Treatment in Paraquat Poisoning

Initial Hospital Management
1. Ensure Airway, Breathing and Circulation are intact
2. Control vomiting with

• 5HT3 antagonists e.g. Ondansetron 8mg (5mg/m2 in children) by slow i.v. injection or i.v. infusion over 15 minutes
• Phenothiazine anti-emetics e.g. prochlorperazine Dopamine antagonists such as metoclopramide should be avoided as they may impair therapy for renal support with dopamine

3. Decontamination:

• Activated charcoal - 100g for adults or 2 g/kg body weight in children [50g Stat and 25g 4 hourly] OR
• Fuller’s Earth - 15% solution; 1 litre for adults or 15ml/kg body weight in children [300ml Stat than 20ml every hour till diarrhoea] 
• NOTE: The use of gastric lavage without administration of an adsorbent has not shown any clinical benefit.
• *[] recommendation from Sarawak Handbook of medical emergencies
• A purgative should also be used, e.g. mannitol or magnesium sulphate
• Rehydrate the patient to optimise renal clearance of paraquat, paying attention to the possibility of fluid overload and electrolyte imbalance. 
• NOTE: Forced diuresis is not recommended

4. Do not give supplemental oxygen unless serious hypoxia is present

Subsequent Management

• i.v. fluids – the kidney is the major route of excretion of paraquat and renal function must therefore be closely monitored and optimum function maintained.
• analgesics – aggressive analgesia (e.g. opiates) may be required since patients can have severe pain from oral, oesophageal or abdominal corrosive injury.
• mouth care for ulceration and inflammation. - patients should be kept nil by mouth if there is a suspicion of oropharyngeal or oesophageal injury

Immunosuppresion

• widely practised as a treatment of paraquat self-poisoning
• The theory is that as paraquat leads to an acute inflammatory response, interference with this may inhibit the processes that follow that then lead to lung fibrosis and death
• might have a role in moderate to severe poisoning
• methyprednisolone 15mg/kg +/- Cyclophosphamide 15mg/kg followed by a high dose Dexamethasone [Sarawak Handbook 3rd edition]
• other treatment used are 1 g of cyclophosphamide daily for 2 days and 1 g of methylprednisolone daily for 3 days
• current practice 15mg/kg in 250 NS for 2 days

References:

1. Medical Management of Paraquat Ingestion http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3243009/#b84
2. Paraquat Poisoning. http://www.syngenta.com/global/corporate/en/pqmedguide/documents/paraquat-booklet.pdf
3. Sarawak Handbook of Medical Emergencies 3rd Edition