1. Clinical Overview
Desmopressin is a synthetic analogue of the natural pituitary hormone arginine vasopressin (ADH). It has potent antidiuretic activity with minimal pressor effects. It is a cornerstone therapy for central diabetes insipidus and is widely used for primary nocturnal enuresis in children. The 0.1mg/ml concentration is typically available as a nasal spray or oral/sublingual solution.
| Onset | Duration | Bioavailability |
|---|---|---|
| Intranasal: 15-30 minutes; Oral/Sublingual: 30-60 minutes; Intravenous: 15-30 minutes. | Intranasal/Oral: 8-12 hours; Intravenous: 4-8 hours. | Intranasal: 3-5%; Oral: 0.08-0.16%; Sublingual: 0.25%. |
2. Mechanism of Action
Desmopressin is a selective agonist for V2 receptors (and to a lesser extent, V1b receptors) located primarily in the renal collecting ducts. Activation of V2 receptors increases the synthesis and insertion of aquaporin-2 water channels into the apical membrane of collecting duct principal cells. This dramatically increases water permeability, allowing water reabsorption from the tubular fluid back into the hypertonic renal medulla, resulting in concentrated urine and reduced urine volume.
3. Indications & Uses
- Central (Cranial) Diabetes Insipidus
- Primary Nocturnal Enuresis (in children ≥5 years)
4. Dosage & Administration
Adult Dosage: **Diabetes Insipidus (Intranasal):** 10-40 mcg (0.1-0.4 ml) daily in 1-3 divided doses. **Oral/Sublingual:** 0.1-0.8 mg daily in 2-3 divided doses. Start low, titrate based on diuresis control.
Administration: **Intranasal:** Use calibrated spray. Prime before first use. Blow nose gently before administration. **Oral/Sublingual:** Take 1 hour before or 2 hours after meals for better absorption. For sublingual, place tablet under tongue and allow to dissolve completely. Fluid restriction is crucial 1 hour before and up to 8 hours after dose, especially for enuresis.
5. Side Effects
Common side effects may include:
- Headache
- Nausea
- Mild abdominal pain
- Nasal congestion/irritation (with nasal spray)
- Rhinitis
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Loop Diuretics (Furosemide, Torsemide) | Increased risk of hyponatremia; synergistic electrolyte depletion. | Major |
| Thiazide Diuretics (Hydrochlorothiazide) | Increased risk of severe hyponatremia. | Major |
| Glucocorticoids (e.g., Prednisolone) | May decrease antidiuretic effect. | Moderate |
| Lithium, Demeclocycline | Antagonize the antidiuretic effect of desmopressin. | Moderate |
| SSRIs, TCAs, Antipsychotics (e.g., Carbamazepine, Oxcarbazepine) | Increased risk of SIADH/hyponatremia. | Moderate |
| NSAIDs (Ibuprofen, Diclofenac) | Increased risk of water retention and hyponatremia. | Moderate |
| Loperamide | May potentiate desmopressin's effects and increase hyponatremia risk. | Moderate |
7. Patient Counselling
- DO take the dose exactly as prescribed, at the same time(s) each day.
- DO restrict fluid intake from 1 hour before until 8 hours after taking the dose (especially for enuresis).
- DO monitor your weight daily; rapid gain may indicate fluid retention.
- DO inform all doctors and dentists you are taking desmopressin.
- DONT drink excessive amounts of water or other fluids.
- DONT use the nasal spray if you have a cold or nasal congestion without consulting your doctor.
- DONT double the dose if you miss one. Skip it and take the next scheduled dose.
8. Toxicology & Storage
Overdose: Signs of water intoxication: Headache, nausea, vomiting, abdominal cramps, weight gain, lethargy, confusion, drowsiness, seizures, coma, and hyponatremia-induced cerebral edema leading to respiratory arrest.
Storage: Store below 25°C. Protect from light and moisture. Do not freeze. For nasal spray: Store upright. Keep the bottle tightly closed. Do not expose to high temperatures. Keep out of reach of children.