Block Ii Pharmacology Of The Uterus

Front 1

oxytotic drugs

Back 1

-induce or help labor
-prevent postpartum hemorrhage
-help in breast feeding
-induce or manage abortion

Front 2

myometrial contractility

Back 2

-smooth muscle
-involves membrane Ca channels
-spread of excitation by gap junctions
-gap junctions increase through pregnancy by steroid hormones
-gap junctions allow for spontaneous, synchronized contractions

Front 3

Uterine innervation

Back 3

-parasympathetics from pelvic nerve
-sypmathetics from inferior mesenteric and hypogastric ganglia

Front 4

Nerve Receptors of the Uterus

Back 4

-alpha 1: excitatory
-beta 2: inhibitory
--Beta sensitivity increases late in pregnancy

Front 5

Oxytocin

Back 5

-excitatory receptors on the myometrium
-sensitivity increases by increasing receptor numbers throughout pregnancy
-levels of oxytocin increase also

Front 6

Prostaglandins E & F

Back 6

E1, E2, and F2 alpha have oxytocic effects
-have effects throughout pregnancy
-their effects also increse through pregnancy
-can be used early in pregnancy

Front 7

Estrogen and Progesterone

Back 7

-estrogen increses in last 2-3 weeks of pregnancy
-leads to the increased censitivity to oxytocin and prostaglandins
-progesterone decreases at the same time

Front 8

Stages of Labor

Back 8

Stage 1: cervical dilation
Stage 2: delivery of fetus
Stage 3: delivery of placenta

Front 9

Stage 1

Back 9

-cervical dilation
-complets at 10cm
-cervix soften and stretches

Front 10

Stage 2

Back 10

-delivery of placenta
-uterus contracts to a very small size
-placenta is separated from the uterine wall
-smooth muscle clamps blood vessels to prevent bleeding

Front 11

Causes of Postpartum Bleeding

Back 11

-uterine atony (doesn't contract)
-trauma or lacerations (can't contrace properly)
-retained placenta (can't contract enough)
-maternal hemorrhagic disease (mother can't clot)

Front 12

Milk Ejection

Back 12

-neurogenic/hormonal reflex
1-suckling sensation
2-hypothalamic release of oxytocin
3-contraction of alveolar myoepithelial cells
4-milk expression

Front 13

Oxytocic Drugs

Back 13

-oxytocin
-prostaglandins
-ergot alkaloids

Front 14

Indications for Oxytocin

Back 14

-initiate or manage labor
-initiate milk let-down

Front 15

Adverse Effects of Oxytocin

Back 15

high doses have an ADH effect leading to water toxicity
-they have similar structures

Front 16

Effects of Oxytocin

Back 16

-produces rhythmic uterine contractions with appropriate time of relaxation
-short half-life (12-17min) allows moment to moment control

Front 17

Contraindications to Oxytocin

Back 17

-unfavorable fetal position (ex: breech)
-potential uterine ruptrue (by many previous pregnancies or c-sections)
-maternal exhaustion
-fetal distress

Front 18

Administration of Oxytocin

Back 18

-IV-allows best fine control, but highest risk for water toxicity
-IM-for labor and lactation induction
-intranasal-for lactation

Front 19

Oxytocin Dangers to Fetus

Back 19

-anoxia-contractions decrease circulation
-abruptio placentae (early separation)
-damage to fetus by too quick birth through too small pelvis

Front 20

Prostaglandins in Use

Back 20

-dinoprostone: PGE2
-carboprost: 15 methyl PGF2 alpha
-misoprostol: PGE1 analogue

Front 21

PG for Labor Termination

Back 21

-first trimester (up to 7 weeks)
-misoprostol with mifepristone (approved) or methotrexate (off label)
-PG only contracts uterus and must use something to kill fetus

Front 22

PG in Postpartum Bleeding

Back 22

-carboprost
-misoprostol (advantage in storage, oral dose and cost)

Front 23

PG in Stage 1 of Labor

Back 23

-dinopristone--at doses below initiation of contraction
-often used with oxytocin to allow lower doses of both

Front 24

PG in Induction of Labor

Back 24

-misoprostol or dinoprostone
-not approved but easy storage and low cost

Front 25

ERgot Alkaloids

Back 25

-alpha adrenergic and serotinergic agonist
-increase lenght and force of uterine contractions
-sensitive early in pregnancy, but incresed later
-also trests Parkinson's and migraine

Front 26

Indications for Ergot Alkaloids

Back 26

-limited to postpartum or post abortion bleeding
-causes very strong contractions that have a high risk of stillbirth

Front 27

Ergonovine

Back 27

-most potent ergot alkaloid
-also the least toxic

Front 28

Tocolytic Drugs

Back 28

-used to delay labor or treat dysmenorrhea
-special circumstances
-50% respond to rest and hydration
-must have < 4cm dilation and < 80% effecement
-only druint weeks 20-36
-NOT if membranes are ruptured (risk of infection)
-also give drugs for lung maturation

Front 29

Calcium Agonist
Nifedipine (Procardia)

Back 29

-blocks surface membrane Ca channels
-used in preterm labor and to treat dysmenorrhea
-systemic risk of hyotension, tachycardia, and flushing

Front 30

Beta 2 Agonists

Back 30

-ritodrine, terbutaline, fenotorol, albuterol
-stimulate beta 2 receptors and decrease intracellular Ca
-decreases uterine contractions

Front 31

Indications for Beta 2 Agonists

Back 31

-pretern labor (ritodrine)
-abnormal uterine activity
-complications of C-section
-dysmenorrhea (terbutaline)

Front 32

Magnesium Sulfate

Back 32

-competes with Ca for binding
-controls siezures associated with eclampsia and severe preeclampsia
-higher doses prevent uterine contractions
-usefullness is questionable

Front 33

Prostaglandin Synthesis Inhibitors

Back 33

-Indomethecin (Indocin) and NSIDs
-block MAO and COX
-used to prevent dysmenorrhea
-risk of GI distress and bleeding
-NOT used to slow labor b/c blocks synthesis if PGI2
--get premature closure of ductus arteriosus and maternal bleeding and GI problems