How does Stromectol work?
Stromectol is an antiparasitic agent that is taken orally to treat predominantly parasitic worm infections. It binds to nerve and muscles cells in the worms, causing paralysis and death of the worm. It is effective against roundworms when they are present in the intestines. It is also used to treat infection of onchocera – a parasitic worm that causes river blindness – when it is in the tissue phase of its growth.
Stromectol is indicated for the treatment of parasitic worm infections from Strongyloides. Strongyloidiasis is an infection caused by the roundworm (Strongyloides stercoralis). Strongyloides infection occurs when the skin comes into direct contact with contaminated soil. The small young roundworms burrow into the skin, migrate to the lungs, burrow into the airways, and are then swallowed. Next, the worms mature in the intestines and burrow into the intestinal wall, where they begin producing eggs. Stromectol is effective against the intestinal stage of the worm.
Onchocerciasis is a tropical disease caused by an infestation of the worm Onchocerca volvulus. Repeated bites from blackflies cause infection. These flies are found next to streams and rivers in remote tropical regions. This association has led to the disease being called river blindness. Infection with the worms causes skin swelling, itching and inflammation. Eye damage is caused by multiple microscopic worms called microfilariae. These worms migrate to the cornea surface of the eye, where they cause vision loss that can become permanent. Stromectol is effective against the microfilariae form of the worm.
For patients with strongyloidiasis of the intestinal tract, the dose of Stromectol is 200 mcg per kg and is given as a single dose. For the 3 mg tablet of Stromectol, this translates to:
- 15 to 24 kg – 1 tablet,
- 25 to 35 kg – 2 tablets,
- 36 to 50 kg – 3 tablets,
- 51 to 65 kg – 4 tablets,
- 66 to 79 kg – 5 tablets,
- and > 80 kg – 200 mg per kg.
For patients with onchocerciasis, the dose of Stromectol is 150 mcg per kg and is given as a single dose. For the 3 mg tablet of Stromectol, this translates to:
- 15 to 25 kg – 1 tablet,
- 26 to 44 kg – 2 tablets,
- 45 to 64 kg – 3 tablets,
- 65 to 84 kg – 4 tablets,
- and ? 85 kg – 150 mcg per kg.
Warnings & Precautions
Skin or systemic reactions
Stromectol may cause significant skin reactions in patients with onchocerciasis. This is thought to happen because of an inflammatory response to the death of the worm microfilariae. Treatment is supportive with antihistamines and anti-inflammatory drugs.
Patients who are immunocompromised may require repeat treatment to control infections of roundworm.
Additional pediatric warnings
Stromectol should be used with extreme caution, or not at all, in patients younger than two years of age or less than 15 kg. This is because these patients have a blood-brain barrier that is less well developed and run the risk of developing neurotoxic effects from Stromectol.
Stromectol has not been tested extensively in children weighing less than 15 kg. For children 15 kg or more, the dose of Stromectol is 200 mcg per kg as a single dose. Stromectol should be used with extreme caution, or not at all, in patients younger than two years of age or less than 15 kg. These patients have a blood-brain barrier that is less well developed and run the risk of developing neurotoxic effects from Stromectol.
Stromectol has not been extensively studied in pregnant women. Some studies have shown that Stromectol does not appear to harm the developing fetus, but there are few well-controlled studies to support this. Avoid using Stromectol during pregnancy.
The safety of Stromectol has not been established in breastfeeding mothers. Its active ingredient (ivermectin) is found in breastmilk. Treatment with Stromectol should be avoided unless the treatment benefit outweighs the possible harm to the child.
In patients 65 years and older, there is insufficient evidence to determine whether they have a different response to Stromectol than younger patients. Care should be taken to monitor treatment and patient response, particularly in those with renal failure or hepatic failure.
Stromectol is contraindicated in patients with hypersensitivity to Stromectol.
Common side effects of Stromectol include:
- Skin rash, itching and swelling
- Muscle pains
Less common side effects include:
- Confusion, drowsiness, or changes in mental status
- Eye inflammation
- Stevens-Johnson syndrome
Overdose with Stromectol
Persons who have overdosed with Stromectol report headaches, dizziness, abdominal pain, weakness, seizures, and loss of consciousness. Treatment is supportive. Treatment of Stromectol overdose is supportive and may include intubation and ventilation.
Vitamin K antagonists (e.g., warfarin) may interact with Stromectol. In some patients taking warfarin and Stromectol, an increased International Normalized Ratio (INR) has been reported. In some cases, this has led to an increase in bleeding events.
Frequently Asked Questions