Pharmacology-Drugs in Pregnancy

Question 1

When is the best time to prevent medication effects on the fetus?

Answer 1

Prior to conception

Question 2

How do medications generally affect the fetus as the pregnancy continues on?

Answer 2

Embryo = death. Fetus = major malformations -> retarded growth as the pregnancy goes on

Question 3

GI changes in pregnancy

Answer 3

Decreased gastric acid and higher pH

Question 4

CV changes in pregnancy

Answer 4

Plasma volume expanded, increased CO

Question 5

Changes in blood during pregnancy

Answer 5

Plasma albumin levels decrease

Question 6

Changes in kidney during pregnancy

Answer 6

Increased renal blood flow, increased GFR (increased clearance) but tubular absorption rates stay the same

Question 7

Hepatic changes during pregnancy

Answer 7

CYP3A4 increased (methadone), CYP2D6 decreased, increased glucuronidation (increased clearance of lamotrigine and betamethasone)

Question 8

Definition of a congenital defect

Answer 8

Minor (does not need surgery) or major (needs surgery) deviation from normal morphology or function that happens during embryonic or fetal development.

Question 9

What factors are considered when determining if a medication is teratogenic? What is a common confounder?

Answer 9

Proven exposure at critical time, consistent findings by > 2 epi studies, rare exposure = rare defect, teratogenic in animals and biologically plausible. A common confounder are drugs administered for conditions which are teratogenic in themselves (e.g. diabetes + insulin = caudal regression or SGA baby due to diabetes).

Question 10

Limb reduction, ear, renal and cardiac defects happen in babies exposed to what drug?

Answer 10

Thalidomide (critical period of 27-40 days post-conception)

Question 11

Possible defect in using topamax or lamotrigine, which are class C drugs

Answer 11

Cleft lip and palate. Note that lamotrigine is still the safest drug for seizures.

Question 12

Pregnancy class of ACE inhibitors

Answer 12

C & D. Class C for minor cardiovascular abnormalities in 1st trimester exposure. Class D for fetal kidney dysgenesis, oligiohydramnios, pulmonary hypoplasia, growth restriction and still birth (Potter’s sequence)

Question 13

Pregnancy class of valproic acid and gentamycin

Answer 13

Class D. Valproic acid = neural tube defects, increase prevention with folic acid supplementation.

Question 14

Pregnancy class of prenatal vitamins and levothyroxine

Answer 14

Class A

Question 15

Pregnancy class of penicillin and tylenol

Answer 15

Class B

Question 16

Pregnancy class of nifedipine, sumatriptan and lamotrigine

Answer 16

Class C

Question 17

Pregnancy class of isotretinoin (acetone), misoprostol and warfarin

Answer 17

Class X. Isotretinoin can cause spontaneous abortion in 40%, 25% of pregnancies show CNS, CV and craniofacial malformations (small eyes, retinoid regression).

Question 18

Warfarin use in 1st trimester? 2nd? 3rd?

Answer 18

1st = 25% have embryopathy (microcephaly, nasal hypoplasia, stippled vertebrae) if exposed in 6-9 week period. 2nd = mental retardation and blindness 3rd = maternal hemorrhage and still birth.

Question 19

Category for drugs that have not yet been classified

Answer 19

Class N

Question 20

What drug used to treat bacterial vaginosis is a possible teratogen?

Answer 20

Metronidazole (flagyl): carcinogenic in rodents but no associated malformations. Avoid in 1st trimester.

Question 21

What drug used to treat bacterial infections can cause ototoxicity in 1-2% of babies?

Answer 21

Aminoglycosides

Question 22

What drugs used for UTIs can cause hyperbilirubinemia but have no associated malformations?

Answer 22

Sulfonamides. They compete with bilirubin-binding sites and may result in kernicterus.

Question 23

What drugs used to treat bacterial infections can cause arthropathy in children?

Answer 23

Quinolones, they have a high affinity for bone and cartilage.

Question 24

Most common preventable cause of mental retardation in babies

Answer 24

Alcohol (especially binge drinking) can cause the distinct phenotype of fetal alcohol syndrome.

Question 25

Absent philtrum, midface hypoplasia, low nasal bridge, low set ears, microcephaly and shorted palpebral fissures.

Answer 25

Fetal alcohol syndrome

Question 26

Illicit drug that can cause fetal vascular disruptions? Dose-related IUGR? IUGR, cardiac defects, facial clefts? Neonatal withdraw and psychiatric effects?

Answer 26

Cocaine = vascular. Marijuana = IUGR does-related. Amphetamine = IUGR, cardiac defects and facial clefts. Heroin/Methadone = withdraw + psych.

Question 27

Drugs that can cause gastroschisis

Answer 27

Illicit drugs. This can also be found in people that are very young and very old.

Question 28

Drugs used to stop preterm labor (tocolytics)?

Answer 28

17-OH-progesterone for more long term. Acutely used: MgSO4, beta-mimetics, indomethacin (can cause pre-mature closure of PDA = polyhydramnios), Ca-channel blockers (IUGR)

Question 29

Medications that help you deliver the baby

Answer 29

Oxytocin, cervical ripening agents (PGE1 and dinoprostone)

Question 30

Drug used to dilate the cervix. Associated with Mobius syndrome (CN palsy, limb malformation, craniofacial abnormalities) when used in 1st trimester.

Answer 30

Misoprostol. Note that this drug is category X due to risk of uterine contractions and miscarriage.

Question 31

Drugs used post-delivery to treat maternal hemorrhage

Answer 31

Oxytocin, methyl ergonovine and PGE1 and PGF2 alpha

Question 32

Drugs used for fetal benefit

Answer 32

Beta-methasone for pulmonary immaturity (may cause cleft palate/lip) and penicillin for neonatal GBS.

Question 33

Things to consider w/lactation

Answer 33

Consider dose, portion excreted in milk and amount absorbed by infant.It is also important to assess how they respond to drugs like codeine that have varied metabolism.

Question 34

Drugs absolutely contraindicated in lactation

Answer 34

MTX and Li (may also cause Ebstein’s anomaly in pregnancy)