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. |
| Molecular Weight | 875.1 Da |
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 | Avoid use in first trimester unless benefit outweighs risk. Animal studies show teratogenicity at high doses. |
| 2nd trimester | Limited data; use only if clearly needed. No known fetal harm from limited human data. |
| 3rd trimester | Limited data; consider risk-benefit. Potential for neonatal adverse effects unknown. |
Clinical note
Comprehensive clinical and safety monograph for STROMECTOL (STROMECTOL).
| Placental transfer | Ivermectin crosses the placenta in animals; human data limited but suggests transfer occurs. |
| Breastfeeding | Ivermectin is excreted in breast milk in low amounts. Not expected to cause adverse effects in nursing infants. Use with caution. |
| Lactation Rating |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
Hypersensitivity to ivermectin or any component of the formulation
| 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 |
| Food/Dietary | Food, especially a high-fat meal, can increase absorption of ivermectin by up to 2.6-fold. Take Stromectol on an empty stomach (at least 1 hour before or 2 hours after a meal). Avoid grapefruit juice as it may alter metabolism. |
Loading safety data…
| L2 (Safer) |
| 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 | 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. |
| Clinical Pearls | Ivermectin (STROMECTOL) is first-line for strongyloidiasis and onchocerciasis. For strongyloidiasis, a single 200 mcg/kg dose is standard; immunosuppressed patients may require repeated doses. In onchocerciasis, initiate cautiously due to Mazzotti reaction risk. Not active against adult filariae; co-administer with doxycycline for sustained effect. Avoid in Loa loa co-infection due to risk of encephalopathy. |
| Patient Advice | Take Stromectol on an empty stomach with a full glass of water. · Do not eat for at least 2 hours after taking the medication. · May cause dizziness, so avoid driving or operating machinery until you know how it affects you. · Report any severe skin rash, itching, or eye redness immediately. · Complete follow-up stool exams are necessary to confirm cure of strongyloidiasis. |