Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ERGAMISOL vs HETRAZAN
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Levamisole is an anthelmintic and immunomodulator. It acts as a nicotinic acetylcholine receptor agonist at the neuromuscular junction in nematodes, causing spastic paralysis. Its immunomodulatory effects are thought to involve stimulation of T-cell activation and phagocytosis.
Diethylcarbamazine (HETRAZAN) sensitizes microfilariae to phagocytosis by immobilizing them and altering their surface, making them more susceptible to destruction by host immune cells. It also has anthelminthic activity against adult worms.
Adjuvant therapy in combination with fluorouracil for the treatment of Dukes' C colon cancer (FDA-approved, now discontinued),Off-label: treatment of steroid-resistant nephrotic syndrome in children, and as an adjuvant in melanoma and other cancers
Treatment of lymphatic filariasis (Wuchereria bancrofti, Brugia malayi),Treatment of tropical pulmonary eosinophilia,Treatment of loiasis (Loa loa)
150 mg orally once daily
2 mg/kg orally three times daily after meals for 3 weeks (total dose 120 mg/kg per course). Maximum single dose: 10 mg/kg.
2-4 hours (terminal); prolonged in hepatic impairment (up to 8-12 hours) and renal impairment (increase by 1.5- to 2-fold).
Terminal elimination half-life is 8-12 hours in patients with normal renal function; may be prolonged in renal impairment.
Hepatic metabolism primarily via CYP450 enzymes (CYP2B6 and CYP3A4) to active metabolites. Levamisole undergoes extensive biotransformation to its major metabolites, p-hydroxy-levamisole and levamisole sulfoxide.
Diethylcarbamazine is rapidly absorbed and extensively metabolized in the liver via N-oxidation and N-demethylation, involving multiple CYP enzymes. The major metabolite is diethylcarbamazine N-oxide.
Renal (parent drug and metabolites): ~70% in urine; Fecal: ~25% primarily as metabolites; <5% unchanged in urine.
Renal excretion of unchanged drug accounts for approximately 50-60% of elimination; the remainder is metabolized hepatically with metabolites excreted in urine. Fecal elimination is minimal (<5%).
20-30%, primarily to albumin.
Protein binding is approximately 10-20%, primarily to albumin.
1.0-1.5 L/kg; indicates extensive tissue distribution, including penetration into liver and kidneys.
Volume of distribution is 1.5-2.5 L/kg, indicating extensive tissue distribution.
Oral: 40-60% (extensive first-pass metabolism).
Oral bioavailability is approximately 90% due to well absorption from the gastrointestinal tract.
GFR 30-60 m L/min: no adjustment; GFR <30 m L/min: not recommended
No specific GFR-based dose modifications available; use with caution in renal impairment due to potential accumulation. Monitor for adverse effects.
Child-Pugh A: no adjustment; Child-Pugh B or C: avoid use
Child-Pugh A: No adjustment needed. Child-Pugh B: Reduce dose by 50%. Child-Pugh C: Contraindicated.
2.5 mg/kg orally once daily; maximum 150 mg daily
2 mg/kg orally three times daily after meals for 3 weeks (total dose 120 mg/kg per course). Maximum single dose: 10 mg/kg. For children <15 kg, dosage based on 1 mg/kg initially, then increase gradually.
No specific adjustment; monitor for renal function and potential QT prolongation
Initiate at lower end of dosing range (2 mg/kg per dose) due to potential age-related decrease in renal function. Monitor closely for adverse effects.
None specifically required for ergamisol (levamisole). However, use of levamisole as an immunomodulator has been associated with agranulocytosis and other severe hematologic reactions.
HETRAZAN is contraindicated in patients with onchocerciasis (river blindness) due to the risk of severe Mazzotti reaction, including ocular damage and encephalopathy. Treatment should not be initiated in areas where onchocerciasis is endemic or in patients with suspected onchocerciasis.
Agranulocytosis (may occur weeks after initiation and is reversible upon discontinuation), hemolytic anemia (especially in patients with G6PD deficiency), neurologic effects (seizures, dizziness, headache), hepatotoxicity, and hypersensitivity reactions.
Severe allergic or inflammatory reactions (Mazzotti reaction) in patients with onchocerciasis; encephalopathy in loiasis with high microfilarial loads; ocular damage (e.g., uveitis, optic neuritis) in onchocerciasis; thrombocytopenia; aminotransferase elevations; use in pregnancy only if clearly needed.
Known hypersensitivity to levamisole; patients with a history of agranulocytosis induced by levamisole; concomitant use with alcohol (disulfiram-like reaction); caution in patients with hepatic or renal impairment.
Onchocerciasis (active or suspected),High-grade Loa loa microfilaremia (>8000 microfilariae/m L),Hypersensitivity to diethylcarbamazine or any component of the formulation
Avoid alcohol during therapy due to potential disulfiram-like reaction (nausea, vomiting, flushing). No specific food restrictions; maintain adequate hydration. Grapefruit juice may inhibit CYP2C19 metabolism, potentially increasing levamisole levels; consider avoidance.
Grapefruit juice may inhibit CYP450 metabolism; avoid concurrent intake. Administer with food to reduce gastrointestinal distress.
Ergamisole (levamisole) is classified as FDA Pregnancy Category C. Animal studies have shown embryotoxicity and teratogenicity at doses comparable to human doses. There are no adequate and well-controlled studies in pregnant women. Use only if potential benefit justifies potential risk to fetus. In first trimester, avoid use; second and third trimester, use with caution if indicated.
Animal studies have not been conducted; no adequate human data. Use only if benefit outweighs risk. No known teratogenic effects in first trimester; limited data in second and third trimesters.
Levamisole is excreted in human milk in low amounts; M/P ratio is not established. Because of potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Excreted into breast milk; M/P ratio unknown. Use with caution due to potential for adverse effects in infant.
Pharmacokinetics in pregnancy are not well characterized. No specific dose adjustments are recommended; however, due to potential for altered metabolism, use lowest effective dose and monitor maternal toxicity closely.
No specific dose adjustments recommended; pharmacokinetics may be altered but data insufficient to guide changes.
Levamisole (ERGAMISOL) is primarily used as an immunomodulator in adjuvant therapy for stage III colon cancer after surgical resection. It is often combined with fluorouracil. Monitor for agranulocytosis, especially in patients with poor metabolizer status of CYP2D6. Agranulocytosis can occur weeks to months after initiation; obtain baseline CBC and repeat periodically. Levamisole can cause a metallic taste and reversible ANCA-positive vasculitis. Avoid in patients with known hypersensitivity or bone marrow depression.
HETRAZAN (diethylcarbamazine) is primarily used for lymphatic filariasis and loiasis; monitor for Mazzotti reaction (fever, rash, arthralgias) in high microfilarial loads; contraindicated in onchocerciasis due to severe ocular reactions; administer with food to reduce GI upset.
Take levamisole exactly as prescribed, usually for 3 days every 2 weeks for 1 year. Do not miss doses.,Report any signs of infection (fever, sore throat, mouth sores) immediately as it can lower white blood cell count.,You may experience a metallic taste; this is harmless and may resolve with time.,Avoid alcohol consumption as it may increase risk of adverse effects.,Inform your doctor if you are pregnant, planning to become pregnant, or breastfeeding.,Do not take any other medications or supplements without consulting your doctor.
Take with food to minimize nausea.,Report any severe itching, rash, fever, or vision changes.,Complete full course even if symptoms improve.,Avoid grapefruit juice which may affect metabolism.,May cause dizziness or drowsiness; avoid driving if affected.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ERGAMISOL vs HETRAZAN, answered by our medical review team.
ERGAMISOL is a Anthelmintic Immunomodulator that works by Levamisole is an anthelmintic and immunomodulator. It acts as a nicotinic acetylcholine receptor agonist at the neuromuscular junction in nematodes, causing spastic paralysis. Its immunomodulatory effects are thought to involve stimulation of T-cell activation and phagocytosis.. HETRAZAN is a Anthelmintic that works by Diethylcarbamazine (HETRAZAN) sensitizes microfilariae to phagocytosis by immobilizing them and altering their surface, making them more susceptible to destruction by host immune cells. It also has anthelminthic activity against adult worms.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ERGAMISOL and HETRAZAN depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ERGAMISOL is: 150 mg orally once daily. The standard adult dose of HETRAZAN is: 2 mg/kg orally three times daily after meals for 3 weeks (total dose 120 mg/kg per course). Maximum single dose: 10 mg/kg.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between ERGAMISOL and HETRAZAN in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. ERGAMISOL is classified as Category C. Ergamisole (levamisole) is classified as FDA Pregnancy Category C. Animal studies have shown embryotoxicity and teratogenicity at doses comparable to human doses. There are no adeq. HETRAZAN is classified as Category C. Animal studies have not been conducted; no adequate human data. Use only if benefit outweighs risk. No known teratogenic effects in first trimester; limited data in second and thir. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.