Lecture 32 - Uterotrophic drugs Flashcards
Oxytocic drugs cause or augment _____ of the uterus, while Tocolytic drugs suppress them.
Contractions
Oxyticic drugs can be remembered with the acronym: POE and Tocolytic can be remembered with the acronym: MCCOB
P - Prostaglandins
O - Oxytocin
E - Ergot Alkaloids
M - Magnesium sulfate C - Calcium Channel Blockers O - Oxytocin antagonists C - COX inhibitors B - Beta-agonists
Postpartum hemorrhage is considered loss of greater than or equal to ______mL of blood. The issue arises when there is uterine ______ (it doesn’t contract enough back onto itself after delivery of the child –> maternal sinuses remain open to leak blood).
500mL
Atony
In the weeks leading up to labor, Estrogen produces changes in the myometrium that facilitate contractions. These changes include increasing _____ and _____ receptors, increasing ______ light chain kinase, increasing ______ (Ca++ binding protein), and increasing gap junction formation.
Oxytocin
Prostaglandin
Myosin light chain kinase
Calmodulin
Rising levels of _____ releasing hormone, produced both by the fetus and the mother, are thought to induce labor. In the fetus, it increases levels of Cortisol which causes fetal production of ______ –> Some leaks into the amniotic fluid and binds myometrial cells –> results in an ______ response that is thought to trigger labor.
Corticotrophin releasing hormone
Surfactant
Inflammatory response
What does it mean when a provider says they are going to “Pit” a pregnant female patient?
It means they’re going to administer Pitocin, the trade name for Oxytocin, to induce labor or treat post-partum hemorrhage. It is given by IV infusion and has a half-life of 3-4mins.
Other than inducing labor, what can Oxytocic drugs be used for?
To treat post-partum hemorrhage from uterine atony.
Oxytocin causes ______ (rhythmic or sustained?) contractions.
Rhythmic
Oxytocin works by increasing ______ influx/release from SR, decreasing ______ efflux, decreasing myosin light chain ______, and stimulating ______ production.
Keep in mind K+ efflux offsets the action of Oxytocin –> causes rhythmic contractions.
Ca++
Ca++
Phosphatase
Prostaglandin
Oxytocin can cause _______ if given an IV bolus (it can reach the heart, stimulating production of _____).
It can also have an Antidiuretic effect bc its structure is very similar to ______.
Because of these possible side-effects, what should be monitored closely in patients receiving IV Oxytocin?
Hypotension
ANP
ADH (Vasopressin)
Monitor fluid intake!
Methyl ______ is an Ergot Alkaloid given to treat post-partum hemorrhage ONLY if Oxytocin isn’t working.
Why is it not given to induce labor?
It is given either IV or IM, but keep in mind Ergot Alkaloids can increase BP due to their action on _____ receptors.
Methyl Ergonovine
Bc it causes SUSTAINED contractions.
Alpha-1 (on vascular smooth muscle)
Prostaglandin _____ (dinoprost) is given for post-partum hemorrhage.
It can also be used for chemical _____ in combination with Methotrexate. How does this work?
F2alpha
Abortion
Methotrexate arrests cell division in the embryo, and 5-7 days later Prostaglandin F2alpha is given to induce uterine contraction to expel the embryo.
Do prostaglandins induce rhythmic or sustained contractions?
Rhythmic
Prostaglandins can be administered orally, injected into amniotic sac or uterine wall, as a gel in the cervical canal, or through a ______, which is a small reservoir inserted into the uterus from which the prostaglandins can diffuse (looks like a tampon and is removed similarly, by pulling the string/removal tape).
Side effects include _____, ______, and ______ (think GI).
Pessary
Nausea
Vomiting
Diarrhea
Prostaglandin _____ (dinoprostone) is used to induce cervical effacement. How is it administered?
E2
Pessary
Tocolytics should only be given short-term (about 48 hours). In what situation would they be given and why?
They would be given to mothers who are about to give birth prematurely. The extra 48 hours provides time to administer Betamethasone to induce surfactant production in the fetal lungs –> protect the fetus from respiratory failure after birth.
_______ is a Beta-agonist used as a Tocolytic. It acts on Beta2 receptors –> increases _____ –> leads to phosphorylation of _______ –> decreased contraction. It is injected SubQ, and can cause ______, hyperglycemia, and _____ edema.
Terbutaline
cAMP
MLCK
Tremors (Remember there are Beta2 receptors in NMJs –> activation leads to leaking of ACH into NMJ)
Pulmonary edema
_______ Sulfate is another tocolytic that acts by competitively inhibiting Ca++ influx through voltage-gated Ca++ channels. It is also used to prevent and treat ______ in women with preeclampsia and eclampsia.
There is concern for _______ of fetal bone if used more than 5-7days, as it will replace Ca++ in the fetal bone –> increased fracture risk.
Which reflex should be monitored in mothers receiving this and why?
Magnesium Sulfate
Seizures
Demineralization
Patellar reflex –> Magnesium sulfate has a steep dose response curve –> small difference between the therapeutic dose and dose needed to paralyze intercostal muscles needed for breathing.
_______ is a Ca++ channel blocker commonly used as a Tocolytic. It is given ______ (route?). It can have side effects in the mother, the most concerning of which is ________ (it can block Ca++ channels on vascular smooth muscle).
Nifedipine
Orally
Hypotension
Indomethacin is a ______ inhibitor given orally or IV. Bc it decreases the production of Prostaglandins, there is concern that it may cause premature closure of the _____ _____ (communication between Pulmonary artery and Aorta) in the fetus, which remains open in response to PGE2 binding receptors here causing vascular smooth muscle relaxation.
It is never given for more than _____hrs or after _____wks gestation.
COX inhibitor
Ductus Arteriosus
48hrs
32wks
_______ is an Oxytocin antagonist administered _____ (the same way Oxytocin/Pitocin is).
Atosiban
IV
