Endocrine Pharmacology Flashcards
(47 cards)
Goal of Tx for canine hypothyroidism
Replace hormone the body is not producing
- Liothyronine: T3
- LEVOTHYROXINE: T4 (soloxine)
Levothyroxine requires ____(more/less)____ frequent dosing & has ___(higher/lower)___ risk of causing thyrotoxicosis (excessive T4 levels) than liothyronine
less, higher (I think)
Levothyroxine pharmacologic considerations
- Must be given for rest of pt life
- Monitored by measuring T4 levels
- Thyro tabs are the only vet approved
-Drugs that may interfere with T4 levels: phenobarbital, zonisamide, sulfonamides, lucocorticoids, phenylbutazone, quinidine
Goal of Tx in hyperthyroidism in cats
-stop excessive hormone productions
Pharmacologic tx options for feline hyperthyroidism
- Thioureylenes
- Iodides
Thioureylenes- Methimazole & Carbimazole
- inhibit thyroid hormone synthesis
- Consistently efficacious
- Side effects uncommon and most are manageable
Thioureylenes– PTU (propylthiouracil)
- inhibit thyroid hormone synthesis
- inhibit conversion of T4 -> T3 in tissues
- also efficacious
- Higher incidence of serious side effects
Iodides and Iodinated contrast agents
- Inhibit thyroid hormone synthesis
- inhibit release of pre-formed hormone
- Inhibit T4> T3 conversion in periphery (contrast agents)
- Efficacy is variable and often transient
Clinical signs of acute hypocalcemia
Hyperesthesia/pawing at the face, tremors, progressing flaccid paralysis, seizures, hyperthermia, bradycardia
Pariparturient hypocalcemia
Milk fever, eclampsia
- sudden increase in calcium usage, patient can’t adapt rapidly enough
- acute
Acute Hypocalcemia RoA
- Oral vs IV (parenteral for emergencies)
- Parenteral ca options: Ca gluconate or Ca chloride
Acute Hypocalcemia, calcium RoA contraindications
-Ca Chloride is caustic: NO SQ/IM
-Ca Gluconate: dilute if giving Sq, IV IS BEST
Ca is incompatible with some fluids/drugs
-Rapid IV admin of Ca can cause arrhythmias (monitor ECG!)
Chronic Hypocalcemia (HypoPTH): oral Ca options
Ca Carbonate and Ca propionate: gi tract must be able to absorb calcium
Hypoparathyroidism results in inability of the body to convert _____ to it’s active form ________
Vit D –> Calcitrol
No PTH –> the GIT can’t absorb Ca
Biggest potential side effect of calcitriol is
hypercalemia
Hypoglycemia can be managed with (3 things)
1) Diet: Frequent, small carb meals
2) Dextrose 50% sol’n: Mucosal absorption is decent, no dextrose SQ, IV no more than 5%
3) Glucagon hormone: IV, not common
Chronic hypoglycemia goal and tx options (2)
Address the cause and if not alter the glucose produced and used
- diet
- Corticosteroids: prednisone
Hyperglycemia
- Doesn’t require therapy
- Diabetes mellitus (DM)- insulin deficiency
Oral hypoglycemic agents
- CAUSE hypo, don’t Tx hyper!
- Glipzide(glucotrol): sulfonylurea – only effective in ~30% of cats; may accelerate B-cell loss
- Only useful in type II diabetes where pancrease can still secrete some insulin (CATS ONLY)
Oral hypoglycemic agents MoA
Stimulate insulin secretion by the pancreatic B-cells (blocking K channels)
-also increase tissue sensitivity to insulin
T/F: all insulin are inectible and similar potency (except detemir)
TRUE
Regular Insulin/Humulin-R/Crystalline/Neutral Insulin
- short acting
- IV, IM, SQ
- Commonly used for hosp pt not eating
- Duration: Short to long term mgmt
NPH (Isophane), Lente, Vetsulin/Caninsulin
- SQ only
- Intermediate acting insulin
- Protamine or zinc are added to delay absorption and extend clinical effect
- good for starting insulin
- not adequate control in felines
Protamine zinc/PZI, Glargine, & Detemir
- SQ only
- Long acting insulin
- Glargine: forms microprecipitate in physiologic pH, very gradual absorption (flat curve)
- Prozinc: may have shorter duration than the rest; Long acting (particularly in cats)
- Determir: has much higher potency in dogs (4x), requires special dosing and may be difficult to dose in smol doggos
