Desmopressin Acetate

Synthetic Vasopressin Analog Antidiuretic Hormone Analog

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog Oral 0.1-0.2 mg q8-24h Duration: Therapy is lifelong for diabetes insipidus; for vWD, administer 30 minutes before procedure.
Notes: Start with lowest dose and titrate based on water intake and urine specific gravity. For vWD, use 1 mcg/kg subcutaneously or intravenously.
Dog Subcutaneous or Intravenous 1-4 mcg/kg q8-24h Duration: For vWD, administer 30 minutes before procedure; for DI, as needed.
Notes: For vWD, use 1 mcg/kg; for DI, use 2-4 mcg/kg. Monitor for water retention.
Cat Oral 0.1-0.2 mg q8-24h Duration: Lifelong for DI.
Notes: Titrate to effect. Cats may be more sensitive to adverse effects.
Cat Subcutaneous or Intravenous 1-2 mcg/kg q8-24h Duration: For DI, as needed.
Notes: Use lower end for cats.
Horse Intravenous 0.02-0.04 mg Once for diagnostic testing Duration: Single dose for water deprivation test.
Notes: Used in the diagnosis of PPID; monitor water intake.
Rabbit Oral 0.05-0.1 mg q12-24h Duration: Lifelong for DI.
Notes: Limited data; use cautiously.

Clinical Indications & Species Uses

General Indications
  • Central diabetes insipidus
  • von Willebrand disease (mild to moderate)
Dog (Canine)
  • Central diabetes insipidus
  • von Willebrand disease (mild to moderate)
  • Nocturnal enuresis (off-label)
Cat (Feline)
  • Central diabetes insipidus
  • von Willebrand disease (rare, off-label)
Horse (Equine)
  • Central diabetes insipidus (rare)
  • Equine pituitary pars intermedia dysfunction (PPID) - diagnostic testing (off-label)
Rabbit & Small Mammals
  • Central diabetes insipidus (rare, off-label)
Exotic & Other Species
  • Central diabetes insipidus in ferrets (off-label)

Pharmacology & Mechanism of Action

Drug Class: Synthetic Vasopressin Analog | Pharmacological Group: Antidiuretic Hormone Analog

Mechanism of Action: Desmopressin acetate is a synthetic analog of the antidiuretic hormone arginine vasopressin (ADH). It primarily acts on V2 receptors in the renal collecting ducts, increasing water reabsorption by promoting the insertion of aquaporin-2 channels into the apical membrane of the tubular cells. This results in decreased urine volume and increased urine osmolality. Additionally, desmopressin increases plasma levels of von Willebrand factor (vWF) and factor VIII by stimulating their release from endothelial cells, which is beneficial in treating certain bleeding disorders.

Pharmacodynamics: Desmopressin produces a dose-dependent antidiuretic effect, with maximal urine concentration occurring within 1-2 hours after administration. The effect on vWF and factor VIII is rapid, with peak levels achieved within 30-60 minutes after intravenous or subcutaneous administration. The duration of antidiuretic effect varies by species and route, typically lasting 8-24 hours. Desmopressin has minimal vasopressor activity compared to vasopressin, making it safer for use in patients with cardiovascular disease.

⚡ Pharmacokinetics Summary

Absorption: Desmopressin is well absorbed after oral administration, but bioavailability is low (approximately 0.1-0.5%) due to extensive degradation in the gastrointestinal tract. Intranasal and parenteral routes provide higher bioavailability. After oral administration, peak plasma concentrations occur within 1-2 hours.
Distribution: Desmopressin distributes widely into extracellular fluids. It does not cross the blood-brain barrier to a significant extent. The volume of distribution is approximately 0.2-0.3 L/kg in dogs.
Metabolism: Desmopressin is metabolized primarily in the liver and kidneys by proteolytic enzymes. The metabolic pathway involves cleavage of the disulfide bond and subsequent degradation.
Excretion: Desmopressin is excreted primarily in the urine, both as unchanged drug and metabolites. Renal clearance accounts for about 50% of total clearance. The elimination half-life is short, ranging from 1.5 to 3.5 hours in dogs and cats.
Half-Life: Dogs: 1.5-3.5 hours; Cats: 2-4 hours; Humans: 1.5-2.5 hours
Bioavailability: Oral: 0.1-0.5%; Intranasal: 10-20%; Subcutaneous/Intravenous: 100%
Protein Binding: Desmopressin is minimally bound to plasma proteins (<10%).

Available Formulations & Strengths

Oral Tablet 0.1 mg, 0.2 mg (Oral)
Oral Solution 0.01% (0.1 mg/mL) (Oral)
Nasal Spray 0.01% (0.1 mg/mL) (Intranasal)
Injectable Solution 4 mcg/mL, 15 mcg/mL (Subcutaneous, Intravenous)

Contraindications & Clinical Warnings

Contraindications:
  • Hypersensitivity to desmopressin or any component of the formulation
  • Hyponatremia or conditions with fluid overload
  • Renal insufficiency with oliguria or anuria
  • Psychogenic polydipsia (relative contraindication)
Warnings & Clinical Precautions:
  • Use with caution in patients with cardiovascular disease, as fluid retention may exacerbate hypertension or heart failure.
  • Monitor serum sodium and urine output, especially in the elderly or very young.
  • In von Willebrand disease, desmopressin is not effective in all subtypes; test for response before use.
  • Avoid in patients with severe renal impairment.
  • Use in pregnant or lactating animals only if clearly needed; safety not established.

Adverse Effects & Reactions

Common:

  • Water intoxication (hyponatremia) if fluid intake is not restricted
  • Vomiting
  • Diarrhea
  • Abdominal cramps
  • Nasal irritation (with intranasal use)

Serious / Severe:

  • Seizures due to severe hyponatremia
  • Cerebral edema
  • Thrombosis (rare, with high doses)
  • Anaphylaxis (rare)

Rare:

  • Allergic reactions
  • Local injection site reactions
  • Hypotension (with rapid IV administration)

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Nonsteroidal anti-inflammatory drugs (NSAIDs) May increase the antidiuretic effect and risk of water retention. Moderate
Chlorpromazine May enhance the release of ADH, increasing the risk of water intoxication. Moderate
Carbamazepine May potentiate the antidiuretic effect. Moderate
Diuretics May reduce the antidiuretic effect and increase urine output. Moderate
Glucocorticoids May increase the risk of hyponatremia. Mild

Overdose & Toxicity Management

Signs of Toxicity:

  • Headache
  • Confusion
  • Lethargy
  • Muscle cramps
  • Seizures
  • Coma
  • Hyponatremia
  • Fluid retention

Emergency Treatment Protocol: Discontinue the drug immediately. Restrict fluid intake. Administer hypertonic saline (3% NaCl) intravenously if severe hyponatremia with neurological signs. Monitor serum electrolytes and neurological status. In severe cases, consider furosemide to promote diuresis. Supportive care is essential.

Food Animal Withdrawal Times

Not approved for food animals; withdrawal times not established. Use in food animals is off-label and prohibited in some countries.

Storage, Handling & Regulatory Information

Storage Temperature: Store at room temperature (20-25°C) for tablets and injectable; nasal spray may be refrigerated.

Light Sensitivity: Light-sensitive — protect from direct exposure.

Handling & Special Conditions: Protect from light and moisture. Do not freeze. Keep out of reach of children.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved for use in dogs for central diabetes insipidus and von Willebrand disease; not approved for cats or other species, but commonly used off-label.

Extra-Label (Off-Label) Use: In the US, extra-label use in food animals is prohibited under AMDUCA if an approved drug exists for that species. For companion animals, extra-label use is permitted with veterinary oversight.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Desmopressin is a valuable drug for managing central diabetes insipidus and mild to moderate von Willebrand disease in dogs and cats. For diabetes insipidus, oral tablets are convenient but may require higher doses due to low bioavailability. The intranasal route can be used but is less practical in animals. For von Willebrand disease, desmopressin is most effective in type I; a trial is recommended to assess efficacy. Monitoring water intake, urine specific gravity, and serum sodium is essential to avoid water intoxication. In horses, desmopressin is used diagnostically for PPID, but its use is limited. Always consider the cost and availability of the drug, and educate owners on proper administration and potential adverse effects.

References & Literature

  • 📚 Plumb's Veterinary Drug Handbook
  • 📚 Papich Veterinary Pharmacology and Therapeutics
  • 📚 Compendium of Veterinary Products (CVP)