Usage
- Di-iodohydroxyquinoline is prescribed for the treatment of intestinal amebiasis, a parasitic infection of the intestines caused by Entamoeba histolytica. It is effective against the trophozoite form of the parasite residing within the intestinal lumen.
- Pharmacological classification: Antiparasitic, luminal amebicide. Also exhibits mild antibacterial and antifungal properties.
- Mechanism of Action: The precise mechanism is not fully elucidated, but it is believed to involve chelation of metal ions essential for parasitic metabolism, thereby disrupting energy production and other vital pathways within the Entamoeba histolytica trophozoites. It acts primarily within the intestinal lumen and is poorly absorbed systemically.
Alternate Names
- Iodoquinol
- 5,7-Diiodo-8-hydroxyquinoline
- Brand names: Yodoxin (Note: Brand names can vary regionally; this list may not be exhaustive).
How It Works
- Pharmacodynamics: Di-iodohydroxyquinoline exerts its antiparasitic effect by disrupting the metabolism of Entamoeba histolytica trophozoites within the intestinal lumen. It does not affect amebae in the liver or other tissues due to its minimal systemic absorption. The drug’s mild antibacterial and antifungal properties may contribute to its overall efficacy against intestinal infections.
- Pharmacokinetics:
- Absorption: Oral absorption is poor and erratic.
- Metabolism: A substantial portion of the absorbed drug is metabolized in the liver.
- Elimination: Primarily eliminated in feces, with a small amount excreted in urine.
- Mode of Action: At the molecular level, di-iodohydroxyquinoline acts by chelating metal ions, such as iron and copper, that are crucial for the function of various enzymes involved in the parasite’s metabolic processes. This chelation inhibits these enzymes, leading to disruption of energy production and other essential metabolic pathways, ultimately causing the death of the parasite.
- Elimination pathways: Primarily fecal excretion. Hepatic metabolism plays a role in the detoxification and elimination of the small amount of the drug that gets absorbed.
Dosage
Standard Dosage
Adults:
- 650 mg orally three times a day for 20 days. The total daily dose should not exceed 2 g.
Children:
- 30-40 mg/kg/day orally, divided into three doses for 20 days.
Special Cases:
- Elderly Patients: Due to potential age-related decline in liver and kidney function, caution is advised. Start with a lower dose and monitor for adverse effects.
- Patients with Renal Impairment: Use with caution. Dosage adjustment may be necessary based on the degree of impairment.
- Patients with Hepatic Dysfunction: Use with caution as the liver metabolizes a portion of the drug. Dosage adjustment may be necessary based on liver function tests.
- Patients with Comorbid Conditions: Exercise caution in patients with thyroid disorders as the drug can interfere with thyroid function tests.
Clinical Use Cases
The clinical use of di-iodohydroxyquinoline is limited to the treatment of intestinal amebiasis. It is not indicated for amebic liver abscess or other extraintestinal forms of amebiasis. The dosages mentioned under “Standard Dosage” apply to these cases. It is not typically used in settings like intubation, surgical procedures, mechanical ventilation, ICU, or emergency situations.
Dosage Adjustments
Dose adjustments may be necessary in patients with renal or hepatic impairment. The specific adjustment will depend on the severity of the impairment and should be determined based on clinical judgment and monitoring of the patient’s response to therapy.
Side Effects
Common Side Effects:
- Nausea, vomiting, diarrhea, abdominal cramps
- Anorexia
- Headache
- Pruritus ani
- Skin rash
Rare but Serious Side Effects:
- Optic neuritis, optic atrophy (especially with prolonged use)
- Peripheral neuropathy
- Thyroid enlargement, thyroid function abnormalities
Long-Term Effects:
- Optic neuritis and optic atrophy can occur with prolonged use.
Adverse Drug Reactions (ADR):
- Severe skin reactions (e.g., exfoliative dermatitis, erythema multiforme)
- Anaphylaxis (rare)
Contraindications
- Hypersensitivity to di-iodohydroxyquinoline or any 8-hydroxyquinoline derivatives.
- Pre-existing optic neuropathy.
- Hepatic disease.
- Iodine hypersensitivity.
Drug Interactions
- Iodine-containing medications: May potentiate the effects of iodine, leading to thyroid dysfunction.
- Coumarin anticoagulants: Theoretically, di-iodohydroxyquinoline could enhance the anticoagulant effects due to potential alterations in gut flora synthesizing vitamin K.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: C (FDA). Use with caution if benefits outweigh risks. Animal studies have shown adverse effects, and there are no adequate and well-controlled studies in pregnant women.
- Breastfeeding: Excretion in breast milk is unknown. Caution advised.
Drug Profile Summary
- Mechanism of Action: Chelates metal ions, disrupting parasitic metabolism.
- Side Effects: GI disturbances, headache, rash, rarely optic neuritis/atrophy.
- Contraindications: Hypersensitivity, optic neuropathy, hepatic disease, iodine hypersensitivity.
- Drug Interactions: Iodine-containing medications.
- Pregnancy & Breastfeeding: Category C; caution advised.
- Dosage: Adults: 650 mg TID for 20 days; Children: 30-40 mg/kg/day divided TID for 20 days.
- Monitoring Parameters: Thyroid function tests (if used long-term), eye examination (if any visual symptoms appear).
Popular Combinations
Di-iodohydroxyquinoline is typically used as monotherapy. Combined regimens are generally not recommended.
Precautions
- General Precautions: Monitor for signs of optic neuritis and thyroid abnormalities, especially with prolonged use.
- Specific Populations: Use cautiously in patients with renal or hepatic impairment, and in pregnant/breastfeeding women.
- Children & Elderly: Monitor for adverse effects and adjust dosage as needed.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Di-iodohydroxyquinoline?
A: Adults: 650 mg orally three times daily for 20 days; Children: 30-40 mg/kg/day orally, divided into three doses, for 20 days.
Q2: What are the common side effects?
A: Nausea, vomiting, diarrhea, abdominal cramps, headache, and skin rash.
A: Optic neuritis, optic atrophy, peripheral neuropathy, and severe skin reactions.
Q4: Is Di-iodohydroxyquinoline safe to use during pregnancy?
A: Pregnancy category C. Use with caution if benefits outweigh risks.
Q5: Can Di-iodohydroxyquinoline be used to treat amebic liver abscess?
A: No, it is not effective against extraintestinal amebiasis.
Q6: What is the mechanism of action of Di-iodohydroxyquinoline?
A: It chelates metal ions essential for the parasite’s metabolism.
Q7: Are there any drug interactions I should be aware of?
A: Concomitant use with other iodine-containing medications can exacerbate thyroid abnormalities.
Q8: Can I prescribe Di-iodohydroxyquinoline for a patient with liver disease?
A: Use with caution in patients with liver disease. Dosage adjustments may be necessary.
Q9: What are the contraindications to using Di-iodohydroxyquinoline?
A: Hypersensitivity to the drug, pre-existing optic neuropathy, hepatic disease, and iodine hypersensitivity.
