Propylene glycol is used in many parenteral medications and as a food additive. Toxicity may occur if large quantities of parenteral medications are administered or certain foods are ingested in a short period. Diagnosis of an affected patient requires a high level of clinical suspicion.
Uses of propylene glycol:
(1) solvent
(2) antifreeze
(3) emulsifier
(4) preservative
Foods containing propylene glycol:
(1) beer
(2) dairy products
(3) fruit juices
(4) candy
Medications containing propylene glycol:
(1) IV nitroglycerin products
(2) benzodiazepines (chrlodiazepoxide, lorazepam and diazepam)
(3) barbiturates
(4) dilantin
(5) oral antibiotics
(6) lanoxin
(7) silver sulfadiazine
Clinical findings:
(1) deafness
(2) sudden collapse
(3) cardiac arrhythmias with cardiac arrest
(4) hepatic injury
(5) renal injury
(6) seizures
(7) CNS depression (confusion, coma)
Laboratory findings:
(1) hyperosmolality with elevated osmolal gap
(2) metabolic acidosis with anion gap and elevated lactate levels
(3) hemolysis with hemoglobinuria
If propylene glycol containing drugs are administered in the same infusion set as red blood cells, then hemolysis of the red blood cells may occur.
The differential diagnosis includes alcohol or drug intoxication or withdrawal, which can result in further administration of drugs containing propylene glycol.
Diagnosis is by measuring the concentration in the blood, usually by gas chromatography (GC) or GC-mass spectroscopy. Symptoms of intoxication occur when the serum concentration is > 18 mg/dL (2.4 mmol/L).
where:
• The plasma volume for an newborn infant is about 50 mL per kg and for an adult is roughly 40 mL/kg. For a 75 kg adult over 54,000 mg propylene glycol would be required to cause intoxication assuming bolus administration.
• The half-life is 1.8 to 3.3 hours in adults. According to Fligner et al, the half-life was 16.9 hours in an infant.
