A patient with rodenticide overdose

Dr WL Yip, AED, QMH

Case report

• F/44, housewife

• Found lying on the floor with decrease in responsiveness

• Found an empty pack of ‘stilnox’ and an empty can of beer lying around

• Argued with her husband one day ago

• Brought to AED ~0730

Examination

• BP 120/60 P 100

• Temp 35.70C

• SaO2 98 with RR 22

• Drowsy, with GCS E4 V5 M5

• H’stix 4.7

• ECG NSR 85/min

Further management

• Bld / Urine samples taken, with result pending

• Admit medical due to full ‘O’ ward

• Patient woke up after 2 hours

• Admitted taken 20 tabs of stilnox and 1 can of beer, and denied other drugs taken

• Pending seeing psychiatrist

Investigation…

• At 1400, found INR 7.7, PT 86.8, PTT 57.1• Repeated… INR 7.6• Further questioning… taken 1 pack of rat

poison bought over the counter few days ago

• Contacted her husband…• found a pack of rat poison ~5 days ago in

dust-bin at home

Other investigation results

• Hb 14.5

• Urine toxicology: BDZs, zolpidem metabolites

• Otherwise unremarkable

Management

• Clinically stable

• No bleeding clinically

• Transfusion of 4 units of FFP

• Daily vitamin K1 10mg

• INR 1.4 the next day

• Seen by psychiatrist – depression

Psychiatric ward

• Form 123, transferred to PYNEH psychiatric ward

• Continued daily oral vitamin K (10mg QD)

• INR finally back to 1.0 after 9 days

• Vitamin K was continued for 1 more week afterwards

INR

Day 0 Day 1 Day 3 Day 6 Day 9

7.7 1.4 2.0 1.7 1.0

FFPvit K1 (iv)

vit K (po)

Rodenticides

• Warfarin / Superwarfarin

• Arsenic

• Cholecalciferol

• Sodium monofluoroacetate

• Strychine

• Thallium

Warfarin / Superwarfarin

Warfarin / Superwarfarin

• Commonest in Hong Kong

• Anticoagulants

• prevent vitamin K from reducing to its active form

• inhibit hepatic synthesis of coagulation factors II, VII, IX, and X and the anticoagulant proteins C and S

Vitamin K metabolism

Coagulation pathway

Initiation of coagulation

Superwarfarin

• Brodifacoum, bromadiolone

• Warfarin-resistance rats

• Clinical effects occur after depletion of the mentioned factors (~3-4 days)

• Longer acting (weeks to months)

• Longer half-life (156 vs. 17 hrs)

• 100-folds more potent

Clinical features

• Rarely symptomatic, unless delayed presentation

• Signs of bleeding• Reported complications: Spontaneous intra-

abdominal hemorrhage, hematuria, hematemesis, spontaneous hemoperitoneum, intracerebral hemorrhage, death

Investigation

• Clotting profile, repeated in 24-48 hours

• Drug level if available

• Pregnancy test for females of childbearing age

Management

• GI decontamination

• Activated charcoal

• Specific treatment– Vitamin K– FFP

Vitamin K

• 15-120mg/d in divided doses

• T1/2 = 6 hours

• Antagonizes effects of warfarin • Indicated in INR>2• ‘reverse’ anticoagulation, but not ‘prevent’ its

effect• Anaphylactoid reaction if given iv• Caution if already anticoagulated for other reasons

Superwarfarin poisoning

• Required higher daily dose and longer duration (in months) of vitamin K

FFP

• Indicated if evidence of bleeding despite use of vitamin K

比山埃毒百倍 警檢鼠藥器皿毒鼠強奪命案枉死增至 243人 

16/09/2002

【中國組報道】南京驚天毒殺案後第二日，部分留醫者家屬昨夜收到醫院發出病危通知，死亡人數可能進一步攀升。而摻在受害者早餐中的毒藥，證實是毒性比山埃還要強烈一百倍的老鼠藥「毒鼠強」；警方在案發地點和盛園的水井旁發現殘留毒鼠強的器皿，一名案發後失蹤的和盛園員工成重大疑犯。有消息稱，毒殺案死者人數高達二百四十三名，而非官方公布的四十一人… 

Tetramethylene Disulfotetramine

• C4H8N4O4S2

• GABA-antagonist, with CNS excitation• Onset of symptoms several to 30 min (max.

13 hours)• 6-12 mg is sufficient to cause death• Proven to be toxic thru oral, inhalation and

dermal routes• Rapid absorption with slow elimination

Mild toxicity

• Headache

• Dizziness

• Fatigue

• Anorexia

• Nausea and vomiting

• Numbness of lips

• Listlessness

Severe toxicity

• Loss of consciousness

• Seizures

• Foaming at the mouth

• Urinary incontinence

• Coma

• Death from respiratory failure

Management

• Confirm its presence in vomitus, blood or urine

• Symptomatic / supportive treatment

• Gastric lavage and activated charcoal

• Charcoal hemoperfusion

• Hemodialysis

?Antidote

• No specific antidote

• Vitamin B6 and DMPS (2,3-dimercapto-1-sulphonate)

• Inhibit convulsion and reduce mortality in animal studies

• No data a/v in human cases

Thank you