Fomepizole Drug Information

Fomepizole injection is indicated as an antidote for ethylene glycol (such as antifreeze) or methanol poisoning, or for use in suspected ethylene glycol or methanol ingestion, either alone or in combination with hemodialysis (see DOSAGE AND ADMINISTRATION ).

The most frequent adverse events reported as drug-related or unknown relationship to study drug in the 78 patients and 63 normal volunteers who received fomepizole injection were headache (14%), nausea (11%), and dizziness, increased drowsiness, and bad taste/metallic taste (6% each). All other adverse events in this population were reported in approximately 3% or fewer of those receiving fomepizole injection and were as follows: Body as a Whole: Abdominal pain, fever, multiorgan system failure, pain during fomepizole injection, inflammation at injection site, lumbalgia/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 To report SUSPECTED ADVERSE REACTIONS, contact Sagent Pharmaceuticals at 1-866-625-1618 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Drug Interactions: Oral doses of fomepizole (10 to 20 mg/kg), via alcohol dehydrogenase inhibition, significantly reduced the rate of elimination of ethanol (by approximately 40%) given to healthy volunteers in moderate doses. Similarly, ethanol decreased the rate of elimination of fomepizole (by approximately 50%) by the same mechanism. Reciprocal interactions may occur with concomitant use of fomepizole and drugs that increase or inhibit the cytochrome P450 system (e.g., phenytoin, carbamazepine, cimetidine, ketoconazole), though this has not been studied.

Pregnancy: Animal reproduction studies have not been conducted with fomepizole. It is also not known whether fomepizole can cause fetal harm when administered to pregnant women or can affect reproduction capacity. Fomepizole should be given to pregnant women only if clearly needed.

Pediatric Use: Safety and effectiveness in pediatric patients have not been established.

Fomepizole should not be administered to patients with a documented serious hypersensitivity reaction to fomepizole or other pyrazoles.

Nausea, dizziness, and vertigo were noted in healthy volunteers receiving 50 and 100 mg/kg doses of fomepizole (at plasma concentrations of 290 to 520 mcmol/L, 23.8 to 42.6 mg/L). These doses are 3 to 6 times the recommended dose. This dose-dependent CNS effect was short-lived in most subjects and lasted up to 30 hours in one subject. Fomepizole is dialyzable, and hemodialysis may be useful in treating cases of overdosage.