Oxytocin: Electrolyte effects

Oxytocin is structurally similar to anti-diuretic hormone (ADH, vasopressin) and both are released from the posterior pituitary. Onset is ~1 min when given IV, and t1/2 is ~5 min.

• The most common side effect is hypotension
• Prolonged infusions can result in water retention and hyponatremia due to cross reactivity with the vasopressin receptor, giving rise to water intoxication.

Symptoms include AMS, headache, muscle cramps and nausea. Treatment is to stop the infusion and fluid restrict.