L13 Cortocosteroids Flashcards
Corticosteroids are a member of what type of hormones
Steroid
Corticosteroids are secreted by what
the cortex of the adrenal gland
Where are the adrenal glands located?
Above the kidney
What are the major regions of the adrenal gland
Capsule
Adrenal cortex
Adrenal Medulla
There are two major types of corticosteroids
Mineralocorticoids and glucocorticoids
Like aldosterone and cortisol
What are mineralocorticoids’ functions
- regulate water and electrolyte balance
- Principal endogenous mineralocorticoids
What are glucocorticoid functions
- Regulate carbohydrate and protein metabolism
- are principal endogenous glucocorticoids
What effect do mineralocorticoids have with glucocorticoids
Some glucocorticoids, such as cortisol and several synthetic derivatives (drugs), also exert some mineralocorticoid activity due to incomplete receptor selectivity
Why are glucocorticoids important?
- endogenous cortisol promotes metabolic changes that
allow us to adapt to physiological stresses - Synthetic glucocorticoids suppress inflammation, allergy
& immune responses
What controls the production of cortisol from glucocorticoids
The HPA (hypothalamic pituitary adrenal) axis
Corticotrophin-releasing hormone from what stimulates release of what and from where
(CRH) from the hypothalamus stimulates the release of corticotrophin (ACTH) from the anterior pituitary gland
Corticotrophin stimulates _____ production by the adrenal cortex
Cortisol
Cortisol exerts physiological effects on many tissues and also inhibits ____ and CRH via a negative feedback loop
corticotrophin
Synthesis of endogenous cortisol
- glucocorticoids are not stored preformed, but synthesized and released as needed.
- cholesterol, is converted to pregnenolone, in a rate-limiting step regulated by corticotrophin
- Pregnenolone is converted by a series of enzymatic steps to cortisol
Diagram of cortisol production from cholesterol
Cholesterol
↓
Pregnenolone
↓
Cortisol (has ketone and OH groups)
Ketoconazole
an anti-fungal drug, blocks cortisol synthesis by inhibiting cholesterol side-chain convertase
What does stress do to cortisol
Increase cortisol levels
Diagram of the actions of cortisol
Stress
↓
HPA
↓
Cortisol
↓
bind to cortisol-binding globulin in blood and go to tissues
↓
Will bind to cytosolic glucocorticoid receptor
↓
Translocate to cell nucleus
↓
Transcription of glucocorticoid-responsive genes
↓
Protein translation
↓
Effects metabolism
Metabolism (glucocorticoid effect)
- ↓ uptake and utilization of glucose by peripheral tissues,
- ↑ synthesis of glucose by liver (gluconeogenesis)
- ↑ breakdown of fat and muscle
- ↑ glycogen formation,- ’creating a stockpile of glucose’
⇒ tendency to hyperglycaemia
At physiological levels, the effects of cortisol on water & electrolyte balance (mineralocorticoid effect) & on organ systems (e.g. ↓ vasodilatation, ↑ breakdown of bone) is relatively minor.
Too much endogenous cortisol production causes
Cushings disease
Cushing’s disease is often
due to an ACTH-secreting
tumor of
pituitary gland
Cushing disease features in ppl
- Buffalo hump
- Moon face
- increase abdominal fat
- Thin skin
- Thin arms and legs
- easy bruising and poor wound healing
Cushing disease treatment
y surgery (to remove tumour), but pharmacologic therapy can be considered
pasireotide
– a somatostatin receptor agonist that inhibits ACTH release from pituitary reduces cortisol synthesis by adrenal glands
Too little endogenous cortisol production
Addisons disease
-Weight loss, fatigue, painful muscles & joints
Addison disease treatment
Treatment involves replacement therapy. Physiologic doses of natural glucocorticoids (cortisol* hydrocortisone) are given daily in split doses: 2/3 in the morning & 1/3 in the evening to mimic natural pattern of hormone secretion.
Major pharmacological effects of glucocorticoids
- Cortisol deficiency treatment mimics normal levels and patterns of secretino and action
- Given in supraphysiological doses (has pos and neg effects)
supraphysiologic doses, which can produce positive and negative effects:
- General effects on metabolism, water & electrolyte balance & organ
systems (blood pressure, bones etc.) - Negative feedback effects on hypothalamus/pituitary –> atrophy of adrenal gland
- Anti-inflammatory and immunosuppressive effects
Clinical uses of glucocorticoids list
- Replacement therapy,
- To inhibit inflammation associated with (what)
- To suppress the immune system
- As an adjunct therapy in cancer
- To stimulate lung development in the fetus (dexamethasone*)
- Replacement therapy,
where the goal is to mimic the physiologic patterns of cortisol action. cortisol
Low, physiologic doses used for long periods -> minimal side-effects
- To inhibit inflammation associated with
asthma beclomethasone*
inflammatory bowel disease, arthritis
various conditions of the skin (eczema), eye (allergic conjunctivitis), nose (rhinitis)
High doses used, but given locally -> some localised side-effects
allergic reactions (to drugs, insect venoms, etc.)cortisol, prednisolone etc
High oral doses used, but for a short period minimal side-effects
Note: Glucocorticoids inhibit inflammatory reactions, by altering transcription of a wide range of genes involved in the inflammatory process.
- To suppress the immune system
in organ or bone marrow transplantation
in autoimmune diseases (prednisolone)
in asthma (beclomethasone)
High, oral doses used for long periods -> significant side-effects
- As an adjunct therapy in cancer
given with cytotoxic drugs to treat specific cancers (inhibit lymphocyte proliferation)
to decrease chemotherapy-induced nausea and vomiting
to reduce swelling in brain tumors (dexamethasone*)
High, oral doses used for long periods -> significant side-effects
- To stimulate lung development in the fetus (dexamethasone*)
given at 24-34 weeks gestation if birth expected within 7 days
High, oral doses used for short periods minimal side-effects
Note: Glucocorticoids can be given by variety of routes: Some are active ______ (i.m. or i.v). Some are given____ (aerosol, eye-drops, creams, injected intra-articularly) to reduce side-effects.
orally and systemically
topically
Serious adverse effects of Glucocorticoids (GCs)
- high, oral dosing of GCs for long periods, e.g. immunosuppressive therapy, cancer
- Cushing’s disease
include reductions in:
- response to infection,
- wound healing,
- capacity to synthesize
corticosteroids, etc.
Endogenous (e.g. cortisol) and
exogenous (e.g. dexamethasone)
glucocorticoids inhibit secretion
of ___ ____ _____
CRF, corticotrophin & cortisol
Exogenous glucocorticoids inhibit
the secretion of endogenous
glucocorticoids, causing____ of the adrenal gland
atrophy
rapid withdrawal of glucocorticoids is associated with
acute adrenal insufficiency
(low production of cortisol)
Decrease resistance to stress & infections
Cortisone and Cortisol
- Anti-inflammatory
- Na+ retaining
- Short DoA (8-12hr)
- Replacement and emergencies
- Cortisone is inactive then converted to active cortisol
Natural
Prednisone and Prednisolone
- Anti-inflammatory
- Some Na+ retaining
- Medium DoA (12-36 hr)
- Used as anti-in and immunosuppressive agents
- Sone inactive until converted to prenisolone
Dexamethasone
- Anti-inflammatory
- Minor Na+ retaining
- Long DoA (36-72 hr)
- Potent anti-in and immunosuppressive agents
- When water rentention is undesirable
Beclomethasone
- Anti-inflammatory
- Not Na+ retaining
- Longer DoA (72+ hr)
- Poorly absorbed
- Usually topically for rhinitis and inhaled for asthma
