Usage
Desmopressin is prescribed for managing central diabetes insipidus, primary nocturnal enuresis (bedwetting), and von Willebrand’s disease type I. It’s also used as a diagnostic agent for the renal concentration capacity test. Pharmacologically, it is classified as an antidiuretic hormone analog. It mimics the action of vasopressin (antidiuretic hormone or ADH), increasing water reabsorption in the kidneys and reducing urine production.
Alternate Names
Desmopressin acetate is the chemical name. Brand names include DDAVP, Stimate, Minirin, and others. Noctiva and Nocdurna are brand-specific names for formulations used to treat nocturia.
How It Works
Pharmacodynamics: Desmopressin binds to V2 receptors in the renal collecting ducts, increasing water permeability through aquaporin-2 channels, leading to decreased urine output and increased urine osmolality. It also promotes the release of von Willebrand factor (vWF) and factor VIII from endothelial cells, improving hemostasis in certain bleeding disorders.
Pharmacokinetics: Desmopressin can be administered intravenously, subcutaneously, intranasally, or orally. Bioavailability varies depending on the route of administration, with IV and subcutaneous routes offering the highest bioavailability, followed by intranasal and then oral. It is metabolized by the liver and kidneys and excreted primarily in the urine.
Mode of Action: The primary mode of action involves binding to vasopressin V2 receptors in the kidneys and stimulating the insertion of aquaporin-2 water channels into the cell membranes of renal collecting duct cells. This facilitates water reabsorption back into the bloodstream. It also stimulates release of factor VIII and von Willebrand factor from endothelial cells, through a distinct mechanism that involves interaction with V1 receptors.
Elimination: Desmopressin is primarily eliminated through renal excretion, with some hepatic metabolism also contributing.
Dosage
Standard Dosage
Adults:
- Central Diabetes Insipidus: Initial: 0.05 mg orally twice daily. Maintenance: 0.1-1.2 mg/day divided into two or three doses. Intranasal: 10-40 mcg/day. Adjust dosage according to the diurnal pattern of fluid balance.
- Nocturnal Enuresis: 0.2 mg orally at bedtime. May increase to 0.6 mg if needed.
- Nocturia: 0.83 mcg (for patients 65 years and older) or 1.66 mcg (for patients under 65) intranasally 30 minutes before bedtime. The lower dose for older patients carries a reduced risk of hyponatremia. After at least 7 days, the dose for older patients can be increased to 1.66 mcg if the serum sodium has remained normal.
- von Willebrand Disease/Mild Hemophilia A: IV: 0.3 mcg/kg over 15-30 minutes. Intranasal: 150 mcg (one nostril for patients under 50 kg) or 300 mcg (both nostrils for patients over 50 kg).
Children:
- Central Diabetes Insipidus: Oral: Starting dose 0.05 mg twice daily. Adjust as needed. Intranasal: 5-30 mcg/day (age 3 months-12 years) or 10-40 mcg/day (age over 12 years). Adjust based on response.
- Nocturnal Enuresis: 0.2 mg orally at bedtime (age 6 years and older). May increase to 0.6 mg if needed.
Special Cases:
- Elderly Patients: May be more sensitive to the effects of desmopressin. Start with lower doses and titrate cautiously. Monitor serum sodium closely.
- Patients with Renal Impairment: Contraindicated in moderate to severe renal impairment. Reduce dosage in mild impairment.
- Patients with Hepatic Dysfunction: Dose adjustment might be needed. Monitor closely.
- Patients with Comorbid Conditions: Use with caution in patients with cardiac disease, hypertension, or other conditions that can cause fluid or electrolyte imbalance.
Clinical Use Cases:
Dosing in clinical scenarios like intubation, surgical procedures, mechanical ventilation, ICU use, and emergencies needs to be individualized based on patient’s condition and fluid balance. Consult a specialist if the drug is being used in these situations.
Dosage Adjustments:
Adjust dosages based on patient-specific factors like renal or hepatic function, concomitant medications, and individual response.
Side Effects
Common Side Effects:
Headache, nausea, flushing, abdominal cramps, nasal congestion. Hyponatremia can occur, especially in children, which is why fluid restriction is often recommended.
Rare but Serious Side Effects:
Water intoxication, hyponatremia (low sodium), seizures (especially in children), allergic reactions.
Long-Term Effects:
Hyponatremia can be a significant long-term concern, requiring regular monitoring.
Adverse Drug Reactions (ADR):
Severe hyponatremia can lead to seizures, coma, and even death.
Contraindications
Hypersensitivity, moderate to severe renal impairment, hyponatremia, uncontrolled hypertension, conditions causing fluid or electrolyte imbalances.
Drug Interactions
Desmopressin may interact with drugs like carbamazepine, chlorpromazine, NSAIDs, tricyclic antidepressants, and others. These interactions can either increase the risk of hyponatremia or affect desmopressin’s effectiveness. Loperamide and other medications can slow down gastric emptying, thereby affecting oral desmopressin’s absorption. Consult detailed drug interaction resources for comprehensive information.
Pregnancy and Breastfeeding
Pregnancy Safety Category B. While generally considered safe, potential risks should be weighed against benefits. Desmopressin can be excreted in breast milk in small amounts, with limited risk to the infant; however, caution is recommended, especially with newborns or preterm infants.
Drug Profile Summary
- Mechanism of Action: Binds to V2 receptors, increases water reabsorption, releases von Willebrand factor and factor VIII.
- Side Effects: Headache, nausea, flushing, hyponatremia, water intoxication (rare).
- Contraindications: Hypersensitivity, moderate/severe renal impairment, hyponatremia.
- Drug Interactions: Carbamazepine, chlorpromazine, NSAIDs, tricyclics.
- Pregnancy & Breastfeeding: Category B; use with caution.
- Dosage: Varies by condition and age; see dosage section for details.
- Monitoring Parameters: Urine output, serum sodium, fluid balance.
Popular Combinations
Desmopressin is often used in combination with tranexamic acid for bleeding disorders.
Precautions
Screen for allergies, underlying medical conditions, and electrolyte imbalances. Closely monitor fluid intake, especially in children and the elderly. Pregnant and breastfeeding women should consult their physician.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Desmopressin?
A: Dosage varies depending on the indication and patient specifics. Refer to the detailed dosage section above.
Q2: How does Desmopressin differ from vasopressin?
A: Desmopressin is a synthetic analog of vasopressin with a longer duration of action and greater selectivity for V2 receptors, minimizing vasoconstrictive side effects.
A: Headache, nausea, vomiting, drowsiness, confusion, seizures, and coma can indicate water intoxication. Prompt medical attention is essential.
Q4: Can Desmopressin be used in patients with heart failure?
A: Use with extreme caution as fluid retention can worsen heart failure. Close monitoring is necessary.
Q5: What are the key monitoring parameters during Desmopressin therapy?
A: Urine output, serum sodium levels, and signs of fluid overload (e.g., weight gain, edema) should be regularly monitored.
Q6: What is the role of fluid restriction in Desmopressin treatment?
A: Fluid restriction helps prevent hyponatremia, especially in children receiving Desmopressin for nocturnal enuresis.
Q7: Can Desmopressin be used during pregnancy?
A: It’s generally considered safe (Pregnancy Category B), but the benefits and risks should be carefully evaluated.
Q8: Are there any specific precautions for elderly patients taking Desmopressin?
A: Start with a lower dose and monitor closely for hyponatremia and other side effects due to increased sensitivity.
Q9: What should I do if a patient experiences symptoms of hyponatremia while taking Desmopressin?
A: Discontinue Desmopressin immediately and consult a physician. Management of hyponatremia depends on its severity and might involve fluid restriction or hypertonic saline infusion.
