Ch18: Pharmacology Flashcards
what changes with aging: pharmacodynamics or pharmacokinetics
pharmacokinetics = metabolism, distribution, elimination, absorption
pharmacodynamics knows no age
(4) examples of HIGHLY protein-bound drugs, thus need lower dose in context of aging and low plasma protein
- warfarin (99% bound)
- phenytoin
- valproic acid (Depakote)
- diazepam (Valium)
(4) examples of HIGHLY protein-bound drugs, thus need lower dose in context of aging and low plasma protein
- warfarin (99% bound)
- phenytoin
- valproic acid (Depakote)
- diazepam (Valium)
when compared with a healthy 40-yo adult, CYP450 isoenzyme levels can drop by up to _____% in elders after age 70yo
30%
risks of anticholinergic medications in elderly (5)
- confusion
- urinary retention
- constipation
- visual disturbances
- hypotension
1st-generation antihistamines widely known not to use with older adults (Beers Criteria) d/t systemic anticholinergic effects and reduced clearance (5)
- diphenhydramine (Benadryl)
- chlorpheniramine (Chlor-Trimeton)
- hydroxyzine (Atarax)
- promethazine (Phenergan)
- cyproheptadine (Periactin)
worst OAB medication that has the most systemic anticholinergic side effects
oxybutynin (Ditropan)
if you HAVE to use this for the treatment of OAB, the sustained release is generally better tolerated than the immediate release
be aware that this now comes OTC as “Oxytrol for Women”
discuss which (2) SSRIs are not a good choice for elderly, and which (3) are
BAD CHOICE:
- paroxetine (Paxil), has the most anticholinergic effects and is also the most sedating
- fluoxetine (Prozac) has only a small amount of anticholinergic effects, but is the LONGEST half-life, thus sticks around forever in older adult
GOOD CHOICES: - citalopram (Celexa) - escitalopram (Lexapro) - sertraline (Zoloft) ^^ all of these have NO systemic anticholinergic effects :)
discuss why TCAs are not a good choice for elderly, and which (1) one has the least side effects
most TCAs have very strong anticholinergic effects, sedating, cause hypotension. This is strongest with amitriptyline and nortriptyline
the only one that does not have systemic anticholinergic effects is trazodone, but is still very sedating.
[women vs. men] tend to have higher risk of arrhythmias/ QT prolongation / torsades de pointes with macrolide antibiotics (erythromycin, clarithromycin, azithromycin)
women
never exceed ____mgs per day (adults & elderly) of this SSRI d/t risk for QT prolongation
40mg of citalopram (Celexa)
do not exceed 20mg in elders >60yo
which SSRI has risk of QT prolongation
citalopram (Celexa)
higher risk of QT prolongation in someone taking citalopram (SSRI) and these GI medication….
PPIs (all)
cimetidine (Tagamet), an H2 blocker, but ranitidine and famotidine do NOT have this risk!! better choices
does escitalopram have risk for QT prolongation?
No :)
safer than citalopram in this regard
prescribing principle: drugs with a [shorter vs. longer] half life tend to be better choices for elderly adults
shorter half-life = better choice
elderly adults tend to have reduced metabolism and clearance of drugs, thus the effects hang around longer
which CYP450 isoenzyme is the most important
3A4
why is sliding-scale insulin a bad idea?
- treats hyperglycemia AFTER it has already occurred, instead of preventing it in the first place
- “reactive” approach that can lead to rapid changes in blood sugar levels exacerbating BOTH hyper and hypoglycemia
- instead, one should adjust meal-time insulins, correction insulin is ok during temporary illness
1 unit of rapid-acting insulin lowers blood glucose by about…
50mg/dL
priority risk of aspirin in elderly
GI bleeding
even for secondary prevention, there is little evidence to support aspirin for a patient older than….
> 85yo
better alternative to chronic prophylactic antibiotics for chronic UTI in elderly woman
topical estrogen
estradiol topical <25mcg 2x weekly
AACE/ADA recommended A1c goal for those who are frail or have limited life expectancy
<8%
risks of hypoglycemia outweigh the benefits of stringent glycemic control
as we age, we have less ____ receptor sites rendering drugs that act at these sites less effective
beta receptors
less efficacy of SABAs (e.g., albuterol) and beta blockers
alternative choices = inhaled antimuscarinics (SAMAs, LAMAs) and calcium channel blockers
should statins be started or continued in elderly adults?
CONTROVERSIAL
- HIGH intensity statins should be avoided for folks at high risk of AEs, including: \+ age 80yo or older \+ impaired renal function \+ frailty \+ multiple comorbidities \+ also taking a fibrate
– MODERATE intensity statins are preferred for those at high risk for AEs
- USPSTF: in adults 76yo and older with no history of ASCVD there is insufficient evidence to assess benefits/risk to initiating statins for primary prevention (even in the presence of high LDL, just no h/o ASCVD)
- CONTINUATION: remains a benefit for someone who has established ASCVD after 85yo. And for those who are at high risk but havent had a cardiac event, e.g., T2DM
once someone has been on a PPI for >_____, 60-90% will develop rebound hypersecretion when they try to come off
> 2 months (8 weeks)
consider tapering the medication with reducing the dose, followed by every other day use, swapping in a H2 blocker BID and antacid PRN
consequences of long-term PPI use
- potential decrease in the absorption of select micronutrients requiring an acidic stomach environment = IRON, B12
- increased risk of fracture likely d/t decreased calcium absorption
- hypomagnesemia
of all the calcium supplements, which is best absorbed in a low-acid GI environment (e.g., someone on PPI therapy)
calcium CITRATE
Beer’s criteria perspective on PPI use
avoid scheduled use for >8 weeks in elderly adults unless they are high risk
HIGH RISK:
- oral steroid use
- chronic NSAID use
- erosive esophagitis
- Barrett’s esophagitis
- pathologic hypersecretory condition
- demonstrated need for maintenance treatment (e.g., failed H2 blockers and antacids)
why is TMP-SMX not a great choice antibiotic for older adults
can cause hyperkalemia
this is because the drug is structurally similar to potassium-sparing diuretics
inhibits potassium secretion at the distal tubule of the kidneys
priority risk: ACEI/ARBs plus TMP-SMX
hyperkalemia
priority risk: spironolactone plus TMP-SMX
hyperkalemia
what would be the benefit of taking an ACEI or ARB in the morning in someone who is borderline hyperkalemia and taking their BP meds at night?
taking in the morning allows for overnight excretion of renal potassium, in order to avoid hyperkalemia
