MODULE 7
Pharmacotherapy during Pregnancy
Quick facts:
Teras = Greek word meaning “monster”
Teratogenesis = “to produce a monster”
Teratogens – adverse affects in pregnancy
Effects structural formation in fetal tissue
Effects organ function in fetal tissue
Causes fetal demise
2 individuals of concern:
1) Pregnant women
2) Fetus
Fetal-placental barrier – not effective, many drug molecules can cross and cause harm
to fetus
Adverse effects in pregnant women – causes harm to fetus
Ex: on antihypertensive, dose was too large BP ↓ dramatically ↓ tissue
perfusion fetus experiences same effects
Stages of Fetal Development
3 stages:
1) Preimplantation period – 1-2 weeks of pregnancy before implantation, “all or
none” period, women don’t know they are pregnant at this time
Exposure to teratogen at this stage:
o Death
o No effect at all
2) Embryonic period – 3-8 weeks, point of maximum sensitivity, all structures
are being developed
Exposure to teratogen at this stage:
o Structural abnormalities
3) Fetal period - 9-40 weeks or until birth
Exposure to teratogen at this stage:
o Effects organ functions
Drug Use during Pregnancy
3 reasons:
1) Treatment of pre-existing illness – more women are waiting until older age to
have children
Chronic disease may develop as age progresses – DM, HTN, etc.
Evaluate each risk of classification of drug
o Drug/dose can be changed during pregnancy to ↓ risk
2) Treatment of complications related to pregnancy
, Develops chronic disease during pregnancy – gestational DM, HTN, etc.
3) Treatment of conditions unrelated to pregnancy
Develops infection during pregnancy
Nurse’s role – main consideration to determine which drug to prescribe – think about pt
condition w/ perspective to how it effects the fetus
Pregnancy test – consider any women of child bearing age to potentially be pregnant
when/if admin drug that is highly teratogenic
Pharmacokinetics during Pregnancy
Absorption – due to hormonal changes
↓ GI motility – affects absorption in GI
↓ gastric emptying – affects absorption in GI
↑ HCl production – affects absorption of drugs that are acidic/base
Nausea/vomiting – affects whether or not PO drugs can be kept down
Distribution – total body water ↑ by 50% to help perfuse fetal tissue hemodilution of
protein stores highly protein bound drugs needs to be adjusted
↑ HR ↑ perfusion to fetus
Metabolism – as fetal tissue grows CYP450 enzyme system starts to work fetal tissues
metabolize drug molecules subtherapeutic levels adjust dose
Excretion – potential effects of teratogenic become more concentrated caused by ↑ BF to fetus
Pregnancy Categories – categorizes risk category of many types of drugs that are administered
to an adult pt
5 categories:
1) A – encouraged to take these drugs during pregnancy
2) B – safe in 1st and 2nd trimester
3) C - ↑ risk during pregnancy
4) D – effects organ function, almost never used in pregnancy BUT benefits
could outweigh risks
5) X – absolutely not given during pregnancy
Pharmacotherapy of Pediatric Patient
Quick facts:
Same drugs given to adults are given to children DOSE IS SMALLER
Majority of drugs given to peds pt:
Respiratory drugs
Antibiotics
Behavioral drugs
Dose of drug is calculated by pt’s weight in kg
Pharmacokinetics of Pediatric Patient
Birth to 3-5 yr – differences present due to immature systems
3-5 yr+ - pharmacokinetics same as adult
Absorption:
, GI:
↑ stomach pH not enough HCl
↓ gastric motility, emptying, peristalsis
Tissue:
not enough BF to those areas
IM/SQ absorbed much more slowly
Skin:
↑ permeability very few layers lotions or topical can be highly toxic
Distribution:
has more water dilute many protein stores
has more fate
Liver:
less protein production ↓ chance of protein binding , ↑ chance of toxicity
Blood-brain barrier:
not mature some drug molecules can cross
Metabolism:
hepatocytes and CYP450 system not mature until age 3-5
slower metabolism
↑ risk for toxicity due to half life of drug being so high
Excretion:
kidneys and nephrons not mature
excretion of drug is limited ↑ risk of toxicity
Pediatric Considerations: Medication Administration – actual admin is determined by age
infants
toddlers
preschoolers
school-age
adolescents
Medication Safety in Pediatric Patient
Drug dosages – dramatically lower than adults, weight based
Adverse reactions – nonverbal, behaviors, crying, grimacing
Adherence – dependent on caregivers some unfortunately does not consider child’s
needs before their own
Pharmacotherapy of Geriatric Patient
Quick facts:
Polypharmacy – biggest concern
drug-drug interactions
getting multiple prescriptions filled at different pharmacy
Physiological changes – effects pharmacokinetics
Pharmacotherapy – lower dose, ↓ frequency, “start low and go slow”