Levamisole

BRAND NAMES

Levamisole brand names:

• Ergamisol

• Decaris

• Tramisol

MECHANISM OF ACTION

Levamisole acts by stimulating nicotinic acetylcholine receptors in parasitic worms, causing sustained muscle contraction and spastic paralysis, which allows the host body to expel them through normal intestinal movement. It also has mild immunomodulatory effects, enhancing certain immune cell functions.

PHARMACOKINETICS

Absorption

Levamisole is rapidly and well absorbed after oral administration, with peak plasma concentrations typically reached within about 1.5 to 2 hours, indicating good bioavailability.

Distribution

Levamisole has a moderate distribution in the body, with an apparent volume of distribution of approximately 1–2 L/kg, indicating it distributes beyond the bloodstream into body tissues.

Metabolism

Levamisole is extensively metabolized in the liver, primarily through oxidation and hydrolysis, producing several inactive metabolites.

Elimination

Levamisole is eliminated mainly through the urine, with a smaller portion excreted in feces, mostly in the form of its metabolites; its elimination half-life is approximately 3–6 hours.

PHARMACODYNAMICS

Levamisole exhibits pharmacodynamic effects primarily as an anthelmintic by causing paralysis of parasitic worms through stimulation of nicotinic receptors, leading to their expulsion. In addition, it has immunomodulatory activity, enhancing T-cell function and macrophage activation, which contributed to its past use in certain immune-related and cancer therapies.

ADMINISTRATION

Levamisole is administered primarily by the oral route in tablet form, with dosing usually given as a single dose or short course depending on the type of parasitic infection; it has also been used in veterinary medicine via oral or injectable formulations.

DOSAGE AND STRENGTH

• Typical human dose (historical use): ~2.5 mg/kg as a single oral dose for worm infections

• Tablet strengths: commonly 50 mg and 150 mg

• Veterinary doses: vary by species and formulation

DRUG INTERACTIONS

• Increased risk of bone marrow suppression with other myelotoxic drugs

• May enhance effects of immunomodulators or immunosuppressants

• Caution with anticoagulants (possible altered coagulation)

• Avoid with drugs causing hepatotoxicity (added liver stress)

FOOD INTERACTIONS

• No significant food interactions reported

• Can be taken with or without food

• Food does not significantly affect absorption

CONTRAINDICATIONS

Levamisole is contraindicated in patients with hypersensitivity to the drug, existing blood disorders like leukopenia or agranulocytosis, severe liver disease, and autoimmune conditions. It is generally avoided in pregnancy and breastfeeding unless absolutely necessary.

SIDE EFFECTS

• Nausea

• Vomiting

• Abdominal pain

• Headache

• Agranulocytosis

• Leukopenia

• Skin rash

• Vasculitis

• Flu-like symptoms

OVER DOSE

Levamisole overdose may cause severe bone marrow suppression such as agranulocytosis or leukopenia, along with nausea, vomiting, dizziness, and possible neurological symptoms. Treatment is supportive with close monitoring of blood counts.

TOXICITY

Levamisole toxicity is mainly due to its effects on the bone marrow and immune system, leading to agranulocytosis, leukopenia, and increased risk of serious infections. It can also cause skin vasculitis, rash, and flu-like symptoms. In severe cases, toxicity may be life-threatening if not identified and managed early.