Veterinary Medicine in Community Pharmacy

When a veterinarian prescribes a medication, that prescription is often filled at a local community pharmacy. Some pharmacists have specialized training in veterinary medicine and become veterinary pharmacists, but most community pharmacists have little formal training in this area. It is difficult to know how to treat veterinary “patients” when different species and breeds can have vastly different responses to a treatment. Precise selection of medication and dose is essential. As student pharmacists, we sought to expand our knowledge of veterinary pharmacy by researching commonly prescribed medications for companion animals and exploring specific veterinary medicine topics.

To identify medications that veterinarians commonly prescribe and learn more about popular veterinary topics, we interviewed 6 veterinarians and 3 veterinary pharmacists in northwest Ohio.

Question 1

Of the medications that are commonly prescribed for companion animals, which ones would you like community pharmacists to know more about and why?

To answer this question, we analyzed the results of our interviews to determine which medications were nominated most frequently (see Figure). Then, we further researched important points that pharmacists should know about those top requested medications using Plumb’s Veterinary Drug Handbook and Veterinary Pharmacology and Therapeutics.

Facts About 6 Medications

Here are some facts about the 6 medications for pets most often mentioned by our sample group of veterinarians and veterinary pharmacists:

Cephalexin: The antibiotic cephalexin is commonly used to treat susceptible bacterial infections in dogs and cats.1 It is only available as human-labeled products, but veterinarians often prescribe it over other veterinary-specific antibiotics when it is more cost effective for the owner. Adverse reactions are rare and usually mild. The oral dosage forms may cause gastrointestinal effects such as vomiting or diarrhea. Cephalexin can be given with food to avoid or reduce stomach upset.

Methimazole: The thyroid medication methimazole is contraindicated in animals with liver disease, autoimmune disease, or concurrent hematologic abnormalities. Pet owners should be aware that this medication does not cure thyroid disease and will only decrease the amount of thyroid hormone in the body. Tablets should be stored at room temperature in light-resistant containers.

Nonsteroidal anti-inflammatory drugs:

A popular nonsteroidal anti-inflammatory drug (NSAID) called carprofen is indicated to treat arthritis pain and inflammation in geriatric canines, as well as acute pain after soft-tissue and orthopedic surgery.1 OTC NSAIDs should be avoided due to high toxicity in both dogs and cats; they can cause renal failure, gastric ulcerations, and perforations. For example, ibuprofen is contraindicated in both cats and dogs due to increased sensitivity to adverse effects at therapeutic doses.

Insulin: The main treatment for diabetes in both cats and dogs is insulin. There is a wide variety of human insulin products and also some veterinary insulin products available for use in cats and dogs. Cats are most commonly prescribed insulin glargine, while dogs are more likely to respond to Vetsulin.1 Vetsulin is a veterinary porcine insulin product that was recently reapproved in the United States. It is used mainly for dogs because canine insulin is more similar to porcine insulin than human insulin. Common retail pharmacies do not often carry veterinary-labeled products such as Vetsulin, but pharmacists should be aware that its concentration is 40 U/mL and that it requires a U-40 syringe, as approved by the FDA for veterinary use.

Metronidazole: Metronidazole is an antibiotic and antiprotozoal used to treat parasites and anaerobic infections.2 Similar to cephalexin, metronidazole is only available as human-labeled products and is administered either as an injection or orally.1 It is important to note that absorption of metronidazole is enhanced by food in dogs, while the opposite is true in humans. Metronidazole is notorious for its metallic taste, which makes some oral dosage forms unpalatable for animals. Capsules or compounded suspensions are the best oral dosage forms for masking the unpleasant taste.

Levothyroxine: Levothyroxine is primarily used in dogs for hypothyroidism. Dogs receive a starting dose of 18 to 22 mcg/kg orally twice a day, much higher than a human dose due to higher clearance and lower bioavailability of the drug in canines. It should be noted that a high-fiber pet food may reduce absorption of levothyroxine.

Question 2

Are veterinary prescriptions usually filled onsite or at a pharmacy associated with the veterinary practice?

Although some veterinary practices have a veterinary pharmacy onsite, most simply keep a small stock of medications to dispense and send prescriptions for drugs they do not have on hand to an outside community pharmacy. Even if veterinarians have a drug on hand, they will provide a prescription to the owner if a community pharmacy can offer it at a lower cost. Cost effectiveness for the owner is often the deciding factor in where a prescription is filled. Many veterinarians state that they have good relationships with their local community pharmacies and always send their prescriptions to those pharmacies.

Question 3

What kind of information do you expect pharmacists to be able to provide to pet owners about the medications their cat or dog will be receiving?

We heard mixed opinions regarding what kind of information pharmacists should provide. Some veterinarians said they preferred that pharmacists refer pet owners’ questions back to the veterinarian. Other veterinarians wanted pharmacists to be able to provide key counseling points, such as the expected action of the medication, how to use and administer the drug, and potential adverse effects—just as they would in counseling a human patient.

Many of the veterinarians we interviewed had encountered a case where a pharmacist changed a dose or advised a dose change without consulting the veterinarian and it resulted in detrimental effects for the animal. This often occurs when pharmacists see a drastically higher or lower dose than they are used to seeing in humans and assume it is incorrect. It is important to realize that the absorption and metabolism of certain medications in cats and dogs can be significantly different compared with humans. To avoid confusing pet owners or causing medication errors, pharmacists should direct questions about dosing or specific treatment options to the veterinarian prior to consulting with the owners or altering treatment.

What We Learned

We gained a lot of insight and knowledge from speaking with veterinarians and veterinary pharmacists. One issue that we learned about during our research process was the importance of proper recommendation of OTC products for animals. Pharmacists should know that without a veterinarian’s consent, they cannot legally recommend any OTC human medications for animals. Even if pharmacists receive continuing education about the proper OTC medication use in animals, they still may not independently give suggestions. One reason for this is the toxicity potential of these drugs in animals. For example, half of a regular strength acetaminophen tablet may result in death if taken by a feline.

Currently, there is no board certification available for veterinary pharmacy. According to Calvin Freedman, the president of the American College of Veterinary Pharmacists (ACVP), there is an expanding need for veterinary specialists in areas such as ophthalmology, dermatology, and oncology. The success of medical therapy in animals has translated to the ability of animals to receive medications rather than euthanization. Although at this time there are no accreditation standards, ACVP hosts meetings and educational conferences on topics that involve compounding techniques and pharmacology of medications in animals. Other organizations may provide advanced courses and access to mentors. Furthermore, there are currently 28 US colleges with pharmacists in veterinary medicine teaching hospitals that focus on service, research, and academia. Pharmacy students who are interested in veterinary pharmacy can also participate in experiential rotations at colleges of veterinary medicine, veterinary practices, or zoos.

Over the course of our project, we discovered that many veterinarians are receptive to pharmacist counseling, provided the pharmacist has the proper education. If, however, pharmacists lack training in the area of veterinary medicine, as is often the case, veterinarians prefer to have questions referred back to them.

We look forward to further exploring veterinary pharmacy and believe that pharmacy students and pharmacists would greatly benefit from education on medication use in this unique portion of our patient population.

References

1. Plumb DC. Plumb’s Veterinary Drug Handbook. 6th ed. Ames, IA: Blackwell Publishing; 2008.

2. Riviere JE, Papich MG. Veterinary Pharmacology and Therapeutics. 9th ed. Ames, IA: Wiley-Blackwell; 2009.