The Top 10 Things You Should Know Before Filling Veterinary Prescriptions

Gigi Davidson, BSPharm, Dipl.ICVP

NC State University College of Veterinary Medicine

Disclosure

• Gigi Davidson declare(s) no conflicts of interest, real or apparent, and no financial interests in any company, product, or service mentioned in this program, including grants, employment, gifts, stock holdings, and honoraria.

Objectives

Identify information resources most useful to community pharmacists when filling prescriptions for animal patientsIdentify

Recognize the overarching principles of veterinary drug laws and regulationsRecognize

Describe the impact of species-specific vital signs, metabolic capacity, gastrointestinal physiology, and dietary habit on drug disposition in animalsDescribe

Review the most common veterinary-only drugsReview

List most common dispensing errors for veterinary prescriptionsList

#1 Veterinary Information Resources

One Stop Veterinary Drug Information

Plumb’s Veterinary Drugs (electronic)www.plumbsveterinarydrugs.com

• Desktop, smartphone, tablet versions available

• Veterinary Medication Guides (client education)

Plumb’s Veterinary Drug Handbook (print)Donald C. PlumbWiley-BlackwellJanuary 2015 (8th edition)

• Desk-size and pocket-size formats available

• 9th Ed. 2018

Veterinary PDR Equivalent

Compendium of Veterinary Products

• https://bayerall.naccvp.com/?u=bayer&p=dvm

• Free with online registration

• US and Canadian versions

• Over 6010 product package inserts

• Charts

• Anthelmintics and Parasiticides

• Biologicals (vaccines)

• Withdrawal times

Phone app “CVP Vet”

Disease State Management

The Merck Veterinary Manual (print)Merck & Co., Inc.July 2016 (11th edition)

The Merck Veterinary Manual (electronic)www.merckvetmanual.com

• Free

• Updated continuously

Today’s Veterinary Practice

Today’s Veterinary Practice (electronic)

• http://todaysveterinarypractice.navc.com/

• Free with registration

• Current topics

• Clinical resources

• Disease state management

Today’s Veterinary Practice (print)

#2 Understand Veterinary Abbreviations

What Does This Mean??

What is the dose?

Veterinary dosing is commonly allometric

and not empiric

mg/kg

mg/lb

mg/m2

Species Specific formulas

Chemotherapy

Do not misinterpret empiric dosing as allometric dosing

amlodipine: 0.625 mg/CAT not 0.625mg/kg

atenolol 6.25 mg/CAT not 6.25mg/kg

Check in: Translate the

Script

#3 Understand Veterinary Drug Law

Overarching Principle: Animals are food for humans.

“Intended Use”

In the US, the only species that cannot be consumed as food are:

• Humans

• Endangered list species

• Horses (intermittently)

Human dietary preferences determine if an animal or their byproducts are “food”

• Cattle, chickens

• Meat, milk, eggs

• Buffalo, ostrich

• Meat, milk, eggs

• Rattlesnakes

Food animal or pet? Always assume food!

Which are most likely food animals?

Humans Eat Animals: Consequence #1: Withdrawal Times

WDT: the length of time after the last dose during which an animal or its byproducts may not be consumed as food

• Must be supplied by veterinarian on prescription

• Examples:

• Do not sell for slaughter for 5 days after last dose.

• Discard milk for 36 hours after last dose.

• Discard eggs for 14 days after last dose.

Humans eat animals:Consequence #2:

OTCs must be used as labeled

FDA approves veterinary OTC’s:

• For target species

• For approved indication(s)

• At approved dose

• By approved route

• For approved duration

Extralabel use of veterinary OTC must be directed by veterinarian

• Pharmacists may NOT recommend use of human OTCs in animals

• Scenario

Law Continued: Understanding Veterinary Credentials

Can a physician write a prescription for his dog?

Law: Prescription Verification• Veterinarians are NOT eligible for NPI

numbers:• CMS identifier

• DEA strongly opposes use of DEA number for non-controlled substances

• NCPDS recommends use of prescriber state license ID number to verify

NOTE: Some non-controlled substances are reportable in the Virginia PMP (e.g. gabapentin and naloxone) and require the prescriber’s DEA number for reporting.

Law: Generic Substitution

• Veterinarians are unaware of CMS requirements to dispense generics

• Veterinarians are unaware of the Dispense As Written signature line

• Call veterinarian to verify if Brand is required or if generic substitution is permitted

Elements of a Veterinary Prescription Label*

• Pharmacy name, address, and phone number

• Prescription number

• Date of initial dispensing

• Name and species of the animal patient Note: VA requires name of animal owner and species of patient for CII PMP reporting

• Directions for use

• Name and strength of the drug product (or active ingredients in a compounded prescription)

• Quantity or volume of drug product dispensed

• Name of the prescribing veterinarian

• Any withdrawal times stated for food-producing animals

• Name of the dispensing pharmacist

• Expiration or beyond-use date

• Number of refills

*American Veterinary Medical Association-https://www.avma.org/KB/Policies/Pages/Guidelines-for-Veterinary-Prescription-Drugs.aspx

#4 Be Aware of The Most Common Dispensing Errors

Veterinarians’ Perceptions NCSU Survey March

2015 (Sorah E, Davidson G. Royal

K. Dispensing Errors for Non-Human Patients in the

Community Pharmacy Setting:

A Survey of Pharmacists and

Veterinarians. Poster. SVHP

Portland, ME, June 2015.)

Insulin substitutions

Levothyroxine dosage changes

RPh recommended human OTC

Inappropriate counseling

Wrong drug salt dispensed

AVMA Survey September 2014

(Cima, Greg. Substitution errors. JAVMA (2014): 462-

465.

Insulin substitutions

Levothyroxine dosage changes

RPh recommended human OTC NSAID instead of prescribed NSAID

Other Potential Errors

Drugs withdrawn for human safety are commonly used in animals

• Cisapride

• Bromides

• Phenylpropanolamine

• Diethylstilbestrol

Metabolic capacity of a species may result in completely different drug disposition compared to humans

• Levothyroxine

• Digoxin

• Diazepam

#5 Understand the Patient’s Metabolic Capacity

Feline Metabolic Limitations

Glucuronide conjugation (deficient)

• Targeted Functional Groups: -OH, -COOH, NH2, =NH, -SH moieties attached to either phenolic (ring) or alcoholic (straight-chain)

• Targeted Drugs: Acetaminophen, Azo Dyes, Benzodiazepines, Benzyl alcohol, Benzoic acid derivatives, Carprofen, Chloramphenicol, Codeine, Morphine, Lamotrigene, Phenazopyridine, Phenols, Propofol, Salicylates, Zidovudine

Methylation (deficient in thiopurine methyltransferase)

• Targeted Functional Groups: --SH (purines)

• Targeted Drugs: Azathioprine, 6-mercaptopurine

Canine Metabolic Limitations

Acetylation (absent)

• Targeted Functional Groups: Aromatic—NH2

• Targeted Drugs: Dapsone, Hydralazine, Isoniazid, Procainamide, Sulfonamides

Metabolic Capacities: Canine Genetic Anomalies-ABCB1-Δ and BBB

Affected Dog BreedsBreed Approximate Frequency

of Mutation (%)Australian Shepherd (standard and mini)

50

Border Collie <5Collie 70English Shepherd 15German Shepherd 10Herding Breed Crosses 10Long-Haired Whippet 65McNab 30Mixed breeds 5Old English Sheepdog 5Shetland Sheepdog 15Silken Windhound 30

Targeted Drugs• Acepromazine

• Butorphanol

• Chemotherapy agents• Doxorubicin• Paclitaxel• Vinblastine• Vincristine

• Loperamide

• Macrocyclic lactones• Ivermectin• Milbemycin• Moxidectin (used in doses higher than labeled for

heartworm prevention)• Selamectin

#6 Understand the Patient’s Gastrointestinal Physiology/Diet

Effects of Dietary Habit

Carnivores

• More acidic gastrointestinal pH

• Low pH kills raw diet pathogens

• Shorter, faster gastrointestinal tract

Omnivores Herbivores

• More alkaline gastrointestinal pH

• Volatile fatty acids from carbohydrate digestion

• Longer, slower gastrointestinal tract

Effect of Gastric pH on Drug Disposition

• Weak acids are more bioavailable in dogs and cats due to lower GI pH (lower dose compared to

humans.)

• Weak acids are less bioavailable in horses due to higher GI pH. (higher dose compared to humans)

• Sustained-release or extended-release dosage forms designed for the human GI tract are unlikely

to have the same release profile in non-human patients. Drug contents may be released

prematurely or not at all, depending on pH and GI tract length.

#7 Know Likely Toxins for Each Species

Toxic Excipients and Foods in Dogs, Cats, and BirdsDrug/Excipient/Food Species Affected Toxicity

Alcohols Dogs, cats, birds Central nervous system toxicity

Avocado Birds Pulmonary congestion, nonsuppurative inflammation of the liver, kidney, pancreas, skin, and proventriculus

Benzocaine, benzoic acid derivatives Cats Red blood cell oxidative injury, hemolytic anemia

Chocolate Dogs, birds Cardiovascular and central nervous system stimulation

Cremophor Dogs Histamine release, anaphylaxis

Fat, fatty foods Dogs Increased risk of pancreatitis

Garlic, onions Dogs, cats Hemolytic anemiaGrapes, raisins Dogs Renal toxicityMacadamia nuts Dogs Lethargy, hyperthermia, ataxia, vomiting

Pennyroyal Cats HepatotoxicityPolysorbate 80 Dogs Histamine release, anaphylaxis

Raw yeast dough Dogs Alcohol poisoning, gastrointestinal dilatation and volvulus

Xylitol Dogs, birds Profound hypoglycemia and hepatocellular necrosis

#8 Know Species Vital Sign Thresholds

Fever Thresholds in Various Species

Pulse and Respiratory Rate Ranges

Gestational Periods by Species

#9 Be Familiar With Veterinary-Only Drugs

Veterinary Fluoroquinolones

Enrofloxacin (Baytril®)

Marbofloxacin (Zinequin®)

Pradofloxacin (Veraflox®)

Danofloxacin (Advocin®)

Orbifloxacin (Orbax®)

Veterinary NSAIDs

Carprofen (Rimadyl®)

Deracoxib (Deramaxx®)

Firocoxib (Previcox®)

Robenacoxib (Onsior®)

Grapiprant (Galliprant®)

Flunixin (Banamine®)

Phenylbutazone (Butazolidin®)

Veterinary Endocrine Agents

Trilostane (Vetoryl®)

Pergolide (Prascend®)

Estriol (Incurin®)

Diethylstilbestrol (DES®)

Domperidone (Equidone®)

#10 Know Where to Report a Veterinary ADE

Adverse Drug Events

FDA Form 1932a “Veterinary

Adverse Experience, Lack of Effectiveness

or Product Defect Report”

https://www.fda.gov/AnimalVeterinary/SafetyHealth/ReportaProblem/ucm055305.htm#Drugs_and_Devices

May be reported by veterinarian, pet owner or pharmacist

VeterinarianCan determine if truly an ADE or if related to disease

May choose to report to FDA using form 1932a

Report Errors to?

For immediate discontinuation of therapy or other resolutionPet owner

For needed monitoring or additional therapyVeterinarian

To broaden database for dispensing errorsBoard of

Pharmacy

Pharmacy Dispensing Complaint Form AVMA

Summary

Keep these 10 tools sharp and readily retrievableKeep

Call veterinarians for questionsCall

Report any adverse events or errors to veterinarianReport

Learn as much as you can about non-human patientsLearn

Questions?