Oxytocic And Tocolytics Flashcards

1
Q

As the pregnancy gets closer to parturition, what hormonal shift happens?

A

Shifts from progesterone > estradiol dominance to estradiol > progesterone dominance

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2
Q

What effect does progesterone have on the pregnancy?

A

Causes hyperpolarization of myometrial cells (preventing contractions); decreases adrenergic receptors, inhibits oxytocin synthesis, inhibits estrogen receptor synthesis; promotes storage of prostaglandin synthesizing enzymes

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3
Q

What effect does progesterone have on the adrenergic of the uterus?

A

Decreases adrenergic receptors

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4
Q

Prior to parturition, what hormone inhibits synthesis of oxytocin receptors and estrogen receptors?

A

Progesterone

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5
Q

When closer to parturition and the hormones shift to estradiol > progesterone, what effect does this have on the uterus?

A

Promotes uterine contractility, increases oxytocin receptors, promotes cervical ripening, increases local prostaglandins release from the placenta (which cause myometrial contractions)

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6
Q

What effect do local prostaglandins released from the placenta have on the uterus?

A

Causes myometrial contractions

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7
Q

What prostaglandins predominate in reproduction?

A

PGF2 and PGE2

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8
Q

What is responsible for the mild Braxton Hicks contractions during pregnancy?

A

PGF2 and PGE2

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9
Q

What produces the prostaglandins important for contractions during parturition?

A

The placental unit

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10
Q

What is the function of oxytocin?

A

Induces smooth muscle contraction - important for myoepithelial cells in breast and myometrium in uterus

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11
Q

What do tocolytics do to the pregnancy?

A

Maintain pregnancy

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12
Q

What do oxcytocics do to pregnancy?

A

Promote labor

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13
Q

Where is oxytocin synthesized?

A

Paraventricular and supraoptic nuclei of the hypothalamus

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14
Q

What is neurophysin?

A

Oxytocin protein carrier protein

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15
Q

What kind of receptors are oxytocin receptors?

A

Gq - coupled to PLC

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16
Q

How is oxytocin administered?

A

Parenteral, sublingual, nasal; not orally

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17
Q

What is the drug of choice for labor induction?

A

Pitocin

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18
Q

What is Pitocin?

A

Synthetic oxytocin

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19
Q

What are contraindications of Pitocin?

A

Not intended as abortifacient; large baby; hypertonic uterine contractions; previous C sections

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20
Q

What prostaglandin contracts the uterus and produces hyperalgesia?

A

PGE2

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21
Q

What are the effects of PGE2 in regards to pregnancy/labor?

A

Contracts uterus; produces hyperalgesia; promotes softening of the cervix

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22
Q

PGER is coupled to what?

A

Gi

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23
Q

PGF2 causes what effects in regards to labor/pregnancy?

A

Causes uterine contractions

24
Q

PGFR is coupled to what?

A

Gq - stimulates IP3

25
Q

What effects do prostaglandins have on pregnancy/labor?

A

Induces local myometrial contractions; promotes cervical ripening prior to delivery

26
Q

What effect do prostaglandins have on the cervix?

A

Ripening - softening, thinning, dilating

27
Q

What is indomethacin?

A

NSAID - inhibits COX and therefore prostagladin synthesis

28
Q

What is Indomethicin used for in pregnancy/labor?

A

Reduces uterine contractions and cervical ripening

29
Q

What is dinoprostone?

A

Natural PGE

30
Q

What is misoprostol?

A

Synthetic PGE

31
Q

What is dinoprost?

A

PGF2 alpha

32
Q

What is Carboprost?

A

PGF2 alpha used i.m.

33
Q

What can misoprostol be used for?

A

Ripen (dilate) cervix for labor; abortifacient

34
Q

What can carboprost be used for?

A

Used in any trimester as an abortifaceint or to induce labor

35
Q

What can dinoprostone be used in treatment of?

A

Hydatidiform mole

36
Q

What is ergonovine? What is its effect?

A

It is an ergot; causes contraction of the uterus

37
Q

What is ergometrine? What does is do?

A

Ergot; causes contraction of uterus

38
Q

What are ergots used for medically?

A

Control postpartum bleeding

39
Q

What receptors do ergots work on?

A

Alpha adrenergic, dopaminergic, and 5-HT2 receptors

40
Q

What is ergotamine? Use?

A

Ergot; used in migraines for its contraction of blood vessels

41
Q

What can be used to control postpartum bleeding?

A

Ergots; oxytocics

42
Q

What are tocolytics used for?

A

Suppress uterine smooth musc contration; suppress premature labor

43
Q

Who is an optimum candidate for tocolytic therapy?

A

Women in early phase of acute preterm labor, when cervical dilation is not advanced

44
Q

What is terbutaline?

A

Beta 2 agonist

45
Q

What is nifedipine?

A

Calcium channel blocker (dihyropyridines)

46
Q

What are the downstream effects of calcium binding calmodulin?

A

Activates MLCK, which phosphorylates myosin light chain, promoting contraction

47
Q

What are the downstream effects of beta 2 agonists?

A

Gs - activates AC and increases cAMP; cAMP activates protein kinase A which inhibits MLCK (decreasing smooth muscle contraction)

48
Q

During what week is terbutaline used in pregnancy?

A

After week 20

49
Q

What effect does magnesium sulfate have on uterine contractions?

A

Inhibits them by competing with calcium; causes smooth muscle relaxation

50
Q

What is atosiban?

A

Oxytocin receptor antagonist

51
Q

What are the concerns with the use of atosiban?

A

Increased fetal mortality

52
Q

What NSAID is used as a tocolytic? What is its mechanism?

A

Indomethacin; blocks cox and inhibits prostaglandin formation

53
Q

What are the PGE agonists used as oxytocics?

A

Misoprostal and dinoprostone

54
Q

What are the PGF2 alpha agonists used as oxytocics?

A

Dinoprost, carboprost

55
Q

What beta 2 agonist is used as a tocolytic?

A

Terbutaline