Ppt chapter 53-1

Chapter 53
Drugs Affecting Uterine Motility
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Question
• Which of the following hormones is responsible for
uterine contractions?
– A. Progesterone
– B. Estrogen
– C. Prolactin
– D. Oxytocin

Answer
• D. Oxytocin
• Rationale: Oxytocin is the hormone responsible for
uterine contractions.

Physiology
Contractions and related changes
• The induction of labor is related to oxytocin.
• The oxytocin receptors that are located in the
endometrium increase during labor and reach peak levels
at birth.
• Prostaglandins also have a role in preparing the uterus
for labor and delivery.
• Prostaglandin E2 (PGE2) leads to sensitization of the
myometrium to oxytocin.

Uterine Muscles

Pathophysiology
• Occasionally, uterine function proceeds abnormally.
• Two main categories of obstetric situations require drug
administration to initiate the onset of contractions:
– Labor that does not begin at term
– Pregnancy that is detrimental to the patient or her
fetus

Oxytocics
• Oxytocic drugs are synthetic forms of the endogenous
posterior pituitary hormone oxytocin.
• They produce uterine contractions and milk ejection for
breast-feeding.
• Prototype drug: oxytocin (Pitocin)

Oxytocin: Core Drug Knowledge
• Pharmacotherapeutics
– Given by IV drip infusion to initiate or augment
(improve) labor contractions
• Pharmacokinetics
– Administered: IV. Onset: immediate. Elimination:
liver, kidneys, and mammary glands.
• Pharmacodynamics
– Synthetic, exogenous oxytocin has the same effects
on the body as natural, endogenous oxytocin.

Oxytocin: Core Drug Knowledge (cont.)
• Contraindications and precautions
– Cephalopelvic disproportion and unfavorable fetal
positions
• Adverse effects
– Nausea, vomiting, uterine hypertonicity, and cardiac
arrhythmias
• Drug interactions
– Sympathomimetic drugs

Oxytocin: Core Patient Variables
• Health status
– Assess pelvic adequacy.
• Life span and gender
– Assess duration of pregnancy.
• Lifestyle, diet, and habits
– Consider the patient’s risk of water intoxication.
• Environment
– Assess environment where the drug will be given.

Oxytocin: Nursing Diagnoses and
Outcomes
• Risk for Fetal or Maternal Injury related to uterine
hypertonicity secondary to oxytocin therapy
– Desired outcome: The mother and fetus will
progress through labor and delivery without injury
while on oxytocin therapy.
• Excess Fluid Volume related to drug-induced water
intoxication and altered electrolyte levels
– Desired outcome: The patient’s fluid status will
remain normal while on oxytocin therapy.

Oxytocin: Planning and Interventions
• Maximizing therapeutic effects
– Assess cervical ripening using the Bishop scoring
system before oxytocin therapy starts.
– Use an infusion pump for precise administration of
oxytocin.
• Minimizing adverse effects
– Piggyback the diluted oxytocin solution into a
primary IV line.
– The FHR monitor continuously records the patient’s
uterine contraction pattern.

Oxytocin: Teaching, Assessment and
Evaluation
• Patient and family education
– Educate the patient and family about the rationale
for oxytocin use.
– Explain that the patient and fetus will be monitored
closely.
• Ongoing assessment and evaluation
– Throughout induction, monitor continually for
evidence of adverse maternal or fetal effects.

Question
• Which of the following is the severe adverse effect(s) of
oxytocin?
– A. Water intoxication
– B. Uterine rupture
– C. Permanent CNS damage to the fetus
– D. Both B and C
– E. All of the above

Answer
• E. All of the above
• Rationale: Severe adverse effects include water
intoxication and rupture of the uterus.
• Other adverse fetal effects are premature ventricular
contractions and other arrhythmias, impaired fetal
oxygenation, permanent brain or CNS damage, and
death.

Tocolytics
• Drugs that inhibit uterine activity are classified as
tocolytics.
• Preterm labor is the medical complication requiring the
administration of tocolytics.
• Tocolytics are used when true labor begins after 20
weeks’ gestation and usually before completion of the
34th gestational week.
• Currently, several drugs are used for their tocolytic
properties.
• Prototype drug: terbutaline (Brethine)

Terbutaline: Core Drug Knowledge
• Pharmacotherapeutics
– Off-label to control preterm labor in pregnancies of
20 to 34 weeks
• Pharmacokinetics
– Administered: SC or oral. Onset of action is faster
when given SC.
• Pharmacodynamics
– Beta-receptor agonist (stimulant) that selectively
prefers the beta-2 receptors over beta-1 receptors .

Terbutaline: Core Drug Knowledge (cont.)
• Contraindications and precautions
– Contraindicated before the 20th week of pregnancy
• Adverse effects
– Tachycardia, hypotension, dyspnea, nervousness,
transient hyperglycemia, pulmonary edema, cerebral
and myocardial ischemia, nausea, and vomiting
• Drug interactions
– Other beta stimulants

Terbutaline: Core Patient Variables
• Health status
– Assess for contraindications to therapy.
• Life span and gender
– Pregnancy Category B
• Environment
– Assess environment where drug will be given.

Terbutaline: Nursing Diagnoses and
Outcomes
• Risk for Injury to the mother from adverse effects of drug
therapy
– Desired outcome: No adverse effects will occur from
drug therapy.
• Risk for Injury to infant stemming from premature delivery
or adverse effects from drug therapy
– Desired outcome: Drug therapy will prevent
premature delivery of infant and will not cause adverse
effects to the newborn.
• Excess Fluid Volume, pulmonary edema, related to potential
adverse effects of drug therapy
– Desired outcome: The patient’s fluid volume will
remain within normal limits.

Terbutaline: Planning and Interventions
• Maximizing therapeutic effects
– Begin drug therapy as soon as possible after preterm
labor is diagnosed.
• Minimizing adverse effects
– Closely monitor the patient’s fluid status and avoid
fluid overload.
– If the patient demonstrates signs of adverse effects,
the dosage of terbutaline should be decreased.

Terbutaline: Teaching, Assessment, and
Evaluation
• Patient and family education
– Educate the patient and family about the therapeutic
and adverse effects of the drug.
– Explain to the patient the rationale for lying on her
left side.
• Ongoing assessment and evaluation
– Monitor the maternal heart rate, FHR, and maternal
blood pressure and fluid status throughout
terbutaline therapy.

Question
• Terbutaline inhibits contractility of uterine smooth muscle
by inhibition of the alpha receptors in the uterine smooth
muscle.
– A. True
– B. False

Answer
• A. True
• Rationale: Terbutaline is a beta-receptor agonist
(stimulant) that selectively prefers the beta-2
receptors over beta-1 receptors.
• Stimulation of these receptors inhibits contractility of
uterine smooth muscle.

Ppt chapter 53-1

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