Uterine Drugs Flashcards

1
Q

What is a tocolytic?

A

Reduces uterine contractility -> suppresses preterm labor

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2
Q

Prostaglandin drug examples and which PG they mimic (3)

A

PGE: dinoprostone and misoprostol
PGF2a: dinoprost

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3
Q

Oxytocin drug (1)

A

Pitocin

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4
Q

2 Ergots

A

Ergonovine & Ergotamine

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5
Q

4 tocolytics and their classes

A

Terbutaline (b2 agonist), Magnesium Sulfate, Atosiban (Oxytocin receptor antagonist), Indomethacin (NSAID)

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6
Q

MOA and uses of oxytocics

A

Stimulate uterine smooth muscle contraction e.g. induce labor, control postpartum hem or atony

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7
Q

What intracellular second messenger stimulates Ca release from the SR?

A

IP3

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8
Q

How is [Ca] regulated (decreased) in the cell

A

Na-Ca antiporter utilizes Na gradient set up by Na-K ATPase to kick Ca out of cell

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9
Q

What happens to muscle below the Ca threshold?

A

Myosin light chains are dephosphorylated by MLC phosphatase -> relax

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10
Q

What are neurophysins, and how do they come into play?

A

Oxytocin and ADH carrier proteins, released from posterior pituitary with the hormones

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11
Q

3 triggers for oxytocin release

A

Cervical dilation, mechanical stim of vagina or uterus, suckling reflex

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12
Q

What type of receptor is the oxytocin receptor (OTR) and where is it found (3)

A

GCPR w phospholipase C. Found in 1. myoepithelial cells of mammary gland 2. pregnant myometrium esp late 3. CNS

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13
Q

What substance is an inhibitor of oxytocin release?

A

Alcohol

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14
Q

What is the caveat of oxytocin stimulating uterine contractions

A

Only works well during 3rd trimester of pregnancy

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15
Q

At high concentrations, OT can do what???

A

Act like ADH –> antidiuretic + vasoactive

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16
Q

OT being a peptide means what pharmacologically?

A

Can’t be given orally

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17
Q

Oxytocin removal by

A

liver or kidney

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18
Q

How is oxytocin’s effect modified at pregnancy term?

A

Oxytocinase activity increased, comes from uterus and placenta -> degrades

19
Q

Contraindications for Pitocin (4)

A

Not an abortifacient, cephalo-pelvic disproportion, hypertonic uterine contractions, previous c-section (risk of uterine rupture)

20
Q

Precursors to PGE2 (what is it made from)

A

Membrane cleavage of arachidonic acid (part of fatty tail) -> PGH2 by COX -> PGE2

21
Q

Actions of PGE2 (4)

A

Contracts uterus, softens cervix, hyperalgesia, fever

22
Q

Action of PGF2

A

Uterine contractions

23
Q

PGs’ role in labor

A

Functions close to site of synthesis (deactivated before it circulates), major component of physiological labor via contractions and softening of cervix. Can be used as abortifacients.

24
Q

Natural PGE drug name and use

A

Dinoprostone: as above + treatment of hydatidiform mole

25
Q

Synthetic PGE drug name

A

Misoprostol

26
Q

Natural PGF2a

A

Dinoprost

27
Q

Carboprost: what is it and what is it used for?

A

PGF-2a used IM in any trimester -> abortifacient or induces labor

28
Q

What are the stages of cervical changes in pregnancy

A
  1. Softening 2. Ripening/ dilation (collagen dispersion, leukocyte infiltration, inc hydration and compliance) 3. Postpartum (incl leukocyte activation and inc cytokines)
29
Q

What drug is a progesterone receptor antagonist?

A

Mifepristone

30
Q

Side effects of PG therapy

A

Pain, inflammation, fever, vomiting, diarrhea

31
Q

Action of ergots

A

Potent smooth muscle stimulation

32
Q

AEs of ergots

A

vascular constriction gangrene in periphery, convulsive ergotism (poisoning), greatly inc risk of fetal mortality

33
Q

2 major actions of ergots and which ergots mediate each

A
  1. Uterine contraction (ergonovine = ergometrine) via a1, DA, and 5HT2 receptors controls postpartum bleeding 2. Contraction of blood vessels (ergotamine) to treat migraines
34
Q

MgSO4 MOA

A

Competes with Ca -> relaxes smooth muscle

35
Q

Use of terbutaline

A

IV or PO after 20 weeks gestation to delay labor

36
Q

AEs of terbutaline

A

Inc HR, pulm edema, hyperglycemia, and precipitate MI by inc O2 demand w inc HR

37
Q

Use of MgSO4

A

Used IV to prevent seizures assoc w eclampsia

38
Q

Atosiban MOA

A

Inhibits OTR’s activation of IP3 = oxytocin receptor antagonist

39
Q

Atosiban use

A

Delay labor, rapid onset - within minutes

40
Q

Pros and cons of Atosiban vs beta receptor agonists in delaying labor (3)

A

Atosiban: fewer maternal side effects but inc fetal mortality and inferior in delaying labor

41
Q

Indomethacin MOA

A

Inhibitor of COX 1 & 2 -> dec PG -> dec uterine contraction

42
Q

Which PG induces labor AND ripens the cervix?

A

Dinoprostone

43
Q

Use of ergonovine and contraindication

A

Reduces postpartum bleeding. NEVER used to induce labor.