Choice of antidote methionine usage on patients with acute paracetamol poisoning in the specialized toxicology unit in Sri Lanka

Abstract

Objective: This study was carried out to evaluate the choice of antidote, oral methionine, 4 doses of 2'59 q4h or intiavenous N acetylcysteine (iv NAC) 3OOmg/kg over 20 hours in the treatment of acute paracetamol overdose. Both drugs are on the-World Health Organization drug list for treatment of paracetamol poisoning. Method: This is a retrospective consecutive case series of acute paracetamol poisoning presenting between January 2013 and June 2015 to Toxicology unit, Teaching Hospital Peradeniya, Sri Lanka. The choice of treatment was with the admitting medical officer. We analyzed records of patients for treatment received, toxicity and recorded adverse effects. Results: There were 91 6 patients (609 female) with an acute paracetamol overdose including 406(44.32Vo) direcl admissions and 509(55.560/o) transfers. Median age was 20(lQR=24-17). 87 patients (9.50%) were treated with methionine, 195(21.28%) patients were treated with NAC and 634(69.21%) patients were not treated with an antidote. There is a significant difference (P<0.05) in duration of hospital stay. time to admission and ingested dose between methionine ind NAC treated patients (Tablel). Patients with persistent nausea and vomiting were given intravenous fluid replacement. Antiemetics were given to 96(49.23o/o) in NAC group and 41(47 .12o/o) in methionine group. Four patients on NAC treatment were changed to methionine due to anaphylactic reactions. One patient on irethionine was changed over to iv NAC due to vomiting and discovery of pregnancy during treatment in.another. Minor adverse events'iike headache, faintishness, drowsiness etc. occurred in28.680/o in NAC group. Methionine group showed headache, dizziness. faintishness, drowsiness elc. in 27 .43o/o. Forly eight (55.1 7%) vomited before ireatment and 1 1 vomited after treatment in methionine group. 140(71.8%) vomited before and 25(12.82o/o) vomited after treatment in the NAC group. Vomiting prior to antidote treatment was more likely in the group who were assigned to NAC [OR 0.48 (95%Cl0.2S 0.82)]. This group had ingested a lqrggr. dose of paracetamol f[9* was no difference in the proportion of patients who vomited after treatment with either NAC or Methionine, [OR 0.98 (95oloCl 0.462.10)1. No Liver failure, renal lmpairment and death occurred in either group. Conclusion: Oral methionine is still considered a treatment option in paracetamol poisoning. lt is well tolerated and can be administered in remote circumstances after paracetamol poisoning. The treatment protocol for oral methionine is simple, and therapy is completed within 12 hours compared to NAC. Admitting medical officers consider methionine as a treatment option despite iv NAC being available.