10 Questions
What is the primary goal of physiological replacement therapy?
To replace cortisol in adrenal cortex dysfunction
What is a contraindication for the use of glucocorticoids?
Infectious diseases
What is a potential complication of glucocorticoid therapy?
All of the above
What should a clinician consider before starting glucocorticoid treatment?
The underlying disorder's severity and patient's predisposition to complications
What is a mode of glucocorticoid therapy used in adrenal cortex dysfunction?
Physiological replacement therapy
What is the purpose of trial and error in glucocorticoid therapy?
To determine the optimal dose and frequency of glucocorticoids
Why may steroids with greater mineralocorticoid activity be contraindicated?
In heart and renal diseases
What is the primary goal of immunosuppressive therapy?
To suppress the immune system
What is the purpose of intermittent therapy?
To reduce the risk of complications
What can occur following iatrogenic HPA axis suppression?
Hypoadrenocorticism or Addison's disease
Study Notes
Glucocorticoids
- Steroid agents produced and released by the adrenal cortex cells, synthesized from cholesterol
- Examples: cortisol and corticosterone, which have some degree of mineralocorticoid activity
- Pharmacological actions:
- General effects on metabolism, water, and electrolyte balance, and organ systems
- Negative feedback effects on the anterior pituitary and hypothalamus
- Anti-inflammatory and immunosuppressive effects
Control of Glucocorticoid Secretion
- Controlled by the Hypothalamus-Pituitary-Adrenal Axis (HPAA)
- Negative feedback effect: high concentrations of glucocorticoids inhibit the release of CRH from the hypothalamus and ACTH from the pituitary
Uses of Glucocorticoids
- Topical dermatological therapy
- Intra-lesional or sublesional administration (particularly in horses), which can cause steroid arthropathy
- Ophthalmic disorders: retinitis, choroiditis, optic neuritis, orbital cellulites, and some neurologic diseases
Adrenal Cortex Antagonist
- Mitotane (o,p'-DDD): suppresses adrenal cortical activity in dogs, indicated for canine pituitary-dependent hyperadrenocorticism (Cushing's syndrome)
- Amphenone B: inhibits 17-ketosteroid production in humans and dogs
- Metyrapone: blocks cortisol production (but not corticosterone production) in young pigs
Immunosuppressants
- Cyclosporin A: specifically inhibits T cells early in their immune response to antigenic and regulatory stimuli, without affecting suppressor T cells
Use of Glucocorticoids in Therapy
- Diagnose first, define specific objectives of glucocorticoid use
- Use appropriate dose, frequency, and duration
- Corticosteroids are not curative
- Doses of glucocorticoids are arrived at by trial and error
- Use intermittent therapy
- Avoid using glucocorticoids in infectious disease, Cushing's syndrome, diabetes mellitus, late stages of pregnancy, and animals predisposed to epileptic-like seizures
- Steroids with greater mineralocorticoid activity are contraindicated in heart and renal diseases
Questions to Ask Before Starting Glucocorticoid Treatment
- How serious is the underlying disorder?
- How long will therapy be required?
- Is the patient predisposed to any complications of steroid therapy?
- What is the anticipated glucocorticoid dose?
- Have other modes of therapy been utilized?
Modes of Glucocorticoid Therapy
- Physiological replacement therapy: required when the adrenal cortex is partially or fully unable to secrete cortisol (e.g., in hypoadrenocorticism or Addison's disease)
Learn about the pharmacological actions of glucocorticoids, their synthesis, and effects on metabolism, water, and electrolyte balance. This lesson covers the basics of glucocorticoids and immunosuppressants, including their role in the adrenal cortex. Understand the differences between glucocorticoids and corticosteroids. A comprehensive quiz for veterinary medicine students.
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