Antenatal and Perinatal Pharmacology

Question 1

Misoprostol MOA

Effects (2)

Clinical indications (2)

Contraindications (2)

PKs

Maternal S/E
Fetal S/E

Price

Answer 1

MOA: PGE1 analog

Effects: induces uterine contractions, maintains ductus arteriosus patency

Indications: termination of pregnancy if <70 days, off-label cervical ripening

Contraindications: pregnancy (unless aborting), prior C-section

PKs: stable at room temperature, oral with rapid onset

Maternal S/E: fever, chills, N/V/D, tachysystole (if given intravaginal)
Feta S/E: hypoxia due to tachysystole or prolonged uterine contractions

Price: cheap

Question 2

Dinoprostol MOA

Effects (2)

Clinical indications (2)

What makes it difficult to give? (2)

Contraindications (2)

Maternal S/E
Fetal S/E

Answer 2

MOA: PGE2

Effects: induce uterine contractions, promotes cervical ripening

Indications: inducing labor, terminating pregnancy (week 12-20)

Difficult at times because it requires refrigeration and is very expensive

Contraindications: pregnancy (unless aborting), prior C-section

Maternal S/E: back pain, N/V/D, fever, chills, etc.
-during abortion, fever unresponsive to NSAIDs
Fetal S/E: hypoxia due to tachysystole or prolonged uterine contractions

Question 3

Carboprost MOA

Effects (2)

Clinical indications (2)

How is it given?

What is the problem with it?

Answer 3

MOA: PGF2a analog

Effects: induces uterine contractions

Indications: induce abortion (13-20 weeks), post-partum refractory bleeding

Given by deep IM injection (expensive, too)

There are tons of side-effects and it is rarely given

Question 4

Oxytocin effects (2)

Clinical indications (2)

Contraindications (2)

Maternal S/E (1)

Answer 4

Effects: increases force, frequency and duration of uterine contractions

Indications: induction of labor, post-partum hemostasis for refractory bleeding

Contraindications: fetal lungs not mature, cervix is not ripe

S/E: water intoxication (rare)

Question 5

Ergot alkaloids MOA

Effects (2)

Contraindications (2)

What is the historical association?

Answer 5

Stimulates adrenergic, dopaminergic and serotonergic receptors (constrictor action)

Effects: prolonged/tonic uterine contraction, vascular constriction

St. Anthony’s fire - mania, psychosis, vomiting, etc.

Question 6

Bottom line for:

PGs

Oxytocin

Ergot alkaloids

Answer 6

PGs: work well for ripening cervix (must happen prior to contractions), and can cause uterine contractions at any time in pregnancy

Oxytocin: used to induce/normalize contractions, helps with post-partum bleeding

Ergot alkaloids: second choice for post-partum bleeding

Question 7

4 indications for antenatal corticosteroids

Answer 7

Women between 24-36 wks of gestation with one of the following:

• threatened pre-term labor
• antepartum hemorrhage
• pre-term ROM
• conditions requiring C-section (pre-eclampsia and HELLP)

Question 8

How many doses, route of administration, and over what interval for:

Betamethasone

Dexamethasone

What is the MOA for both?

Answer 8

Betamethasone: 2 doses by IM injection over 24 hrs

Dexamethasone: 4 doses by IM injection over 12 hrs

MOA - induces transcription of surfactant proteins in type 2 pneumocytes

Question 9

Why are Betamethasone and Dexamethasone better choices than Cortisol for fetal surfactant production?

What does this mean for the mom?

Answer 9

Because the placenta metabolizes cortisol to cortisone

It means that mom can be given cortisol without affecting the baby

Question 10

Magnesium sulfate is used for (2)

What is it also thought to decrease the risk of?

What is the MOA?

Answer 10

Prevent pre-eclamptic seizures and tocolysis

It is a neuroprotector, thus decreasing risk of cerebral palsy

MOA: inhibiton of ACh release at the uterine NMJ

Question 11

What is the drug of choice for tocolysis in the USA?

Answer 11

Magnesium sulfate

Question 12

Terbutaline MOA

Contraindications (3)

What is included in the “evidence-based conclusions”?

Answer 12

Increases cAMP, leads to K+-channel mediated hyperpolarization, dephosphorylation of myosin light chains

Cardiac arrhythmias, poorly controlled thyroid disease or DM

Conclusion: delays labor for 2-7 days, but no evidence of benefit to the fetus and mother experiences side-effects

Question 13

According to the Cochrane evidence-based conclusiosn, what is preferable for tocolysis?

Answer 13

CCB - Nifedipine

Question 14

What 2 drugs appear to be the best choices for tocolysis?

Answer 14

Nifedipine and Indomethacin

Question 15

Alprostadil MOA

Route of administration

What is the effect of using it?

Adverse-effects (4)

Answer 15

PGE1 analog

Parenteral

Maintains a patent ductus arteriosus

Pyrexia* (fever), hypotension, tachycardia, apnea

Question 16

What is used to close a PDA?

What are the adverse effects?

Answer 16

NSAIDs (ibuprofen) and Indomethacin (classically used)

Decreased kidney function: oliguria, edema and mild HTN

Question 17

What are the first-line drugs for moderate maternal HTN? (2)

Answer 17

Oral a-methyldopa (a2 agonist)
Oral labetalol (a/B blocker)

Question 18

What are the second-line drugs for severe maternal HTN? (3)

Answer 18

Parenterl labetalol (a/B blocker)
Hydralazine (arterial vasodilator)
Sodium nitroprusside (arterial + venous vasodilator)

Question 19

Which drugs for HTN are contraindicated in pregnancy?

Answer 19

ACE-inhibitors and ARBs