Lecture 12: Endocrine Pharmacology Flashcards
Thyroid hormones bind to which receptor?
Nuclear receptor located in the nucleus of the target cell
Steroid hormones bind to which receptor
Intracellular receptor
e.g. glucocorticoids (cortisol), mineralocorticoids (aldosterone), androgens, oestrogens and progestogens.
Peptide hormones bind to where on the target ccell
Cell surface receptor
e.g. cholecystokinin (CCK) and gastrin.
Name the administration routes for drugs and which one is the main mode used for endocrine
- Oral or rectal
- Percutaneous/subcutaneous (into the skin)
- Intravenous (into the bloodstream)
- Intramuscular (into the muscle)
- Intrathecal (into the CSF)
- Inhalation (into the lungs)
Subcutaneous is the main mode of drug administration for endocrine
Name the routes that drugs are eliminated by the body
- Urine
- Faeces
- Milk, sweat
- Expired air
Prolactin is secreted by which cells in the anterior pituitary
Secreted by lactotrophs
Lactotrophs are regulated by which hormone?
Dopamine
Dopamine inhibits the lactotrophs
Secreted by the hypothalamus
What is the effect of prolactin?
Stimulates lactation
High levels of prolactin lead to?
Hyperprolactinaemia: high levels of prolactin in the blood
Can lead to hypogonadotrophic hypogonadism (in males can lead to low testosterone level)
Raised prolactin switches off the gonadotrophins
Name some drugs that affect prolactin?
Any drugs that interfere with dopamine action can cause hyperprolactinaemia
e.g. antipsychotics, antipressants, H2 receptor antagonists
How is prolactinoma managed?
Medical treatment is first line: Dopamine agonists e.g. cabergoline.
Dopamine agonist can cause cardiac issues e.g. cardiac fibrosis and valvopathy. Also can cause psychosis etc
Vasopressin is secreted by ______
Neurohypophysis (posterior pituitary)
When is vasopressin (ADH) released?
In response to low plasma volume (Increased serum osmolality)
Describe the relationship between diabetes insipidus and antidiuretic hormone
DI occurs when ADH is either no longer secreted or is secreted by the kidneys are no longer responsive
_____is a synthetic analogue of vasopressin with no vasoconstrictor effects and a longer half life
Desmopressin
Describe the mechanism of action of ADH
It binds to V1 receptors in vascular smooth muscle causing vasoconstriction.
It binds to V2 receptors in the collecting duct causing an increase in the number of aquaporin channels. Causing an increase in reabsorption of water
When is intranasal preparation of desmopressin not used?
After pituitary surgery
Describe levothyroxine?
Form of Thyroxine (T4) used to treat hypothyroidism
Travels bound to protein and is metabolised in the body to triiodothyronine (T3)
Long half life
Name the two types of thionamides (antithyroid drugs) used clinically
Carbimazole
Prophylthiouracil (PTU)
Which thionamides is the drug of choice?
Carbimazole
Why? as its tolerated well and contain a longer half life.
PTU is less active and shorter half life is it is usually second line
What are the possible side effects of thionamides?
Agranulosytitis- low white blood cell count. Increase risk of infection
Define agranulosytitis
Low white blood cell count
Describe the mechanism of action for thionamides?
Both: reduce thyroid hormone synthesis
PTU also reduces the conversion of T4 to T3 peripherally
Which thionamide is the drug of choice during an acute thyroid storm
Thyroid storm is a life-threatening health condition that is associated with untreated or undertreated hyperthyroidism.
PTU because of its ability to reduce the conversion of T4 to T3
