What are the uses and dosages of Pittressin (vasopressin) in medical conditions?

Uses and Dosages of Pitressin (Vasopressin) in Medical Conditions

Vasopressin (Pitressin) is primarily indicated to increase blood pressure in adults with vasodilatory shock who remain hypotensive despite fluids and catecholamines, with specific dosing recommendations for post-cardiotomy shock (0.03-0.1 units/minute) and septic shock (0.01-0.07 units/minute). 1

Primary Indications and Dosing

Septic Shock

• First-line agent: Norepinephrine remains the first-choice vasopressor 2, 3
• Adjunctive therapy: Vasopressin can be added to norepinephrine when:
  • Additional agent is needed to maintain adequate blood pressure
  • Goal is to decrease norepinephrine dosage 2
• Dosage: 0.01-0.07 units/minute 1
  • Specifically, up to 0.03 units/minute is recommended when added to norepinephrine 2, 3
  • Higher doses (>0.03-0.04 units/minute) should be reserved for salvage therapy 2

Post-Cardiotomy Shock

• Dosage: 0.03-0.1 units/minute 1

Anaphylaxis

• Used when anaphylaxis is unresponsive to epinephrine 2
• Dosage: 0.01-0.04 units/minute
• Preparation: 25 U/250 mL of 5% dextrose water or normal saline (0.1 U/mL) 2

Diabetes Insipidus

• Historically used for diabetes insipidus before newer analogs like DDAVP 4, 5
• Pitressin tannate in oil was previously used as daily injections 4
• Now largely replaced by DDAVP (1-deamino-8-D-arginine vasopressin) due to:
  • Better efficacy
  • Fewer side effects
  • Intranasal administration route 5

Administration Guidelines

Preparation

• Dilute 20 units/mL multiple dose vial contents with:
  • Normal saline (0.9% sodium chloride) or
  • 5% dextrose in water (D5W)
• Final concentration should be either 0.1 units/mL or 1 unit/mL 1
• Discard unused diluted solution after:
  • 18 hours at room temperature
  • 24 hours under refrigeration 1

Route of Administration

• Intravenous administration only 1
• Should be administered through central venous access when possible 3
• Continuous blood pressure monitoring via arterial catheter is recommended 3

Clinical Considerations

Monitoring Parameters

• Target mean arterial pressure (MAP) of 65 mmHg in most patients 2, 3
• Monitor for signs of tissue perfusion:
  • Lactate levels
  • Skin perfusion
  • Mental status
  • Urine output 3

Contraindications

• Known allergy or hypersensitivity to 8-L-arginine vasopressin or chlorobutanol 1
• Not recommended as single initial vasopressor for sepsis-induced hypotension 2
• Not recommended for cardiogenic shock without proper monitoring (ScvO2/CO) 2

Adverse Effects

• Can worsen cardiac function 1
• Reversible diabetes insipidus 1
• Common adverse reactions include:
  • Decreased cardiac output
  • Bradycardia
  • Tachyarrhythmias
  • Hyponatremia
  • Ischemia (coronary, mesenteric, skin, digital) 1

Special Populations

• Pregnancy: May induce uterine contractions 1
• Pediatric use: Safety and effectiveness not established 1, though limited studies exist for neonatal hypotension 6
• Geriatric use: No specific safety issues identified 1

Clinical Pearls

• Vasopressin's action is independent of catecholamine receptor stimulation, making it effective in patients with alpha-adrenergic receptor down-regulation often seen in septic shock 2
• When used as adjunctive therapy, vasopressin may allow reduction of norepinephrine dosage, potentially reducing catecholamine-associated adverse effects 2, 3
• Antibody formation against vasopressin has been reported with long-term use, potentially leading to resistance to treatment 7
• Vasopressin should be tapered gradually as hemodynamic stability improves 3