Day 3: Jayakumar Geriatric PK Flashcards
What are the three categories that define the “elderly”?
- Chronological (how old they actually are)
- Change in social role (something like retiring)
- Change in capabilities (losing ability to drive, take care of themselves)
Do all people have the same rate of decline as they age?
No, the rates of decline and disease state manifestation differ greatly between individuals
What is an elderly patients functional age depend on?
- Environment
- Physical abilities
- Cognition
- Comorbid conditions
What happens to geriatric patients in terms of body composition?
Total body water decrease
Lean body mass decreases
Albumin levels fall
Body fat will increase
What happens to the CNS as geriatric patients age?
Brain parenchyma size
Loss in cognition
What happens to the cardiovascular system as people age?
Baroreceptor activity starts to fall
Cardiac output drops
SA/AV node conduction time takes long with lowers heart rate
**these changes can cause older people to get dizzy and increase risk of falling
What happens to the liver of patients when they age?
Hepatic blood flow decreases
Liver parenchyma size (liver gets smaller)
What happens to GI of patients as they age?
Absorption decreases
Has delayed gastric emptying
Gastric PH changes (increases)
What happens to renal function as people age?
GFR decreases
Renal blood flow decrease
Renal mass decreases
Tubular secretion
How many areas of PK does aging effect?
ALL OF THEM!
ADME
How is active transport effected as people age?
Part of Absorption
It gets reduced
Things like Vit B12, Iron, Calcium
How is transdermal absorption effected for elderly?
Changes int eh skin DECREASE absorption
You get reduced tissue blood perfusion and its not as well hydrated
How is IM absorption for people as they age?
It becomes reduced and erratic
They lose muscle mass and its not as well vascularized and should be avoided in elderly if possible
How is the distribution of hydrophilic medications in older patients?
They have a decreased Vd, since they have more fat it means the drug will stay in the plasma and and cause an increase in dose
EX of drugs:
Gentamicin
Digoxin
Ethanol
What happens with the distribution of lipophilic medications in geriatric patients?
They have an increased Vd, since they have more fat it will deposit itself in there
That means you have a prolonged duration of drug effect
Ex of drugs:
Propofol
Diazepam
Chlordiazepoxide
How are phase I and phase II metabolism effected as we age?
Phase I metabolism (cytochrome P450 oxidative) decreases which means it increases T1/2 and will increase drug concentrations
Phase II metabolism (conjugation) is largely unaffected
How is the metabolism of pro-drugs effected in geriatric patients?
They will have a decrease in first pass activation
This means slowed of decreased activation and lower plasma concentrations of the drug
How is excretion effected in geriatric patients in terms of renal function and GFR?
They have a decrease in renal function (nephron atrophy and hypoplasia)
They have a decrease in GFR (reduced renal blood flow and decreased filtration)
**this is important because most drugs and/or metabolites are eliminated really
What is a problem with geriatric patients and their CrCl and what is done to try and fix this?
Since older people have muscle atrophy they hav less creatinine produced
This leads us to have to compensate for muscle mass by if Scr is less than 0.8 or 1 we will round it up to earthier 0.8 or 1 mg/dL
This can be an issue because compensation can lead to UNDERESTIMATING true clearance and thus UNDERDOSING medications
What happens with the kinetic parameter with absorption and the parts associated with it as well as the clinical significance of it?
Absorption : Unchanged
Gastric pH : increases
Secretory capacity : Decreased
GI blood flow : diminished
Clinical significance is little to none
What happens with the kinetic parameter with distribution and the parts associated with it as well as the clinical significance of it?
Distribution : diminished
Plasma albumin : diminished
Protein affinity : decreased
Clinical significance : Moderate
What happens with the kinetic parameter with metabolism and the parts associated with it as well as the clinical significance of it?
Size of liver : decreased
Hepatic blood flow : decreased
Clinical significance : minor
What happens with the kinetic parameter with renal function and the parts associated with it as well as the clinical significance of it?
GFR : decreased
Renal plasma flow : decreased
Clinical significance : major
What are the pharmacodynamic changes that happen to geriatric patients?
Aging may result in altered drug response (drug sensitivity)
What are the 4 mechanisms that can use pharmacodynamic alterations?
- Changes in receptor numbers
- Changes in receptor affinity
- Post-receptor alterations in response (what happens when it binds)
- Attenuation of homeostatic mechanics
***depending on the med you can have an increase or decrease in sensitivity
What are the most common medications that will lead to hospitalization of geriatric patients?
Insulin : 44%
Warfarin : 33%
Antiplatlet : 13%
Oral hypoglycemic agents : 11%
What are the Beer’s Criteria?
It’s a reference for clinicians about the Risk of PIMS (potentially inappropriate medication) used in older adults
**goal is to reduce unnecessary exposure to PIMS
What are some drugs to know that are on AGS Beer’s criteria?
Anticholinerics ( 1st gen antihistamine)
Antipsychotics
Meperidine
Benzodiazepines
Estrogens
Sulfonylureas
Insulin
NSAIDS
Muscle Relaxants
Digoxin
What s the STOPP/Start criteria
It’s a screening tool for older people for prescriptions (STOPP) and a screen tool to alert to right treatment (START)
**alternative to Beers
What is OBRA90?
It required that a pharmacist review medications on a monthly basis for patients in a long-term care facility
**good because it evaluates if a pt actually needs the meds that they are on and looks for ways to optimize the treatment of the pt
What is the FDA Modernization Act of 1997?
FDA added geriatric use section to special population section of drug labeling/package inserts
** in the hand outs given to a pt they now they need include information pertaining to geriatric specific considerations
