Uterine Drugs

Question 1

What is a tocolytic?

Answer 1

Reduces uterine contractility -> suppresses preterm labor

Question 2

Prostaglandin drug examples and which PG they mimic (3)

Answer 2

PGE: dinoprostone and misoprostol
PGF2a: dinoprost

Question 3

Oxytocin drug (1)

Answer 3

Pitocin

Question 4

2 Ergots

Answer 4

Ergonovine & Ergotamine

Question 5

4 tocolytics and their classes

Answer 5

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

Question 6

MOA and uses of oxytocics

Answer 6

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

Question 7

What intracellular second messenger stimulates Ca release from the SR?

Answer 7

IP3

Question 8

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

Answer 8

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

Question 9

What happens to muscle below the Ca threshold?

Answer 9

Myosin light chains are dephosphorylated by MLC phosphatase -> relax

Question 10

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

Answer 10

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

Question 11

3 triggers for oxytocin release

Answer 11

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

Question 12

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

Answer 12

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

Question 13

What substance is an inhibitor of oxytocin release?

Answer 13

Alcohol

Question 14

What is the caveat of oxytocin stimulating uterine contractions

Answer 14

Only works well during 3rd trimester of pregnancy

Question 15

At high concentrations, OT can do what???

Answer 15

Act like ADH –> antidiuretic + vasoactive

Question 16

OT being a peptide means what pharmacologically?

Answer 16

Can’t be given orally

Question 17

Oxytocin removal by

Answer 17

liver or kidney

Question 18

How is oxytocin’s effect modified at pregnancy term?

Answer 18

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

Question 19

Contraindications for Pitocin (4)

Answer 19

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

Question 20

Precursors to PGE2 (what is it made from)

Answer 20

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

Question 21

Actions of PGE2 (4)

Answer 21

Contracts uterus, softens cervix, hyperalgesia, fever

Question 22

Action of PGF2

Answer 22

Uterine contractions

Question 23

PGs’ role in labor

Answer 23

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.

Question 24

Natural PGE drug name and use

Answer 24

Dinoprostone: as above + treatment of hydatidiform mole

Question 25

Synthetic PGE drug name

Answer 25

Misoprostol

Question 26

Natural PGF2a

Answer 26

Dinoprost

Question 27

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

Answer 27

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

Question 28

What are the stages of cervical changes in pregnancy

Answer 28

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

Question 29

What drug is a progesterone receptor antagonist?

Answer 29

Mifepristone

Question 30

Side effects of PG therapy

Answer 30

Pain, inflammation, fever, vomiting, diarrhea

Question 31

Action of ergots

Answer 31

Potent smooth muscle stimulation

Question 32

AEs of ergots

Answer 32

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

Question 33

2 major actions of ergots and which ergots mediate each

Answer 33

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

Question 34

MgSO4 MOA

Answer 34

Competes with Ca -> relaxes smooth muscle

Question 35

Use of terbutaline

Answer 35

IV or PO after 20 weeks gestation to delay labor

Question 36

AEs of terbutaline

Answer 36

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

Question 37

Use of MgSO4

Answer 37

Used IV to prevent seizures assoc w eclampsia

Question 38

Atosiban MOA

Answer 38

Inhibits OTR's activation of IP3 = oxytocin receptor antagonist

Question 39

Atosiban use

Answer 39

Delay labor, rapid onset - within minutes

Question 40

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

Answer 40

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

Question 41

Indomethacin MOA

Answer 41

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

Question 42

Which PG induces labor AND ripens the cervix?

Answer 42

Dinoprostone

Question 43

Use of ergonovine and contraindication

Answer 43

Reduces postpartum bleeding. NEVER used to induce labor.