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Oxytocics in Obstetrics, Indications and contraindications

Oxytocics are the drugs of varying chemical nature that have the power to excite the contractions of the Uterine muscles.

The important ones:-

  1. Oxytocin
  2. Ergot derivatives
  3. Prostaglandins

Oxytocin

Oxytocin has a duration of action of approximately 20 minutes.

Oxytocin loses its effectiveness unless preserved at correct temperature (2-8 degree Celsius).

◾Preparations used:

  • Synthetic oxytocin
  • Syntometrine
  • Desamino oxytocin
  • Oxytocin nasal solution

◾Indications- Oxytocin may be conveniently used in pregnancy, labour or puerperium.

Therapeutic- During pregnancy-

  • To accelerate abortion- inevitable or missed and to expel hydatidiform mole
  • To stop bleeding following evacuation of uterus
  • To induce labour
  • To ripen the cervix before induction

During labour-

  • Augmentation of labour
  • Uterine inertia
  • Inactive management of third stage of labour
  • Following expulsion of Placenta as an alternative to Ergometrine

During Puerperium- To minimise blood loss and to control postpartum hemorrhage.

Diagnostic– Contraction stress test (CST) and Oxytocin sensitivity test (OST)

◾Contraindications-

  • Grand multipara
  • Contracted pelvis
  • History of Caesarean section or Hysterectomy
  • Malpresentation
  • Obstructed labour
  • Incoordinate uterine contraction
  • Fetal distress
  • Hypovolaemic state
  • Cardiac disease

◾Dangers of oxytocin-

  1. Uterine hyperstimulation (overactivity)
  2. Uterine rupture
  3. Water intoxication
  4. Hypotension
  5. Antidiuresis
  6. Fetal distress, fetal hypoxia or even fetal death.

◾Routes of administration-

  • Controlled intravenous infusion is widely used method
  • Bolus IV or IM
  • Intramuscular- Syntometrine
  • Buccal tablets or nasal spray

Ergot Derivatives

◾ Preparations used- Ergometrine and Methergin.

Onset of action is comparatively slower while the duration of action is long.

◾Indications-

  • To stop Haemorrhage following delivery, abortion or expulsion of hydatidiform mole
  • Prophylactic use in late second or in third stage, to hasten separation of Placenta and to minimise blood loss.

◾Hazards-

  • Nausea and vomiting
  • Rise in blood pressure, stroke
  • Rarely gangrene of the toe

◾Contraindications-

  • Rh negative mother
  • Severe pre- eclampsia and eclampsia
  • Organic cardiac diseases
  • Suspected pleural pregnancy
  • Heart disease or severe hypertensive disorders

Prostaglandins (PGs)

Prostaglandins are the derivatives of prostanoic acid from which they derive their names.

◾Use in Obstetrics-

  • Induction of abortion
  • Termination of molar pregnancy
  • Induction of labour
  • Cervical ripening prior to induction of abortion or labour
  • Augmentation of labour
  • Management of atomic Postpartum Haemorrhage
  • Medical management of tubal ectopic pregnancy

◾ Contraindications-

  • Hypersensitivity to the compound
  • Uterine scar
  • Active cardiac, pulmonary, renal or hepatic disease, hypotension
  • Bronchial asthma

◾Preparations–

  1. Dinoprostone
  2. Misoprostol
  3. Dinoprost tromethamine

Remarks about Oxytocics

All the Oxytocics have following functions-

  • To arrest Haemorrhage following delivery or abortion (Ergot preparation are better)
  • For induction of labour (Prostaglandins have got distinct advantage over Oxytocin)
  • In Augmentation of labour (oxytocins)
  • For Induction of abortion (Prostaglandins)

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