Pregnancy and Lactation Flashcards
(47 cards)
Counseling tips for lactating women include
Eat a balanced diet
Take prenatal vitamins (do not take if not specified for pregnant women!)
Intake should be no more than 0-1 cups of coffee, tea, or caffeinated beverage daily
Avoid raw meat (listeria) or fish with high mercury levels
Eat plenty of fruits and veggies, wash before eating!
What pharmacokinetics change with pregnancy (specifics)
- Maternal plasma volume increases
- Cardiac output increases
- Glomerular filtration increases (drug excretion decreases)
- Body fat increases (VoD increases)
- Plasma albumin decreases (VoD increases; unbound drugs cleared faster)
- Hepatic perfusion increases
- Delayed gastric emptying (N/V)
- Gastric pH increases
- Estrogen and progesterone increase
Overall, PK changes in pregnancy lead to
Increased volume of distribution
**Increased clearance
decreased protein binding
shorten or lengthen elimination half life
What factors affect movement of drug from maternal to fetal circulation
Lipophilicity protein binding molecular weight drug pKa placental CYP450
Highly lipophilic drugs…
more easily cross the placental barrier to enter fetal circulation
What conditions must be present to allow hydrophilic drugs (like lithium) to cross the placental barrier
Protein binding low enough
Molecular weight low enough
Highly protein bound drugs have a
lower free fraction available to diffuse into fetal circulation (AKA less crosses over)
-UNLESS you keep levels of the drug high enough, in which it may cross over solely due to the amount of drug present
How do least and most maternally protein bound drugs differ
Least protein bound reach higher concentrations in fetus than highly protein bound drugs
If a drug is more highly bound in the fetus rather than maternal, it will concentrate on
the fetal side
What happens to albumin in mom and baby
Lowers in mom but increases in baby!
But as pregnancy progresses, the ratio may change despite consistent maternal dosing
How does molecular weight affect drug movement
Low molecular weights (<500 Da) easily cross the placenta Larger molecules (600-1000 Da) cross more slowly >1000 Da do NOT cross the placental barrier
How do fetal and maternal pH compare
Fetal pH is slightly lower (7.3) than maternal pH (7.4)
So, some degree of ion trapping can concentrate drugs on the fetal side
What is pKa
a measure of acid strength
What were we made aware that the fetal CYP450 system does
Placenta converts prednisolone to the INactive prednisone
So, prednisolone can be used in pregnant patients without the risk of fetal exposure to an active corticosteroid!
Can anesthesia and analgesia drugs be used in pregnancy?
Not usually; they cross the placental barrier well and fetal effects can be noted at birth (respiratory depression 2/2 mom on narcotics)
Why do we get baby out ASAP after C-Section
because mom is given analgesics and anesthetics! We dont want to harm baby
Fetal CYP450 appears when
as early as 14 weeks, and increases throughout pregnancy
Glucuronidation is immature until
near or after birth
So, fetus can metabolize drugs that cross the placenta, and toxic agents can be found in the fetus
These anti-HTN are believed to be safe during pregnancy
CCB, Nifedipine Beta blockers Methyldopa Hydralazine CCB Magnesium Sulfate (IV infusion as inpatient)
These anti-HTN are contraindicated in pregnancy
ACE
ARB
-can both lead to fetal renal failure
These antibiotics are safe in pregnancy
Nitrofurantoin (macrobid, macrodantin)
Penicillins, cephalosporins
These antibiotics are NOT safe in pregnancy
Sulfonamides (displace bilirubin from albumin and enhance kernicterus
These antiemetics are safe in pregnancy
Promethazine (phenergan)
Ondansetron (zofran) if unrefractory
Vitamin B6!
A side effect of antiemetics in pregnancy are
Phenergan: anticholinergic, acute dystonia, akathisia
Zofran: headache
