Pituitary Gland Drugs
DRUGS AFFECTING THE POSTERIOR PITUITARY GLAND
ADH (Vasopressin) affecting drugs
Desmopressin
This is an ADH mimic that is the most effective treatment for neurogenic diabetes insipidus
– It has higher activity on V2 receptors in collecting tubule rather than V1 receptors
– Not effective for nephrogenic form of diabetes insipidus
– Also used for nocturnal enuresis by reducing night-time urine production
– Treats Von Willebrand disease as it stimulates production of Factor VIII
Terlipressin
This is an ADH mimic with a higher affinity for V1 receptors.
– It causes vasoconstriction of arterioles especially supplying the gut.
– Used to treat noradrenaline resistant hypotension and portal hypertension.
Vaptans
e.g. Conivaptan + Tolvaptan
These are antagonists of ADH receptors, which are used to treat SIADH
– Conivaptan blocks both V1a and V2 receptors non-specifically to treat SIADH
– Tolvaptan is a selective V2 receptor antagonist to treat SIADH
Oxytocin
This is used for the induction and maintenance of labour as stimulates uterine contraction
– Also stimulates milk ejection from the breast
– First line drugs to control postpartum uterine bleeding
Side effects
• Water reabsorption
• Hypertension
DRUGS AFFECTING ANTERIOR PITUITARY GLAND
Drugs influencing Prolactin
Prolactin secretion is also affected by drugs used on the central nervous system which affect dopaminergic activity. These will include antipsychotics + Antidepressants + Anxiolytics
As prolactin secretion is inhibited by Dopaminergic neurones, drugs which try to decrease prolactin secretion often try to stimulate the dopaminergic system.
e.g. Bromocriptine + Cabergoline
These are dopamine D2 agonists which can act within the central nervous system
– They are used to inhibit prolactin secretion in prolactin-secreting tumours and galactorrhoea
Drugs influencing Growth Hormone
Somatotropin
These is a synthetic version of growth hormone which is administered via injection
– Used to stimulate growth in replacement therapy in people with GH deficiency and Turner syndrome
GH antagonists
e.g. Pegvisomant
This is a GH antagonist that is used specifically for the treatment of acromegaly.
– It opposes the actions of growth hormone but will not help to shrink the pituitary tumour.
Somatostatin analogs
e.g. Octreotide + Lanreotide (longer-acting analog)
These mimic the role of somatostatin to inhibit growth hormone release
– Used to treat acromegaly
– Also used to counter diarrhea through the inhibition of GI secretions, slowing of GI motility and inhibition of gallbladder secretion.
– Used to treat VIP-secreting tumours like gastrinoma, glucagonoma
Side effects
• Vitamin B12 Deficiency due to decreased release of intrinsic factor
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