Uterine Contraction Stimulant

Question 1

Oxytocics

Answer 1

(Drug acting on the myometrium)

Oxytocin

Used to stimulate contraction of the uterus, much like the action of the hypothalamic hormone oxytocin (stored in the posterior pituitary)

Question 2

Types of Oxytocics

Answer 2

Ergonovine (Ergotrate)- given IM or IV- used to prevent and treat postpartum hemorrhage and postabortion uterine atony(failure to contract after delivery).

Methylergonovine (Methergine)- given IM or IV directly after delivery, then continued in the oral form to promote uterine involution. Stimulate late stage labor.

Oxytocin (pitocin, syntocinon)- used to induce labor and to promote uterine contractions after labor. (available in a nasal form to stimulate milk ‘let down’ in lactating women)

Question 3

Therapeutic Action & Indications

Answer 3

• Oxytocics directly affect neuroreceptor sites to stimulate contraction of the uterus (esp. effective in the gravid uterus).
• Causes myoepithelium of the lacteal glands to contract, resulting in milk ejection in lactating women.
• Oxytocin –synthetic form of the hypothalmic hormone

Oxytocin (nasal form) stimulate milk ‘let down’ in lactating women and to treat breast engorgement.

Breast engorgement - painful overfilling of the breasts with milk. This is usually caused by an imbalance between milk supply and infant demand.

Question 4

Pharmacokinetics

Answer 4

• Oxytocics – rapidly absorbed, metabolized in the liver, and excreted in urine and feces; cross the placenta and enter breast milk; not used during pregnancy
• Used during lactation –due to effects on milk ejection (necessary to evaluate baby for adverse effects assoc. with hormone)
• Route- IV
  Onset - immediate
  Duration- 60 minutes
• Route – IM
  Onset -3-5minutes
  Duration – 2-3h
• T1/2 -1-6min. With tissue metabolism and excretion in the urine.

Question 5

Contraindications & Caution

Answer 5

Contraindicated in the presence of any known allergy to oxytocics and with cephalopelvic disproportion, unfavorable fetal position, early pregnancy.

Caution – in patients with coronary disease, hypertension, lactation and previous cesarean section (effects on artery contraction and uterine contraction).

Cephalopelvic disproportion(CPD) occurs when a baby’s head or body is too large to fit through the mother’s pelvis.

Question 6

Adverse Effects

Answer 6

• Cardiac arrhythmias
• hypertension
• fetal bradycardia
• nausea & vomiting
• uterine rupture
• severe water intoxication
• anaphylactic reaction

Question 7

Nursing Implication

Answer 7

• Regulate oxytocin delivery between contractions if given to stimulate labour (regulate dosage appropriately)
• Monitor blood pressure periodically during and after administration (monitor for adverse effects)
• Monitor uterine tone and involvement and amount of bleeding (ensure safe and therapeutic drug usage)
• Monitor fetal heartbeat if given during labor