Lecture 32 - Uterotrophic drugs

Question 1

Oxytocic drugs cause or augment _____ of the uterus, while Tocolytic drugs suppress them.

Answer 1

Contractions

Question 2

Oxyticic drugs can be remembered with the acronym: POE and Tocolytic can be remembered with the acronym: MCCOB

Answer 2

P - Prostaglandins
O - Oxytocin
E - Ergot Alkaloids

M - Magnesium sulfate
C - Calcium Channel Blockers
O - Oxytocin antagonists
C - COX inhibitors
B - Beta-agonists

Question 3

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).

Answer 3

500mL

Atony

Question 4

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.

Answer 4

Oxytocin

Prostaglandin

Myosin light chain kinase

Calmodulin

Question 5

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.

Answer 5

Corticotrophin releasing hormone

Surfactant

Inflammatory response

Question 6

What does it mean when a provider says they are going to “Pit” a pregnant female patient?

Answer 6

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.

Question 7

Other than inducing labor, what can Oxytocic drugs be used for?

Answer 7

To treat post-partum hemorrhage from uterine atony.

Question 8

Oxytocin causes ______ (rhythmic or sustained?) contractions.

Answer 8

Rhythmic

Question 9

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.

Answer 9

Ca++

Ca++

Phosphatase

Prostaglandin

Question 10

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?

Answer 10

Hypotension

ANP

ADH (Vasopressin)

Monitor fluid intake!

Question 11

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.

Answer 11

Methyl Ergonovine

Bc it causes SUSTAINED contractions.

Alpha-1 (on vascular smooth muscle)

Question 12

Prostaglandin _____ (dinoprost) is given for post-partum hemorrhage.

It can also be used for chemical _____ in combination with Methotrexate. How does this work?

Answer 12

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.

Question 13

Do prostaglandins induce rhythmic or sustained contractions?

Answer 13

Rhythmic

Question 14

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).

Answer 14

Pessary

Nausea

Vomiting

Diarrhea

Question 15

Prostaglandin _____ (dinoprostone) is used to induce cervical effacement. How is it administered?

Answer 15

E2

Pessary

Question 16

Tocolytics should only be given short-term (about 48 hours). In what situation would they be given and why?

Answer 16

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.

Question 17

_______ 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.

Answer 17

Terbutaline

cAMP

MLCK

Tremors (Remember there are Beta2 receptors in NMJs –> activation leads to leaking of ACH into NMJ)

Pulmonary edema

Question 18

_______ 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?

Answer 18

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.

Question 19

_______ 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).

Answer 19

Nifedipine

Orally

Hypotension

Question 20

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.

Answer 20

COX inhibitor

Ductus Arteriosus

48hrs

32wks

Question 21

_______ is an Oxytocin antagonist administered _____ (the same way Oxytocin/Pitocin is).

Answer 21

Atosiban

IV