Endocrine Flashcards
Levothyroxine is a replacement for
T4
Why is levothyroxine better than liothyronine
Requires less frequent dosing and has a lower risk of causing thyrotoxicosis
What is levothyroxine dosed in and how is it administered
mg/kg orally BID
How long after starting therapy should you start measuring T4 levels
4 weeks
What drugs could interfere with thyroid test results
Phenobarbital, zonisamide, glucocorticoids, phenylbutazone, quinidine
What is the only veterinary approved thyroid drug
Thyro tabs
What are the three pharmalogical ways to treat hyperthyroidism
Prevent production
Prevent release of preformed hormone
Prevent conversion of T3 to T4 in tissues
Methimazole is a ____ and inhibits ____
Thioureylene
Hormone synthesis
Methimazole is consistently ___ and side effects are ___
Efficacious
Uncommon and most are manageable
What are the mild/common side effects of Methimazole
GI signs (vomiting), transient hematologic changes on CBC
What are the severe/uncommon side effects of Methimazole
Refractory GI signs, idiosyncratic reactions (facial excoriation, hepatopathy, bone marrow suppression)
What are the forms of Methimazole
Tapazole, felimazole, transdermal methimazole
What are the parenteral calcium options and when would they be given
Ca Gluconate, Ca Choloride
Emergency Acute Hypocalcemia
Ca Chloride is ____ and should never be given ___
Caustic, SQ/IM
Rapid IV administration of Calcium can cause
Arrhythmias
Why should Ca Chloride and Ca Gluconate be given IV
So they are immediately diluted and don’t sit one spot for long periods of time
What are the Oral Ca options for chronic hypocalcemia
Ca Carbonate, Ca Proprionate
What is required when giving oral calcium
GI tract must be able to absorb the calcium
What causes the GI tract to not be able to absorb calcium
No PTH (hypoparathyroidism) Vitamin D is not converted to calcitriol
What is given to increase calcium absorption
Calcitriol
Calcitriol is the _____ activated form of vitamin D and is the most ____
Most potent activated form of Vitamin D and is the most rapid
What is the biggest potential side effect of calcitriol
Hypercalcemia
How can dextrose be administered
Orally
Intravenous bolus in emergency (50% diluted 1:4)
Ongoing IV (5% concentration)
How is glucagon adminitered and in what measurement
IV injection - nanograms
Not commonly used
What is the equation to determine amount of stock to add
% desired over % stock times volume in bag
What is the primary goal of DM therapy
Address insulin deficiency not to bring down blood glucose
Oral hypoglycemic agents cause ___
hypoglycemia, they don’t treat it
The only clinically relevant oral hypoglycemic drug is
Glipizide
Glipizide is used for ____ and only in ____
Type II diabetes in cats
Mechanism of Action of Glipizide
Stimulate insulin secretion by the pancreatic beta cells by blocking K channels
Increase tissue sensitivity to insulin
Insulin is produced by
Beta cells of the islets of Langerhans in the endocrine pancreas
Exogenous Insulins are all given by
Injection (IV, SQ, IM)
What are the different durations of action for exogenous insulin
Short, Intermediate and Long acting
The potency of various formulations is usually very similar except for ___
detemir - 4x higher
What is the only insulin that can be given IV
Regular insulin
Regular insulins duration of action is ___ and is usually used for
Short acting
Used for hospitalized patients that aren’t eating
What are the intermediate acting insulins
NPH, vetsulin/caninsulin
How are intermediate acting insulins given
SC only
Vetsulin/Caninsulin is good for
Good starting insulin for dogs
What are the long acting insulins
Protamine Zinc, Glargine and Detemir
How are long acting insulins given
SC Only
Which drug forms microprecipitates in physiologic pH which results in very gradual absorption
Glargine
Which drug is a veterinary approved product and may have a shorter duration particularly in cats
PZI - Protamine Zinc
What are the only two mineralcorticoids
Fludrocortisone and DOCP
Where are glucocoirticoids produced
zona fasciculata
What are the Glucocorticoid drugs
Prednisone, dexamethasone, triamcinolone, methylprednisolone
Glucocorticoids are used for their _____ effects
anti-inflammatory
Glucocorticoid Non-genomic effect
Glucocorticoid receptors in the membrane - rapid effects
Glucocorticoid Genomic effects
Nuclear type GCRs in the cytoplasm - increase or decrease gene expression
Physiological Effects of Glucocorticoids
Increase calcium excretion
Reduce fever
Suppress immune response
Lymphotoxic
Adverse Effects of Glucocorticoids
PU/PD, Catabolic, antagonize insulin, inhibit fertility, stress leukogram, Increase GI acid and decrease mucus
Clinical uses for glucocorticoids
Diagnostic testing
Physiologic Replacement Therapy (Addison’s)
Anti-inflammatory (allergies)
Immunosuppressive
Glucocorticoids are well absorbed ___ or ____
Orally or Parenterally
Glucocorticoids are ___ bound
Protein
The specific transporter for glucocorticoids is ____ and it has a ____ affinity and ____ capacity
Transcortin
High Affinity and Low Capacity
The secondary transport for glucocorticoids is ____ and it has a ____ affinity and ____ capacity
Albumin
Low Affinity and High Capacity
Which glucocorticoids are Pro-drugs and must be hydrolyzed
Prednisone –> prednisolone
Cortisone –> Cortisol
Methylprednisone –> methylprednisolone
Metabolites are excreted in ___
Urine
List Glucocorticoids in order of potency
Cortisol, Prednisone, Tramcinolone, Dexamethasone
What are the salt esters
Succinate and phosphate
What are the insoluble esters
Pivalate, acetate and acetonide
What do salt esters do
Make steroid soluble and suitable for IV administration
Salt esters the onset may be ___ but duration is ____
Onset may be faster but duration is unchanged
Insoluble esters ___ onset and have a ____ duration
Delayed onset and long duration
Less soluble the ester the longer it will take to absorb
Opaque suspensions cannot be give by ___
IV
Short Term (3-5 days) Side Effects of glucocorticoids
Not serious
Stress leukogram, decreased thyroid
PU/PD
Fetal abnormalities/abortion
Long term (> 1 wk) Side Effects of Glucocorticoids
Susceptibility to infection
Skin changes (collagen disease, delayed wound healing)
Hypertension
Latrogenic Addison’s
Where are mineralcorticoids produced
Zona glomerulosa
What do mineralcorticoids regulate
Na retention and K excretion by the kidney
How is Fludrocortisone given
Orally BID
How is DOCP given
Parenterally (IM, SC)
What is Typical Addison’s
Lacking both glucocorticoids and mineralcorticoids
What drugs are needed for typical addison’s
prednisone and DOCP/Fludrocortisone
What is atypical addison’s
Lacking just glucocortocoid
What drug is needed for atypical addison’s
just prednisone
