Drugs affecting Pituitary

a) ADH (Vasopressin) affecting drugs

  • Desmopressin

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.

 

  • VaptansConivaptan + 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

 

b) Oxytocin drugs

  • Oxytocin – 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: As very similar to ADH, can cause water reabsorption + hypertension

 

DRUGS AFFECTING ANTERIOR PITUITARY GLAND

 

a) 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.

 

  • 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

 

b) 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 antagonistsPegvisomant

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 analogsOctreotide + 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

Sign up to our mailing list to get an exclusive 10% discount on In2Med courses!