Iodoquinol

IODOQUINOL

Iodoquinol (diiodohydroxyquin) is a halogenated hydroxyquino-line. It is an effective luminal amebicide that is commonly used with metronidazole to treat amebic infections. Pharmacokinetic data are incomplete but 90% of the drug is retained in the intes-tine and excreted in the feces. The remainder enters the circula-tion, has a half-life of 11–14 hours, and is excreted in the urine as glucuronides.

The mechanism of action of iodoquinol against trophozoites is unknown. It is effective against organisms in the bowel lumen but not against trophozoites in the intestinal wall or extraintestinal tissues.

Infrequent adverse effects include diarrhea—which usually stops after several days—anorexia, nausea, vomiting, abdominal pain, headache, rash, and pruritus. The drug may increase protein-bound serum iodine, leading to a decrease in measured ¹³¹I uptake that persists for months. Some halogenated hydroxyquinolines can produce severe neurotoxicity with prolonged use at greater than recommended doses. Iodoquinol is not known to produce these effects at its recommended dosage, and this dosage should never be exceeded.

Iodoquinol should be taken with meals to limit gastrointestinal toxicity. It should be used with caution in patients with optic neu-ropathy, renal or thyroid disease, or nonamebic hepatic disease. The drug should be discontinued if it produces persistent diarrhea or signs of iodine toxicity (dermatitis, urticaria, pruritus, fever). It is contraindicated in patients with intolerance to iodine.