Furazolidone

Glucose-6-phosphate dehydrogenase (G6PD) determinations: recommended prior to treatment in Caucasians of Mediterranean and Near Eastern origin, Orientals, and blacks; if a deficiency is found, furazolidone should be given with caution since hemolytic effects may be exacerbated in these patients; dosage adjustments and/or discontinuation of the medication may be required.

Studies in humans have not been done. However, teratogenic effects on the human fetus or newborn infants have not been reported.

Studies in animals have not shown that furazolidone, given in doses far exceeding recommended human doses for long periods of time, causes adverse effects on the fetus.

It is not known whether furazolidone is distributed into breast milk. However, breast-feeding is not recommended in nursing infants up to 1 month of age because of the possibility of hemolytic anemia due to glutathione instability in the early neonatal period.

Carcinogenicity/Tumorigenicity

Several studies in rodents, given chronic, high-dose furazolidone orally, have shown that this medication is tumorigenic. Furazolidone has been shown to cause mammary neoplasia in two strains of rats. In addition, furazolidone has been shown to cause pulmonary tumors in mice.

Note: Furazolidone may cause mild, reversible hemolytic anemia in G6PD-deficient patients. Furazolidone should be discontinued if hemolytic anemia occurs in these patients.

The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:

Those indicating need for medical attention — Incidence rare:

Hypersensitivity reactions (fever; itching; joint pain; skin rash or redness)—incidence approximately 0.6%

Leukopenia (sore throat and fever)—incidence approximately 0.2%

Those indicating need for medical attention only if they continue or are bothersome — Incidence less frequent: Gastrointestinal disturbances (abdominal pain, diarrhea, nausea, or vomiting), Headache

Those not indicating need for medical attention — Incidence more frequent: Dark yellow to brown discoloration of urine