Exam 2: Prescribing Considerations for Special Populations

What are the risks of birth defects from drug medication?

3-5% of live births born with birth defects

2-3% estimated to be related to drugs

What are the drug-related adverse fetal effects?

Teratogenic --> physical, anatomical defects

Fetotoxicity --> injury, biochemically there is injuries - like fetal alcohol system or drug dependent

Late 1st trimester to birth

Ex: NSAID's --> renal dysfunction

What meds can pregnant women take?

OTC, herbal, and Rx drugs

What is the timing of teratogenic effects?

Weeks 1-2 higher likelihood of “all or nothing” effects --> if an effect, pregnancy is natural terminated

Weeks 2 - 8 structural organ abnormalities due to medications

Week 8 retardation/delay of growth and CNS abnormalities

Greatest risk 5-10 weeks

What were the effects of thalidomide during pregnancy?

used to help with morning sickness, but very damaging

anatomically there were teratogenic effects - affects limbs

"Rebirth" as FDA approved drug and used for --> multiple myeloma and cutaneous leprosy lesions

How are drugs absorbed in the placenta in pregancy?

Placenta is organ of exchange

placenta gives at least 50-100% of drug or other things from mom to fetus

What are the FDA Fetal Risk Categories?

A-D, X

What do the FDA Fetal Risk Categories regulate?

1. Potential of systemic drug to cause birth defects

2. Reliability and documentation

- Lack of human studies

- Difficulty extrapolating animal studies to potential human effects

3. Categories based on risk and benefit

Describe Class A of FDA Fetal Risk Categories

considered safe

studies in women fail to document fetal risk

<1%

Describe Class B of FDA Fetal Risk Categories

considered safe

studies confirming animal studies without fetal risk or animal studies showing fetal risk not confirmed in human studies

Describe Class C of FDA Fetal Risk Categories

benefits must outweigh risks

studies in women and animals lacking or shown fetal risk... we think it will be okay but not 100%

most are B and C drugs

Describe Class D of FDA Fetal Risk Categories

studies with evidence of human fetal risk

avoid unless benefit warrants drug use in serious medical situations

Describe Class X of FDA Fetal Risk Categories

Studies with evidence of serious fetal risk in animals/humans

Contraindicated as fetal risk outweighs maternal benefits

Why can the FDA classification be problematic?

outdated

ambiguous data

lack guidance

categories reflect risks, benefits to mom, toxicity

What should we consider when prescribing during pregnancy?

1. Expected benefits exceed risks

2. Special caution in 1st trimester

3. Lowest therapeutic doses

4. Shortest duration of therapy

5. Avoid newly introduced drugs

How do drugs get into the breast milk?

cross placenta and excreted to some extent to the breast milk

What factors contribute to a drug crossing into breast milk?

highly lipid soluble

low protein binding

What should you recommend when prescribing during nursing?

1. Recommend minimizing infant exposure -->

- Timing of feeding vs drug ingestion

- Consider pump-and-save then pump-and-discard strategy

2. adjust dosing

3. recognize potential effects on infant and explain to patient

What is the FDA's guidelines for nursing?

guidlines lacking

if safe for fetus, then safe for breast feeding

lower drug in breast milk and less exposure time

What is the CYP system like in children? toddler to puberty?

underdeveloped

elevated metabolism from toddler until puberty

When does metabolism approach adult function?

during teenage years metabolism approaches adult function

When does renal function (elimination) become comparable to adults?

6-12 months

What form of drug should a child be prescribed?

liquid or chewable tablet

What is the dosing of children like?

dose by weight

What should be considered regarding compliance for children?

drug is administered by parent

bad taste

What is true of drug absorption in elderly patients?

GI pH is higher as patients age

Digestion tends to be slower

Some may have

difficulty swallowing

What is true of the p450 enzyme in elderly patients?

drug metabolism is decreased by this enzyme

this affects phase 1 metabolism

What is the compliance of meds like in adults?

may not comply due to money or memory