Definition of Oxytocin | Chapter 15 | Midwifery For Diploma In Nursing

Definition of Oxytocin – This course is designed to understand the care of pregnant women and newborn: antenatal, intra-natal and postnatal; breast feeding, family planning, newborn care and ethical issues, The aim of the course is to acquire knowledge and develop competencies regarding midwifery, complicated labour and newborn care including family planning.

Definition of Oxytocin

Pharmacology:

Oxytocin is an octapeptide, synthesized in supraoptic & parventricular nuclei of the hypothalamus. By carrier protein, it is transported from the hypothalamus to pituitary it is eventually released. Its half life is 3-4 min. and duration of action is about 20 min.

Mode of action:

1. It causes myometrial contraction by altering transmembrane ionic currents in myometrial smooth muscle cells. The uterine contractions are similar to the physiological pattern i.e. causing fundal contraction with relaxation of the cervix.

2. It causes contraction of myo-epithelial cells surrounding mammary alveoli, which leads to milk ejection.

3. It has weak ant diuretic effect.

Rotes of administration:

1. Controlled IV infusion (widely used)

2. Bolus I.V or LM

• Buccal tablets
• Nasal spray

Indication/Oxytocics in obstetrics practice:

A. Therapeutic:

1. Pregnancy:

• To accelerate abortion.
• To induce labour.
• Augmentation of labour.
• Uterine inertia.
• Inactive management of third stage of labour along with ergometrine.
• Following expulsion of placenta as an alternative to ergormetrine.
• To stop bleeding following evacuation of the uterus.

2. Puerperium: To minimize blood loss and control of PPH,

B. Diagnostic:

• Oxytocin challenge test (OCT).
• Oxytocin sensitivity test (OST).

Complications of oxytocin:

A. Maternal:

• Rupture uterus.
• Hypotension
• Anti-diuresis leading to water intoxication in high dose.
• Uterine hyperstimulation.

C. Fetal:

• Fetal asphyxia
• Fetal death
• Fetal distress

Doses of oxytocin:

For induction of labour:

Principles:

Oxytocin should be started with low dose and titrated until optimal response and that dose is to be continued at least 30-60 min. beyond delivery.

Table: Calculation of dose from drop in 500 ml 5% DA

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