A Prospective Clinical Trial of Pulse Therapy with Glucocorticoid and Cyclophosphamide in Moderate to Severe Paraquat-poisoned Patients

Abstract

Paraquat (PQ) is a widely used bipyridyl contact herbicide with a good safety record when used properly. Most cases of PQ poisoning result from PQ suicidal ingestion. There are three degrees of severity in PQ poisoning (1, 2). Mild poisoning can cause oral irritation and gastric upset, and brings complete recovery. Moderate to severe poisoning produces acute renal failure, and in severe cases, hepatitis followed by pulmonary fibrosis, leading to death after 2 to 3 wk. Acute fulminant poisoning results in death within 1 wk from multiple organ failure and cardiovascular collapse. Retrospective studies (3–6) show that good predictors of outcome may be plasma and urine concentrations within the first 24 h of intoxication. The urine PQ tests taken on admission are reasonable guides to predict the severity of poisoning and have the advantage that a qualitative or semiquantitative result may be easily and rapidly obtained in an emergency situation (5–7). The results of treatments for PQ poisoning, including absorbents, pharmacological approaches (8), radiotherapy (9), hemodialysis, and hemoperfusion (10), were disappointing. Although the high-dose cyclophosphamide (CP) and dexamethasone (DX) treatments, including intravenous CP 5 mg/kg/d and DX 24 mg/d for 14 d, had a 75% survival rate after PQ poisoning (11), a subsequent study (12) did not demonstrate the efficacy of this approach. Therefore, the efficiency of highdose CP and DX in PQ poisoning remains controversial. Recently, pulse therapy with CP and methylprednisolone (MP), including intravenous CP or MP 1 g/d for 2 to 3 d, has been used to treat effectively many patients with severe lung damage from systemic lupus erythematosus (SLE) and Wegener’s granulomatosis (13, 14), with greater efficacy and less side effects than those of high doses of CP therapy. In addition, our preliminary report (15) demonstrated that pulse therapy might be effective in treating patients with moderate to severe PQ poisoning. Because the previous study was not prospective and only included a small number of patients, we designed the prospective study to evaluate its efficacy in treating a large group of PQ-poisoned patients. METHODS