[Evaluation of adsorption effect of activated charcoal on oral paraquat poisoning: an experimental study on large animal].

OBJECTIVE

To study the adsorption effect of activated charcoal suspension on paraquat (PQ) in gastrointestinal tract of beagles exposed to PQ.

METHODS

Twenty healthy male beagles were randomly divided into experimental group and control group, with 6 beagles in each group. 20% PQ solution (a dose of 30 mg/kg) was prescribed through stomach for beagles in both groups. After exposure to PQ for 30 minutes, the beagles in experimental group were given activated charcoal suspension (1.0 g/kg of type I activated charcoal powder mixed with 100 mL of normal saline) by gavage, while the control group was only given equal volume of normal saline. After exposure to PQ for 10 minutes, 30 minutes, and 1, 2, 4, 8, 12, 24, and 48 hours, blood was collected from hepatic portal veins and peripheral veins to detect the PQ concentration change in the plasma. The toxicokinetics software DAS 2.1.1 was applied to analyze PQ concentration and compare the change in toxicokinetics parameters between the both groups. The change in vital signs including heart rate (HR), respiratory rate (RR) and pulse oxygen saturation (SpO) was dynamically monitored 10 minutes before exposure, 4 hours and each day from the 1st to the 7th day after exposure.

RESULTS

After exposure to PQ, the poison concentration in the plasma of hepatic portal veins and peripheral veins in the control group rose quickly and reached peak 4 hours later. It fell quickly at first, and fell slowly 8 hours later. But in the experimental group, the increase rate to the peak was significantly slow. Besides, PQ peak fell more obviously than that in the control group and it was about 50% of the control group (μg/L: 123.50±11.67 vs. 255.18±12.29 in blood from hepatic portal veins, 122.35±11.72 vs. 250.86±11.15 in blood from peripheral veins). After 8 hours it fell much more quickly than that of the control group. After exposure to PQ for 48 hours, PQ concentration in the plasma was still lower than that of the control group (μg/L: 0.53±0.18 vs. 15.98±5.58 in blood from hepatic portal veins, 0.31±0.01 vs. 15.03±4.82 in blood from peripheral veins, both P < 0.01). With the toxicokinetics analysis, compared with the control group, the maximum concentration (Cmax) and area under the curve (AUC) of PQ in the plasma of hepatic portal veins and peripheral veins in the experimental group were significantly decreased [Cmax (μg/L): 125.07±9.49 vs. 255.18±12.29 in blood from hepatic portal veins, 123.38±9.52 vs. 250.86±11.15 in blood from peripheral veins; AUC (mg×L×h): 1.6±0.2 vs. 3.3±0.4 in blood from hepatic portal veins, 1.5±0.2 vs. 3.2±0.3 in blood from peripheral veins], time to the peak (Tmax) of PQ was slowed (hours: 5.3±1.9 vs. 4.0±0.0 in blood from hepatic portal veins, 4.7±1.5 vs. 4.0±0.0 in blood from peripheral veins), and PQ plasma half-life (t) and mean retention time (MRT) were significantly shortened [t (hours): 3.8±1.2 vs. 15.4±3.7 in blood from hepatic portal veins, 3.5±1.0 vs. 15.5±2.7 in blood from peripheral veins; MRT (hours): 8.0±1.5 vs. 13.4±1.2 in blood from hepatic portal veins, 7.6±1.3 vs. 13.3±1.2 in blood from peripheral veins; all P < 0.01]. After exposure to PQ, HR and RR in both the experimental group and the control group increased and reached to the peak about the 4th day and then the increase rate began to slow down gradually; SpO slowed down gradually and reached to the valley about the 4th day and then it began to recover, but the change range of vital signs in the experimental group was smaller than that of the control group, and the parameters were significantly better than those of control group [4-day HR (bpm): 134.50±3.04 vs. 142.00±6.43, 4-day RR (times/min): 31.00±0.58 vs. 34.33±0.94, 4-day SpO: 0.900±0.006 vs. 0.873±0.005, all P < 0.05].

CONCLUSIONS

Activated charcoal administrated at 30 minutes after PQ poisoning can slow down the increase rate of PQ concentration in the plasma, decrease the peak concentration and has less influence on vital signs in beagles.