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Pharm III Unit II > 8 Drugs in Pregnancy > Flashcards

8 Drugs in Pregnancy Flashcards

1
Q

What is the most important thing to remember about drugs in pregnancy?

A

No drug is 100% safe

Always assume fetal exposure

Weigh the risks vs benefits

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2
Q

Two main concerns when considering whether to give a pregnant woman a drug

A

Whether or not the drug is teratogenic

Whether or not the drug can affect the fetus near term

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3
Q

What is the definition of a teratogen?

A

An agent that causes birth defect/congenital malformation or abnormal development in an exposed embryo or fetus

They can be dose-dependent and selective for target organs, and my exert effects at specific times in development

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4
Q

Name that pregnancy category:

Adequate and well-controlled human studies demonstrate no risk

A

Category A

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5
Q

Name that pregnancy category:

Animal studies demonstrate no risk but no human studies have been performed

OR

Animal studies demonstrate a risk but human studies have demonstrated no risk

A

Category B

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6
Q

Name that pregnancy category:

Animal studies demonstrate a risk, but no human studies have been performed. Potential benefits may outweigh the risks

A

Category C

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7
Q

Name that pregnancy category:

Human studies demonstrate a risk. Potential benefits may outweigh the risks

A

Category D

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8
Q

Name that pregnancy category:

Animal or human studies demonstrate a risk. The risks outweigh the potential benefits

A

Category X

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9
Q

What were the old FDA labeling levels?

A

Pregnancy

Labor and Delivery

Nursing mothers

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10
Q

What are the new FDA labeling levels?

A
  1. 1 Pregnancy (includes L&D)
  2. 2 Lactation
  3. 3 Females and Males of Reproductive Potential
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11
Q

How is drug absorption different in pregnancy?

A

High circulating levels of progesterone SLOW GASTRIC EMPTYING and GUT MOTILITY —> slower drug absorption

Also, N/V! Avoid oral drugs when possible, esp in early pregnancy

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12
Q

How is drug metabolism different in pregnancy?

A

Hepatic drug metabolizing enzymes are induced during pregnancy —> rapid metabolic degradation of drugs, esp lipid soluble drugs

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13
Q

How is drug excretion different in pregnancy?

A

Renal plasma flow increased by 100% and GFR by 70% —> drugs that are eliminated by the kidney are eliminated more rapidly than non-pregnant women

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14
Q

How does the increase in total blood volume in pregnant women effect pharmacokinetics?

A

Change in CO, BP, and GFR —> changes in volume distribution of drug and metabolism, absorption, excretion, protein binding, and placenta passage

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15
Q

For practical purposes, assume that any drug taken during pregnancy will…

A

Cross the placenta and reach the fetus

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16
Q

Why do we assume that any drug can in theory cross the placenta?

A

Because it’s fundamentally an organ of exchange

Semipermeable barrier and site of metabolism (oxidative reaction)

Myriad of transporters allow for adequate exchange of nutrients between mother and fetus

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17
Q

Drugs that have crossed the placenta enter fetal circulation via the ________, and about _____% of the venous blood flow enters the fetal liver; the remainder enters general fetal circulation

A

Umbilical vein

40-60%

Basically there’s a constant flux of fetal exposure

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18
Q

______ drugs tend to diffuse rapidly across the placenta and enter fetal circulation

A

Lipophilic

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19
Q

Polar compound transfer is also dependent on…

A

Maternal-fetal concentration gradient

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20
Q

How does molecular size and pH affect placental exchange?

A

MW <500 Da cross the placenta easily, >1000 cross poorly

Non-ionized cross more easily than ionized

Ex: Warfarin vs Heparin

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21
Q

How do placental transporters affect pharmacokinetics?

A

MDR-1 (p-glycoproteins) pumps back into maternal circulation a variety of drugs (ie - cancer drugs vinblastine and doxorubicin; antiHIV protease inhibitors)

This can be a problem in HIV positive mothers - we WANT the fetus to be exposed to the antiretrovirals

22
Q

How does protein binding affect pharmacokinetics?

A

Degree of protein binding may affect the rate of transfer and amount of drug transferred, but other considerations (lipid solubility, placental blood flow, ionization) impact this rate

Maternal/fetal plasma protein binding affinities (sulfonamides)

23
Q

How do placental and fetal drug metabolism affect pharmacokinetics?

A

Placental barrier
Metabolic capacity of the placenta
Incomplete metabolism by fetal liver

24
Q

Conditions for which treating a pregnant mother may be worth the risk

A

Hypertension
Hyperglycemia
HYPOTHYROID** Must have thyroid for proper development

25
Q

Drugs that may have a beneficial effect in the fetus

A

Some that help avoid pre-term labor
Corticosteroids to mature lungs
Antivirals to prevent transmission of herpes or HIV
Drugs for fetal heart problems
Thyroid replacement therapy
FOLIC ACID to prevent neural tube defects

26
Q

What is the daily recommended amount of folic acid for all pregnant women to prevent development of neural tube defects?

A

400µg/day

27
Q

What are some examples of drugs NOT used in pregnancy

A

Those that damage or inhibit the synthesis of DNA and/or RNA (Actinomycin D)

Antimetabolites and other cancer treatments (rapidly proliferating cells affected the most)

Radiation: therapeutic or accidental, free radicals can damage enzymes

Thalidomide: folic acid antagonist

Isotretinoin: affects cell differentiation/proliferation

Hormones may alter development

28
Q

Treatment for threatened abortions in the 40s-70s that lead to healthy babies who then developed cancer in their twenties

A

Diethylstilbestrol (no longer on the market)

29
Q

What kind of cancer to children of women who took diethylstilbestrol during pregnancy get?

A

Adenocarcinoma of the vagina or cervix

Multiple abnormalities of the vagina, cervix, and uterus considering of vaginal and/or cervical ridges

30
Q

Leading PREVENTABLE cause of intellectual disability

A

Fetal Alcohol Syndrome

Dose response effect

No known safe level of alcohol use during pregnancy

31
Q

How does alcohol affect a fetus?

A

It diffuses through the placenta, with concentration in the fetal blood reaching the same as the mother’s blood within a few minutes

Amniotic sac acts as a reservoir for alcohol, prolongs exposure

The fetus is only able to metabolize alcohol 10% as fast as the mother - fetal liver does not have significant ALDH activity

Buildup of acetylaldehyde and ethanol decrease transfer of folic acid, amino acids, glucose, and other nutrients across the placental barrier

32
Q

What is the result of a pregnant woman taking Warfarin?

A

Vitamin K antagonist embryofetopathy

Multiple abnormalities:
• Saddle nose
• Depressed nasal bridge
• Epiphyseal stippling
• Vertebral calcifications
• Intellectual disability
• Short neck
• Fetal death
33
Q

Drug used as a sedative and to combat nausea in pregnant women —> multiple limb deformities

A

Thalidomide

34
Q

What exactly does thalidomide do to the fetus?

A

May damage DNA through oxidative stress —> multiple limb deformities

Has orphan drug status now - can only be used with strict control

35
Q

Medication used systematically for the treatment of acne —> teratogenic even with a single exposure in the first three weeks of pregnancy

A

Isotretinoin (retinoids)

36
Q

MOA for retinoids causing birth defects

A

Activate retinoic acid receptors that bind to specific DNA sequences and affect cellular differentiation and proliferation or induce apoptosis

37
Q

What types of birth defects do you see with Isotretinoin?

A 
Hydrocephaly
Microcephaly
Intellectual disability
Ear and eye abnormalities
Cleft lip and palate
Heart defects

Mother also has increased risk of miscarriage, premature delivery, and infant deaths

38
Q

What do women who want to take isotretinoin have to do?

A

Must enroll in the iPLEDGE program, have a negative pregnancy test and use two forms of birth control, one of which is surgical or hormonal starting ONE MONTH PRIOR and continuing one month after therapy

Might need to stay on BC longer - can still have birth defects if conception occurs 5 weeks after d/c

39
Q

Which drugs are among the most common teratogens prescribed to women of childbearing age

A

Anticonvulsants

Increasing use in treating disorders other than epilepsy (psychiatric disorders, pain management)

40
Q

Which anticonvulsants are “safest” in pregnancy?

A

Gabapentin
Clonazepam
LEVETIRACETAM
LAMOTRIGINE

They are Cat C but have the most abundant and consistent data for low structural and neurodevelopmental teratogenic risk

41
Q

Which anticonvulsants are considered Cat D and less safe than the “L drugs”?

A

Phenytoin
Phenobarbitone
Carbamazapine
Topiramate

42
Q

Which anticonvulsant is considered CatX and should NOT be used in pregnancy?

A

Valproate

Substantial risk for major congenital malformation, adverse neurodevelopmental consequences and autism/austism spectrum disorder

43
Q

What is Fetal hydantoin syndrome?

A

Due to exposure to phenytoin during pregnancy

Cleft lip/palate
Congenital heart disease
Slowed growth
Mental deficiency

44
Q

Fetal exposure to carbamazepine causes…

A

Craniofacial abnormalities
Developmental delay
Mental insufficiency

45
Q

Valproic acid in the first trimester is associated with…

A

Significantly increased risks of major and minor malformations, including a 20x increase in neural tube defects, cv abnormalities, genitourinary defects, developmental delay, endocrine disorders, limb defects, and autism

46
Q

Which drug did mom take?

Left upper limb, short left forearm, absent thumb, ulnar deviation at wrist, and contracture of fingers at PIP joint

A

Valproic acid

47
Q

Which drug did mom take?

Trigonocephaly, broad forehead, thin arched eyebrows, flat nasal bridge, thin upper lip

A

Valproic acid

48
Q

Drug used to treat HCV and RSV that poses the greatest risk of birth defects due to occupational exposure

A

Ribavirin

—> Malformations of skull, palate, eye, jaw, limbs, skeleton, and GI tract

Can also cause intrauterine fetal death

49
Q

A kid needs Ribavirin for his severe RSV infection. What do you need to do to mitigate risk for health staff

A

Can cause both male and female mediated teratogenicity so no healthcare workers of reproductive age can administer it

50
Q

What precautions are taken for patients who are taking ribavirin?

A

Females must receive pregnancy testing before starting, every month while being treated, and every month for the 6 months following d/c

Contraception requirements exist for both males and females of childbearing potential. Must use two forms of BC during treatment and for 6 months after d/c

Pharm III Unit II (8 decks)

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