Forensic Toxicology

Quetiapine Overdose

April 18, 2012 by fortox in Forensic Toxicology, Toxins with 0 Comments

Quetiapine is an antipsychotic used to treat the symptoms of schizophrenia and bipolar disorder. Its brand name is “Seroquel” which is also used as an antidepressant and occasionally prescribed in lower dosages as a sleeping aid. Combined with alcohol, Seroquel can be dangerous, even fatal. A common misconception is that because alcohol and Seroquel are both legal drugs, mixing them is not dangerous. Quetiapine is metabolised by CYP 3A4 in the body and prolongs the QT interval.


Structure of Quetiapine


Annual sales of Quetiapine are approximately $5.7 billion worldwide and $2.9 billion in the United States. There have been reports of the drug being used with cocaine (referred to as “Q-Ball”). But the drug is also used recreationally and is known on the street as “quell”, “Snoozeberries” or “Susie-Q”. It has also been reported that when Seroquel is used with methadone it causes the user to experience a buzz or opioid euphoria. Quetiapine has sometimes been used as a date rape drug which causes the victim to lose consciousness before a sexual attack, especially when co-administered with alcohol.


Adverse effects of Quetiapine can include the following;

  • Drowsiness
  • Difficulty cooling down body temperature
  • Light-headedness
  • Indigestion
  • Stomach pain or swelling
  • Headache/stuffy nose
  • Difficulty concentrating and difficulty speaking
  • Unusual dreams
  • Decreased sexual desire or ability
  • Tingling, numbness or burning in the arms or legs
  • Loss of coordination
  • Irritability
  • Increased appetite/weight gain
  • Constipation
  • Fainting


Serious side effects of Quetiapine can include the following;

  • Seizures
  • Uncontrollable and spontaneous mobility in the arms and legs or face, tongue and lips
  • Very high body temperatures
  • Sweating
  • Confusion
  • Sore throat
  • Difficulty breathing
  • Rashes/hives/blisters
  • Bleeding/bruising
  • Irregular heartbeat
  • Stiff muscles, body or joint pain and weakness
  • Erection lasts for hours and can be painful
  • Vision changes
  • Fainting
  • Death


Biological samples which can be taken from the body for analysis by a forensic toxicologist include the following;

  • Blood
  • Vitreous
  • Urine
  • Bile
  • Liver
  • Kidney
  • Brain
  • Skeletal muscle
  • Cardiac muscle
  • Stomach contents



Lethal levels which can be detected in these biological samples by a forensic toxicologist are outline in the table below;


Source Lethal Level
Blood 4-21mg/L
Vitreous 0.9-5mg/L
Urine 3-151mg/L
Bile 12-158mg/L
Liver 1.1-120mg/kg
Kidney 4.2mg/kg
Brain 1.2mg/kg
Skeletal muscle 5.9mg/kg
Cardiac muscle 5.3mg/kg
Stomach contents 64-1600mg/L


(Adapted from Molina 2010:264)




Molina, D.K. (2010). Handbook of Forensic Toxicology for Medical Examiners. CRC Press : Boca Raton




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