Evatocin Mechanism of Action

Pharmacology: Oxytocin acts primarily on uterine myofibril activity by increasing the permeability of the cell membranes to sodium ions, thus augmenting the number of contracting myofibrils, and thereby enabling the uterus to produce the necessary number of contractions. The effect depends on the uterine threshold of excitability. The pharmacological and clinical properties of Oxytocin are identical with naturally occurring oxytocin principle of the posterior lobe of the pituitary. Oxytocin injection does not contain amino acids characteristic of vasopressin, and therefore has fewer and less severe cardiovascular effects. Oxytocin when given in appropriate doses during pregnancy is capable of eliciting graded increase in uterine motility from a moderate increase in rate and force of spontaneous motor activity to sustained titanic contractions. Oxytocin is promptly effective after parenteral administration. Following intramuscular injection, the myotonic effect on the uterus appears in 3-7 minutes, and persists for 30-60 minutes. With intravenous injection, the uterine effect appears within one minute and is of more brief duration.