Past Papers · SAQ
Vasopressin & Analogues
2017A Q20
Exam questionDescribe the pharmacology of vasopressin (70% of marks) and its analogues (30% of marks).
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| Field |
Vasopressin (argipressin)
Cardiovascular · Cardiovascular · Level 1
|
DESMOPRESSIN (dDAVP)
Endocrine · Endocrine · Level 2
|
TERLIPRESSIN
Endocrine · Endocrine · Level 2
|
|---|---|---|---|
| Mechanism of action | Acts at the GPCR Vasopressin receptors V1 on vascular smooth muscle V2 on the nephron V3 (prev V1b) on pituitary |
Acts at the GPCR Vasopressin receptors |
Acts at the GPCR Vasopressin receptors |
| Physiological effects | CVS: - in the presence of shock, vasopressin causes an increase in MAP and SVR via its vasoconstrictor effect. - In low doses it causes vasodilation in certain vascular beds in animal models. - It causes pulmonary vasodilation in hypoxic and physiological conditions. GU: a reduction in urine output and polydipsia is seen following administration in DI GIT: Gastric smooth muscle contraction Other: Increase in vWF and Factor 8 can be detected |
Vasoconstriction (less) |
Vasoconstriction |
| Absorption | IV only |
BA |
IV only |
| Distribution | limited data |
— | — |
| Protein binding | No PB |
20% |
30% |
| Volume of distribution | 0.14 L/kg |
0.2-0.32 L/kg |
0.5 L/kg |
| Metabolism | Metabolised by peptidases (Vasopressinases) to amino acids |
Minimal hepatic metabolism |
minimal |
| Excretion | 65% unchanged in urine |
65% unchanged in urine |
urine |
| Half-life | 10-35 mins |
2-3hrs |
50-70min |
| Adverse Effects Toxicity | Hyponatraemia with H2O retention |
OD – Hyponatremia (Seizure, altered mental state, arrythmias, edema) |
Hyponatraemia with H2O retention |
| Chemical Pharmaceutics | Prod hypothal. |
Deamino Arginine Vasopressin |
Prodrug of lysine Vasopressin |
| Class Group | Endogenous vasopressin hormone, clinically used as a non-adrenergic vasopressor. |
Vasopressin Analogue |
Vasopressin Analogue |
| Indications Uses | Catecholamine sparing drug in shock |
Central DI – ADH replacement (Intranasal/parenteral) |
Commonly used to stop bleeding of varices in the food pipe (oesophagus). Hepatorenal syndrome |
| Introduction | Is a naturally occurring nonapeptide-9AA. Produced hypothal. released by the posterior pituitary. similar to oxytocin complex molecule wt |
Synthetic analogue of 8-arginine vasopressin (ADH) Antidiuretic peptide drug displays enhanced antidiuretic potency, fewer pressor effects due to V2-selective actions, and a prolonged half-life and duration of action compared to endogenous ADH |
analogue of vasopressin – Prodrug used as a vasoactive drug in the management of hypotension. It has been found to be effective when norepinephrine does not help Longer duration of action than Vasopressin |
| Legacy Cicm Level | Level 1 |
Level 2 |
Level 2 |
| Main Action | Acts at the GPCR Vasopressin receptors |
Acts at the GPCR Vasopressin receptors |
Acts at the GPCR Vasopressin receptors |
| Onset Peak Duration | Rapid onset |
— | — |
| Presentation | measured in international units |
sublingual tablet, intra nasal spray, IV/IM |
IV |
| Route And Dose | IV infusion |
sublingual tablet, intra nasal spray, IV/IM |
IV |
Past papers