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Flashcards in Uterus Drugs Deck (30)
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1

___: goal of labor induction is to stimulate uterine contractions before the spontaneous onset of labor, resulting in vaginal delivery

Oxytocics: goal of labor induction is to stimulate uterine contractions before the spontaneous onset of labor, resulting in vaginal delivery

2

Drugs used for cervical ripening and purpose? 

DinoprostoneMisoprostol (prostaglandins)

reduces the rate of failed induction, used when induction is indicated but status of cervix is unfavorable

3

Dinoprostone ( __ analog)
Misoprostol ( __ analog)

  • Dinoprostone: PGE2 
    • vaginal insert, and cervical gel
  • Misoprostol: PGE1 
    • intravaginally, orally or sublingually
  • ripens cervix 
  • stimulates uterine contractions
  • these alone initiate labor in many women, and obviates need for oxytocin

4

Prostaglandins AEs

  • Tachysystole
  • Fever
  • Chills
  • Vomiting
  • Diarrhea

5

___ is the preferred drug for inducing labor when the cervix is favorable or ripe

(ripening agent should be used ___ oxytocin in women with unfavorable cervixes)

Oxytocin is the preferred drug for inducing labor when the cervix is favorable or ripe

(ripening agent should be used before oxytocin in women with unfavorable cervixes)

6

Oxytocin

  • elicits milk ejection in lactating women
  • 2nd half of pregnancy: uterine smooth muscle becomes increasingly sensitive to stimulant action of endogenous oxytocin
  • exogenously given to induce uterine contractions and maintain labor

7

Oxytocin signaling pathway 

GQ → GOAT HAG

GnRH
Oxytocin
ADH (V1-receptor)
TRH

Histamine (H1-receptor)
Angiotensin II
Gastrin

8

Oxytocin MOA

  • Gq - activates voltage-gated Ca2+ channels → myometrial contraction
  • also increases prostaglandin synthesis → further stimulating uterine contractions

9

oxytocin is most commonly given as ___ for labor induction

oxytocin is most commonly given as IV infusion for labor induction

10

Oxytocin AEs

  • Serious toxicity is rare
  • excessive stimulation of uterine contractions before delivery can cause fetal distress, placental abruption, or uterine rupture
  • High concentrations can activate vasopressin receptors → excessive fluid retention → hyponatremia, HF, seizures, death

11

____ = MC cause of postpartum hemorrhage

Managed with uterine massage and oxytocic drugs (3)

Uterine atony = MC cause of postpartum hemorrhage

Managed with uterine massage and oxytocic drugs:

Oxytocin (first-line, given IV or IM)
Ergot alkaloids
Prostaglandins

12

Methylergonovine

 

  • Ergot Alkaloid
  • Partial agonist at a-adrenergic receptors and some serotonin receptors
  • uterus sensitvity to stimulant effects of ergot alkaloids increase dramatically during pregnancy

13

Methylergonovine AEs

  • HTN
  • headache, nausea, vomiting
  • chest pains

14

Methylergonovine contraindications

  • Angina pectoris
  • Myocardial infarction
  • Pregnancy
  • Cerebrovascular accident
  • Ischemic attack
  • Hypertension

15

Carboprost Tromethamine

PGF2a analog

Given IM

 

16

Misoprostol

PGE1 analog

Given vaginally or orally

17

Tocolytics: given if going into labor < __ weeks of gestation

  • Uterine Relaxants 
  • preterm labor <37 weeks of gestation
  • preterm birth = leading cause of neonatal mortality in US
  • Management:
    • Bed rest
    • Tocolytics
      • magnesium sulfate
      • indomethacin
      • nifedipine
    • Glucocorticoids

18

Glucocorticoids can be given if gestational age is < ___ weeks

Glucocorticoids can be given if gestational age is < 34 weeks

19

primary purpose of tocolytic therapy is to ____ to allow ____ given to the mother to achieve their maximum effect

 

primary purpose of tocolytic therapy is to delay delivery to allow glucocorticoids given to the mother to achieve their maximum effect

 

20

Glucocorticoids accelerate ____ and decrease risk of neonatal ____, intracranial bleeding, and mortality

Glucocorticoids accelerate maturation of fetal lungs and decrease risk of neonatal respiratory distress syndrome, intracranial bleeding, and mortality

21

MC tocolytic agents used for treating preterm labor

magnesium sulfate

indomethacin

nifedipine

(Atosiban and B2-agonists as well)

22

Magnesium Sulfate

  • primary tocolytic agent
  • uncouples excitation-contraction in myometrial cells through inhibition of cellular action potentials
  • AEs
    • mother should be monitored for respiratory depression or cardiac arrest
    • crosses placenta and may lead to respiratory and motor depression of the neonate

23

Prostaglandins ___ uterine contractions during normal labor

NSAIDs are used to ___ preterm labor, ___  is the main NSAID for this use

Prostaglandins stimulate uterine contractions during normal labor

NSAIDs are used to delay preterm labor, Indomethacin is the main NSAID for this use

24

Indomethacin can cause premature closure of ____ 

effect is mc after ___ weeks of gestation → not recommended to be given after this time

Can also cross placenta and cause ____ d/t decreased fetal renal blood flow if used >48 hrs

Indomethacin can cause premature closure of ductus arteriosus 

effect is mc after 32 weeks of gestation → not recommended to be given after this time

Can also cross placenta and cause oligohydraminos d/t decreased fetal renal blood flow if used >48 hrs

25

Nifedipine

  • Calcium channel blocker
  • Blocks entry of Ca2+ into myometrial cells inhibiting contractility
  • Effective and safe
  • associated with more frequent successful prolongation of pregnancy compared to other tocolytics
  • AE: maternal tachycardia, palpitations, flushing, headaches, dizziness, nausea

26

___ is a competitive oxytocin antagonist

Not available in the US

Atosiban is a competitive oxytocin antagonist

Not available in the US

27

B2 agonists 

  • ↑ cAMP - activates PKA
  • PKA phosphorylates smooth muscle myosin light chain kinase (MLCK)
  • lower affinity of MLCK for Ca2+-calmodulin complex
  • SmMLCK dose not phosphorylate myosin
  • myometrial smooth muscle relaxes

28

Bagonist AEs

  • palpitations, tremor, nausea, vomiting, nervousness, anxiety, chest pain, shortness of breath, hyperglycemia, hypokalemia, hypotension
  • Serious complications: pulmonary edema, cardiac insufficiency, arrhythmias, myocardial ischemia, maternal death
  • Black Box Warning/Contraindication: deaths and serious adverse reactions with terbutaline given to pregnant women
    • Injectable terbutaline limited to 72 hrs to treat preterm labor

29

Abortifacients

Mifepristone (antiprogestin)

Misoprostol (prostaglandin analog)

Methotrexate (folic acid antagonist)

30

First give ___, then give ___ 24-72 hrs later to produce early abortion (< 8 weeks pregnant)

___ is used off-label for early abortion

 Major adverse effects: ___

 

First give Mifepristone, then give misoprostol 24-72 hrs later to produce early abortion (< 8 weeks pregnant)

 Major AE: Cramping, Diarrhea

Methotrexate is used off-label for early abortion

 Major AE: Cramping, Nausea