Ivermectin is a derivative of avermectin, a naturally occurring substance produced by the soil bacterium Streptomyces avermitilis. Since its discovery in the late 1970s, it has become a cornerstone of both veterinary and human medicine for controlling parasitic diseases. While human-grade ivermectin is prescribed orally for specific conditions, veterinary forms, including injections, are formulated for animal use only and can be dangerously potent for humans.
How an Ivermectin Injection Works
An ivermectin injection delivers a powerful dose of the antiparasitic agent into an animal's system. The drug works by targeting specific nerve and muscle functions unique to invertebrates, causing paralysis and death of the parasite.
The Mechanism of Action
Ivermectin's primary mode of action relies on its ability to bind to glutamate-gated chloride channels. These channels are crucial components of nerve and muscle cell communication in invertebrates but are generally absent in mammals at therapeutic concentrations, which gives the drug a wide safety margin in its intended use.
- Binding and Hyperpolarization: Once injected, ivermectin is absorbed and travels through the bloodstream. It binds to the parasite's glutamate-gated chloride channels, forcing them to open permanently.
- Inhibitory Effects: This sustained opening allows an influx of chloride ions into the nerve cell, causing the cell membrane to become hyperpolarized. This state prevents the electrical nerve signals necessary for normal muscle function.
- Paralysis and Death: The resulting nervous system disruption leads to flaccid paralysis of the parasite, which is then unable to feed or move. This ultimately leads to the parasite's death and its elimination from the host animal's body.
Uses of Ivermectin Injections in Animals
Ivermectin injections are widely used in veterinary medicine for their broad-spectrum efficacy against a variety of internal and external parasites. Its use has significantly improved the health and productivity of livestock and has been a reliable part of parasite control in companion animals.
Common veterinary uses include:
- Livestock (Cattle and Swine): Treatment and control of gastrointestinal roundworms, lungworms, lice, and mange mites. Injections are administered subcutaneously in specific areas, such as the neck for swine and behind the shoulder for cattle.
- Companion Animals (Dogs and Cats): Prevention of heartworm disease at low doses. At higher doses, it may be used off-label to treat other parasites like demodectic mange, scabies, and ear mites.
The Critical Distinction: Animal vs. Human Formulations
It is imperative to distinguish between ivermectin products for animals and those for humans. Veterinary ivermectin injections and other formulations are not safe for human use.
The Dangers for Humans
- Concentration: Veterinary products, especially those for large animals like cattle, contain a much higher concentration of ivermectin. A dose suitable for a 2,000-pound animal can be toxic or lethal to a human.
- Inactive Ingredients: The inactive ingredients used in animal products are not evaluated for human safety and may cause adverse reactions.
- Risk of Overdose: Intentional or accidental ingestion of animal ivermectin can lead to overdose and serious side effects, including nausea, vomiting, seizures, coma, and even death. The FDA has issued strong warnings against this practice.
The COVID-19 Misinformation
During the COVID-19 pandemic, misinformation spread falsely claiming ivermectin was a treatment. The FDA and other major health organizations have repeatedly stated that there is no scientific evidence to support this claim and that using veterinary ivermectin for COVID-19 is dangerous.
A Comparison of Ivermectin Formulations
| Feature | Veterinary Ivermectin Injection | Human Ivermectin (Oral Tablet) |
|---|---|---|
| Primary Use | Treatment and control of a wide range of internal and external parasites in livestock and pets. | Treatment of specific parasitic worm infections like strongyloidiasis and onchocerciasis. |
| Concentration | Often much higher, designed for large body mass animals like cattle. | Precisely dosed for human use based on body weight. |
| Administration | Subcutaneous injection. | Oral tablets. |
| Safety | Considered safe for its intended animal species when used as directed. | Safe for humans when prescribed by a doctor and obtained from a pharmacy. |
| Toxicity in Humans | High risk of severe toxicity and death due to high concentration and unapproved inactive ingredients. | Overdosing is still dangerous, but human formulations are much safer at prescribed doses. |
Side Effects and Precautions
While effective, ivermectin injections are not without risks, especially when not used correctly.
- General Side Effects in Animals: Potential side effects include stomach upset, vomiting, diarrhea, and neurological signs such as stumbling, trembling, and head pressing.
- Herding Dog Sensitivity: Certain dog breeds, including Collies, Australian Shepherds, and Shetland Sheepdogs, carry a genetic mutation (MDR1) that makes them more susceptible to ivermectin toxicity. Veterinarians must be aware of this sensitivity when administering the drug.
- Potential Drug Interactions: For both veterinary and human use, ivermectin can interact with other medications, particularly affecting the P-glycoprotein transporter system. It has also been reported to interact with warfarin.
Conclusion
In summary, an ivermectin injection is a veterinary medication that works by targeting and paralyzing the nervous system of parasites in animals, leading to their death and elimination. Its primary use is in livestock and pets for the control of a broad spectrum of internal and external parasites, contributing significantly to animal health and agriculture. However, it is crucial to recognize that veterinary ivermectin products are formulated specifically for animals and are not safe for human use due to dangerously high concentrations and different inactive ingredients. The misuse of animal ivermectin in humans can lead to severe and potentially fatal consequences. This reinforces the importance of always following a veterinarian's guidance for animal treatment and consulting a licensed healthcare provider for human health concerns.
