16 The pituitary and the adrenal cortex Flashcards
16.01 HYPOTHALAMIC HORMONES
Somatostatin analogues: octreotide, lanreotide, pasireotide - actions
octapeptide analogues of natural somatostatin
they inhibit various endocrine, neuroendocrine, exocrine and paracrine functions
16.01 HYPOTHALAMIC HORMONES
Somatostatin analogues: octreotide, lanreotide, pasireotide - MOA
inhibit pathologically increased secretion of growth hormone (GH) and of peptides and serotonin produced within the gastro-entero-pancreatic endocrine system
octreotide also constricts splanchnic blood vessels
16.01 HYPOTHALAMIC HORMONES
Somatostatin analogues: octreotide, lanreotide, pasireotide - abs/distrib/elim
given SC
octreotide: peak action is at 2h, and the suppressant effect lasts for up to 8h
16.01 HYPOTHALAMIC HORMONES
Somatostatin analogues: octreotide, lanreotide, pasireotide - clinical use
octreotide: carcinoids, hormone-secreting tumours, acromegaly, bleeding oesophageal varices
lanreotide: thyroid tumours
pasireotide: Cushing’s syndrome when surgery is inappropriate or has been ineffective
16.01 HYPOTHALAMIC HORMONES
Somatostatin analogues: octreotide, lanreotide, pasireotide - adverse effects
pain at injection site and GI disturbances
gallstones, post-prandial hyperglycaemia
cases of hepatitis and pancreatitis have also been reported
16.02 HYPOTHALAMIC HORMONES
GnRH analogues: buserelin, leuprorelin, gonadorelin - actions
stimulate the synthesis of follicle-stimulating hormone (FSH) and luteinising hormone (LH) and their release
16.02 HYPOTHALAMIC HORMONES
GnRH analogues: buserelin, leuprorelin, gonadorelin - MOA
analogues of natural gonadotrophin-releasing hormone (gonadorelin, LHRH or GnRH)
after an initial stimulation of gonadotrophin release, it down-regulates the hypothalamic-pituitary-gonadal (HPG, also called HPO) axis such that a decrease in ovarian steroid secretion into the postmenopausal range occurs
16.02 HYPOTHALAMIC HORMONES
GnRH analogues: buserelin, leuprorelin, gonadorelin - abs/distrib/elim
given by SC injection
gonadorelin is rapidly hydrolysed in plasma and excreted in urine with a half-life of ~4 min
buserelin half-life after injection is ~80 min
16.02 HYPOTHALAMIC HORMONES
GnRH analogues: buserelin, leuprorelin, gonadorelin - clinical use
evaluation of anterior pituitary hormones
endometriosis, infertility treatment, hormone-dependent tumours
16.02 HYPOTHALAMIC HORMONES
GnRH analogues: buserelin, leuprorelin, gonadorelin - adverse effects
weight changes, mood changes, sleep disturbances, GI disturbances, dizziness
risk of skeletal fractures increases with duration of therapy (decrease in bone mass may occur)
16.03 ANTERIOR PITUITARY HORMONES
Prolactin inhibitors: bromocriptine, cabergoline, quinagolide - actions
inhibit prolactin secretion
16.03 ANTERIOR PITUITARY HORMONES
Prolactin inhibitors: bromocriptine, cabergoline, quinagolide - MOA
inhibit prolactin secretion without affecting normal levels of other pituitary hormones
bromocriptine can also reduce elevated levels of growth hormone (GH) in patients with acromegaly
these effects are due to stimulation of dopamine receptors
16.03 ANTERIOR PITUITARY HORMONES
Prolactin inhibitors: bromocriptine, cabergoline, quinagolide - abs/distrib/elim
given orally
metabolised by liver
bromocriptine peak concentrations occur after 2h
16.03 ANTERIOR PITUITARY HORMONES
Prolactin inhibitors: bromocriptine, cabergoline, quinagolide - clinical use
prolactinomas
acromegaly
infertility
hyperprolactinaemia
polycystic ovarian syndrome
16.03 ANTERIOR PITUITARY HORMONES
Prolactin inhibitors: bromocriptine, cabergoline, quinagolide - adverse effects
nausea, vomiting, dizziness, constipation, postural hypotension
16.04 POSTERIOR PITUITARY HORMONES
Vasopressin and analogues: desmopressin, vasopressin, terlipressin - actions
smooth muscle vasoconstriction
renal actions: increase the rate of insertion of aquaporins in collecting duct into luminal membrane
16.04 POSTERIOR PITUITARY HORMONES
Vasopressin and analogues: desmopressin, vasopressin, terlipressin - MOA
vasopressin binds to V2 receptors in the basolateral membrane of the cells in the distal tubule and collecting ducts of the nephron
main effect in the collecting duct is to increase the rate of insertion of aquaporins into the luminal membrane, thereby increasing permeability of the membrane to water
also activates urea transporter
smooth muscle contraction by acting on V1A receptors
stimulates blood platelet aggregation and mobilisation of clotting factors
16.04 POSTERIOR PITUITARY HORMONES
Vasopressin and analogues: desmopressin, vasopressin, terlipressin - abs/distrib/elim
given via SC/IM/IV injection or IV infusion
desmopressin can be given by nasal spray
vasopressin is rapidly eliminated with a plasma half-life <10 min and short duration of action
16.04 POSTERIOR PITUITARY HORMONES
Vasopressin and analogues: desmopressin, vasopressin, terlipressin - clinical use
diabetes insipidus, bleeding oesophageal varices
16.04 POSTERIOR PITUITARY HORMONES
Vasopressin and analogues: desmopressin, vasopressin, terlipressin - adverse effects
angina (due to coronary vasoconstriction)
headache
nausea
16.04 POSTERIOR PITUITARY HORMONES
Vasopressin and analogues: desmopressin, vasopressin, terlipressin - special notes
treatment with desmopressin without concomitant reduction of fluid intake may lead to water retention/hyponatraemia
16.05 MINERALOCORTICOID
Fludrocortisone - actions
acts on the distal renal tubule to increase Na+ reabsorption and increase excretion of K+ and H+
16.05 MINERALOCORTICOID
Fludrocortisone - MOA
mineralocorticoids interact with intracellular receptors in the kidney controlling transcription of specific genes that cause: ↑number of Na+ channels, ↑number of Na+ pumps
16.05 MINERALOCORTICOID
Fludrocortisone - abs/distrib/elim
given orally
16.05 MINERALOCORTICOID
Fludrocortisone - clinical use
used (with a glucocorticoid) for replacement therapy in adrenal insufficiency
postural hypotension
16.05 MINERALOCORTICOID
Fludrocortisone - adverse effects
few
hypokalaemia can occur and is increased by thiazides and loop diuretics
peripheral oedema (avoid in older people with postural hypotension who already have peripheral oedema)
