Detectable serum ethylene glycol levels after subcutaneous injection of antifreeze

To the Editor:

Ethylene glycol (EG) poisoning is commonly seen in the emergency department (ED). Poisoning from EG ingestion, including the pharmacokinetics, mechanisms of action, and treatment interventions is well described in the literature.¹ Human toxicity from inhalation and dermal exposure is unreported, and animal studies do not support induction of toxicity from these types of exposures.² Neither human nor animal toxicity from subcutaneous (SC) injection of EG has been reported or described in the literature, and there is no available data regarding systemic absorption of subcutaneously injected EG in these groups. We present two cases of EG toxicity from reported SC injections in a joint suicide attempt between friends.

The patients injected antifreeze into their abdomens 2 h prior to arrival to the ED after reading about it as a method for suicide on the internet. Specifically, they reported reading that if they injected the antifreeze into the fat they would die more quickly. A short time after injecting themselves with the antifreeze, they drove themselves to the hospital. Security searched the truck in which the patients arrived in but did not find any antifreeze containers in the vehicle to confirm the reported exposure.

Patient A, a 24-year-old female (86 kg) with a history of anxiety, depression, and previous suicide attempts injected 40 ml of EG-containing antifreeze subcutaneously using four syringes. On arrival to the ED, she was asymptomatic but became confused, combative, and was subsequently intubated within 1 h of arrival. During her period of intubation, she was sedated with midazolam and propofol. Serum EG levels were measured on arrival (51 mg/dL), on the morning of hospital day (HD) 2 (53 mg/dL), the evening of HD 2 (37 mg/dL), HD 3 (21 mg/dL), and HD 4 (13 mg/dL) (Table 1). An EG half-life of 19.9 h was calculated based on these serum levels. Her lowest serum bicarbonate was on arrival (17 mmol/L) and highest creatinine was 0.8 mg/dL. She was extubated on the afternoon of HD 2 and received a total of five doses of fomepizole.

Table 1. Patient ethylene glycol levels, creatinine levels, and bicarbonate levels.

	On Arrival	Morning of HD#2	Evening of HD#2	HD#3	HD#4
Ethylene glycol levels (mg/dL)
Patient A	51	53	37	21	13
Patient B	55	34	–	17	–
Creatinine (mg/dL)
Patient A	0.7	0.8	–	0.8	–
Patient B	0.8	0.8	–	0.9	–
Bicarbonate (mEq/L)
Patient A	17	20	–	25	–
Patient B	19	14	–	22	–

Patient B, a 35-year-old female (88 kg), also attempted suicide with Patient A by injecting 60 ml of EG-containing antifreeze subcutaneously with six different syringes, as well as ingesting an unknown amount of clonazepam and eszopiclone. She had multiple medical problems including bipolar disorder, anemia, gastritis, gastric bypass, and previous overdose. On arrival to the ED, she was also asymptomatic but within 1 h of arrival became confused, combative, then rapidly became unresponsive, lost her gag reflex, and required intubation for airway protection. Sedation with midazolam, fentanyl, and propofol was required for agitation while she was intubated. Serum EG levels were measured on arrival (55 mg/dL), HD 2 (34 mg/dL), HD 3 (17 mg/dL) (Table 1). An EG half-life of 23.1 h was calculated based on the serum levels obtained. Her lowest serum bicarbonate was on HD 2 (14 mmol/L) and highest creatinine was 0.9 mg/dL. She was extubated on the morning of HD 3 and received a total of four doses of fomepizole.

Both patients received fomepizole approximately 2 h after arrival to the ED, thiamine (100 mg every 6 h), and were intubated for less than 48 h. Toxicology screens at the time of arrival were negative for ethanol, salicylate, and acetaminophen in both patients. Patients A's urine drug screen was negative, but Patient B's tested positive for benzodiazepines. Thiamine and fomepizole were continued until the patients’ EG levels were less than 20 mg/dL; hemodialysis was not required. Ultimately, both recovered fully without any lasting end organ effects and adamantly denied ingesting EG orally.

Previous studies indicate the half-life of ingested EG is around 3–9 h, and this is extended to 14–17 h in the presence of ADH blockade with fomepizole.^3–7 The calculated half-lives in our cases were longer than those routinely cited for oral ingestions in patients treated with fomepizole. This may be partially related to the fomepizole, but may also represent continued absorption from the SC tissues. Additional evidence to support continued absorption is suggested by the rise in EG levels in Patient A noted several hours after admission and the loading dose of fomepizole.

These cases demonstrate previously unreported SC injection of EG resulting in systemic absorption and symptoms of toxicity. From these two patients, we are able to report successful treatment of SC EG using techniques currently used to manage EG ingestions. We have shown that SC EG does in fact, slowly get absorbed into the systemic circulation causing some of the typical manifestations seen with EG poisoning by ingestion.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.