Uterine Drugs Flashcards
What 4 things cause uterine contraction?
Estrogen, prostaglandins, oxytocin, stretching
What 4 things cause uterine relaxation?
beta-adrenergic drugs, progesterone, alcohol, MgSO4
What increases in # and sensitivity prior to labor and delivery?
Oxytocin receptors
During the 2nd trimester, the uterus is resistant to stimulation but what can cause strong labor like contractions?
Prostaglandins
What is the most common cause of postpartum hemorrhage?
Uterine atony (lack of myometrial contractions fail to squeeze and constrict the spiral arteries)
How much BF is getting to the placenta at term?
~500mL/ min
How much blood loss is considered to be postpartum hemorrhage for both vaginal delivery and C-section?
Vaginal delivery ~500mL
C-section ~1000mL
What is 1st line treatment for postpartum hemorrhage?
Massage
In regards to premature labor, the earlier the preterm, the greater the what?
Risks for the baby
What is the most common RF for premature labor?
Previous preterm labor or preterm birth
If preterm labor needs to happen before the 37th week, what drugs should be given and why?
Give corticosteroids to induce lung development
Pitocin drug class?
Oxytocin
Syntocin drug class?
Oxytocin
Ergonovine Maleate (Ergotreate) drug class?
Ergot alkaloids
Dinoprostone drug class?
Prostaglandins
Carboprost tromethamine drug class?
Prostaglandins
Misoprostol drug class?
Prostaglandins
Tranexamic acid drug class?
Non-uterotonic drugs
Magnesium drug class?
Tocolytic agents
Nifedipine drug class?
Tocolytic agents
Indomethacin drug class?
Tocolytic agents
Progesterone drug class?
Tocolytic agents
What is the MOA for Pitocin and Syntocin?
Oxytocin receptor agonists
What is DOC for inducing labor at term (if needed)?
Pitocin and Syntocin given IV
cause timed contractions = more physiological
What is the use for Pitocin and Syntocin given IM?
Prevention of hemorrhage (if not already on IV, and 2nd line after massage
What is the use for Pitocin and Syntocin given via the nasal route?
Milk let-down reflex
What is the half life for Pitocin and Syntocin?
Short- 1-6 min
allows for on-off timed contractions
What are the SEs of Pitocin and Syntocin? (4)
Water intoxication, uterine rupture, anaphylaxis, sinus bradycardia of fetus
(Water intoxication and uterine rupture only with large doses, sinus bradycardia due to forceful contractions)
What is the contraindication to Pitocin and Syntocin?
Any non-vaginal delivery
What is the MOA for Ergonovine Maleate (Ergotreate)?
Contraction of uterine smooth muscle through activation of serotonin and alpha-adrenergic receptors
(“always on”)
When is Ergonovine Maleate (Ergotreate) used?
After completion of labor and delivery of placenta to produce firm uterine contractions and decrease uterine bleeding, 3rd line (after massage and oxytocin)
How long after Ergonovine Maleate (Ergotreate) given IV is it active?
Rapid action (30-40 seconds)
How long after Ergonovine Maleate (Ergotreate) given orally is it active?
10 min
How long do the actions of Ergonovine Maleate (Ergotreate) last?
Several hours
What is the SE for Ergonovine Maleate (Ergotreate)?
Transient HTN (contracts all smooth muscle)
What is the contraindication for Ergonovine Maleate (Ergotreate)? (3)
Never used to induce labor, peripheral vascular/ CAD
What is the DOC for inducing abortions during the 2nd trimester?
Prostaglandins
What drug is used for expulsion of uterine contents (abortion) and is 4th line (after massage, oxytocin, and ergots) for postpartum atony?
Prostaglandins
What is the use of Dinoprostone in the gel form?
Cervical ripening prior to delivery at term
Which of the Prostaglandins is associated with the worst diarrhea as a SE?
Dinoprostone (black box warning)
What are the SEs of the prostaglandins? (3)
GI disturbances, vomiting, diarrhea
also fever, chills, HA
What are the contraindications for use of Prostaglandins for abortions? (7)
Acute pelvic inflammation Acute cardiac/ pulm/ renal/ hepatic disease Asthma HTN Anemia Jaundice Epilepsy
What is the MOA for Tranexamic acid?
Antifibrinolytics = inhibits plasminogen activation
What is the use for Tranexamic acid?
Limits mortality from postpartum hemorrhage, given in combo with uterotonic therapy (oxytocin, ergots, PGE)
How is Tranexamic acid given with standard uterotonic therapy?
IV
What is the MOA for magnesium?
Relaxes uterus
What is considered “1st line” for prevention of premature labor or to delay premature labor until the 37th week?
magnesium
What drug can prevent convulsion in preeclampsia and is used to treat preeclampsia?
magnesium
How is magnesium administered?
IV and slowly (hospital only)
What are the SEs of magnesium?
Flu-like sxs
What is the MOA of Nifedipine?
L-type calcium channel blocker (inhibits Ca2+ influx/ smooth muscle contractions)
What is Nifedipine used for?
Prevents premature labor or delays premature labor until 37th week
How is Nifedipine administered?
Orally (can be given at home)
What is the MOA for indomethacin?
Inhibits COX enzyme (reduction of prostaglandin synthesis)
When is indomethacin used?
Prevents premature labor or delays premature labor until 37th week
What are the SEs of indomethacin? (2)
Maternal GI irritation, partial closure of fetal ductus arteriosus (usually remains open by PGE)
What is progesterone used for with respect to labor?
Delays premature labor (until 37th week) when given prophylactically from 16th-37th week to women with a history of premature labor
Why are progesterone NOT effective for acute treatment with respect to labor and delivery?
Work via nuclear receptors (slow reaction) and because progesterone is already naturally present (rises throughout pregnancy)
