Endocrine Drugs Flashcards
What is the biologically active thyroid hormone?
T3
Which thyroid hormone comes 100% from the thyroid?
T4
T/F. T3 comes 100% from the thyroid.
False. 20% from thyroid, the rest is converted from T4 at liver, kidney, muscle
What is the goal of hypothyroidism treatment?
replacement therapy (replace Thyroid hormones)
Is levothyroxine a T3 or T4 replacement? Liothyronine?
levothyroxine: T4
liothyronine: T3
Why would you use liothyronine over levothyroxine?
when dogs can’t convert T4 to T3
What is the dosing of levothyroxine?
mg/kg BUT mg/m^2 if the patient is over 50lbs
T/F. Tyro-tabs are the only vet approved product for hypothyroid tx, but some patients may do better with Soloxine.
True
What are some different treatments you could use for a cat with hyperthyroidism?
- radioactive iodine
- Hill’s I/D diet
- Methimazole
- Surgery
- Iodides
Should you use Hill’s I/D if your hyperthyroid cat is indoor/outdoor? What about if you have a multi-cat household?
- indoor/outdoor: no because cat could be eating something else outside
- you can use with multi-cat houses but the other cats must also get 1tbsp of regular food once/day
How does Methimazole work?
stops production of new thyroid hormones
What are some mild side effects of methimazole? Some major side effects?
Mild - GI signs, lethargy, hematology changes
Major - idiosyncratic: facial excoriation, hepatoopathy, bone marrow suppression
What are routes of administration for methimazole?
- transdermal: pinna of ear
- oral
____% of calcium is bound to plasma proteins. Only _____ calcium is active.
- 50%
- unbound, ionized
PTH and Calcitriol (increase/decrease) calcium.
Calcitonin (increases/decreases) calcium.
- increase
- decreases
Which species do you think of when you think of hypocalcemia?
dairy cattle
What are some causes of hypocalcemia?
- partirient paresis (milk fever)
- parturient eclampsia in lactating dogs
- primary hypoparathyroidism
What can you use parenterally to treat hypocalcemia? Route of administration?
- Ca gluconate - IV (most common), IM, subQ
- Ca chloride - IV ONLY
What are some oral calcium supplements used? What species?
calcium carbonate - small animals
calcium proprionate - cattle (food supplement)
What can you use for longterm management of hypocalcemia?
Calcitriol
What are some potential side effects of calcium drugs?
hypercalcemia, arrhythmias, cardiac arrest
T/F. In hypoglycemia, there is typically too much insulin.
True
What are some mechanisms to treat acute/transient hypoglycemia?
- diet (carbs)
- Dextrose (50% solution), Karo syrup on gums
- Glucagon (IV)
When using IV dextrose to treat chronic hypoglycemia, the solution should be no more than _____% dextrose.
5%
T/F. To treat chronic hypoglycemia, you could use frequent, small high carb meals and corticosteroids.
True
prednisone/perdnisolone
Which type of diabetes mellitus is not typically found in dogs?
type 2
Glipizide can be used to treat type ____ diabetes mellitus in _____. It’s route of administration and MOA are…..
- type 2 diabetes in cats
- oral
- directly stimulates insulin secretion of beta cells in the pancreas
T/F. Detemir is an example of a Sulfonylurea.
False. Glipizide is a Sulfonylurea
Vet preparation of insulin come in ____IU/mL concetration, while human come in _____IU/mL.
- vet: 40
- human: 100
Describe the duration and potency of insulin.
- Duration: short, intermediate, long depending on drug
- Potency: all similar except Detemir (potent in dogs)
Regular/crystalline/neutral insulin are examples of ______-acting insulin. (duration)
short-acting
What do we use Humulin-R for?
-hospitilized patients not eating
Describe the onset/peak/duration for Humulni-R when given IV compared to when given IM/subQ.
- IV: immediate onset, peak at 0.5-2hrs, lasts 1-4 hours
- IM/subQ - onset in 10-30 minutes, peak at 1-5 hours, lasts 3-10 hours
What are the two intermediate-acting insulins we learned about? Route of administration?
NPH (Humulin-N)
Vetsulin/Caninsulin
subQ ONLY
Why are protamine and zinc added to NPH and Vetsulin?
to delay absorption and extend the clinical effect
What is the onset. peak, and duration of NPH and Vetsulin?
- intermediate-acting insulins
- onset: 0.5-2hrs, peak 2-10 hours, lasts 4-24 hours
- BID
What are some examples of long-acting insulin? Route of administration?
Protamine Zinc (PZI)
Glargine
Detemir
–> subQ
Insulin pens were designed for __________ (insulin drug). They are offered as _____IU pens in ______ increments.
- Vetsulin
- 8IU, 0.5IU increments
- 16IU, 1IU increments
Which zone of the adrenal cortex produces glucocorticoids? Mineralocorticoids?
- glucocorticoids: zona fasciculata
- mineralocorticoids: zona glomerulosa
What is the endogenous glucocorticoid? mineralocorticoid?
- glucocorticoid: cortisol
- mineralocorticoid: aldosterone
Which drugs are glucocorticoids?
Prednisone/Prednisolone
Dexamethasone
Triamcinolone
Methylprednisolone
Which glucocorticoid drug is most potent?
- Dexamethasone
- 7.5-10x more potent than prednisone
- 40x more potent than cortisol
Why are glucocorticoids typically used?
anti-inflammatory
immunosuppression too
How are base steroids given? How long do they last in the bloodstream?
- orally
- Prednisone - 24 hours
- Dexamethasone >48 hours
What are the two main types of excipients added to glucocorticoids?
salt esters
insoluble esters
Why would you add a salt ester to a steroid?
make the steroid soluble and suitable for IV administration
the onset is faster but duration not changed
What are the two types of salt esters?
Na succinate
Na phosphate
What are the three types of insoluble esters?
pivalate, acetate, acetonide
Why would you add an insoluble ester to a steroid?
- less soluble so takes longer to absorb
- delayed onset/longer duration (WEEKS TO MONTHS)
- NOT for IV use
What are some side effects associated with short term glucocorticoid use?
serious side effects are uncommon
- will see laboratory changes (neutrophilia, lymphopenia)
- PU/PD/PP/panting
What are some side effects associated with long term glucocorticoid use?
- increases susceptibility to infection/immunosuppression
- skin changes (thin skin, alopecia)
- delay wound healing and effect CT
- Addison signs with withdrawal (iatrogenic Addison’s)
- pulmonary thromboembolism
- hypertension
Why should you not use glucocorticoids with NSAIDs?
can cause GI ulceration and perforation
Aldosterone causes ____ excretion and _____ retention.
K
Na
What are 2 mineralocorticoids?
DOCP
Fludrocortisone
What are mineralocorticoid drugs used for?
sodium retention
Which mineralocorticoid is oral and life long?
Fludrocortisone
Which mineralocorticoid is IM or subQ once every month?
DOCP
What are animals with Atypical Addison’s deficient in? What do you treat it with
- glucocorticoid (cortisol)
- prednisone
What are animals with Typical hypoadrenocorticism deficient in? What do you treat with?
- mineralocorticoids and glucocorticoids
- prednisone and either fludrocortisone or DOCP
When treating Cushing’s disease, which methods could you use to target adrenal gland tissue?
- surgery
- Mitotane: cytotoxic to adrenal cortical cells of zona fasciculata; start with high dose and lower dose when you get the cortisol production that you want
When treating Cushing’s disease, which methods could you use to target production of glucocorticoids by the adrenal cortex?
- Trilostane: inhibits cortisol production, 2x/day forever, narrow therapeutic index
- Ketoconazole: inhibits ENZYMES in the steroidal synthesis pathway –> risk of hepatic toxicity because it’s very potent
When treating Cushing’s disease, which methods could you use to target production of ACTH by the pituitary?
- DOPAMINE AGONISTS
- Pergolide: equine, suppresses ACTH production
- Selegiline: canine, inhibits MAO-B which causes an inhibition in the breakdown of dopamine; metabolized to an amphetamine –> isn’t really treating Cushing’s, just making the dog feel better
Side effects of giving an animal a lot of glucocorticoid drugs can look like _____________ disease.
Cushing’s
