Walters-Uterine Motility Drugs

Front 1

Describe oxytocin

Back 1

MOA: Oxytocin activates PLC-->increases synthesis of IP3-->triggers release of Ca2+ from SR-->activates MLCK, interaction b/t actin and myosin and uterine contraction
USES:
1. induce labor to facilitate delivery or inevitable abortion
2. control postpartum bleeding (uterine contraction compresses bleeding vessels)
3. treat breast engorgement during lactation
Side effects:
Large doses cause relaxation of vascular smooth muscle-->flushing and reflex tachycardia (obstetrical doses don't cause significant changes in BP)

Front 2

describe dinoprostone

Back 2

naturally occurring PGE2
Uses:
1. abortifacient (Prostin E2)-to evacuate uterus after intrauterine death; vaginal suppositories contain highest dose of PGE2; intended for use during pregnancy weeks 12-20
2. induce cervical ripening (softening and dilation of cervix to allow expulsion of fetus)
a. Prepidil-endocervical gel containing lowest dose
b. Cervidil-vaginal insert containing medium dose

Front 3

describe carboprost

Back 3

15-methyl- of PGF2α (semisynthetic derivative of PGF2α)
USES:
1. abortifacient (given IM during wks 13-20)
2. to control postpartum bleeding
note-doesn't have direct effect on fetus (NOT feticidal); evacuate uterus via direct effects on uterine smooth muscle

Front 4

describe mifepristone

Back 4

progesterone receptor modulator
Use-abortifacient
MOA:
1. increases the sensitivity of the myometrium to contraction by PGs-->detachment of the conceptus from the uterine wall
2. cause vascular changes that decrease placental viability and decreases secretory activity of the myometrium-->cause sloughing of the endometrium

Front 5

describe methylergonovine

Back 5

class-oxytocic ergot alkaloid
MOA-stimulation of uterine smooth muscle at α1 (primary) and 5-HT receptors-->increase force and frequency of uterine contractions
Uses:
1. postpartum or post-abortion to control bleeding
2. for postpartum atony of the uterus
Side effects:
1. IV-can lead to sudden hypertension and CVAs (give IV slowly)
2. headaches w/ HTN

Front 6

describe magnesium sulfate

Back 6

MOA:
1. competes w/ Ca2+ to prevent contraction of uterine smooth muscle
2. antagonizes Ca2+ dependent neuronal depolarization
USES:
1. delay parturition
2. control seizures in pre-eclampsia or eclampsia

Front 7

describe pre-eclampsia and eclampsia

Back 7

PRE-ECLAMPSIA: characterized by HTN, edema and proteinuria
MOA-autoantibodies activate angiotensin II AT1 receptors Effect- can't increase levels of adrenomedullin during pregnancy; adrenomedullin is a vasodilator that stimulates production of nitric oxide, decreases aldosterone response to hyperkalemia and causes natriuresis
ECLAMPSIA-develops from severe HTN; characterized by convulsions and coma during pregnancy or 1st week postpartum
Severe HTN during pregnancy-treat w/ hydralazine or labetalol

Front 8

describe terbutaline

Back 8

β2 agonist
MOA-relaxes uterine smooth muscle
Use-controls pre-term labor (not approved)
FDA side effects:
1. parenteral terbutaline should not be used for prevention or prolonged treatment (> 48-72 hrs) of preterm labor due to risk of serious maternal cardiovascular events and death
2. oral use should not be used b/c it hasn't been shown effective and carries the same risks to mother as parenteral

Front 9

describe Ca channel blockers

Back 9

not approved as tocolytics (uterine contraction inhibitors)
Side effects:
1. pulmonary edema
2. dyspnea
3. MI
4. fetal death-due to drop in maternal BP decreasing fetal blood supply
Recommendations:
1. Don't use w/ IV β agonists
2. Don't use IV nicardipine or high oral doses of nifedipine if mother is cardiovascularly compromised or if she's had multiple gestations
3. Monitor BP and cardiotocography when using immediate release formulations