Noromectin is ivermectin. It’s a brand name for veterinary ivermectin products made by Norbrook Laboratories Limited, a pharmaceutical company based in Northern Ireland. The active ingredient in every Noromectin formulation is ivermectin at the same concentrations found in other veterinary ivermectin brands. Think of it the way store-brand ibuprofen relates to Advil: same drug, different label.
What’s Inside Noromectin
Noromectin comes in several formulations, each designed for a different species or method of application. The injectable version is a sterile solution containing 1% ivermectin, which works out to 10 mg of ivermectin per milliliter. The pour-on version for cattle delivers 0.5% ivermectin applied directly to the skin along the animal’s back. The oral paste for horses contains 18.7 mg of ivermectin per gram, with each syringe delivering enough (140 mg total) to treat a horse weighing up to 700 kg (about 1,540 pounds).
These concentrations are identical to what you’d find in other veterinary ivermectin products on the market. The inactive ingredients (the solvents and carriers that help deliver the drug) may differ slightly between brands, but the active compound and its concentration are the same.
How It’s Used in Livestock
Noromectin is a broad-spectrum parasiticide, meaning it kills a wide range of internal and external parasites. In cattle, the FDA-approved injection treats gastrointestinal roundworms, lungworms, cattle grubs, mites, and several species of lice. The pour-on formulation also covers horn flies. The drug works by paralyzing the nervous system of parasites, which eventually kills them.
The injectable form was approved by the FDA in April 2007 under an abbreviated application (ANADA 200-437), which is the generic drug approval pathway for animal medications. This approval covers cattle, swine, reindeer, and American bison. Dosing is weight-based: cattle receive 1 mL per 110 pounds of body weight injected under the skin near the shoulder, while swine get 1 mL per 75 pounds behind the ear.
Withdrawal Periods for Food Animals
Because Noromectin is used in animals that enter the food supply, there are mandatory waiting periods between the last dose and when the animal can be slaughtered or its milk consumed. These withdrawal periods give the drug time to clear the animal’s system so residues don’t end up in meat or dairy products.
For the injectable formulation, the withdrawal times are 35 days for cattle, 18 days for swine, and 56 days for both reindeer and American bison. The pour-on version requires 28 days before slaughter for cattle. Neither formulation is approved for use in lactating dairy cows producing milk for human consumption, and the pour-on specifically should not be used in pregnant heifers within 60 days of calving.
Why Noromectin Is Not for Humans
While Noromectin contains the same active compound found in prescription ivermectin tablets for people, it is formulated exclusively for animals. The concentrations are far higher than what a human would safely take, and the inactive ingredients have only been evaluated for safety in the animal species listed on the label. A single syringe of the horse paste, for instance, contains 140 mg of ivermectin, many times the dose a human would receive even in a clinical setting.
The FDA has issued direct warnings that animal ivermectin products can cause serious harm in people. Veterinary formulations are not manufactured under the same quality controls required for human pharmaceuticals, and the dosing is calibrated for animals that may weigh ten times more than a person. Human-approved ivermectin exists as a separate, prescription product with its own dosing, safety testing, and manufacturing standards.
How Noromectin Compares to Other Brands
The original ivermectin product for livestock was Ivomec, made by Merial (now part of Boehringer Ingelheim). Noromectin entered the market as a generic alternative through Norbrook Laboratories. In practical terms, veterinarians and livestock producers choose between these brands based on price, availability, and preference. The drug itself, its mechanism, and its effectiveness against the same parasites are equivalent. If a veterinarian switches an operation from one brand to another, the dosing schedule and withdrawal periods remain the same because the active ingredient and its concentration are standardized.
Other generic veterinary ivermectin brands exist as well, including Ivermectin and various store-brand labels sold through agricultural supply retailers. All contain the same drug at the same labeled concentrations, differing only in manufacturer and price point.