Introduction: Acute paraquat (PQ) poisoning is associated with high case fatality rate. Following a report of 108 cases of poisoning from 2011 to 2013, the distribution, sale, and use of PQ was recently prohibited in the Philippines. However, there still is a need to gather additional information on the manifestations of PQ poisoning in the Philippines. Hence, this study aimed to identify the clinical presentation and outcomes of cases of PQ poisoning seen in a hospital at northern Philippines.

Case presentation: Nine cases of oral PQ poisoning from 2011 to 2013 were included in this series. All cases were intentional. Majority (88%) of the patients were females. Seven of the nine (77%) cases were from Baggao, Cagayan, a nearby agricultural town. Mean age was 30 (range 21-47). Initial presenting symptoms were vomiting, difficulty in swallowing, abdominal pain and gastrointestinal bleeding. Of the nine cases, four died (44%) in the hospital. Three (33%) survived without complications. Long-term outcomes of the remaining two cases (22%) were unknown. All patients who eventually died developed dyspnea during their hospital stay, and subsequently went into acute respiratory failure. Azotemia and leukocytosis were also recorded among those who died.

Discussion: High mortality rate among PQ poisoning patients can be attributed to the absence of antidote and the unsatisfactory outcomes of post-exposure management.

Conclusion: Mortality rate for this series was 44%, and all died of progressive respiratory failure. Gastrointestinal toxicity was universal in the nine reported cases. Azotemia and leukocytosis were the other significant findings observed among the cases of fatal poisoning.

Keywords: paraquat, herbicide, ingestion, poisoning, case report

1. Sabzghabaee AM, Elizadi-Mood N, Montazeri K, Yaraghi, A, Golabi M; Fatality in paraquat poisoning. Singapore Med J, 5: 496-500, 2010.
2. Gawarammana I, Buckley N; Medical Management of paraquat ingestion. British Journal of Pharmacology, 72:745-757, 2011.
3. Afzali S, Gholyaf M; The Effectiveness of Combined Treatment with Methylpredisolone and Cyclophosphamide in Oral Paraquat Poisoning. Arch Iranian Medicine, 11:387-391, 2008.
4. Agarwal R, Srinivas R, Agarwal A N, Gupta D; Immunosup­pressive therapy in lung injury due to paraquat poisoning: a meta­analysis. Singapore Med J, 481:1000-1005, 2007
5. Paraquat Poisoning- a practical guide to diagnosis, first aid and hospital treatment. Health Assessment and Environmental Safety Department Syngenta and the Medical Toxicology Unit, Guy’s & St Thomas’ Hospital NHS Trust, London, UK. [pocket insert]
6. House Bill Number 5678: An Act Prohibiting the Distribution, Sale and Use of Paraquat in the Philippines. 17th Congress, Republic of the Philippines House of Representatives.
7. Senarathna, L, Eddleson M, Wilks, MF, Woollen BH, To­menson JA, Roberts DM, Buckley NA; Prediction of outcome after paraquat poisoning by measurement of the plasma paraquat concentration. QJ Med, 102:251–259, 2009.
8. Shi Y, Bai Y, Zou Y, Cai B, Liu F; The Value of Plasma Paraquat concentration in Predicting Therapeutic Effects of Haemoperfu­sion in Patients with Acute Paraquat Poisoning. PLoS ONE, 7:e40911, 2012.
9. Ja-Liang L, Dan-Tzu L, Kuan-Hsing C, Wen-Huang H, Ching- Wei H, Hsiang- Hao H, Tzung-Hai Y; Improved survival in severe paraquat poisoning with repeated pulse therapy of cyclophos­phamide and steroids. Intensive Care Med, 37:1006-1013, 2010.
10. Koo J, Yoon JW, Choi MJ, Park II, Lee YK, Kim SG, Oh JE, Seo JW, Kim HJ, Noh J; Rapid analysis of plasma paraquat us­ing sodium dithionite as a predictor of outcome in acute paraquat poisoning. Am J Med Sci. 338:373-7, 2009.
11. Pavan M; Acute Kidney Injury Following Paraquat Poisoning in India. Iranian Journal of Kidney Diseases, 7, 2013.
12. Hong SY, Yang DH, Hwang KY; Associations between labora­tory parameters and outcome of paraquat poisoning Toxicology Letters, 118: 53-59, 2000.
13. Li LR, Sydenham E, Chaudhary B, You C; Glucocorticoid with cyclophosphamide for paraquat-induced lung fibrosis. Cochrane Database Syst Rev, 7:CD008084, 2014.
14. He F, Xu P, Zhang J, Zhang Q, Gu S, Liu Y and Wanag J; Efficacy and safety of pulse immunosuppressive therapy with glucocorticoid and cyclophosphamide in patient with paraquat poisoning: A metanalysis. International Immunopharmacology, 27:1-7, 2015.