Oxytocin

INTRODUCTION

Indications

IV: Induction of labor at term. Facilitation of uterine contractions at term. Facilitation of threatened abortion. Postpartum control of bleeding after expulsion of the placenta. Intranasal: Used to promote milk letdown in lactating women. Unlabeled Use: Evaluation of fetal competence (fetal stress test).

Action

Stimulates uterine smooth muscle, producing uterine contractions similar to those in spontaneous labor. Stimulates mammary gland smooth muscle, facilitating lactation. Has vasopressor and antidiuretic effects. Therapeutic Effects: Induction of labor (IV). Milk letdown (intranasal).

Adverse Reactions/Side Effects

Maternal adverse reactions are noted for IV use only

CNS: maternal: COMA, SEIZURES fetal: INTRACRANIAL HEMORRHAGE. Resp: fetal: ASPHYXIA, hypoxia. CV: maternal: hypotension; fetal: arrhythmias. F and E: maternal: hypochloremia, hyponatremia, water intoxication. Misc: maternal: increased uterine motility, painful contractions, abruptio placentae, decreased uterine blood flow, hypersensitivity.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• If administered IV during childbirth, be alert for maternal seizures or decreased consciousness that progresses to coma. Report seizures or coma-like responses to the physician or nursing staff immediately.

• Monitor any signs of fetal distress or asphyxia, such as decreased fetal heart rate, arrhythmias, meconium discharge, or decreased or absent fetal movements. Report these signs to the physician or nursing staff immediately.

• Assess maternal blood pressure periodically and compare to normal values (See Appendix F). Report low blood pressure (hypotension), especially if patient experiences dizziness, fatigue, or other symptoms.

• Monitor signs of maternal fluid and electrolyte imbalances, such as low sodium levels (hyponatremia), low chloride levels (hypochloremia), or a relative increase in body fluid (water intoxication). Signs include headache, confusion, lethargy, irritability, decreased consciousness, and neuromuscular abnormalities (muscle weakness and cramps). Report these signs to the physician or nursing staff.

Interventions

• During childbirth, implement physical agents, relaxation techniques, and manual therapies (massage, others) as needed to help reduce pain during uterine contractions.

Patient/Client-Related Instruction

• If used intranasally to facilitate breast-feeding, make sure patient uses proper administration technique and does not exceed the recommended dose or frequency of intranasal applications.

Pharmacokinetics

Absorption: Well absorbed from the nasal mucosa.

Distribution: Widely distributed in extracellular fluid. Small amounts reach fetal circulation.

Metabolism and Excretion: Rapidly metabolized by liver and kidneys.

Half-life: 3–9 min.

Contraindications/Precautions