Desmopressin (DDAVP) is a synthetic analogue of arginine vasopressin (AVP) and an FDA-approved prescription medication indicated for central diabetes insipidus, primary nocturnal enuresis, and bleeding management in mild hemophilia A and von Willebrand disease type I. It exerts its primary therapeutic effects through V2 receptor activation in the renal collecting duct, increasing water reabsorption, and through DDAVP-mediated release of von Willebrand factor and factor VIII from endothelial storage sites. Research has also explored desmopressin effects on memory consolidation through vasopressinergic pathways in the brain, though controlled trials in healthy volunteers have produced inconsistent results, with some studies finding no measurable cognitive benefit. Desmopressin is available as nasal spray, sublingual tablet, and injectable formulations; use outside approved indications requires physician supervision, and hyponatremia is a documented and potentially serious risk, particularly in elderly patients. Desmopressin dosage and clinical contexts Desmopressin dosing varies by formulation and approved indication per FDA labeling. The nasal spray (DDAVP nasal spray, 100 mcg/mL) carries an FDA-indicated dose of 10–40 mcg once or twice daily for central diabetes insipidus; the intranasal formulation is no longer approved for primary nocturnal enuresis in adults due to hyponatremia risk. Oral and sublingual tablets include DDAVP for primary nocturnal enuresis (FDA label: 0.1–0.4 mg oral) and Nocdurna for nocturia in adults (FDA label: 27.7 mcg sublingual for women, 55.3 mcg sublingual for men, taken 1 hour before bed; FDA-approved 2018). Injectable desmopressin (4 mcg/mL) is indicated at 0.3 mcg/kg IV for perioperative hemostasis in hemophilia A and von Willebrand disease type I. The sublingual formulation for nocturia represents a significant expanded indication — nocturia affects a large proportion of older adults, and desmopressin's water-retention mechanism can reduce nightly urination frequency. Desmopressin vs vasopressin: Desmopressin is a structural modification of vasopressin — deamination of the N-terminal cysteine and substitution of D-arginine for L-arginine — that eliminates vasopressor (V1a receptor) activity while preserving antidiuretic (V2 receptor) potency, and dramatically extends the half-life from ~10 minutes to 1.5–3 hours. This selectivity makes desmopressin clinically safer than vasopressin for antidiuretic indications; vasopressin is reserved for contexts requiring vasopressor activity (septic shock, vasodilatory shock).