Using Animal and Human Drugs in Veterinary Pharmacy


Some common human drugs are toxic when used in animals.

When caring for pets and other animals, it’s important for pharmacists to remember that there are differences between some veterinary and human drugs.

For example, non-steroidal anti-inflammatory drugs (NSAIDs) for humans should never be given to dogs and cats as they are quite dangerous, according to Amy Savarino, PharmD, chief pharmacist at Texas A&M University Veterinary Medical Teaching Hospital in College Station, Texas, during her presentation on veterinary basics for pharmacists at the American Pharmacists Association 2022 Annual Meeting & Exposition. “It is very important we give dogs veterinary NSAIDs, not over the counter [human medications]. They are contraindicated in dogs with steroids,” Savarino stressed.

Dogs are also allergic to xylitol, a sweetener that is added to many human drugs, she added.

Common veterinary NSAIDS for dogs include carprofen (brand names Rimadyl, Novox, Quellin, Vetprofen, and others) and deracoxib (Deramax). Firocoxib (Previcox) tablets or paste and phenylbutazone can be prescribed for dogs and horses, Savarino noted, while robenacoxib (Onsior)can be used to treat both cats and dogs.

Human-labeled drugs commonly prescribed in veterinary medicine include the pain medications gabapentin and pregabalin(Lyrica), used off-labelin dogs and horses. Narcotics such as fentanyl, morphine, methadone, hydromorphone,ketamine, buprenorphine, and hydrocodone are also used. Tramadol can also be used—although, Savarino noted, pharmacists will see larger doses for animals than those for humans, due to animals’ metabolism.

Amoxicillin is perhaps the most common antibiotic used in veterinary medicine.

During her presentation, Savarino also shared guidance on flea, tick, and heartworm prevention medicines—some of the most common veterinary prescriptions.

“Why do dogs need preventatives?” Savarino asked. “Because a dog may have heartworm larvae, but not yet have heart worm.”

These medications include macrocyclic lactones such as those in the avermectin class (ivermectin and selamectin) and milbemycins (milbemycin and moxidectin), which kill the developing larvae and mites. “They are neurotoxic to parasites but do not penetrate the blood-brain-barrier, so they do not affect mammals,” Savarino said.

She advised pharmacists to ensure that patients are not missing doses of these preventive medications.

For flea prevention, growth regulators prescribed include lufenuron (Program), which works within an hour. Methoprene and puriproxyfen prevent the insect from growing and are included in products such as Frontline Plus/Gold and other spot-on products.

New in the past few years for flea and tick prevention are isoxazolines, or GABA inhibitors that cause hyperpolarization. Examples include afoxolaner (Nexgard) sarolaner (Simparica), lotilaner (Credelio), and fluralaner (Bravecto).


Savarino A. Veterinary basics for pharmacists. Presented at: American Pharmacists Association 2022 Annual Meeting & Exposition; March 17-21, 2022; San Antonio, TX.

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