Module 8 - Special Populations Flashcards
Special populations include
- Pregnancy and lactation
- paediatrics
- geriatrics
drugs that are least likely to pass through fetal-placental barrier
- water soluble
- ionized
- bound to plasma proteins (molecules too large)
effects of increased levels of progestins?
- delayed gastric emptying (give more time for absorption to occur)
- increased volume of breath and causes pulmonary vasodilation (higher absorption of inhaled anesthetics only)
changes during pregnancy that affect Absorption
- the blood supply to organs responsible for absorption may change
- increased levels of progestins
- Gastric acidity reduced (affecting ionization of drug)
Changes during pregnancy affecting distribution
- Increased Blood volume can dilute drugs and decrease plasma protein concentrations
- blood flow to uterus and kidneys is increased resulting in higher distribution
- blood flow to skeletal muscle is decreased resulting in lower distribution
- altered lipid levels alter transport and distribution of drugs.
Changes during pregnancy affecting metabolism
Drug metabolism can be increased (drugs become inactive faster) and decreased (drugs become inactive slower) depending on specific CYP450 enzymes.
Changes during pregnancy affecting elimination / excretion
- blood Flow to kidneys increases significantly as pregnancy progresses
- directly increases glomerular filtration rate (GFR) and therefore elimination of MOST drugs is increased (may not be clinically significant)
Considerations: pharmacotherapy during pregnancy
- what is the effect of the CONDITION on the pregnancy? - danger to baby?
- what is the effect of the PREGNANCY on the condition? - Danger to mother?
Def: Teratogens
A substance, organism, or physical agent to which an embryo or fetus is exposed that produces a permanent abnormality on structure or function, causes growth retardation, or results in death.
- extent of significance is very dependent on timing during pregnancy
Examples of teratogens
ACE-I
Statins
Lithium
Some anticonvulsants, antibiotics, etc
- NEVER rely on memory to determine teratogenicity of drug ALWAYS look it up!
FDA pregnancy categories
A - studied in pregnant women and proven to be safe
B - animal studies revealed no harm, BUT no human trial available. OR animal studies showed harm BUT human trials revealed no harm
C - Animal studies revealed har AND no human tails available OR No animal or human studies
D - Studies have revealed harm to fetus but benefits of therapy may outweigh risks in some women
X - studies have confirmed harm and product is contraindicated in pregnancy
Guidlines for pharmacotherapy During Lactation
- administer drug immediately after last feeding to ensure lowest possible levels at next feeding
- Administer drug before longest period between feedings (overnight)
- preference of short half-life drugs with high-protein binding
- consider whether drug is safe to use in infants
- advise pt to check on safety of the drug every time
- avoid natural health product due to lack of reliable information
Drugs that can decrease Milk Production
antihistamines sedating medications some decongestants weight loss medications diuretics high doses of Vitamin B6 Estrogen Nicotine Ergot Alkaloids (for migraines)
MOA: Domperidone
a dopamine antagonist - also increases prolactin levels (indirectly) - off-level used to increase breast milk production
lactation feedback system uses positive feedback - the act of breastfeeding releases more prolactin, which causes more milk production
Adverse effects: Doperidone
Headache, cramping, diarrhea, dry mouth, irregular menstrual bleeding; very small amount passes into breast milk.