STROMECTOL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for STROMECTOL (STROMECTOL).
Ivermectin acts by binding selectively and with high affinity to glutamate-gated chloride ion channels in invertebrate nerve and muscle cells, leading to increased permeability to chloride ions, hyperpolarization of nerve or muscle cells, and death of the parasite. It also interacts with other ligand-gated chloride channels, such as those gated by gamma-aminobutyric acid (GABA).
| Metabolism | Ivermectin is extensively metabolized in the liver by cytochrome P450 (CYP) enzymes, primarily CYP3A4, and possibly CYP2D6. Metabolites are excreted in feces and urine. |
| Excretion | Primarily fecal (90%) as unchanged drug and metabolites; renal excretion accounts for <1% of the dose. |
| Half-life | Terminal elimination half-life is approximately 18 hours (range 10–30 hours) in healthy subjects; prolonged in hepatic impairment. |
| Protein binding | Approximately 93% bound, mainly to human serum albumin. |
| Volume of Distribution | Vd is 2.5–4.0 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability is not precisely determined due to lack of intravenous formulation; estimated to be moderate due to first-pass metabolism. |
| Onset of Action | Oral: onset of clinical effect against Strongyloides stercoralis is observed within 24–48 hours; for Onchocerca volvulus, microfilarial killing occurs within 12 hours. |
| Duration of Action | Oral: A single dose of 200 mcg/kg provides a cure rate of 94–100% for strongyloidiasis; for onchocerciasis, microfilaremia is reduced for 6–12 months. |
Oral: 200 mcg/kg once daily for 1-2 days. For strongyloidiasis, 200 mcg/kg/day for 2 days. For onchocerciasis, single dose of 150 mcg/kg.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. For severe impairment (eGFR <30 mL/min), use with caution; safety data limited. |
| Liver impairment | No specific Child-Pugh based adjustments. Use with caution in severe hepatic impairment (Child-Pugh C) due to increased systemic exposure; monitor for toxicity. |
| Pediatric use | Children ≥15 kg: same weight-based dosing as adults (150-200 mcg/kg). For strongyloidiasis: 200 mcg/kg/day for 2 days. Administer with food. |
| Geriatric use | No specific dose adjustment. Monitor elderly patients for adverse effects due to potential age-related renal or hepatic decline; use lowest effective dose. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for STROMECTOL (STROMECTOL).
| Breastfeeding | Excreted into breast milk in low levels (M/P ratio unknown). Use caution; discontinue breastfeeding during therapy due to potential adverse effects, though low risk is expected. |
| Teratogenic Risk | Pregnancy Category C. First trimester: limited human data, animal studies show increased fetal resorption and malformations at high doses. Second and third trimesters: avoid use unless benefit outweighs risk; no adequate well-controlled studies. |
| Fetal Monitoring |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Hypersensitivity to ivermectin or any component of the formulation","Concurrent use of strong CYP3A4 inducers/inhibitors may require dose adjustment","Lactation (due to potential infant exposure, though relative risk is low)","Severe asthma or other severe respiratory conditions (relative)"]
| Precautions | ["Potential for severe adverse reactions (Mazzotti reaction) in onchocerciasis patients due to microfilariae death","Hypersensitivity reactions, including angioedema and anaphylaxis","Neurotoxicity (e.g., encephalopathy) especially in patients with Loa loa co-infection","Hepatotoxicity and elevated liver enzymes","Ocular reactions (e.g., conjunctivitis, uveitis) in onchocerciasis","Not approved for COVID-19 treatment; misuse can cause serious harm"] |
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| Monitor for maternal Loa loa encephalopathy or Mazzotti reaction in heavily infected patients. Fetal assessment not routinely recommended; consider ultrasound if prolonged high-dose exposure. |
| Fertility Effects | Animal studies show no impairment of fertility. Human data insufficient to determine effect on fertility. |