D004285:Dogs; D004912:Erythrocytes / Q000378:metabolism; D005292:Ferricyanides / Q000008:administration & dosage*; D006856:Hydrogen Cyanide / Q000097:blood / Q000506:poisoning*; D007263:Infusions, Parenteral; D007275:Injections, Intravenous; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D009599:Nitroprusside / Q000008:administration & dosage*; D013861:Thiocyanates / Q000097:blood; D013885:Thiosulfates / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D000931:Antidotes; D005292:Ferricyanides; D007773:Lactates; D013861:Thiocyanates; D013885:Thiosulfates; D009599:Nitroprusside; D006856:Hydrogen Cyanide; D019344:Lactic Acid; C017717:sodium thiosulfate