OB Pharmacology

Question 1

Spontaneous Abortion

Answer 1

Misoprostol (Cytotec) - prostaglandin E1 analog

Surgical, Medical, or Expectant (pass naturally)

Question 2

Misoprostol (Cytotec)

Answer 2

Prostaglandin E1 analog - induces uterine contractions

For missed/incomplete abortion or unlabeled for cervical ripening or postpartum hemorrhage

Intravaginally is highly effective - 70-90% expulsion w/in 24 hours

Question 3

Preterm Labor Drugs

Answer 3

Tocolytics

• Indomethacin
• Nifedipine
• Terbutaline
• Magnesium sulfate

Corticosteroids - Betamethasone (preferred)

Question 4

Tocolytics

Answer 4

Goal: delay delivery 48 hours to allow lung maturity w/ steroids

Indomethacin

Nifedipine

Terbutaline

Magnesium Sulfate

Question 5

Indomethacin

Answer 5

DOC for 24-32 weeks

Decreases prostaglandin productions through cyclooxygenase inhibition

Maternal SE: N, GERD, gastritis, emesis, platelet dysfunction

Fetal SE: ductus arteriosis constriction, oligohydramnios, necrotizing enterocolitis, PDA

CI: ASA allergy, GI ulcers, liver/kidney dysfunction, bleeding issue

Monitor fetus if given >48 hours

Question 6

Nifedipine

Answer 6

1st line: 32-34 weeks; 2nd line: 24-32 weeks

CCB -> myometrial relaxation & peripheral vasodilation

Maternal SE: N, flushing, HA, dizzy, palpitations, HOTN

CI: HOTN, cardiac abnormalities/CHF, decreased ventricular contraction

Do no give w/ magnesium sulfate - synergists can cause respiratory depression

Question 7

Corticosteroids

Answer 7

Reduced (50%) RDS, intraventricular hemorrhage, necrotizing enterocolitis, sepsis, neonatal mortality

Betamethasone - preferred

Dexamethasone in non-sulfide suspension to prevent fetal neurotoxicity

Question 8

Group B Strep

Answer 8

Antibiotic prophylaxis w/ + culture or hx previous birth

Unknown status, maternal fever (>100.4), preterm labor, or PROM >18 hrs

Don’t give w/ planned C-section unless PROM

PCN-G, Ampicillin, Cephazolin (Ancef), Clindamycin, Vancomycin w/ PCN Allergy

Question 9

Premature Rupture of Membranes

Answer 9

Infection may be cause

1g Azithromycin + 2g Ampicillin + Amoxacillin

OR

Clinda + Gent w/ Clinda f/u for 5 days

Question 10

Postpartum Hemorrhage

Answer 10

Uterotonic Drugs

Oxytocin

Misoprostol

Methylergonovine

Carboprost Tromethamine

Question 11

Oxytocin

Misoprostol

Methylergonovine

Carboprost Tromethamine

Answer 11

Oxytocin: DOC for PPH - infusion or IM; 1/2 life 1-6 minutes

Misoprostol: sublingual or per rectum; SE: GI, HA

Methylergonovine: Ergot alkaloid - acts on smooth muscle

• IM or Intramyometrial - severe HTN stroke if IV
• CI: Reynauds, HTN, Scleroderma

Carboprost Tromethamine: IM only; CI: Asthma, HTN, renal failure, decreased cardiac output

Question 12

Preeclampsia - Severe HTN during labor

Answer 12

IV labetalol

IV Hydralazine

PO nifedipine

Question 13

Magnesium Sulfate

Answer 13

Adjust with renal insufficiency

MOA: blocks neuromuscular transmission and decreases acetylcholine @ motor end plate

Get baseline DTRs

-Absent @ 8-10, respiratory paralysis @ 10-15

Calcium gluconate 1g IV to reverse

CI: heart block, myocardial damage, myasthenia gravis, CCB concurrent use

Question 14

Induction of Labor

Answer 14

Oxytocin (Pitocin)

Activates G-protein coupled receptor that triggers increased calcium intracellular uterine contractions

Increases prostaglandin production

Maternal SE: arrythmia, HTN, N/V, pelvic hematoma, PPH, hypertonicity, uterine rupture; severe water intoxication w/ seizure/coma/death

Fetal SE:CV, CNS, Jaundice, retinal hemorrhage, death, low APGAR

Question 15

Diarrhea

Constipation

Answer 15

Diarrhea: rehydration & diet change 1st line - loperamide (C) in small doses w/ severe cases only

Constipation: 1st line - increased fiber and fluids; bulk-forming laxatives preferred - not absorbed: Metamucil, Citrucel, Fibercon, Benefiber

• Mineral absorption: lactulose (B), ducolax
• Magnesium hydroxide crosses placenta - should be safe
• Avoid castor oil (stimulates contractions), mineral oil (decreased vitamin absorption)

Question 16

GERD

Cold Symptoms

Answer 16

GERD: Lifestyle, Sulcrafate preferred - coats lining; TUMS ok

• H2 Blockers 2nd line - Zantax, Taganet
• PPI - Prevacid, Protonix Cat B

Cold Symptoms: warm humidified air, Acetaminophen for fever

• Ipratropium bromide for Rhinorrhea - cat B
• Single doses Sudafed in 3rd trimester ok

Question 17

Analgesics

Answer 17

Acetaminophen (Tylenol) cat C - DOC for maternal pain & fever

-small correlation between use & ADD behavior in child, wheezing or asthma

NSAIDs - avoid

<30 weeks: Cat C -> may cause miscarriage, CV abnormalities, cleft lip/palate

>30 weeks: Cat D -> premature ductus closure, significant abnormalities

Question 18

Drugs to stimulate ovulation

Answer 18

Clomiphene (Clomid)

Metformin (Glucophage)

Question 19

Clomiphene (Clomid)

Answer 19

Ovarian stimulator, selective estrogen receptor modifier

Inhibits normal estrogenic negative feedback - increased GnRH => increased FSH and LH

-causes follicular growth and rupture

Pulse dosing on day 5 menstrual cycle for 5 days - intercourse 5-10 days after regimen complete

Can try again 30 days later - don’t try >6 times

Question 20

Metformin (Glucophage)

Answer 20

Biguanide

Increased menstrual cyclicity, decreased ovulation and androgen levels

Lower live birth rate than Clomid

Helps w/ insulin resistance and weight - used w/ PCOS