Drug - Main points/no explanations

Question 1

Pharmacokinetic changes in pregnancy

Answer 1

generally not needed to change maternal drug dosing a priori

Question 2

Drug effects on fetus/pharmacokinetics

Answer 2

• pregnant women exposed to 3-5 prescriptions during pregnancy and as rule of thumb, drugs with good bioavailability will readily cross placenta

(more lipid soluble, smaller)

Question 3

Key hormones in labor

Answer 3

Prostaglandins for initiation nad uterine contraction

Oxytocin does NOT help with initiation but for maintaining. HUGE increase in receptors at end of pregnancy/early labor. Receptors coupled to Phospholipase C to increase Ca levels in cells

Question 4

What do you do to induce labor

Answer 4

• Dinoprostine in gel applied vaginally to stimulate cervical effacement
• Misoprostol (oral) to induce contractions
• Oxytocin- labor induction after cervical ripening
• postpartum hemorrhage: Oxytocin; if ineffective then ergonovine/methylergonovine

Question 5

Inhibit labor

Answer 5

• NSAID: Indomethacin often first line at 24-32 weeks. pulm HTN postnatally if ductus arteriosus closes. Acetaminophen = safest peripheral analgesic with unlikely closure of DA
• Nifedipine most commonly used 32-34 weeks or 24-32 if maternal contraindications to NSAIDs (platelet disorder, renal dysfunciton, GI ulcer, asthma if aspirin sensitive); fewer maternal side effects but potential concern of decreasing blood flow between uterus/placenta
• if known that mom is at increased risk for preterm labor (hx of spontaneous preterm birth), give 17-alpha-OH-progesterone caproate IM once a week. Begin at 16-20 weeks and continue to 36 weeks
• Mg Sulfate still indicated for pre-eclampsia/eclampsia but UCH doesn’t use for prevention of preterm birth

Question 6

Pregnancy termination

Answer 6

Mifepristone- single oral dose followed by prostaglandin, most commonly Oral misoprostol

**vaginal Gemeprost/IM sulprostone are other prostaglandins used

Question 7

ED drugs

Answer 7

Sildenafil (quicker onset of 1 hr but shorter duration)
Vardenafil (onset in 1 hr but shorter duration)
Tadalafil (delayed onset but longer action)

beware if taking other drugs that will lower BP (nitrate vasodilators, alpha adrenergic blockers, CYP450 inhibitors)

Question 8

Drugs for nausea/vomiting

Answer 8

Anti nausea: Ginger/pyridoxine

Anti-vomit: Doxylamine /other H1 antagonists

Hyperemesis: Metoclopramide- long term use worry about movement disorders

Anti nausea+ anti vomit: Ondansetron (5HT3 antagonist)