Pharmaceutical Care of Canines: Student Summary

Important Considerations

Horizontal orientation – can’t rely on gravity to pull oral dosage forms into gut
More acidic GI and urinary pH compared to humans (due to carnivorous diet)
GI transit time ~12 hours
Elongated ear canal and shape variation
Limited metabolic capacity – toxicity and efficacy concerns
Breed pharmacokinetic differences
Common toxicities – alcohol, estrogen, methylxanthines, NSAIDs, sulfonamides, xylitol
Compounding reminders – flavoring (meat or sweet flavors), 3% rule, salt conversions

Common Disease States

Hypothyroidism

Levothyroxine (0.1 mg/10lb body weight) –> much larger doses than humans
- Using human commercial product can be a large pill burden for some dogs
- Difficult to compound accurately
- Counsel to administer consistently either with or without food
- Do not give concurrently with antacids, sucralfate, or iron; can prevent absorption
- Monitor for signs that dose is too high (rapid heart rate, increased hunger and thirst, panting)
- Administer medication 4-6 hours before thyroid is checked

Hyperadrenocorticism (Cushing’s Disease)

Etiology: most commonly caused by pituitary dysfunction (e.g. pituitary tumors); can also be caused by excessive amounts of glucocorticoids
Symptoms: polyphagia, muscle wasting, potbelly appearance, excessive panting
Treatment options:
- Trilostane (Vetoryl) – drug of choice
  - Use FDA-approved capsules (not bulk substance) as source of API
  - Administer in the morning with food
  - ACTH stimulation test 4-6 hours after dosing
- Mitotane – used for treatment or for medical adrenalectomy
  - Give with high fat food to increase bioavailability
  - Induction needed before changing to maintenance dose
  - Monitor water consumption (must be limited to 80 mL/kg/day)
  - Pregnancy precautions – can cause spontaneous abortion in pets who are pregnant; clients who are pregnant or may get pregnant should take precautions when handling drug

Hypoadrenocorticism (Addison’s Disease)

Etiology: deficiency in mineralocorticoids and/or glucocorticoids
Symptoms: vomiting, diarrhea, lethargy, weight loss (symptoms exacerbated by stressful situations)
Treatment options:
- Desoxycorticosterone pivalate (DOCP) – drug of choice
  - Veterinary only product
  - Very viscous suspension- needs to be shaken vigorously for 2-3 minutes; administer with 20-22 gauge needle and need to make sure needle is not in a blood vessel
  - Expensive
- Fludrocortisone acetate
  - Affordable, but big pill burden (minimize pill burden by wrapping tablets in bread or cheese)
  - Tolerance may build so drug therapy may need to be augmented
- Additional prednisone may needed during stressful periods
Monitor for signs of Addisonian crisis: common symptoms include vomiting, weakness, slow heartbeat (<60 bpm), shivering, collapse –> medical emergency

Diabetes Mellitus

Prevalence: usually T1DM; oral agents don’t work well in canines due to lack of functional beta cells
BG Goal: 100-250 mg/dL; hypoglycemia = < 80 mg/dL; control is not as tight as in human patients
- Want to prevent hypoglycemia and make sure clients have glucose on hand
Treatment: insulin
- Administered after meals
- Don’t substitute insulins without consulting veterinarian
- U-40 vs U-100 syringes
- Dose adjustments usually occur in 0.5-U increments
- Porcine insulin zinc suspension (Vetsulin)- most common
  - Must be shaken before use
- NPH insulin
  - Do not shake; do not substitute brands

Idiopathic Epilepsy

Treatment options:
- Phenobarbital – often drug of choice for initial therapy
  - Concern: hepatotoxicity (must monitor liver function!)
  - High alcohol content in liquid formulation
  - Side effects: sedation and ataxia (should improve over time)
  - Check for drug-drug interactions (phenobarbital is a potent inducer)
  - Monitor levels; emphasize importance of veterinary follow-ups
- Potassium Bromide – may be taken with other medications (like phenobarbital)
  - Loading dose often needed do to long half-life
  - Monitor salt intake
- Levetiracetam
- Zonisamide
  - Sulfa allergy caution
- Gabapentin
  - Commercial products may contain xylitol!
  - Often compounded into liquid formulation; caution with formulations 100mg/mL or higher due to risk of crystallization
- Rescue meds for seizures or cluster seizures for greater than 5 minutes:
  - Diazepam (rectum) or midazolam (intranasal)
  - Do not preload plastic syringes
  - Needleless vial adapters, mucosal atomization devices

Urinary Incontinence

Treatment options:
- Estriol (Incurin)
  - Don’t use in male dogs or pregnant female dogs; decrease dose in a stepwise manner with at least 7 days between dose adjustments
  - Estrogen increases response of urethral smooth muscle
  - Handling precautions for clients pregnant or trying to get pregnant
- Diethylstilbestrol (DES)
  - Must be compounded
  - Pregnancy handling precautions
- Phenylpropanolamine (Proin)
  - Monitor for inappropriate use
Use non-toxic barrier dressings to prevent urine scalding, not diaper rash products

Dermatological Therapeutics

Treatment options:
- Cyclosporine – commonly used; must use modified formulation in animals
  - Compounding not recommended; needs to be an emulsion to be absorbed
  - Sandimmune not bioequivalent to other brand names – must consult veterinarian before switching!
  - Can be given with ketoconazole to increase systemic levels of cyclosporine (cost-saving measure)
- Atopica
  - Can freeze dosage form 30-60 minutes before administration to assist with vomiting
  - Don’t wash out syringe between doses
- Oclacitinib (Apoquel)
  - No literature to support that it causes cancer (can exacerbate existing cancers)

Infectious Disease

Treatment options:
- Amoxicillin/clavulanate (Augmentin, Clavamox) – ratio differences between formulations
  - Veterinary products are expressed in terms of both amoxicillin and clavulanate
- Itraconazole
  - Don’t use bulk powder when compounding – not bioavailable in mammalian species; use commercial product as source of API
- Marbofloxacin (Zeniquin)
  - Must use bulk powder in compounding; cannot be made from oral tablets – not stable
- Tylosin (Tylan)
  - Use gel capsules or mix powder with apple juice to help with palatability
- Ciprofloxacin
  - Crushing tablets before administration may increase bioavailability
- Metronidazole
  - Antimicrobial stewardship considerations; make sure it is appropriately prescribed

Common Cardiovascular Therapeutics

General considerations
- Monitor appetite, water intake, activity level, respiratory rate
- Medication administration should result in as little stress as possible
- Bioavailability can change significantly when converting between dosage forms; consult veterinarian
Pimobendan (Vetmedin)
- If compounding is warranted, citric acid must be added for stability and to address bioavailability concerns
Enalapril
- Recheck kidney function 3-7 days after starting therapy
- Can cause ototoxicity in high doses
- Provide plenty of access to water
Diltiazem
- Make sure to check the dosage form (IR vs. ER, etc.) – it must match dosage and frequency
Hydrocodone bitartrate – antitussive
- Do not dispense formulations containing acetaminophen
- Schedule II considerations (must have a hard copy prescription, ink signature for prescriber, no refills)
Butorphanol tartrate
- Dose reduction with ABCB1 (MDR1) mutations

Common Pain Management Therapeutics

Carprofen – veterinary only product; NSAID
- commercial version of an NSAID that is safe for pets
- Administer with food
Grapiprant (Galliprant)
- Administer without food
- Do not cut 100mg formulation tablets
Tramadol
- Efficacy concerns
- Check for drug-drug interactions
Gabapentin
- Commercial products may contain xylitol!
- Often compounded into liquid formulation; caution with formulations 100mg/mL or higher due to risk of crystallization
CBD
- Efficacy and safety concerns – data still lacking
- Drug-drug interaction concerns
- Regulatory concerns and considerations
Glucosamine/chondroitin sulfate
- Efficacy considerations