Elimination effects of gastric lavage in swine model of paraquat poisoning

Abstract

Objective To evaluate the elimination effect of gastric lavage (GL) in the swine model of paraquat (PQ) poisoning by using the determination of PQ plasma concentration. Methods A total of 17 healthy female domestic swine were randomly divided into PQ group (n=6), PQ+ 1 h GL group (n=6) and PQ+ 6 h GL group (n=5). A dose of 60 mg /kg PQ in 40% PQ solution was administered in all animals through gastric tube. Swine of PQ+ 1 h GL group and PQ+ 6 h GL group were treated with gastric lavage by using 20 L warm water at 1 h and 6 h after ingestion of PQ, respectively. Vital signs and PQ plasma concentration were monitored continuously for 24 h. LC-MS device was used to measure the PQ concentrations in lavage fluid and plasma, and HPLC was performed to measure the fluid drug concentration. Results The 24 h survival rates of PQ group, PQ+ 6 h GL group and PQ+ 1 h GL group were 66.7%, 80% and 100%, respectively. The peak plasma PQ concentration in PQ group was (5.12±3.38)μg/mL, in PQ+ 6 h GL group was (3.99±1.24)μg/mL, and in PQ+ 1 h GL group was (1.96±1.83)μg/mL. The percentage of the total amount of PQ ingested in the gastric lavage fluid in PQ+ 1 h GL group was (24.46±6.49)% and in PQ+ 6 h GL group was (30.72±9.86)% (P>0.05). Alternatively, the gastric lavage process was divided into two successive procedures with 10 L warm water in each instead of 20 L water in one procedure . The content of PQ in lavage fluid from the first 10 L warm water was (20.44±5.59)% and that from the second 10 L warm water was (4.02±1.82)% in PQ+ 1 h GL group (P<0.01), whereas (26.17±7.19)% PQ in gastric lavage fluid from the first 10 L warm water and (7.03±4.29)% PQ in gastric lavage fluid from the second 10 L warm water, in PQ+ 6 h GL group (P<0.01). Conclusions Gastric lavage process carried out in two successive procedures with 10 L warm water in each can eliminate PQ effectively, thus reducing the mortality. The early gastric lavage (1 h) can cause significantly decrease in plasma PQ peak concentration. However, the clearance rate of gastric lavage process is significantly lower in the second procedure in comparison with the first procedure of gastric lavage. Key words: Paraquat; Gastric lavage; Drug concentration; Clearance ratio