Ivermectin: package insert, how to take, contraindications and side effects.

What is it?

Ivermectin is a drug derived from avermectins, which are an isolated class produced by Streptomyces avermitilis through fermentation, which has been used for decades to treat parasitic infestations and worms in humans and animals. 

What is it for?

Its effectiveness has been proven in studies for the treatment of various infections, such as:

1. Ascariasis (roundworm): caused by the parasite Ascaris lumbricoides. 
2. Pediculosis (lice): caused by the mite Pediculus humanus capitis. 
3. Scabies (mange): caused by the mite Sarcoptes scabiei. 
4. Filariasis (elephantiasis): caused by the parasite Wuchereria bancrofti;
5. Intestinal strongyloidiasis: caused by the parasite Strongyloides stercoralis;
6. Onchocerciasis: caused by the parasite Onchocerca volvulus. It is important to highlight that ivermectin does not eliminate this parasite in its adult phase, but it can be considered to eliminate the larvae produced by them.

How does it work? (pharmacodynamics and pharmacokinetics)

Ivermectin acts by interfering with the parasites' nervous system. It selectively acts on channels present in the parasites' nerves and muscles, increasing the permeability of chloride ions in these channels and causing hyperpolarization of the cell membrane.

This action interferes with the transmission of nerve impulses in parasites, leading to muscle paralysis and death of the worms or parasites. In addition, ivermectin can also affect the reproductive system of parasites, reducing fertility and reproductive capacity.

Ivermectin is readily absorbed by the body when taken orally, reaching peak blood concentrations in about 4 hours. The half-life of ivermectin generally ranges from 12 to 36 hours.

How to take?

It is recommended to take ivermectin with water, preferably on an empty stomach, about 1 hour before the first meal of the day or 2 hours after a meal. Check the expiration date before use.

Studies have shown that effective doses range from 150 mcg/kg to 200 mcg/kg per day, in a single dose, orally. The dosage may vary depending on your body weight and the infection being treated, as shown in the tables below.

For strongyloidiasis, filariasis, roundworms, lice and scabies

The recommended amount to treat these infections in a single oral dose is approximately 200 mcg of Ivermectin for each kilogram of weight.

For onchocerciasis

For the treatment of onchocerciasis, the recommended dosage is a single oral dose. The calculation is approximately 150 mcg of Ivermectin for each kilogram of weight.

How to calculate the dose above 80 or 85 kg?

Let's assume a person weighs 120 kg. In this case, you should take the amount of 150 mcg or 200 mcg (according to the infection listed in the tables above) and multiply it by the weight and divide it by the gram of each ivermectin tablet. Example:

200 (mcg) x 120 (kg) = 24,000 / per 6,000 (grams per 6mg tablet) = 4.

So, in this calculation, a person weighing 120 kg should take 4 tablets to treat strongyloidiasis, filariasis, roundworms, lice and scabies (200 mcg according to the table above).

Post-use recommendations for each infection:

Strongyloidiasis: It is important to perform repeated stool tests to verify the absence of infection.

Ascariasis (roundworm): It is necessary to perform stool tests to monitor and certify the cure of the infection.

Filariasis (elephantiasis): Keep up with medical monitoring, as ivermectin does not eliminate these parasites in the adult phase.

Scabies (mange): After treatment, it is recommended to return to the doctor after 1 or 2 weeks to confirm the cure.

Pediculosis (lice): It is important to manually remove the most attached nits or use a fine-tooth comb. This process should be repeated until all nits are removed.

Onchocerciasis: the treatment does not eliminate the parasites Onchocerca adults, repeated monitoring and new treatment with medical supervision are generally necessary

To prevent future infestations for yourself and those around you, wash your hands, especially before meals, avoid walking barefoot, cut and keep your nails clean, drink filtered water, wash and cook food thoroughly, boil underwear, bed linen and towels, do not share personal objects, avoid direct contact with other people during treatment to avoid cross-infestation.

Other instructions for use

Do not use medicine after its expiration date. Store it in its original packaging. 

If the medicine is within its expiration date but has changed in appearance or shape, it is important to consult a pharmacist to check whether it can still be used.

A single dose has the effect of eliminating the parasites. However, it is crucial to carry out stool or blood tests two weeks after starting treatment, so that the doctor can assess whether it is necessary to repeat the dose.

In general, antiparasitic drugs should be used once every 6 months. Frequent use of these medications, especially at short intervals, can increase the risk of adverse effects.

It is important to follow medical advice to ensure the effectiveness of the treatment and obtain the best results without putting your health at risk.

Contraindications

• It should not be used in children weighing less than 15 kg or under 5 years old.
• It should not be used by patients allergic to ivermectin or any of the substances in the formula.
• It is not indicated for patients with meningitis or other diseases in the nervous system central.
• Women pregnant should avoid use unless under medical advice.
• During the breast-feeding, use should only be done with a doctor's prescription, as low amounts of ivermectin are excreted in breast milk.
  

Side effects

During treatment with ivermectin, some of the most common side effects that may occur are:

General adverse reactions (mild and transient):

1. Gastrointestinal disorders: diarrhea, nausea, abdominal pain, anorexia, constipation and vomiting.
2. Changes in the central nervous system: dizziness, drowsiness, vertigo and tremor.
3. Skin reactions: itching, rashes and hives.

Specific reactions of onchocerciasis:

1. Mazzotti-type reactions: arthralgia/synovitis, abdominal pain, enlarged and tender lymph nodes, itching, swelling, rash, hives and fever.
2. Ophthalmic reactions: sensation of abnormalities in the eyes, swelling of the eyelids, inflammation of the anterior uvea, conjunctivitis, inflammation of the cornea and choroidoretinitis/choroiditis (rarely severe).

Other rare adverse reactions and side effects:

1. Tachycardia, facial and peripheral edema, orthostatic hypotension.
2. Headache and myalgia (muscle pain) in less than 1% of patients.
3. Changes in laboratory tests: transient eosinophilia, elevated liver enzymes and increased hemoglobin.

It is important to note that these side effects are mild. If you experience any of these symptoms intensely or persistently, it is recommended to contact your doctor for proper evaluation and guidance.

In case of unusual side effects, it is important to notify the drug manufacturer and also register the incident in the Adverse Drug Event Reporting System – Vigimed. You can access it through the website: http://portal.anvisa.gov.br/vigimed.

Composition

The substances and quantities may vary depending on the manufacturer, but are based on:

• Microcrystalline cellulose;
• Starch;
• Magnesium stearate;
• Dibasic calcium phosphate dihydrate;
• Silicon dioxide;
• Butylhydroxyanisole;
• Citric acid monohydrate.

Technical information:

• Molar mass: 875.1 g/mol
• Metabolism: liver; CYP450
• Chemical formula: C₄₈H₇₄THE₁₄
• Excretion: feces; <1% urine
• Plasma binding: 93%
• Biological half-life: 18 hours

Trade names for Ivermectin

Some of the trade names for the drug ivermectin commonly sold in Brazil are:

• Revectin.
• Ivermec.
• Iverneo.
• Leverctin.
• Plurimec.
• Uciosis.
• Vermectil.
• Soolantra (dermatological cream).

Interactions with other medicines

There are no reports of drug interactions with ivermectin, but it is important to administer it with caution in patients who are using medications that affect the Central Nervous System, such as medications for insomnia, anxiety, depression and some painkillers or alcoholic beverages. 

It is essential to inform your doctor if you are taking any other medication. Never use medication without your doctor's knowledge, as this can be harmful to your health.

Overdose: what happens if you take more than the recommended amount?

If someone uses more than the recommended amount of this medicine, it can cause poisoning. If accidental poisoning or significant exposure to ivermectin occurs, it is important to seek medical help immediately.

The most common symptoms of ivermectin toxicity include skin lesions, hives, swelling, headache, dizziness, lack of energy, nausea, vomiting, abdominal pain, diarrhea, seizures, imbalance, difficulty breathing, and changes in sensation.

If you take too much medication, seek medical help quickly and take the medicine packaging or leaflet with you, if possible. For further guidance, you can also call 0800 722 6001.

Download the original leaflet

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Sources and bibliography:

This article was manually extracted from the original package insert, under the technical supervision of the responsible pharmacist.

. “Ivermectin”. The American Society of Health-System Pharmacists.
. Drug and Health Product Register”. 
. “Ivermectin – Old Drug, New Tricks?”. Trends in Parasitology.
. Stromectol – ivermectin tablet”. DailyMed. 
. Soolantra – ivermectin cream”. DailyMed.
. List of nationally authorized medicinal products” (PDF). European Medicines Agency.