Desmopressin is a synthetic analogue of the natural pituitary hormone arginine vasopressin (ADH). It has potent antidiuretic activity with minimal pressor effects. The 120mcg tablet is a high-dose formulation primarily used for central diabetes insipidus and specific bleeding disorders. It acts on V2 receptors in the renal collecting ducts to increase water reabsorption, concentrating urine and reducing urine volume.
Adult: Diabetes Insipidus: Initial dose 0.1 mg (100 mcg) three times daily. Adjust based on diurnal pattern of polyuria. Usual maintenance: 0.1-0.2 mg (100-200 mcg) two to three times daily. Max: 1.2 mg/day. Bleeding Disorders: 0.3 mcg/kg (approx. 20 mcg for 70kg adult) diluted in 50 mL saline, infused IV over 15-30 min, pre-procedure. Oral dose for bleeding is not standard; IV/SC/Intranasal used.
Note: Tablet to be taken with or without food, but consistently. For enuresis, take at bedtime. Ensure fluid intake is moderated from 1 hour before until at least 8 hours after dose to prevent water intoxication. Do not crush or chew.
Desmopressin is a selective agonist for vasopressin V2 receptors located primarily on the basolateral membrane of the renal collecting duct cells. Activation of these receptors stimulates adenylate cyclase, increasing intracellular cyclic AMP (cAMP). This leads to the insertion of aquaporin-2 (AQP2) water channels into the luminal membrane, greatly increasing its permeability to water. This allows water to move from the collecting duct lumen into the hypertonic renal medulla, resulting in concentrated urine and reduced urine output. At therapeutic doses, it has negligible activity on V1 receptors responsible for vasoconstriction.
Pregnancy: Category B: Animal studies show no risk, but no adequate, well-controlled studies in pregnant women. Use only if clearly needed. Monitor for water retention and hyponatremia.
Driving: Usually no effect. However, if hyponatremia occurs, it can cause dizziness, confusion, or seizures, impairing ability to drive. Patients should be cautioned.
| Loop Diuretics (Furosemide, Torsemide) | Increased risk of severe hyponatremia due to synergistic water retention and sodium loss. | Major |
| Thiazide Diuretics (Hydrochlorothiazide) | Increased risk of hyponatremia. | Major |
| Glucocorticoids (e.g., Prednisolone) | May potentiate water retention and increase risk of hyponatremia. | Moderate |
| Tricyclic Antidepressants (Amitriptyline, Imipramine) | May potentiate antidiuretic effect and increase risk of hyponatremia. | Moderate |
| SSRIs (e.g., Fluoxetine, Sertraline) | May increase risk of hyponatremia, especially in elderly. | Moderate |
| Carbamazepine, Chlorpromazine | May potentiate antidiuretic effect, increasing hyponatremia risk. | Moderate |
| NSAIDs (Ibuprofen, Diclofenac) | May potentiate water retention and increase risk of hyponatremia. | Moderate |
| Loperamide | Concurrent use may potentiate desmopressin's effect and increase plasma levels of desmopressin, increasing toxicity risk. | Major |