Lecture 24 4/24/24 Flashcards
What is the primary goal of glucocorticoid therapy?
reduce the processes that are activated in response to a disease
Why is it important to frequently reevaluate patients undergoing GC therapy?
GC sensitivity differs greatly between individuals
How do physiological, anti-inflammatory, and immunosuppressive doses of GCs relate?
-anti-inflammatory dose is roughly 10 times the physiological dose
-immunosuppressive dose is roughly 2 times the anti-inflammatory dose
What is physiological replacement therapy?
providing GCs in amounts similar to those naturally produced
What is the ideal for replacement therapy?
mimicking the hormonal output of the adrenal gland under basal conditions
Why is it difficult to achieve perfect replacement with GCs?
under normal function, the adrenal gland is able to make minute-to-minute adaptations based on cortisol secretion
Which patients receiving GC replacement therapy typically require mineralocorticoid replacement as well?
those with primary disease, such as Addison’s
What are the characteristics of primary hypoadrenocorticism?
-can be caused by autoimmune adrenal destruction, trauma, neoplasia, or coagulopathy
-GC and MC deficiency
What are the characteristics of atypical hypoadrenocorticism?
-minority of patients with normal serum electrolytes at initial diagnosis
-occurs secondary to gradual loss of adrenocortical tissue
-GC-secreting portion is lost before mineralocorticoid-secreting layer
What are the characteristics of iatrogenic hypoadrenocorticism?
-results from drugs that cause destruction of adrenal cortices
-can cause development of Addison’s secondary to unintentional, non-selective loss of entire adrenal cortex
What are the characteristics of secondary hypoadrenocorticism?
-lack of ACTH synthesis in the pituitary due to neoplasia, inflammation, or trauma
-typically only see a GC deficiency
-can be iatrogenic due to exogenous GC admin. and rapid withdrawal
What are the characteristics of tertiary hypoadrenocorticism?
-lack of CRH
-very rare
-only GC deficiency
What are the characteristics of anti-inflammatory GC therapy?
-typically used for inflammatory and allergic disorders
-must first check for infectious disease; otherwise could kill patient
-once clinical signs are under control, dose should be reduced to lowest necessary concentration
What are the characteristics of immunosuppressive GC therapy?
-GCs are considered initial first-line therapy for many immune-mediated diseases
-used to prevent organ rejection after transplantation
-used to reduce immunological reactions associated with some infectious diseases
-goal is to use higher doses to achieve remission quickly, and then taper dose slowly to the lowest level that maintains remission
What are the goals of giving prednisolone in combination with chemotherapy?
-reduce edema and inflammation
-stimulate appetite
-decrease nausea and vomiting
-alleviate chronic cancer pain
What are the characteristics of prednisolone as the sole treatment in lymphoma cases?
-controls tumor short term; 1-2 months
-side effects include multidrug resistance; cannot choose to start chemo after GC use
-must diagnose before starting GCs, because they can induce apoptosis of neoplastic lymphocytes and complicate diagnosis
How are GCs used in patients with other cancer-like diseases?
-used in patients with hypercalcemia of malignancy
-used to increase blood glucose conc. in patients with insulinoma
What are the characteristics of GC use in shock?
-sometimes used in addition to epinephrine when treating anaphylactic shock, but no studies support benefits
-can be used at a low does for a few days when treating septic shock if necessary for treatment of other conditions
What is the connection between GCs and neurological treatment?
GCs are no longer used in the treatment of brain and spinal cord injuries in animals
What are the characteristics of iatrogenic hyperadrenocorticism?
-typically seen within first 2 weeks of therapy
-signs include polyuria, polydipsia, polyphagia, panting
-more severe signs develop after weeks/months of therapy
-large individual variation
-cats more resistant than dogs
-cats can have severe unique signs such as tearing/sloughing of skin and curling of pinnae
-treatment is cessation of GC therapy
What are the characteristics of HPA axis alteration?
-all GCs suppress CRH and ACTH secretion
-greater suppression and adrenal cortex atrophy occurs with greater anti-inflammatory potency
-usually reversible; full recovery depends on duration, dose, preparation, and application frequency
-abrupt cessation of treatment can result in GC withdrawal syndrome
What are the characteristics of diabetes mellitus with GC use?
-increased insulin resistance
-increased hepatic glucose production
-inhibition of insulin release from beta cells
-cats more susceptible than dogs
-likely to go into remission if steroid-induced
-administration of GCs will typically worsen glycemic control
What are the characteristics of GI ulcerations and hemorrhage with GC use?
-decreased or altered mucus
-decreased mucosal cell turnover
-increased acidic output
-impaired mucosal blood flow
-decreased healing rate
-promotion of bacterial colonization
What are the characteristics of neurological disease and GC use?
-use less potent GCs in these patients
-use lowest possible dose and duration
-no concurrent or successive use of NSAIDs
Which lab abnormalities can be seen with GC use?
-elevation of liver enzymes
-increased glucose and lipase
- increased serum lipids
-increased neutrophils and monocytes
-decreased lymphocytes and eosinophils
What are the characteristics of pancreatitis and GC use?
-previous concern that GCs caused pancreatitis; now dismissed
-possible that GCs could contribute to pancreatitis in sick animals/in a specific subset of animals
-use caution if animal has pancreatitis; avoid GCs
When should tapering of GCs be done?
-therapy that lasts 2 weeks or more
-if high doses were used
-if disease has resolved
What is the general rule for GC tapering?
the longer the induction phase and/or the greater the induction dose, the more stepwise and longer the period between dose reductions
What is the initial dose reduction step taken with GCs?
consolidating the dose, which achieves longer dosing intervals
How many days of therapy are typically required when treating with GCs?
-5 to 7 days for inflammatory diseases
-10 to 28 days for immune-mediated diseases
What are the characteristics of prednisone in horses?
-poor oral bioavailability
-low conversion in the liver
What are the characteristics of prednisolone in horses?
-moderately potent GC with minimal MC activity
-used for lots of inflammatory and immune-mediated diseases
What are the characteristics of dexamethasone in horses?
-admin. IV, IM, or oral
-high vol. of dist.
-treats many inflammatory and immune-mediated diseases
What are the characteristics of fluticasone propionate in horses?
-potent GC
-administered via facemask and inhaler
-used for inflammatory resp. diseases
What are the characteristics of beclomethasone dipropionate in horses?
-administered via inhaler
-very potent
What are the characteristics of methylprednisolone in horses?
-long-acting GC for IA injection
-reduces pain and inhibits joint inflammation
What are the characteristics of betamethasone in horses?
-potent GC with virtually no MC activity
-administered via IA injection
-treats sterile synovitis
What are the characteristics of triamcinolone acetonide in horses?
-potent GC
-intermediate duration of action
-low volume IA injection
What are the potential GC adverse effects in horses?
-laminitis (no evidence)
-gastric ulcers (poor evidence)
-birth defects (poor evidence)
