Introduction
The few adverse effects observed during Antizol^® (fomepizole) Injection administration have been brief and of mild to moderate severity. Possible laboratory abnormalities have been transient and have not produced clinical manifestations. Therefore, treatment with Antizol is considered safe when administered at recommended doses.

Adverse Reactions
The adverse reactions listed below are a compilation of effects reported during clinical trials where investigators indicated the effects were possibly, probably or definitely related to Antizol, or the relationship to Antizol was considered unknown. In addition, these adverse reactions include those reported by healthy volunteers who received doses that were 6-10 times greater than the recommended dose (Jacobsen 1988). Due to the clinical manifestations of ethylene glycol and methanol poisonings, it is difficult to determine whether each of the reported adverse events is due to the drug or to the existing toxicosis.

The most frequent adverse events reported in the 78 patients and 63 normal volunteers who received Antizol were headache (14%), nausea (11%) and dizziness, increased drowsiness and bad taste/metallic taste (6% each)*. All other adverse events reported in approximately 3% or fewer of those receiving Antizol were as follows:

Body as a Whole:
Abdominal pain, fever, multiorgan system failure, pain during Antizol injection, inflammation at injection site, lumbagia/backache, hangover.

Cardiovascular:
Sinus bradycardia/bradycardia, phlebosclerosis, tachycardia, phlebitis, shock, hypotension.

Gastrointestinal
Vomiting, diarrhea, dyspepsia, heartburn, decreased appetite, transient transaminitis.

Hemic/Lymphatic:
Eosinophilia/hypereosinophilia, lymphangitis, disseminated intravascular coagulation, anemia.

Nervous:
Lightheadedness, seizure, agitation, feeling drunk, facial flush, vertigo, nystagmus, anxiety, "felt strange", decreased environmental awareness.

Respiratory:
Hiccups, pharyngitis.

Skin/Appendages:
Application site reaction, rash.

Special Senses:
Abnormal smell, speech/visual disturbances, transient blurred vision, roar in ear.

Urogenital:
Anuria

Laboratory abnormalities possibly related to Antizol treatment include slight transient increases in liver enzymes, eosinophilia, and elevated triglycerides and/or cholesterol. (Jacobsen 1990). These effects have not produced clinical manifestations. Significant laboratory abnormalities observed in patients, such as increased lactate, azotemia and anemia, are likely due to the toxins ingested, rather than treatment with fomepizole.

* Minor allergic reactions (rash and eosinophilia) have been reported. Ethylene glycol plasma and urine levels as well as the presence of urinary oxalate crystals in ethylene glycol poisoning and methanol plasma levels in methanol poisoning should be monitored throughout treatment. Dialysis should be considered in some cases.