drugs acting on uterus Flashcards
goal of cervical ripening
reduce rate of failed induction
cervical ripening drugs
1) dinoprostone
2) misoprostol
use of dinoprostone/misoprostol
promote cervical ripening in women with unfavorable cervices
may also initiate labor - and reduce need for oxytocin
dinoprostone
PGE2
misoprostol
PGE1
prostaglandins AE
tachysystole
fever/chills
v/d
oxytocin use
induce labor when cervix is ripe
ripening agent should be used before when women has unfavorable cervix
oxytocin
peptide hormone
secreted by posterior pituitary
IV infusion
oxytocin MOA
G(q) = PLC – Ca2+ released from SR
ALSO activation of VG Ca2+ channels – calcium induced calcium release
Ca2+ activates MLCK = contraction
oxytocin also increases PG synthesis = more contractions
oxytocin AE
sustained contractions = fetal distress, placental abruption (with too high doses)
activation of vasopressin receptors = fluid retention/water intoxication –> hyponatremia, HF, seizures
management of postpartum hemorrhage
oxytocin (IV or IM)
ergot alkaloids
prostaglandins
methylergonovine
ergot alkaloids - partial agonist at alpha adrenergic and serotonin receptors
uterus is very sensitive to ergot alkaloids during pregnancy
methylergonovine AE
minimal - HTN, HA, n/v, CP
methylergonovine contraindications
pregnancy angina MI CVA HTN
carboprost tromethamine
PGF-2alpha
IM admin
1st line postpartum hemorraghe
oxytocin
2nd line for postpartum hemorrhage
methylergonovine, carboprost tromethamine, misprostone
tocolytics
uterine relaxants
if gestation <37 weeks
given to have time for glucocorticoids to work to develop lungs (if <34 weeks)
magensium sulfate
tocolytic
works like calcium antagonist
uncouple excitation contraction in myometrial cells - via inhibition of cell AP
indomethacin
tocolytic
block PG (via NSAID) only NSAID used for this purpose
nifedipine
tocolytic
CCB - prevent SM contraction - no activation of MLCK
tocoloytic DOC
none
other tocolytics
atosiban
b2 agonist
magnesium sulfate AE
respiratory depression
cardiac arrest
can cross placenta = respiratory/motor depression of baby
indomethacin AE
more neonate AE than maternal**
crosses placenta = oligohydramnios d/t dec fetal RBF if used for more than 48 hours
premature PDA closure
not recommended after 32 weeks
nifedipine AE
maternal tachycardia, palpitations, flushing, HA, dizzy
atosiban
competitive antagonist at oxytocin receptors
b2 agonists as tocolytic
AC = inc cAMP = PKA activated
–> smooth muscle MLCK phosphorylated = lower affinity for Ca2+ calmodulin complex = no phosphorylated myosin - SM relaxed
b2 agonist AE
limited to be given 72 hours to tx preterm labor
palpitations tremor n/v anxiety hypokalemia hypotension pulmonary edema
**black box warning = terbutaline against use in preterm labor - death and serious AE
